00_oma000001 Gsm Fundamentals Issue4.0

7/30/2019 00_oma000001 Gsm Fundamentals Issue4.0

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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GSM Fundamentals

ISSUE 4.0


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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2

Upon completion of this course, you will be able to:

Grasp basic idea of GSM system such as

frequency spectrum, frequency reuse etc.

Grasp the structure of the GSM system and the

protocol used.

Grasp certain numbers that refer to BSS

Grasp the 4 kinds of channel combination and

understand the idea of multi-frame.

Know some radio techniques

Get the idea of EDGE


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References

BSS Feature Description

BSS Signaling Analysis Manual

BSC Technical Manual


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Chapter 1 GSM System Overview

Chapter 2 GSM Network Structure

Chapter 3 Service Area and Number Planning

Chapter 4 Channels on the Wireless Interface

Chapter 5 Radio Techniques

Chapter 6 GPRS & EDGE Introduction


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GSM system overview

The GSM system is a frequency- and time-division cellular system,

each physical channel is characterized by a carrier frequency and a

time slot number

Cellular systems are designed to operate with groups of low-power

radios spread out over the geographical service area. Each group ofradios serve MSs presently located near them. The area served by

each group of radios is called a CELL

Uplink and downlink signals for one user are assigned different

frequencies, this kind of technique is called Frequency Division Duplex

(FDD)

Data for different users is conveyed in time intervals called slots ,

several slots make up a frame. This kind of technique is called Time

Division Multiple Access (TDMA)


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GSM Development

Standard Protocol for GSM take effect

System was named as Global System forMobile Communication

GSM system began to provide service in Europe(2G)

Provide services for the whole world

Micro Cell Technique is used in GSM system

1989

1991

1992

1994

1996


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Cell Technique

A certain radio coverage area formed by a set of transceivers that

connected to a set of antennas is called a CELL.

Macro Cell

In the beginning , High-Power BTSs are adopted to provide services.

The BTS covers a wider area , but its frequency utilization is not

efficient. So , it can only provide a few channels for subscribers.

Micro Cell

Later the Low-Power BTS joins the system for getting a better servicearea with high capacity . At the same time it adopts the frequency

reuse technique to improve the efficiency of the frequency utilization

and also the whole capacity of the network.

Macro Cell and Micro Cell


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Multiple Access Technique

Multiple Access Technique allows many subscribers to use the

same communication medium.

There are three kinds of basic Multiple Access Technique :

FDMA , TDMA and CDMA.

GSM system adopt FDD-TDMA (FDMA and TDMA together).


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FDMA

FDMA uses different frequency

channels to accomplish

communication.

The whole frequency spectrum

available is divided into many

individual channels (for

transmitting and receiving)every

channel can support the traffic for

one subscriber or some controlinformation.

Frequency

Time


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TDMA

TDMA accomplishes the

communication in different

timeslot.

A carrier is divided intochannels based on time.

Different signals occupy

different timeslots in certain

sequence , that is , many

signals are transmitted onthe same frequency in

different time.Time

Frequency


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CDMA

CDMA accomplishes the

communication in different

code sequences.

Special coding is adopted

before transmission, thendifferent information will

lose nothing after being

mixed and transmitted

together on the same

frequency and at thesame time.

Time

Frequency


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GSM 900

Duplex Separation: 45MHzChannel Bandwidth: 200KHz

The Frequency Spectrum

Uplink

890 915 935 960MHz

Downlink


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Duplex Separation: 95MHzChannel Bandwidth: 200KHz

Base Station Receive

1710 1785 1805 1880MHz

Base Station Transmit

DCS 1800



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FrequencySpectrum

Range (MHz) Uplink FrequencyFrequencyPointAvailable

DownlinkFrequency

GSM 450450.4~457.6

460.4~467.6Fu(n)=450.6+0.2(n-259) 259


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Frequency Reuse

The frequency resource of mobile system is very limited.

The different Subscribers can use the same frequency in

different places.

The quality of communication must be ensured.


