We are Developing

How are you

GSM OverviewGSM Overview

Contents Chapter 1 Introduction

Chapter 2 Basic GSM Network Structure

Chapter 3 Radio Coverage

Chapter 4 Radio Transmission Problems

Chapter 5 Air interface

Chapter 6 Traffic Cases

Chapter 7 GSM Services

Banner Advertisement America 1929

Chapter 1 Introduction

Mobile Technology Evolution

Speech1G

GSM13 kbps

HSCSD576 kbps

Circuit Switched

GPRS115 kbps

Packet Switched

EDGE384 kbps

Time

Mobile Technology EvolutionMobile Technology Evolution

WCDMA(UMTS)2 Mbps

HSDPA36 Mbps

HSUPA576 Mbps

Circuit Switching Packet Switching

2G

275G

225G

25G

3G

35G

375G

1G

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Contents Chapter 1 Introduction

Chapter 2 Basic GSM Network Structure

Chapter 3 Radio Coverage

Chapter 4 Radio Transmission Problems

Chapter 5 Air interface

Chapter 6 Traffic Cases

Chapter 7 GSM Services

Banner Advertisement America 1929

Chapter 1 Introduction

Mobile Technology Evolution

Speech1G

GSM13 kbps

HSCSD576 kbps

Circuit Switched

GPRS115 kbps

Packet Switched

EDGE384 kbps

Time

Mobile Technology EvolutionMobile Technology Evolution

WCDMA(UMTS)2 Mbps

HSDPA36 Mbps

HSUPA576 Mbps

Circuit Switching Packet Switching

2G

275G

225G

25G

3G

35G

375G

1G

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Banner Advertisement America 1929

Chapter 1 Introduction

Mobile Technology Evolution

Speech1G

GSM13 kbps

HSCSD576 kbps

Circuit Switched

GPRS115 kbps

Packet Switched

EDGE384 kbps

Time

Mobile Technology EvolutionMobile Technology Evolution

WCDMA(UMTS)2 Mbps

HSDPA36 Mbps

HSUPA576 Mbps

Circuit Switching Packet Switching

2G

275G

225G

25G

3G

35G

375G

1G

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Mobile Technology Evolution

Speech1G

GSM13 kbps

HSCSD576 kbps

Circuit Switched

GPRS115 kbps

Packet Switched

EDGE384 kbps

Time

Mobile Technology EvolutionMobile Technology Evolution

WCDMA(UMTS)2 Mbps

HSDPA36 Mbps

HSUPA576 Mbps

Circuit Switching Packet Switching

2G

275G

225G

25G

3G

35G

375G

1G

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Speech1G

GSM13 kbps

HSCSD576 kbps

Circuit Switched

GPRS115 kbps

Packet Switched

EDGE384 kbps

Time

Mobile Technology EvolutionMobile Technology Evolution

WCDMA(UMTS)2 Mbps

HSDPA36 Mbps

HSUPA576 Mbps

Circuit Switching Packet Switching

2G

275G

225G

25G

3G

35G

375G

1G

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

History of Mobile Communications

1980ndash1985

The first generation of modern cellular mobile networks put into service But it was all based on analog system(1G)

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

History of Mobile Communications

-Due to the projected growth in mobile telecommunications the European PTTs in 1982 decided to develop a Pan-European mobile system using digital technology

-This system is known as GSM a Global System for Mobile Communications

-The first commercial GSM network was launched in June 1992 in Germany International roaming was the important feature for subscribers

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

History of Mobile Communications

-However GSM is not just restricted to Europe Today GSM is available in over 130 countries around the world with more than 200 million subscribers

-Three different frequency bands are available for use by GSM systems GSM 900 1800 and 1900 MHz GSM 18001900 is intended for use in areas of high subscriber density

-Other digital mobile standards include D-AMPS in the US and PDC in Japan

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

History of Mobile Communications

-Universal Mobile Telecommunications System (UMTS) is one of the major new third-generation (3G) mobile systems in development

-UMTS will extend the capability of todayrsquos mobile (inc GSM) cordless and satellite technologies by providing increased capacity (up to 2 Mbs) and a greater range of services including multimedia

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Analog to Digital

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Analog to Digital (1G to 2G)

bullThe main restrictions of analog mobile systems are the limited capacity voice-only services and high operational costdifferent systems are incompatible in terms of equipment and operation eg NMT and TACS

bullWith digital systems such as GSM the available frequency spectrum is used more efficiently leading to increased capacity and reductions in associated costs for network operators equipment suppliers and subscribers

bullAnalog mobile systems were originally designed for voice However digital mobile systems can support voice data and a range of additional services such as a short message service and call forwarding (Call Divert)

bullAnalog mobile systems offered limited international roaming and a low level of security GSM on the other hand offers few restrictions on international roaming and provides advanced security using ciphering and authentication

