Interfaces

GSM Interfaces (Um) Air interface  A bis interface  A Interface  B Interface  C interface 

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MS to BTS BTS to BSC BSC to MSC MSC to VLR MSC to HLR

GSM Interfaces 

D Interface

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VLR to HLR

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E Interface

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MSC to MSC

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 Interface

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MSC to EIR

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G Interface

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VLR to VLR

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H Interface

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HLR to AUC

 AUC

D Interface

H Interface To other  Networks

GMSC

HLR C Interface

MSC

VLR

EIR

B Interface F Interface

A Interface

BSC A bis Interface

Air Interface

MS

GSM Interfaces 

T!e interfaces bet"een MSC an# MS is ca$$e# A% Abis an# Um interfaces&

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'n t!ese interfaces on$ t!ree $aers are #efine#&T!e are not correson#in* to t!e 'SI ('en Sstem Interconnection) mo#e$&

 A Interface  A interface bet"een t!e BSC an# t!e MSC

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 T!e A interface ro+i#es t"o #istinct tes of information% si*na$$in* an# traffic% bet"een t!e MSC an# t!e BSC&

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T!e seec! is transco#e# in t!e TRC an# t!e SS, (Si*na$$in* sstem) si*na$$in* is transarent$ connecte# t!ro*! t!e TRC or on a searate $in. to t!e BSC&

 Abis Interface 

T!e A-bis interface resonsib$e for transmittin* traffic an# si*na$$in* information bet"een t!e BSC an# t!e BTS&

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T!e transmission rotoco$ se# for sen#in* si*na$$in* information on t!e A-bis interface is Lin. Access /rotoco$ on t!e D C!anne$ (LA/D)

(Um) Air Interface 

T!is is t!e interface bet"een t!e mobi$e station an# t!e Base station&

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T!e Air interface ses t!e Time Di+ision M$ti$e Access (TDMA) tec!ni0e to transmit an# recei+e traffic an# si*na$$in* information bet"een t!e BTS an# MS&

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T!e TDMA tec!ni0e is se# to #i+i#e eac! carrier into ei*!t time s$ots&T!ese time s$ots are t!en assi*ne# to secific sers%a$$o"in*  to ei*!t con+ersations to be !an#$e# Sim$taneos$ b t!e same carrier&

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6

5

U Lin.

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0

3

1

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2

1

3

0

4

Do"n Lin. 5

Time S$ot • T!is interface is t!e ra#io interface bet"een t!e

mobi$e station an# t!e net"or. an# ses $aer T!ree messa*es& 1 'n Laer t!ree messa*es "e !a+e t!e #i+ision of messa*e tes into CM (commnication Mana*ement)% MM (Mobi$it Mana*ement)% an# RR (Ra#io Resorce Mana*ement)&

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7

Connection Mana*ement (CM) 

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T!ere are t!ree entities "it!in CM2 Ca$$ Contro$(CC) 3 4!ic! !an#$es t!e roce#res concernin* ca$$ contro$& e&*& set%C!an*e of bearer ser+ice& S$ementar Ser+ice (SS) 3 4!ic! !an#$es sc! as ca$$ bearin*% ca$$ "aitin* % ca$$ for"ar#in* etc& S!ort Messa*e Ser+ice (SMS) 3 Enab$es t!e MS to !an#$e s!ort messa*e transfer to an# from t!e net"or.&

Mobi$it Mana*ement (MM) 

Mobi$it mana*ement !an#$es fnctions for at!entication% $ocation #atin*% i#entification an# ot!ers concernin* t!e mobi$it of t!e mobi$e station&

Ra#io Resorce Mana*ement (RR) 

It contains t!e fnctions concernin* t!e ra#io $in.& Here "e fin# t!e caabi$it to estab$is!%maintain an# re$ease t!e ra#io connection bet"een t!e net"or. an# t!e mobi$e station% "!ic! inc$#es t!e !an#o+er roce#re&

B Interface 

T!e B interface bet"een t!e MSC an# t!e VLR ses t!e MA/5TCA/ rotoco$&

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Most MSCs are associate# "it! a VLR% ma.in* t!e B interface 6interna$6&

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4!ene+er t!e MSC nee#s access to #ata re*ar#in* a MS $ocate# in its area% it interro*ates t!e VLR sin* t!e MA/5B rotoco$ o+er t!e B interface&

C Interface 

T!e C interface is bet"een t!e HLR an# a MSC&

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Eac! ca$$ ori*inatin* otsi#e of GSM (i&e&% a MS terminatin* ca$$ from t!e /ST7) !as to *o t!ro*! a Gate"a to obtain t!e rotin* information re0ire# to com$ete t!e ca$$% an# t!e MA/5TCA/ rotoco$ o+er t!e C interface is se# for t!is rose&

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 A$so% t!e MSC ma otiona$$ for"ar# bi$$in* information to t!e HLR after ca$$ c$earin*&

D Interface 

T!e D interface is bet"een t!e VLR an# HLR&

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It ses t!e MA/5TCA/ rotoco$ to e8c!an*e t!e #ata re$ate# to t!e $ocation of t!e MS an# to t!e mana*ement of t!e sbscriber&

E Interface 

T!e E interface interconnects t"o MSCs&

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T!e E interface e8c!an*es #ata re$ate# to !an#o+er bet"een t!e anc!or an# re$a MSCs sin* t!e -MA/5TCA/9ISU/5TU/ rotoco$&

 Interface 

T!e  interface connects t!e MSC to t!e EIR&

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It ses t!e MA/5TCA/ rotoco$ to +erif t!e stats of t!e IMEI t!at t!e MSC !as retrie+e# from t!e MS&

G Interface 

T!e G interface interconnects t"o VLRs of #ifferent MSCs&

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It ses t!e MA/5G rotoco$ to transfer sbscriber information% #rin* e&*& a $ocation #ate roce#re&