GSM Fundamentals

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ISSUE ISSUE GSM Fundamentals GSM Fundamentals GSM Fundamentals GSM Fundamentals Wireless Curriculum Development Section Wireless Curriculum Development Section Wireless Curriculum Development Section Wireless Curriculum Development Section Engr Chinonso Ezeobi

Transcript of GSM Fundamentals

Page 1: GSM Fundamentals

ISSUEISSUE

GSM FundamentalsGSM FundamentalsGSM FundamentalsGSM Fundamentals

Wireless Curriculum Development SectionWireless Curriculum Development SectionWireless Curriculum Development SectionWireless Curriculum Development Section

Engr Chinonso Ezeobi

Page 2: GSM Fundamentals

INTRODUCTIONINTRODUCTION

,

GSM-FUNDAMENTALS PRESENTED TO NIGERIAN

SOCIETY OF ENGINEERS- ELECTRICAL DIVISION(

NIGERIAN INSTITUTION OF ELECTRICAL AND

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ELECTRONICS ENGINEERS-NIEEE) BY

ENGR CHINONSO EZEOBI

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Contents Contents

Basic Concepts of Cellular Mobile SystemBasic Concepts of Cellular Mobile System

GSM Network Components

Terrestrial Interface

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Terrestrial Interface

Service Area and Number Planning

Channels on The Air Interface

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GSM 900GSM 900

EGSM GSM EGSM GSM

The Frequency SpectrumThe Frequency Spectrum

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Duplex Separation: 45MHz

Channel Bandwidth: 200KHz

880 890 915 925 935 960MHz

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Base Station Receive Base Station Transmit

DCS 1800DCS 1800

The Frequency SpectrumThe Frequency Spectrum

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Duplex Separation: 95MHz

Channel Bandwidth: 200KHz

1710 1785 1805 1880MHz

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Frequency Re-UseFrequency Re-Use

Because frequency resource of mobile system is very limited,

What is Frequency Re-Use?What is Frequency Re-Use?

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very limited,

different Subscribers must use the same frequency in different place.

Of course, the quality of communication must be ensured.

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Frequency Re-UseFrequency Re-Use

How can we reuse frequency?How can we reuse frequency?

7(Site)X 1(Cell)

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7(Site)X 1(Cell) Re-use 2

1

3

4

5

6

7

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Frequency Re-UseFrequency Re-Use

4(Site)X 3(Cell)

Re-use

5

1

9 6

2

7

3

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10

2

7

3

115

9

1

10

212

8

4

11

3

9

5

1

6

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CELLCELL

Omni

1Omni-Directional CellsOmni-Directional Cells

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120degree

1

23

120 Degree Sectors120 Degree Sectors

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Contents Contents

Basic Concepts of Cellular Mobile System

GSM Network ComponentsGSM Network Components

Terrestrial Interface

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Terrestrial Interface

Service Area and Number Planning

Channels on The Air Interface

Radio Technologies

The Future Development

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AUCAUC

OMCOMC

HLRHLR

OSS

NSS

EIREIR

GSM Network ComponentsGSM Network Components

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MEMESIMSIM

MSC/VLRMSC/VLR

BTSBTS BSCBSC

PSTN

MS BSS

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Mobile Station—MSMobile Station—MS

International Mobile EquipmentIdentity (IMEI)

MS=ME+SIMMS=ME+SIM

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Identity (IMEI)– Mobile Equipment

International Mobile SubscriberIdentity (IMSI)

– Subscriber Identity Module

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Subscriber Identity Module – SIMSubscriber Identity Module – SIM

International Mobile SubscriberIdentity (IMSI)

Temporary Mobile SubscriberIdentity (TMSI)

International Mobile SubscriberIdentity (IMSI)

Temporary Mobile SubscriberIdentity (TMSI)

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Identity (TMSI) Location Area Identity (LAI) Subscriber Authentication Key

(Ki) Mobile Station International

Standard Data Network (MSISDN),it is optional.

Identity (TMSI) Location Area Identity (LAI) Subscriber Authentication Key

(Ki) Mobile Station International

Standard Data Network (MSISDN),it is optional.