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Why Wireless

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Why Wireless

source DestinationTransmission medium

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Why Wireless

The kinds of transmission medium

1- Twisted-pair It is very low bandwidth and it is easily tapped either physically or by monitoring its electromagnetic radiation 2- Coaxial cable It is greater bandwidth than twisted-pair but it is very expensive

3- optical fibers It is very high bandwidth very high bit rate

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Why Wireless

4 -Radio (wireless)

It is greatly depending on the particular frequency of the electromagnetic wave

Some of their advantages

a- They are very flexible

b- Portable system can be installed very quicklyc- There are often the most cost-effective solution

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Types of communication

TX RX

TX+RX TX +RX

TX+RX TX +RX

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Multiple-access for Digital Communication Systems

The frequency spectrum must be shared by all the users in the system

Three method for sharing spectrum

FDMA

Frequency-division multiple-access

TDMA

Time-division multiple-access

CDMA

Code-division multiple-access

Most modern systems use combinations

TDMAFDMA

CDMAFDMA

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Multiple-Access

Three ways to separate signals

1 -Frequency

2 -Time

3 -Code

Frequency

Time

Code

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

FDMA

-Frequency-division multiple-access

-Each user is assigned one frequency

frequency

Channel 1 32 4

30 kHzguardband

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

FDMA

Frequency-Division Multiple-Access

ExamplesAMPSFrequency

Time

Code

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

TDMA

Time-division multiple-access

All users transmit at same frequency

Each user transmits at a different time

User 1

User 2

User 3

User 1

User 2

User 3guardtime

20 msectime slot

time

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

TDMA

Frequency

Time

Code

Time-Division Multiple-Access

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

CDMA

Frequency

Time

Code

Code-Division Multiple-AccessExamplesIS-95Bluetooth

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Notes UL uplink (Mobile to BTS) helliphelliphelliphelliphellip DL Downlink (BTS to Mobile)

Overcoming Fading problems by using high sensitive receivers in the mobiles

When Making a call given a freq amp a time slot (discrete call)

Freq Hopping ( used by Military )

Doppler Shift used in speed detection (^f)

Power Measurement is made by the mobile to determine its location from the BTS

The size of a cell is limited to a maximum radius of 35 Km

High-Speed Uplink Packet Access (HSUPA) (375 G) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 576 Mbits

High-Speed Uplink Packet Access (HSUPA) (375 G)

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Chapter 2 Basic GSM Network Structure

We hear Music But we donrsquot see the musicians

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Basic GSM Nodes

AUC Authentication CenterBGW Billing GateWayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationDTI Data Transmission InterworkingEIR Equipment Identity RegisterGMSC Gateway MSCHLR Home Location RegisterISDN Integrated Services Digital NetworkMS Mobile StationMSC Mobile services Switching CenterPLMN Public Land Mobile NetworkPSTN Public Switched Telephony NetworkSMSC Short Message Service CenterSS Switching SubsystemTRC Transcoder Resources ControllerVLR Visitor Location Register

SSSS

D T I

BTSBTS

ISDN

PLMN

PSTN

ISDNISDN

PLMNPLMN

PSTN

SMSC

B G WH L R

E I R

GWMSCGMSC

MSCVLRMSCVLR

MS

Air If

BSCTRCBSCTRC

BSSBSS

AUC

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Administers its Base Station Controller(s) BSC(s)

Call setup routing amp supervision for mobile subscribers Contributes to the short messages transfer tofrom mobile

subscribers

Records charging and accounting data

GSM Overview

Basic GSM Network Structure

Mobile Services Switching Center (MSC)

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

HLR (home location register)The HLR is a centralized network database that stores and manages all mobile subscriptionsPermanent information

bull IMSI MSISDN

bull Services subscribed

bull Service restrictions (eg roaming restrictions)

bull Parameters for additional services

bull info about user equipment (IMEI)

bull Authentication data

Temporary information 1048790

Link to current location of the user

bull Current VLR address (if avail)

bull1048790Current MSC address (if avail)

bull1048790MSRN (if user outside PLMN)

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

VLR (visitor location register)

MSCVLR

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Equipment Identity Register (EIR)

