GSM (GLOBAL SYSTEM FOR MOBILE COMMUNICATION)

GSM (GLOBAL SYSTEM FOR GSM (GLOBAL SYSTEM FOR MOBILE COMMUNICATION)MOBILE COMMUNICATION)

Submitted to :->MR. Ajmer

Submitted by :->HIMANI , POOJA (11 A)

IP PROJECT WORKIII Term

SESSION – 2013 -14

It all started like thisIt all started like this

• First telephone (photophone) – First telephone (photophone) – Alexander Bell, 1880Alexander Bell, 1880

• The first car mounted radio The first car mounted radio

telephone – 1921telephone – 1921

But what’s cellular?But what’s cellular?

HLR, VLR, AC, EIR

MSC

PSTN

BS

What is GSM ?What is GSM ?

Global System for Mobile Global System for Mobile (GSM) is a second generation (GSM) is a second generation cellular standard developed to cellular standard developed to cater voice services and data cater voice services and data delivery using digital delivery using digital modulationmodulation

GSM: HistoryGSM: History• Developed by Group Spéciale Mobile (founded 1982) which was an

initiative of CEPT ( Conference of European Post and Telecommunication )

• Aim : to replace the incompatible analog system

• Presently the responsibility of GSM standardization resides with special mobile group under ETSI ( European telecommunication Standards Institute )

• Full set of specifications phase-I became available in 1990

• Under ETSI, GSM is named as “ Global System for Mobile communication “

• Today many providers all over the world use GSM (more than 135

countries in Asia, Africa, Europe, Australia, America)

• More than 1300 million subscribers in world and 45 million subscriber in India.

Tele Services Tele Services

• Telecommunication services that enable voice communication

via mobile phones

• Offered services

- Mobile telephony

- Emergency calling

GSM OverviewGSM Overview

1st Generation1st Generation

• Start to use in 1989• Call forwarding• All calls• No answer• Engaged• Unreachable• Outgoing calls barring• Incoming calls barring• Global roaming

2nd Generation2nd Generation

• Finished process in 1995• SMS(Short Message Services)• Multi Party Calling• Call holding• Call waiting• Mobile data service• Mobile fax service• Call line identity• Advice of chargingAdvice of charging• Cell broadcastCell broadcast

2+ Generation

• Start to use in 1998Start to use in 1998

• Services developedServices developed

• DECT and GSMDECT and GSM

• VPN(Virtual Private Network)VPN(Virtual Private Network)

• Packet RadioPacket Radio

• SIM developmentSIM development

• Enjoyable servicesEnjoyable services

GSM in WorldGSM in World

Figures: March, 2005

37%

1%4%43%

4%

3%3%

3% (INDIA)

3%

Arab World

Asia Pacific

Africa

East Central Asia

Europe

Russia

India

North America

South America

GSM in IndiaGSM in India

Figures: March 2005

Bharti27%

BSNL22%

Spice 4%

IDEA13%

Hutch19%

BPL6%

Aircel4%

Reliance3%

MTNL2%

Bharti

BSNL

Hutch

IDEA

BPL

Aircel

Spice

Reliance

MTNL

GSM System ArchitectureGSM System Architecture

BSC

BSC

MSC

MS

MS

MS BTS

BTS

BTS

GMSC

PSTNISDNPDN

EIRAUC

HLR

VLR

Outgoing CallOutgoing Call

1.1. MS sends dialled number to MS sends dialled number to BSS BSS

2.2. BSS sends dialled number to BSS sends dialled number to MSCMSC

3,4 MSC checks VLR if MS is 3,4 MSC checks VLR if MS is allowed the requested allowed the requested service.If so,MSC asks BSS to service.If so,MSC asks BSS to allocate resources for call.allocate resources for call.

55 MSC routes the call to GMSCMSC routes the call to GMSC66 GMSC routes the call to local GMSC routes the call to local

exchange of called userexchange of called user7, 8,7, 8,9,10 Answer back(ring back) 9,10 Answer back(ring back)

tone is routed from called tone is routed from called user to MS via user to MS via GMSC,MSC,BSSGMSC,MSC,BSS

Incoming CallIncoming Call1.1. Calling a GSM Calling a GSM

subscriberssubscribers2.2. Forwarding call to Forwarding call to

GSMCGSMC3.3. Signal Setup to HLRSignal Setup to HLR4.4. 5. Request MSRN 5. Request MSRN

from VLRfrom VLR6.6. Forward responsible Forward responsible

MSC to GMSCMSC to GMSC7.7. Forward Call to Forward Call to

current MSCcurrent MSC8.8. 9. Get current 9. Get current

status of MSstatus of MS10.10.11. Paging of MS11. Paging of MS12.12.13. MS answers13. MS answers14.14.15. Security checks15. Security checks16.16.17. Set up 17. Set up

connectionconnection

HandoversHandovers

• Between 1 and 2 – Between 1 and 2 – Inter BTS / Intra BSCInter BTS / Intra BSC

• Between 1 and 3 –Between 1 and 3 –

Inter BSC/ Intra MSCInter BSC/ Intra MSC

• Between 1 and 4 – Between 1 and 4 –

Inter MSCInter MSC

Authentication in GSMAuthentication in GSM

Key generation and EncryptionKey generation and Encryption

Mobile RadioMobile RadioCellular Mobile Cellular Mobile

CommunicationsCommunications

Mobile Comms. PrinciplesMobile Comms. Principles

– Mobile uses a separate, temporary radio Mobile uses a separate, temporary radio channel to talk to the cell sitechannel to talk to the cell site

