Gsm Architecture

GSM PLMN Organisation

MS

Network Switching Subsystem • Switching • Mobility Management • Connection Management • Charging

Air

A

BSS

NSS

O&M Base Station Subsystem • Radio Resource Management • Radio Link Management

1

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

NMS

Network Management System • Fault Management • Configuration Management • Performance Management

Network Management Subsystem AC EIR

HLR

MSC Mobile services Switching Centr GMSCGateway MSC VLR Visitor Location Register HLR Home Location Register EIR Equipment Identity Register AC Authentication Centre

HLR

VLR

GMSC 2

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

MSC

Mobile services Switching Centre (MSC)

MSC • • • • •

3

Call control Mobility management Initiation of paging Collection of changing information often associated with VLR

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

GMSC • • • •

Call control Interrogation of HLR Collection of changing information often used for interworking with external networks

Registers in the NSS

VLR

HLR

• Identification numbers of subscribers • Subscriber Profile • Security information • Routing Information • Services that the subscriber can use

EIR

AC

• Lists for Mobile Equipment (ME) Data for • authentication (SIM) and checks • ciphering 4

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Base Station Subsystem BSC TC

BSC

BTS

TC

BTS

BTS

5

Elements: • Base Station Controller (BSC), Base Transceiver Station (BTS), and Transcoder and Rate Adaptation Unit (TRAU, TC) Functions: • Radio path control, BTS and TC control, synchronisation with MSC • Air and A interface signalling, connection establishment MSNSS • Mobility management, speech transcoding • Collection of statistical data © NOKIA CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Base Station Controller (BSC) BSC

• • • • •

6

© NOKIA

Connection establishment between the MS and the NSS Mobility management Statistical raw data collection Air- and A-interface signalling support BTS and TRAU Control

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Base Transceiver Station (BTS)

Air interface signalling Ciphering Speech processing (channel coding, interleaving, and burst formatting) • Generation of alarms and statistics • Baseband/Radio frequency transformation • • •

7

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Speech Flow in BSS Speech, 64 kbps MSC

13kbit/s compression

TRAU

TRAU

BTS

Channel Coding = redundancy 22.8kbit/s Interleaving and ciphering

Air Interface

8

© NOKIA

22.8kbit/s GMSK modulation

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

33.8kbit/s

TDMA burst formatting

Interfaces VLR

G

BSS

NSS

D VLR

EIR

B

Um

Abis

F

AC

C

BSC

Ater

BT S

HLR

TC

BT S

A

(G)MSC

E

(G)MSC 9

© NOKIA

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Generic GSM architecture BSS - Base Station Subsystem

OMC

VLR BTS

BSC

HLR

MSC IWF

BTS BTS

EIR BSC

NSS - Network Subsystem PSTN ISDN PSPDN

BTS BTS

10

© NOKIA

NMS - Network Management System

SC

MS Air

Abis

AC

A

CTXX1299en_5.0 / 17.12.2002 / Björn Wigforss

Transcoder