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The Base Station

Controller – BSC

The Base Transceiver

The Base Station

Controller – BSC

The Base Transceiver BSS

MSC

Base Station Subsystem – BSSBase Station Subsystem – BSS

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The Base Transceiver

Station – BTS

The Trans-coder – TC

and Sub multiplexer

(SM)

The Base Transceiver

Station – BTS

The Trans-coder – TC

and Sub multiplexer

(SM)

BTSBTS

BSCBSC

TC/SMTC/SMBSS

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AUCAUCHLRHLR

PSTN

NSS

EIREIROMCECEC

The Network Switching SystemThe Network Switching System

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Mobile Switching Center – MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC Inter-Working Function – IWFEcho Cancellor – EC

Mobile Switching Center – MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC Inter-Working Function – IWFEcho Cancellor – EC

MSC/VLRMSC/VLR

BSS

IWFIWF

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Mobile Service Switching Center – MSC Mobile Service Switching Center – MSC

Call Processing

Operations and Maintenance

Support

Call Processing

Operations and Maintenance

Support

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Inter-network & Inter-working

Billing

Inter-network & Inter-working

Billing

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Home Location Register – HLR Home Location Register – HLR

Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

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Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality

Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality

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Visitor Location Register – VLR Visitor Location Register – VLR

Mobile Status(IMSI detached/ attached)

Location Area Identity(LAI)

Temporary Mobile Subscriber Identity(TMSI)

Mobile Status(IMSI detached/ attached)

Location Area Identity(LAI)

Temporary Mobile Subscriber Identity(TMSI)

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Mobile Station Roaming Number(MSRN) Mobile Station Roaming Number(MSRN)

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IMEIIs Checked against White List

If NOT found,

•White List•Black List•Grey List

Equipment Identity Register – EIR Equipment Identity Register – EIR

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IMEIIs Checked against Black/Grey List

If NOT found, checked against Grey/Black List

If NOT found, checked against White List indications

If found, returns a Black or Grey List indicator

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OSS(NMC)

Operation and Maintenance Sub SystemOperation and Maintenance Sub System

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OMCOMC

OMC

Region2

Region 1

Region 3

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Operation and Maintenance Center – OMC Operation and Maintenance Center – OMC

OMC – R: OMC assigned specifically tothe Base Station Subsystem

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OMC – S: OMC assigned specifically tothe Network Switching Subsystem

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OMC Functional ArchitectureOMC Functional Architecture

MMI

Event/AlarmManagement

SecurityManagement

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OS

MMI

DB

ConfigurationManagement

Performance Management

Fault Management

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HLR

VLR

EIR

AUCVLR

B

H

F

GC

D

GSM InterfaceGSM Interface

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MSC

EC IWF

TC

MSC

IWF EC

BTS BSCMS

A

E

Um Abis

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HLR

MSC/VLR

EIRAUCOMC

MSC/VLR

IWF

SigL1: 2MBps TrunksSigL1: 2MBps Trunks

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EC

TC

EC

BSC PSTN

BTS BTS

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Typical Configuration

TS 0 TS 1-15 TS16 TS 17-31

2MBps Trunks2MBps Trunks

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TS = Time slot

TS# Used for

0

1-15

16

17-31

Frame Alignment /Error Checking /Signaling

Traffic

CCS7 Signaling (Other TS may also the used)

Traffic

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Contents Contents

Basic Concepts of Cellular Mobile System

GSM Network Components

Terrestrial Interface

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Terrestrial Interface

Service Area and Number Planning

Channels on The Air InterfaceChannels on The Air Interface

Radio Technologies

The Future Development

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The physical channel is the medium over whichthe information is carriedThe logical channels consist of the informationcarried over the physical channel

The physical channel is the medium over whichthe information is carriedThe logical channels consist of the informationcarried over the physical channel

Physical and Logical ChannelsPhysical and Logical Channels

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00 1 2 3 4 5 6 7

TDMA FRAME

Timeslot

The information carried in one time slot is called a “burst”

The information carried in one time slot is called a “burst”

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Traffic ChannelTraffic Channel

TCHTraffic Channels

Normal Burst

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Speech

TCH/FS

Data

TCH/HSTCH/9.6 TCH/2.4

TCH/4.8

TCH Traffic ChannelTCH/FS Full rate Speech Channel TCH/HS Half rate Speech Channel TCH/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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CCH Control Channels

DCCH BCCH

ACCH

Control ChannelControl Channel

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FCCHSCH

SDCCHBCCH Synch. CH.

ACCH

SACCHFACCH CCCH

RACHCBCH

PCH/AGCH

Broadcast Control Channel – BCCHCommon Control Channel – CCCHDedicated Control Channel – DCCHAssociated Control Channel – ACCH

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CCH

BCCHdownlink only

The information carried on the

BCCH is monitored by the mobile

periodically when it is switched

on and not in a call

The information carried on the

BCCH is monitored by the mobile

periodically when it is switched

on and not in a call

Broadcast Control Channel – BCCHBroadcast Control Channel – BCCH

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BCCH Synch.

