BY

SATYENDRA SINGH RATHORE(11OO331054)

Electronics & Communication Engg.

GSMFundamentals

GSM History1981 Analogue cellular introduced

Franco-German study of digital pan-

European cellular system

1987 MoU signed by over 18

countries

1989 GSM was moved into the ETSI

organization

GSM name changed to Global

System for Mobile communications.

1990 DCS1800 (edited GSM900)

specificationdeveloped

In 1981 analogue cellular was introduced and at about the sametime there was a joint Franco-German study looking at digitalcellular technology and the possibility of making a pan-Europeansystem.

In 1982 a special working committee, Groupe Spécial Mobile(GSM), was formed within the CEPT to look at and continue theFranco-German study.

Description

In 1989 GSM was moved into the ETSI (European

Telecommunications Standards Institute) organization.

Once

under the control of ETSI, the GSM system had it's name

changed to Global System for Mobile communications.

The

committees working on the system changed from GSM

to SMG

(Special Mobile Group). These changes avoided

confusion

between the system name (GSM), and the people

working on the

GSM (Global System for Mobile Communications

Originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones.

It is the default global standard for mobile communications with over 90% market share, and is available in over 219 countries and territories

GSM NETWORK

General architecture of a GSMnetwork

SIM: Subscriber identify module.

ME: Mobile equipment.

BTS: Base transceiver station.

BSC: Base station controller.

HLR: Home location register.

VLR: Visitor location register.

MSC: Mobile services switching center.

EIR: Equipment identity register.

AuC: Authentication Center.

UM: Represents the radio link.

Abis: Represents the interface between the

base stations and base station controllers.

"A": The interface between the base station

subsystem and the network subsystem.

PSTN and PSPDN: Public switched telephone network and packet switched public data network.

FULL FORMS USED IN DIAGRAM

GSM CHANNEL PLANS

Above is a table that shows the relative frequency plans of the three GSMnetworks: GSM900, DCS1800 and PCS1900.

The frequency range of the Uplink and Downlink show how the two bandsare split into the two directions, rather than an uplink being followed by adownlink 200kHz later.

EWSD ( Electronic Digital Switching System/Electronic World Switch Digital) is one of the most widely installed telephone exchangesystems in the world.

EWSD can work as a local or tandem switch or combined local/tandem, and for landline or mobile phones.

It is manufactured by Siemens AG, who claims that EWSD switches perform switching for over 160 million subscriber lines in more than 100 countries.

Bosch built its first EWSD as a local exchange in 1986.

EWSD INTRODUCTION

Hardware

Main subsystems are:

CP (Central Processor)

MB (Message Buffer)

CCNC (Common Channel Network Control)

LINE (Analog Line Group)

LTG (Line Trunk Group)

DLU (Digital Line Unit)

SN (Switching Network)

PA (ISDN Primary Access)

PDC (Primary Digital Carrier)

Software

The software of EWSD is called APS (Automatic Program System). The APS is on a hard drive and includes the operating system, developed by Siemens in cooperation with Bosch.

It is predominantly written in the CHILL language. Application software is switch specific and serves among other things traffic management, path search, and call charging.

Support software serves translating programs, binding modules as well as administration of libraries for generating data. Operating and data communication software serve for co-operation of maintenance centers and switching centers

Technical data

Number of access lines: to 250,000

Number of feeder lines: 240,000

Traffic connection: 25,200

Call attempts in busy hour: 10 million

Operating voltages: -48V -60V -90V

Rate zones: 127, for each zone of 6 tariffs

Tariff change-over at 15 minute intervals

Space requirement with 10,000 access lines: 35 square meters