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MSMS Mobile StationMobile Station

Mobile station provides user access to GSMMobile station provides user access to GSM

network for voice and datanetwork for voice and data

All GSM mobiles comply to GSM standardsAll GSM mobiles comply to GSM standards

Subscriber data is read from a SIM card thatSubscriber data is read from a SIM card that

plugs into MEplugs into ME

SIM ME

MS


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MS (cont..)MS (cont..)

Each MS has a unique number called asEach MS has a unique number called asIMEI number, which is stored in EIR forIMEI number, which is stored in EIR forauthentication purposesauthentication purposes

Mobile camps on to the GSM networkMobile camps on to the GSM networkthrough the BTS serving the cellthrough the BTS serving the cell

Mobile also scans neighboring cells andMobile also scans neighboring cells and

reports signal strengthsreports signal strengthsMobile transmits and receives voice at 13Mobile transmits and receives voice at 13kb/s over the air interfacekb/s over the air interface


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Mobile Station Output PowerMobile Station Output Power

CLASS 1CLASS 1 20 watts20 watts Vehicle and PortableVehicle and Portable

CLASS 2CLASS 2 8 watts8 watts Portable and VehiclePortable and Vehicle

CLASS 3CLASS 3 5 watts5 watts HandHand--HeldHeldCLASS 4CLASS 4 2 watts2 watts HandHand--Held (GSM)Held (GSM)

CLASS 5CLASS 5 0.8 watts0.8 watts HandHand--Held (DCSHeld (DCS

1800)1800)Output power determines:Output power determines:

Accessibility in areas of coverageAccessibility in areas of coverage

Talk Time and Standby timeTalk Time and Standby time


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Mobile Station IdentitiesMobile Station IdentitiesMSISDN : Mobile Station ISDN Number

It is the human identity used to call a Mobile

Station

CC SNNDC MSISDN

98 250 00134

CCCC Country CodeCountry CodeNDCNDC National Destination CodeNational Destination Code

SNSN Serial NumberSerial Number


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IMSI (International MobileIMSI (International Mobile

Subscriber Identity)Subscriber Identity)

MCCMCC Mobile Country CodeMobile Country Code

MNCMNC Mobile Network CodeMobile Network Code

MSINMSIN Mobile Subscriber Identity NumberMobile Subscriber Identity Number

MCC MSINMNC IMSI

3 2 or 3

Not more than 15

NMSI


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IMEI (International MobileIMEI (International Mobile

EquipmentId

entity)EquipmentId

entity)

TAC SPFAC IMEISNR

6 162 15TACTAC Type Approval CodeType Approval Code

FACFAC Factory Assembly CodeFactory Assembly Code

SNRSNR Serial NumberSerial Number

SPSP Spare digit (usually used to specifySpare digit (usually used to specify

software version)software version)


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SIM ( Subscriber Identity Module)SIM ( Subscriber Identity Module)

Removable module inserted when theRemovable module inserted when the

subscriber wants to use the MEsubscriber wants to use the METwo sizes: credit card size and stamp sizeTwo sizes: credit card size and stamp size

SIM features and contents areSIM features and contents are

personalized by the Service Activatorpersonalized by the Service ActivatorROMROM 6kb to 16 kb6kb to 16 kb

RAMRAM 128 bytes to 256 bytes128 bytes to 256 bytes

EEPROMEEPROM 3kb to 8 kb3kb to 8 kb

Space to insert SIM photo


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Contents of SIMContents of SIM

Serial NumberSerial Number

IMSI, Subscriber Key Ki, Ciphering Key KcIMSI, Subscriber Key Ki, Ciphering Key Kc

Algorithms for authentication and cipheringAlgorithms for authentication and cipheringNetwork CodeNetwork Code

PIN, PUKPIN, PUK

Charging InformationCharging Information

Abbreviated DiallingAbbreviated Dialling

Supplementary Features (e.g. Call barring)Supplementary Features (e.g. Call barring)


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SIM SecuritySIM Security

Two level protectionTwo level protection

When mobile is turned on, it will ask forWhen mobile is turned on, it will ask for

user to enter PIN (Personal Id Number)user to enter PIN (Personal Id Number)3 tries for PIN, after that PIN locked3 tries for PIN, after that PIN locked

To unblock PIN, there is PUK (Pin UnblockTo unblock PIN, there is PUK (Pin Unblock