Channels

SCH FCCH

BCCH:Broadcast Control Channel

FCCH: Frequency Correction

Channel

SCH: Synchronization Channel

BCCH:Broadcast Control Channel

FCCH: Frequency Correction

Channel

SCH: Synchronization Channel

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CCH

CCCH

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

RACH: Random Access Control

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

RACH: Random Access Control

Common Control Channel – CCCHCommon Control Channel – CCCH

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RACHuplink

CBCH downlink

PCH/AGCHdownlink

RACH: Random Access ControlChannel

PCH: Paging Channel

AGCH: Access Grant ControlChannel

CBCH:Cell Broadcast Channel

RACH: Random Access ControlChannel

PCH: Paging Channel

AGCH: Access Grant ControlChannel

CBCH:Cell Broadcast Channel

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CCH

DCCH

DCCH is assigned to a singlemobile connection for call setupor for measurement and handoverpurpose.SDCCH: Standalone DedicatedControl Channel

DCCH is assigned to a singlemobile connection for call setupor for measurement and handoverpurpose.SDCCH: Standalone DedicatedControl Channel

Dedicated Control Channel – DCCH Dedicated Control Channel – DCCH

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SDCCH

FACCH SACCH

Control ChannelACCH: Associated ControlChannelSACCH: Slow Associated ControlChannelFACCH:Fast Associated ControlChannel

Control ChannelACCH: Associated ControlChannelSACCH: Slow Associated ControlChannelFACCH:Fast Associated ControlChannel

ACCH

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Search for frequency correction pulse

Search for synchronous pulse

Unscramble system information

Snoop into paging message

FCCH

SCH

BCCH

PCH

Power-off state

Idle state

How to use these channel?How to use these channel?

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Snoop into paging message

Send access pulse

Allocate signaling channel

Set up the call

Allocate voice channel

Conversation

Release the call

PCH

RACH

AGCH

SDCCH

FACCH

TCH

FACCH

Dedicated mode

Idle state

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TDMA Frames

0 1

0 1 102 3 4 5 6 7 2 3 5 764

GSM MultiframeGSM Multiframe

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0 1 2 43 46 47 48 5049

51 – Frame Multiframes

CONTROL CHANNELS

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Timeslots and TDMA FramesTimeslots and TDMA Frames

Higher Capacity Cell

Broadcast TrafficDedicated

00 1 2 3 4 5 6 7

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Dedicated

Traffic00 1 2 3 4 5 6 7

Low Capacity Cell

Combined Traffic00 1 2 3 4 5 6 7

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GSM MultiframeGSM Multiframe

TDMA Frames

0 1

0 1 102 3 4 5 6 7 2 3 5 764

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Engr

0 1 2 43 21 22 23 2524

26 – Frame Multiframes

TRAFFIC CHANNELS

Page 37: GSM Fundamentals

Contents Contents

Basic Concepts of Cellular Mobile System

GSM Network Components

Terrestrial Interface

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Engr

Terrestrial Interface

Service Area and Number Planning

Channels on The Air Interface

Radio TechnologiesRadio Technologies

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Modulation TechniquesModulation Techniques

Amplitude Modulation (AM)

Frequency Modulation (FM)

Phase Modulation (PM)

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– phase modulation can be implemented easilyfor digital signals, this is the method used forthe GSM air interfaces. Phase Modulation isknown as Phase Shift Keying when applied todigital signals

– phase modulation can be implemented easilyfor digital signals, this is the method used forthe GSM air interfaces. Phase Modulation isknown as Phase Shift Keying when applied todigital signals

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1 0 0 1 1 GaussianDigital Filter

Phase Modulator

Gaussian Minimum Shift Keying (GMSK) Gaussian Minimum Shift Keying (GMSK)

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Digital FilterModulator

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Battery LifeBattery Life

Power ControlPower Control

Voice Activity Detection – VAD

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Voice Activity Detection – VAD

Discontinuous Transmission – DTX

Discontinuous Reception – DRX

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Power ControlPower Control

8WBoth Uplink and Downlinkpower settings can becontrolled independentlyand individually.

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Saves radio battery powerReduces co-channel andadjacent channel interference

0.8W

5W

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VAD & DTXVAD & DTX

Encoding the speechsilences at a rate of500 bit/s ratherthan the full 13Kb/s.

Without DTX

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than the full 13Kb/s.

If the mobile doesnot transmit during‘silence’ there is areduction in theoverall poweroutput requirement

With DTX

Comfort Noise

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DRXDRX

DRX allows the mobile station to effectively “switch off”during times when reception is deemed unnecessary.

BCCH Multiframe P = Paging Channel

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P P P P P P BCCH P P

MS Being paged

MS in listen mode

MS receive System

information

MS in listen mode

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Multipath FadingMultipath Fading

•Diversity

•FrequencyHopping

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Engr

Hopping

Time Dispersion

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DiversityDiversity

When diversity is implementedtwo antennas are situated atthe receiver. These antennasare placed severalwavelengths apart to ensure

Approx. 10 wavelengths

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Engr

wavelengths apart to ensureminimum correlation betweenthe two receive paths.

The two signals are thencombined, this ensures that alow signal strength is less likelyto occur.

Compare oradd signals

Resultant Signal