Global System for Mobile Communications - Lecture 1 - Mobile Computing, Lecture notes of Mobile Computing

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Global System for Mobile Communications

TDM

PSTN

AUC

HLR

SCP

SIM

BTS

BSC

Subscriber Identity Module (SIM)

Stores International Mobile Subscriber

Identity (IMSI), identifying the

subscriber, a secret key for

authentication, and other user

information

Can be protected by password

Allows personal mobility

Mobile Equipment -

International Mobile

Equipment Identity (IMEI)

Base Transceiver Station

(BTS) aka “Base Station”

Radio transceivers, defines cell

Radio link protocols with Mobile

800, 900, 1800 and 1900 MHz

frequencies most common

Multiple freq. carriers / BTS

Base Station Controller

(BSC)

Radio channel setup

Handovers

Frequency hopping

Transcoders (TCU) GSM

codec from 13kbps to standard

G.703/64 kbps towards MSC

ME

Base Station Subsystem (BSS)

Mobile Station

Um Abis

A

MSC

GMSC

GSM - Architecture

BSC MSC

HLR

VLR

EIR

AC

BSC

MSC

GMSC

PST

N

PST

N

Um

Um

Abis

A

BTS

BTS

MS

MS

MS - Mobile Station

GSM - Architecture

A Mobile Station consists of two main elements:

The Mobile Equipment or Terminal.

There are different types of terminals distinguished principally by

their power and application:

The `fixed' terminals are the ones installed in cars. Their maximum

allowed output power is 20 W.

The GSM portable terminals can also be installed in vehicles.

Their maximum allowed output power is 8W.

The handheld terminals have experienced the biggest success

thanks to their weight and volume, which are continuously

decreasing. These terminals can emit up to 2 W. The

evolution of technologies allows to decrease the maximum

allowed power to 0.8 W.

The Subscriber Identity Module (SIM).

Mobile Station