Database that validates Mobile Equipments usage It contains White list

for normal handsets Gray list for faulty or non-type approved handsets amp

Black list for stolen handsets

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Short Message Service Center (SMSC)

Receives and stores short messages from mobile subscribers

Forwards short messages to mobile subscribers

If the delivery of short messages fails (due to mobile absent or full

memory condition) it starts a retry schedule to deliver the message

Generates charging data for the short messages delivered

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Manages the Radio Communication with the mobile stations over the air interface

Controls the locating algorithm and handovers between the BTSs Supervises the transport network resources and the operation amp maintenance of each BTS

GSM Overview

Basic GSM Network Structure

Base Station Controller (BSC)

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

FUNCTION OF BSC

bullPaging

bullChannel allocation

bullDynamic power control in MS and BTS

bullLocating the MS

bullHandover

bullFrequency Hopping

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Transcoder Resources Controller (TRC)

Provides the transcoding functionality for speech calls and rate adaptation for data calls

It can be integrated with the BSC or a standalone node It can provide the transcoding resources for up to 16 BSC

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Base Transceiver Station (BTS)

Consists of the radio transmitters receivers and the antenna system required to provide the coverage area for one cell

Converts the GSM radio signals into a format that can be recognized by the BSC

Records and passes to the BSC the periodic power measurement reports

Performs the network end function for the cipheringencryption process

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

The SIM Card contains

A processor and memory

that stores - The international mobile subscriber Identity IMSI

- The Authentication and ciphering keys

The Mobile Equipment is said to be a Mobile Station if the Subscriber Identity Module ( SIM Card ) is added to it

+GSM Overview

Basic GSM Network Structure

Mobile Station (MS)=

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Sim cardStores user addresses

IMSIMSISDNTIMSI rooming etc

Personalization

SIM stores user profile (subscribed services)

RAM available for SMS short numbers userrsquos directory etc

Protection codes PIN PUK

authentication and encryption features

subscriberrsquos secret authentication key (Ki)

Authentication algorithm (ldquosecretrdquo algorithm - A3 ndash not unique)

Cipher key generation algorithm (A8)

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

CC Country CodeNDC Network Destination CodeSN Subscriber Number

VodaFone Egypt MSISDN

20

CC

10

NDC

1100477

SN

Mobile Station ISDN Number (MSISDN)

VodaFone UK MSISDN

44

CC

385

NDC

196099

SN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

International Mobile Subscriber Identity (IMSI)

MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification Number

Vodafone UK IMSI

234

MCC

15

MNC

1234567890

MSIN

Vodafone Egypt IMSI

602

MCC

02

MNC

1234567890

MSIN

GSM Identities

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

International Mobile Equipment Identity (IMEI)

IMEI

6 Digits

TAC

2 Digits

FAC

6 Digits

SN

TAC Type Approval Code The first two digits are the code for the country approvalSN Serial Number

Final Assembly Codes (FAC)

0102 AEG0740 Motorola1020 Nokia30 Ericsson404144 Siemens47 Optional International50 Bosch51 Sony51 Siemens51 Ericsson60 Alcatel70 Sagem75 Dancall80 Philips85 Panasonic

GSM Identities

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Temporary Mobile Subscriber Identity Number (TMSI)

The TMSI can be allocated to the mobile subscriber in order to be used instead of his IMSI during all radio communications The purpose is to keep subscriber information confidential on the air interface

The TMSI is relevant on the local MSCVLR level only and is changed at certain events or time intervals Each local operator can define its own TMSI structure

Basic GSM Network Structure

GSM Identities

GSM Overview

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Mobile Station Roaming Number (MSRN)

When a mobile terminating call is to be set-up the HLR of the called subscriber requests the MSCVLR to allocate an MSRN to the called subscriber

This MSRN is returned via the HLR to the GMSC

The GMSC routes the call to the MSCVLR exchange where the called subscriber is currently registered

The routing is done using the MSRN When the routing is completed the MSRN is released

The interrogation call routing function (request for MSRN) is part of the MAP

All data exchanged between GMSC-HLR-MSCVLR for the purpose of interrogation is sent over S7 signaling

The MSRN is built up like an MSISDN

Basic GSM Network Structure

GSM Identities

GSM Overview

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Basic GSM Network Structure

Security Features

Authentication to secure network against unauthorized access

Ciphering to protect subscriber data sent over the radio path against eavesdropping