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Frequency Reuse

7(Site)X 1(Cell) reuse

2

1

2

3

4

5

6

7


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4 site X 3 cells reuse

1

8

9

210

46

5 37

11

12

R

Frequency Reuse


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Cell Types

Omni

1

120degree

1

23

Omni-directional Cell

120 Degree Cell


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GSM-GPRS Network Component

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU SS7

SMS system

PSTN

ISDN

Internet,

Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CGBG

GGSN

GPRS Backbone

Other PLMN

MS

MS

OMC


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Interface Between Different Entities

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU SS7

SMS system

PSTN

ISDN

Internet,

Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CGBG

GGSN

GPRS backbone

Other PLMN

A

Gb

Gi

Gp

C/D/Gs

Gr/Gs/Gd/GeGc

Ga

Abis

Um

MS

MS

OMC


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Mobile StationMS

International Mobile Equipment Identity (IMEI)

Mobile Equipment

MS=ME+SIM

International Mobile Subscriber Identity (IMSI)

Subscriber Identity Module


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Subscriber Identity Module SIM

International Mobile Subscriber Identity

(IMSI)

Temporary Mobile Subscriber Identity (TMSI)

Location Area Identity (LAI)

Subscriber Authentication Key (Ki)

SIM


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BTS

BSC

TC/SM

BSS

MSC

Base Station Subsystem BSS

The Base Station Controller

BSC

The Base Transceiver Station

BTS

The Trans-coder TC and

Sub multiplexer (SM)


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BTS

BSC

TC/SM

BSS

MSC

Packet Control Unit-----PCU

Packet data

switching

Bridge between

SGSN and BSC

Provide Pb and

Gb interface

GPRSBackbone

PCU SGSN


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Mobile-service Switching Center MSCHome Location Register HLRVisitor Location Register VLREquipment Identity Register EIRAuthentication Center AUCEcho Cancellor EC

AUCHLR

MSC/VLR

PSTN

NSS

EIROMC

BSS

EC

The Network Switching System


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Mobile-service Switching Center MSC

Call Processing

Operations and Maintenance Support

Interface management Inter-network & Inter-working

Billing


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Home Location Register HLR

Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality


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Visitor Location Register VLR

Mobile Status (IMSI attached / detached / busy / idle etc.)

Location Area Identity(LAI)

Temporary Mobile Subscriber Identity(TMSI)

Allocating the Roaming Number


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IMEI is Checked In White List

IMEI is Checked in Black/Grey List

If NOT found

EIR focus on theequipment , not thesubscriber!!

Equipment Identity Register EIR

White List

Black List

Grey List


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OMC Functional Architecture

OS

MMI

DB

Event/AlarmManagement

SecurityManagement

ConfigurationManagement

PerformanceManagement

FaultManagement


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Service Area

PLMN service area

......

Service Area

MSC service area...

Location area...

cell

PLMN service area PLMN service area

MSC service area...

Location area...

cell


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LAI

Location Area Identification

The LAI is the international code for a location area.

MCC: Mobile Country Code It consists of 3 digits .For example: The MCC of China is "460"

MNC: Mobile Network Code It consists of 2 digits .For example: The MNC of China Mobile is "00"

LAC: Location Area Code It is a two bytes hex code.The value 0000 and FFFF is invalid.

For example: 460-00-0011

MCC MNC LAC


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CGI

The CGI is a unique international identification for a cellThe format is LAI+CI

LAI: Location Area Identification

CI: Cell Identity. This code uses two bytes hex code to

identify the cells within an LAI.For example : 460-00-0011-0001

CGI: Cell Global Identification


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BSIC

NCC: PLMN network color code. It comprises 3 bit. Itallows various neighboring PLMNs to be

distinguished.BCC: BTS color code. It comprises 3 bit, used to

distinguish different cells assigned the samefrequency!

NCC BCC

BSIC

BSIC Base Station Identification Color Code)


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CC: Country Code. For example: The CC of China is "86".