Key)Key)10 attempts of PUK allowed10 attempts of PUK allowed

After that SIM is blockedAfter that SIM is blocked


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BTS (Base Transceiver Station)BTS (Base Transceiver Station)

BTS has a set of Transceivers (TRXs) toBTS has a set of Transceivers (TRXs) to

communicate with mobiles in its areacommunicate with mobiles in its area

One BTS covers one or more than one cellOne BTS covers one or more than one cell

The capacity of a cell depends on number ofThe capacity of a cell depends on number of

transceivers in the celltransceivers in the cell

BTS is connected to the BSC through AbisBTS is connected to the BSC through Abis

Interface which is 2MbpsInterface which is 2Mbps

BTS transmits and receives voice at 13kbpsBTS transmits and receives voice at 13kbps

over air interface to the mobiles.over air interface to the mobiles.

BTS commands mobiles to set Tx. Power,BTS commands mobiles to set Tx. Power,

timing advance and Handoverstiming advance and Handovers


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BTSBTS


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BSCBSC Base Station ControllerBase Station Controller

Several BTSs are connected to the BSCSeveral BTSs are connected to the BSCBSC Manages channel allocation,BSC Manages channel allocation,handovers and release of channels athandovers and release of channels atconnected BTSsconnected BTSs

BSC connects to the BTS via the AbisBSC connects to the BTS via the Abisinterface and to the MSC on A interfaceinterface and to the MSC on A interface

BSC has the entire database of cellBSC has the entire database of cell

parameters associated with the BTSs.parameters associated with the BTSs.No mobile data is stored in the BSCNo mobile data is stored in the BSC

Less connections for MSC as intelligenceLess connections for MSC as intelligenceis made common to all BTSs by the BSCis made common to all BTSs by the BSC

Several BTSs are connected to the BSCSeveral BTSs are connected to the BSCBSC Manages channel allocation,BSC Manages channel allocation,handovers and release of channels athandovers and release of channels atconnected BTSsconnected BTSs

BSC connects to the BTS via the AbisBSC connects to the BTS via the Abisinterface and to the MSC on A interfaceinterface and to the MSC on A interface

BSC has the entire database of cellBSC has the entire database of cell

parameters associated with the BTSs.parameters associated with the BTSs.No mobile data is stored in the BSCNo mobile data is stored in the BSC

Less connections for MSC as intelligenceLess connections for MSC as intelligenceis made common to all BTSs by the BSCis made common to all BTSs by the BSC


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BSCBSC


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TRAUTRAU Transcoder RateTranscoder Rate

Ad

aptation UnitAd

aptation Unit

BTS

BSC PSTN

13 kbps 16 kbps 16 kbps 64 kbps

MSC and TRAU


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TRAU (cont..)TRAU (cont..)

The MSC is based on ISDN switching.The MSC is based on ISDN switching.

The Fixed Network is also ISDN based.The Fixed Network is also ISDN based.

ISDN has speech rate of 64 kbps.ISDN has speech rate of 64 kbps.

Mobile communicates at 13 kbps.Mobile communicates at 13 kbps.

TRAU converts the data rates betweenTRAU converts the data rates between

13kbps GSM rate to 64kbps Standard13kbps GSM rate to 64kbps Standard

ISDN rateISDN rateTRAU can be collocated with the BTS,TRAU can be collocated with the BTS,

BSC or MSC or it can be a separateBSC or MSC or it can be a separate

unit.unit.


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Location of TranscoderLocation of Transcoder

Collocated with MSC, BSC, BTSCollocated with MSC, BSC, BTS

Separate UnitSeparate Unit

MSC Transcoder

BSC


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MSCMSC Mobile Switching CentreMobile Switching Centre

BSC

BSC

BSC

BTSs PSTN

HLR

VLR


19/31

MSCMSC


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MSC (cont..)MSC (cont..)

Exchange where calls are established,Exchange where calls are established,maintained and releasedmaintained and released

Database for all subscribers and theirDatabase for all subscribers and their

associated features.associated features.

Communicates with the BSCs on the ACommunicates with the BSCs on the A

interface and with PSTN on fixed line.interface and with PSTN on fixed line.

MSC is weighted on the number of subscribersMSC is weighted on the number of subscribers

it can support. E.g. an MSC of 1 lac subscribersit can support. E.g. an MSC of 1 lac subscribers

means one MSC is enough till subscriber basemeans one MSC is enough till subscriber base

increases upto 1 lac, beyond which anotherincreases upto 1 lac, beyond which another

MSC is required.MSC is required.