Subscriber identity confidentiality

Equipment Identity Check to prevent fraudulent usage of mobile handsets

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

QuestionsQuestions

GSM Overview

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Chapter 3 Radio Coverage

A visible pattern of sound waves

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Dead Spots

Problem of omni directional antennas

GSM Overview

Radio Coverage

Cell Geometry

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

R R

To solve the dead spot problem

bull The number of cells required to cover a given area

bull The cell transceiver power

Tradeoffs R

GSM Overview

Radio Coverage

Cell Geometrical Shape

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Omni-Directional AntennaSectorial Antenna

GSM Overview

Radio Coverage

Transceiver Antenna

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

The cells will take the form of overlapping circles

Due to the obstacles in the coverage area the actual shape of the cells would be Random

Sectorial Antenna

GSM Overview

Radio Coverage

Sectorial Antenna

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Overlaid amp Underlaid CellsNormal Cell Normal Cell

GSM Overview

Radio Coverage

Cell ClassificationMacrocell

Microcell

Slow moving subscribers

Fast moving subscribers

Picocell

In buildingcoverage

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Configure Cell Attributes

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Cell Basic Attributes

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Configure ARFCN

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Allocate ARFCN to TRX

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

To provide coverage for a large service area of a mobile network we have two Options

(A) Install one transceiver with high radio power at the center of the service area

Drawbacks

bull The mobile equipments used in this network should have high output power in order to be able to transmit signals across the coverage area

bull The usage of the radio resources would be limited

(B) Divide the service area into smaller areas (cells)

Advantages

bull Each cell as well as the mobile handsets will have relatively small power transceivers

bull The frequency spectrum might be ldquoreusedrdquo in two far separated cells This yields

Unlimited capacity of the system

Good interference characteristics

GSM Overview

Radio Coverage

GSM Coverage Plan

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Radio Coverage

Radio Access Methods

Frequency Division Multiple Access (FDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Radio Coverage

Radio Access Methods

Time Division Multiple Access (TDMA)

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Radio Coverage

Radio Access Methods

Hybrid TDMAFDMA

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Radio Coverage

Radio Access Methods

Code Division Multiple Access (CDMA)

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 900)

GSM 900 Frequency Allocation

F (MHz)915890

Uplink1 2 3 4 121 122 123 124

F (MHz)

Downlink

960935

1 2 3 4 121 122 123 124

8902

8904

8906

9352

9354

9356

200 KHz

1

1

121

121

Downlink 935 ndash 960 MHz

Uplink 890 ndash 915 MHz

ARFCN Absolute Radio Frequency Channel Number

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

GSM 1800 Frequency Allocation

F (MHz)17851710

Uplink1 2 3 4 371 372 373 374

F (MHz)

Downlink

18801805

1 2 3 4 371 372 373 374

17102

17104

17106

18052

18054

18056

200 KHz

Downlink 1805 ndash 1880 MHz

Uplink 1710 ndash 1785 MHz

GSM Overview

Radio Coverage

Spectrum Allocation (GSM 1800)

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

890 915

935 960

GSM 900With 124 ARFCN

25 MHz

45

MH

z

Uplink

Downlink

1710 1785

1805 1880

GSM 1800With 374 ARFCN

75 MHz

95

MH

z

Uplink

Downlink

GSM Overview

Radio Coverage

Comparison

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Total no of channels (frequencies) = 124

Every channel can be shared between a maximum of 8 subscribers

Maximum no of simultaneous calls = 8 X 124 = 992

Why do we need frequency reuse

The frequency reuse is performed by dividing the whole available frequencies between a group of neighboring cells which is called frequency reuse pattern or a ldquoClusterrdquo and then repeat this cluster over the whole network on 2 conditions

The group of frequencies allocated to a given cell must not be used in the adjacent cells

Enough distance between the cells where the same group of frequencies are reused

GSM Overview

Radio Coverage

Frequency Reuse

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

39 cluster in which the available frequencies are divided into 9 groups and distributed between 3 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

A3

A2

A1

B3

B2

B1

C3

C2

C1

GSM Overview

Radio Coverage

39 Cluster

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

4 12 Cluster

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

412 cluster in which the available frequencies are divided into 12 groups and distributed between 4 sites

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

A3

A2

A1

B3

B2

B1

C3

C2

C1

D3

D2

D1

GSM Overview

Radio Coverage

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

A3

A2

A1

C3

C2

C1

D3

D2

D1

B3

B2

B1

E3

E2

E1

F3

F2

F1

G3

G2

G1

7 21 cluster in which the available frequencies are divided into 21 groups and distributed between 7 sites