– Cell site talks to many mobiles at once, using Cell site talks to many mobiles at once, using one channel per mobileone channel per mobile

– Channels use a pair of frequencies for Channels use a pair of frequencies for communicationcommunication • The forward link for transmitting from the cell siteThe forward link for transmitting from the cell site • The reverse link for the cell site to receive calls from The reverse link for the cell site to receive calls from

the usersthe users

Mobile Comms. PrinciplesMobile Comms. Principles

• Radio energy dissipates over Radio energy dissipates over distance, so mobiles must stay near distance, so mobiles must stay near the base station to maintain the base station to maintain communicationscommunications

• BBasic structure of mobile networks asic structure of mobile networks includes telephone systems and includes telephone systems and radio servicesradio services

Mobile Comms. PrinciplesMobile Comms. Principles

• Where mobile radio service operates in a closed Where mobile radio service operates in a closed network and has no access to the telephone network and has no access to the telephone system, mobile telephone service allows system, mobile telephone service allows interconnection to the telephone networkinterconnection to the telephone network

Mobile Comms. PrinciplesMobile Comms. Principles

• Radio energy dissipates over Radio energy dissipates over distance, so mobiles must stay near distance, so mobiles must stay near the base station to maintain the base station to maintain communicationscommunications

• basic structure of mobile networks basic structure of mobile networks includes telephone systems and includes telephone systems and radio servicesradio services

Mobile Systems Using CellsMobile Systems Using Cells

• The cellular concept employs The cellular concept employs variable low-power levelsvariable low-power levels – cells are sized according to the cells are sized according to the

subscriber density and demand in a subscriber density and demand in a given areagiven area

• Cells can be added to accommodate Cells can be added to accommodate population growthpopulation growth

Cellular System ArchitectureCellular System Architecture

• In modern cellular telephony, rural and In modern cellular telephony, rural and urban regions are divided into areas urban regions are divided into areas according to specific provisioning according to specific provisioning guidelinesguidelines

• Deployment parameters, such as Deployment parameters, such as amount of cell-splitting and cell sizes, amount of cell-splitting and cell sizes, are determined by engineers are determined by engineers experienced in cellular system experienced in cellular system architecturearchitecture

CellsCells

• A cell is the basic geographic unit of A cell is the basic geographic unit of a cellular systema cellular system – The term The term cellularcellular comes from the honeycomb comes from the honeycomb

shape of the areas into which a coverage shape of the areas into which a coverage region is dividedregion is divided

– Cells are base stations transmitting over small Cells are base stations transmitting over small geographic areas that are represented as geographic areas that are represented as hexagonshexagons

– Size varies depending on the landscapeSize varies depending on the landscape

GSM OperationGSM Operation

Speech decoding

Channel decoding

De-interleaving

Burst Formatting

De-ciphering

DemodulationModulation

Ciphering

Burst Formatting

Interleaving

Channel Coding

Speech coding

Radio Interface

Speech Speech

13 Kbps

22.8 Kbps

22.8 Kbps

33.6 Kbps

33.6 Kbps

270.83 Kbps

GSM-Frame StructureGSM-Frame Structure

OPEN INTERFACES OF GSMOPEN INTERFACES OF GSM

• Network Switching Subsystem(NSS)Network Switching Subsystem(NSS)

• Base Station Subsystem(BSS)Base Station Subsystem(BSS)

• Network Management Network Management Subsystem(NMS) or Operation and Subsystem(NMS) or Operation and Support Subsystem(OSS)Support Subsystem(OSS)

• They connect with Air,A,O&M They connect with Air,A,O&M interfacesinterfaces

PROCEDURE OF CALL SET UP PROCEDURE OF CALL SET UP FROM MOBİLE USERFROM MOBİLE USER

SIGNALS AND PROTOCOLSSIGNALS AND PROTOCOLS

• STANDART MESSAGESSTANDART MESSAGES• SENDER WANTS TO SERVICESENDER WANTS TO SERVICE• OPERATOR ASK THAT YOU WANTS TO OPERATOR ASK THAT YOU WANTS TO

TALK ,BUT WHICH USERTALK ,BUT WHICH USER• OPERATOR CONNECT TO RECEIVEROPERATOR CONNECT TO RECEIVER• WHEN THE RECEIVER REPLIES TO WHEN THE RECEIVER REPLIES TO

CALL ,THE CALL STARTSCALL ,THE CALL STARTS• WHEN THE RECEIVER OR SENDER CLOSE WHEN THE RECEIVER OR SENDER CLOSE

THE PHONE , THE OPERATOR FINISH THE PHONE , THE OPERATOR FINISH CONNECTION TO EACH OTHERCONNECTION TO EACH OTHER

PROCEDURE OF SIGNALSPROCEDURE OF SIGNALS

COMMON CHANNEL COMMON CHANNEL SIGNALLING SYSTEM SIGNALLING SYSTEM

• MTP(MASSAGE TRANSFER PART)MTP(MASSAGE TRANSFER PART)

• TUP(TELEPHONE USER PART)TUP(TELEPHONE USER PART)

• SSCP(SIGNALLING CONNECTION AND SSCP(SIGNALLING CONNECTION AND CONTROL PART)CONTROL PART)