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Multiple MSCsMultiple MSCsWhen there is more capacity, there are moreWhen there is more capacity, there are more

than one MSCs.than one MSCs.All MSCs have to communicate with one anotherAll MSCs have to communicate with one another

and to the outside world.and to the outside world.

Very complicated to connect each MSC to eachVery complicated to connect each MSC to each

other and each MSC to PSTNother and each MSC to PSTN

So there is a concept of GMSC (Gateway MSC)So there is a concept of GMSC (Gateway MSC)

BSC

BSC

MSC

MSC

GMSC PSTN


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HLRHLR Home Location RegisterHome Location Register

MSC has all subscriber databaseMSC has all subscriber databasestored in HLRstored in HLR

HLR has all permanent subscriberHLR has all permanent subscriber

databasedatabaseHLR has a database which describesHLR has a database which describes

the subscribers profile i.e. basicthe subscribers profile i.e. basic

features and supplementary servicesfeatures and supplementary services

MSC communicates with the HLR toMSC communicates with the HLR to

get data for subscribers on callget data for subscribers on call


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VLRVLR Visiting Location RegisterVisiting Location RegisterA subscription when activated is registeredA subscription when activated is registered

in VLRin VLR

VLR has all the subscriber numbers whichVLR has all the subscriber numbers which

are active.are active.

VLR has a temporary database of allVLR has a temporary database of allactive subscribers (on/off, locationactive subscribers (on/off, location

information)information)

MSCVL

R

HLR


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VLR (cont..)VLR (cont..)

MSC MSCVLR

HLR

VLR

MSC communicates with HLR forMSC communicates with HLR for

subscribers coming from different MSCs. Ifsubscribers coming from different MSCs. If

the subscriber is found valid, then itthe subscriber is found valid, then it

registers the subscriber in the VLRregisters the subscriber in the VLR


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AUCAUC Authentication CentreAuthentication CentreAuthentication is a process by which aAuthentication is a process by which a

SIM is verifiedSIM is verifiedSecret data and the verification processSecret data and the verification process

algorithm are stored in AUCalgorithm are stored in AUC

AUC is the element which carries out theAUC is the element which carries out theverification of the SIMverification of the SIM

AUC is associated with the HLRAUC is associated with the HLR

MS MSC HLR AUC


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EIR (Equipment Identity Register)EIR (Equipment Identity Register)

EIR is the Mobile Equipment DatabaseEIR is the Mobile Equipment Database

which has a series of IMEIswhich has a series of IMEIs

MSC asks the Mobile to send its IMEIMSC asks the Mobile to send its IMEI

MSC then checks the validity of IMEIMSC then checks the validity of IMEIwith the EIRwith the EIR

All IMEIs are stored in EIR withAll IMEIs are stored in EIR with

relevant classificationsrelevant classifications

EIR

MSC


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Classification of IMEIsClassification of IMEIs

White list: This contains the IMEI of

type approved mobiles

Black List: List of IMEIs which should be

barred because either they are stolen or

are not functioning properly

Grey list: List of IMEIs which are to be

evaluated before they are put in black list


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Billing Centre (BC)Billing Centre (BC)

BC Generates the billing statement forBC Generates the billing statement foreach subscribereach subscriber

BC may be directly connected to the MSCBC may be directly connected to the MSC

or through a mediation deviceor through a mediation deviceMSC sends CDRs (Call Detail Records) toMSC sends CDRs (Call Detail Records) to

the BCthe BC

According to the template of pulse ratesAccording to the template of pulse ratesand units set, BC creates a bill accordingand units set, BC creates a bill according

to the destination called and the callto the destination called and the call

durationduration


29/31

Billing Centre (BC) (cont..)Billing Centre (BC) (cont..)

CDRs

Templates for unit costs


30/31

OMCOMC Operations andOperations and

Maintenance CentreMaintenance Centre

Also called the NOC (Network OperationsAlso called the NOC (Network Operations

centre)centre)It is the central monitoring and remoteIt is the central monitoring and remote

maintenance centre for all networkmaintenance centre for all network

elementselementsOMC has links to BSCs and MSCsOMC has links to BSCs and MSCs


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OMCOMC

OMC System

BSC

BSC

BSC

BTSs

BTSs

BTSs

OMC Terminals

Documents

GSM Network Architecture_02