GSM Overview

Radio Coverage

7 21 Cluster

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Carrier to interference ratio

Itrsquos the difference in power level between the carrier in a given cell and the same carrier received from the nearest cell that reusesthe same frequency

Number of frequencies per site

Traffic ChannelsCI Ratio

39HighHighLow

412MediumMediumMedium

721LowLowHigh

GSM Overview

Radio Coverage

Which Cluster Size to use

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

R cell radius

K cluster size

D repeating distance

1

23

1

23

1

23

1

23

546

71

23

546

71

235

46

71

23

546

71

23

K = 12D

R

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12

546

71

23

98 10

11

12 K = 7

K = 3 D R K 3

Spatial Frequency Re-use in Cell Clusters

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Reuse Pattern(Cluster) -Cells are grouped into Clusters

-Available Band is distributed among the cells of the cluster

ldquo -Nrdquo is the number of cells in a cluster -Each frequency is reused after the same distance

ldquoDrdquo -Reuse Plan = gtgt (DR)sup2= 3N

Where R is the cell radius

5

23

4

7

1

65

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

23

4

7

1

65

D

Cellular System Concepts ldquoFrequency reuserdquo

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Co-channel Interference

bull Cells that have the same set of frequencies called co-channel cells and the interference between them is called co-channel interference

bull We cant remove co-channel interference by increasing the carrier transmitter power as it will increase the interference with the neighboring cells To solve co-channel interference we must separate the co-channel cells by a minimum distance to provide sufficient isolation due to propagation

bull In the case of each cell has the same size and transmitted power the co-channel interference ratio is independent of the transmitted power and depend on the radius of the cell (R) and the distance between the centers of the nearest co-channel cell (D) As the ratio DR increased the interference will be reduced as the distance between the co-channel cells will increase

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

Adjacent Channel Interference

bull It is interference resulting from signals which are adjacent in frequency to desired signal

bull It results from imperfect receiver filters which allow nearby frequencies to leak into the baseband

bull Adjacent frequencies must be avoided in the same cell and preferably in neighboring cells also

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

calculations

1 Up link BW = down link BW = (Total BW (MHZ) =50)2=25 MHZ2 No of frequencies = (uplink bw (MHZ) =25chspacing

(MHZ))=02=125 3Traffic channelscell= (no of frequencies=125cluster size=21) =6

4No of traffic channels= (traffic channelscell=6)8-2=465Trafficsubscriber= (Expected callhouruser=13600)(Average

calluser (second) =90) =00256 Using erlang b table B=2

Traffic channels=46 So trafficcell=3653

7 Subscribercell= (trafficcell=3653) (trafficsubscriber=0025) =14628 No of cells= (No of subscribers=300000)( subscribercell=1462)=206

9 No of BTSrsquos = (no of cells= 206)3=69

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

RESULTS

if we vary the cell size some outputs will change

1 no of cells will decrease 2 no of BTS will decrease

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78

QuestionsQuestions

GSM Overview

• Slide 1
• Slide 2
• Slide 3
• Mobile Technology Evolution
• Slide 5
• History of Mobile Communications
• Slide 7
• Slide 8
• Slide 9
• Analog to Digital
• Analog to Digital (1G to 2G)
• Why Wireless
• Slide 13
• Slide 14
• Slide 15
• Types of communication
• Multiple-access for Digital Communication Systems
• Multiple-Access
• FDMA
• Slide 20
• TDMA
• Slide 22
• CDMA
• Notes
• Slide 25
• Slide 26
• Slide 27
• HLR (home location register)
• VLR (visitor location register)
• Slide 30
• Slide 31
• Slide 32
• FUNCTION OF BSC
• Slide 34
• Slide 35
• Slide 36
• Sim card
• Slide 38
• Slide 39
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Questions
• Slide 45
• Slide 46
• Slide 47
• Slide 48
• Slide 49
• Slide 50
• Configure Cell Attributes
• Cell Basic Attributes
• Configure ARFCN
• Allocate ARFCN to TRX
• Slide 55
• Slide 56
• Slide 57
• Slide 58
• Slide 59
• Slide 60
• Slide 61
• Comparison
• Slide 63
• Slide 64
• 4 12 Cluster
• Slide 66
• Slide 67
• Slide 68
• Slide 69
• Cellular System Concepts ldquoFrequency reuserdquo
• Co-channel Interference
• Slide 72
• Adjacent Channel Interference
• Slide 74
• Slide 75
• calculations
• RESULTS
• Slide 78