NDC: National Destination Code. For example: The NDC of

China Telecom is 139, 138, 137, 136, 135.SN: Subscriber Number. Format:H0 H1 H2 H3 ABCD

Example: 86-139-0666-1234

MSISDN

CC NDC SN

National (significant)Mobile number

Mobile station internationalISDN number


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MCC: Mobile Country Code It consists of 3 digits .For example: The MCC of China is "460"

MNC: Mobile Network Code It consists of 2 digits .For example: The MNC of China Telecom is "00"

MSIN: Mobile Subscriber Identification Number. H1H2H3 S ABCDEFFor example: 666-9777001

NMSI: National Mobile Subscriber Identification MNC and MSINform it together.

For Example of IMSI : 460-00-666-9777001

Not more than 15 digits

3 digits 2 digits

IMSI

MCC MNC MSIN

NMSI

IMSI


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TMSI

The TMSI is assigned only after successful subscriberauthentication.

The VLR controls the allocation of new TMSI numbers and notifiesthem to the HLR.

TMSI is used to ensure that the identity of the mobile subscriberon the air interface is kept secret.

The TMSI consists of 4 bytes( 8 HEX numbers) and determined bythe operator.

TMSI: Temporary Mobile Subscriber Identification)


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IMEI

TAC FAC SNR SP

IMEI

IMEI: International Mobile Station Equipment Identification

TAC: Type approval code, 6 bit, determined by the type approval center

FAC: Final assembly code, 2 bit, It is determined by the manufacturer.

SNR: Serial number, 6 bits, It is issued by the manufacturer of the MS.

SP: 1 bit , Not used.

Check the IMEI in your MS : *#06#


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2 30 16 74 52 3

The physical channel is the medium over which theinformation is carried: 200KHz and 0.577ms

0 1

TDMA FRAME

Timeslot The information carried in one timeslot is called a burst

Physical Channel and Logical Channel

The logical channel consists of the information carried

over the physical channels

TDMA FRAME


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Two types of Logical Channel

Traffic Channel (TCH) :

Transmits traffic information, include dataand speech.

Control Channel (CCH) :

Or Signaling Channel, transmits all kinds ofcontrol information.


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Traffic Channel (TCH)

TCHTraffic Channels

Speech

TCH/FS

Data

TCH/HSTCH/9.6 TCH/2.4

TCH/4.8

TCH Traffic ChannelTCH/FS Full rate Speech ChannelTCH/HS Half rate Speech ChannelTCH/9.6 Data Channel 9.6kb/sTCH/4.8 Data Channel 4.8kb/sTCH/2.4 Data Channel 2.4Kb/s


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FCCHSCH

CCH (Control Channels)

DCCH

SDCCH

BCH

BCCH Synch. CH.ACCH

SACCHFACCH CCCH

RACH CBCH

PCH/AGCH

Broadcast Control Channel BCCHCommon Control Channel CCCHDedicated Control Channel DCCH

Associated Control Channel ACCH

Control Channel (CCH)


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CCH

BCH

BCCHSynch.

Channels

SCH FCCH

The information carried on the BCCH

is monitored by the MS

periodically when it is in idle modeBCCH: Broadcast Control Channel

FCCH: Frequency Correction Channel

SCH: Synchronization Channel

Broadcast Control Channel BCCH


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CCH

CCCH

RACHuplink

CBCH

downlink

PCH/AGCHdownlink

The CCCH is responsible fortransferring control informationbetween all mobiles and thenetwork.

RACH: Random Access Channel

PCH: Paging Channel

AGCH: Access Granted Channel

CBCH: Cell Broadcast Channel

Common Control Channel CCCH


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CCH

DCCH

SDCCH

FACCH SACCH

DCCH is assigned to a singlewireless connection formeasurement and handoverpurpose.

SDCCH: Stand-alone DedicatedControl Channel

ACCH:Associated Control ChannelSACCH: Slow Associated

Control Channel

FACCH: Fast Associated ControlChannel

ACCH

Dedicated Control Channel DCCH


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RACH CCCHCCH

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

DCH

Uplink Logical channel


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FCCH

SCH

BCCH

PCH

AGCH

BCCH

CCCH

CCH

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

DCH

Downlink Logical channel


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Allocate signaling channel

FCCH

SCH

BCCH

PCH

RACH

AGCH

SDCCH

SDCCH

TCH

FACCH

Power-off

Idle mode

Dedicated mode

Idle mode

How to use these channels?

Search for frequency correction burst

Search for synchronous burst

Extract system information

Monitor paging message

Send access burst

Set up the call

Allocate voice channel

Conversation

Release the call


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Packet data channel (PDCH)

Comprising packet service channel and packet control channel

Packet service channel (PDTCH) Combined into the single-directional service channel

Packet control channel

Broadcast control channel: PBCCH Public control channel: PPCH, PRACH, PAGCH

Private control channel: PACCH, PTCCH

TCH

BCCH

SACCH

Packet logic channel

CCCH

TCH


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GSM Logical Channel Combination

Main BCCH combination FCCH + SCH + BCCH + CCCH

SDCCH combination SDCCH/8 + SACCH/8

Combined BCCH BCCH + CCCH +SDCCH/4 + SACCH/4

TCH/FR combination TCH/F + FACCH/F + SACCH/F

TCH/HR combination TCH/H + FACCH/H + SACCH/H


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Packet logic channels (PDCH) can be combined via the following three modes

Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH;

Mode 2: PCCCH+PDTCH+PACCH+PTCCH;

Mode 3: PDTCH+PACCH+PTCCH

In case of small GPRS traffic, GPRS and circuit services use the same BCCH

and CCCH in the cell. In this case, only combination mode 3 is needed in the cell

With the increase of traffic, the packet public channel should be configured in the

cell. Channel combination mode 1 and mode 2 should be adopted

Combination ofpacket logic channel


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TDMA Frames

0 1

0 1 2 43 46 47 48 5049

51 Frame Multi-frames

0 1 10

CONTROLCHANNELS

2 3 4 5 6 7 2 3 5 764

GSM Multi-frames


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GSM Multi-frames

TDMA Frames

0 1

0 1 2 43 21 22 23 2524

26 Frame Multi-frames

0 1 10

TRAFFICCHANNELS

2 3 4 5 6 7 2 3 5 764


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Timing Advance (TA)

Transmission delay t

Transmission delay t

TA

The mobile phone should

send the signal in advance!


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Multi-path Fading

Diversity

Frequency Hopping

Time Dispersion


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DiversityWhats Diversity?

Receive diversity provides an effective technique for both

overcoming the impact of fading across the radio channel and

increasing the received signal to interference ratio.

The former is achieved by ensuring uncorrelated (i.e. low

enough correlated) fading between antenna branches i.e. not

all antennas experience fades at the same time.


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Kinds of Diversity

Time diversity

Coding, interleaving

Frequency diversity

Frequency hopping

Space diversity

Multiple antennas

Polarization diversity

Dual-polarized antennas

Multi-path diversity

Equalizer

t

f


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Frequency HoppingFrequency

f 0

Frame

f 1

f 2

f 3

f 4

Time


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57.6kbps

115kbps

384kbps

2Mbps

GSM

HSCSD

GPRS

EDGE

IMT-2000

9.6kbps

2G

2.5G

3G

GSM Development Evolution


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Data rate of EDGE and GPRS

8PSKGMSK

9.0

13.415.6

21.4

8.811.2

14.817.6

22.4

29.6

44.8

54.4

59.2

0.0

10.0

20.0

30.0

40.0

50.0

60.0

CS-1 CS-2 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9

Kbps


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Downlink, 4 TS, MCS-9

Huawei EDGE Test Result


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The basic idea of GSM

The frequency spectrum used in GSM

The structure of GSM

Certain service area and numbers

Some radio techniques used in GSM

Evolution of GSM

Summary


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00_oma000001 Gsm Fundamentals Issue4.0

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