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BY

G. Sai Chaitanya SagarN. Sirisha

BY

G. Sai Chaitanya SagarN. Sirisha

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INTRODUCTION

T he two most prevalent mobile communication technologies are :

1. GSM Global System for Mobile CommunicationB ased on TD MA technology Mainly used in Europe, Middle-east and Africa

2. CD MA - Code D ivision Multiple Access

B ased on a spread-spectrum technology Mainly used in North America

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GSM ArchitectureGSM ArchitectureGSM can be broadly divided into 3 parts :

T he Radio Subsystem(B SS, BT S, B SC, MS etc)

T he Network & Switching Subsystem(MSC, HLR, VLR etc)

T he Operation Subsystem(OMC, AuC, EIR etc)

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1. Radio Subsystem

T he Radio Subsytem consists of all radio specific entities like :

a. Mobile Station : It comprises of user equipment & softwaresneeded for communication with GSM networks.

It mainly consists of SIM, which stores all user specific data withrelevant to GSM.MS can be identified through IMEI.

b. B ase Station Subsystem : T his main function is to maintainconnection with the MS.

B SS also contains BT S which comprises of all radio equipment.B oth B SS &BT S is controlled by B SC.

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2 . Network and Switching Subsystem

T his is the heart of the GSM. It consists of the following entities :

a. Mobile Service Switching Centre : T his establishes connectionsbetween other MSCs & B SCs through A interface. It handles all thesignaling needed for connection setup. (SS7)

b. Home Location Register : T his is a database which stores userrelevant information. It consists of static information like callforwarding, GPRS etc and also dynamic information like LA.

c. Visitor Location Register : VLR is a dynamic database whichprovides information whenever there is a new MS.

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3 . OPERATION SUBSYSTEM

T he OSS consists of functions for network operation & maintenance.

a. Operation & Maintenance Centre : It monitors other networkentities via O interface. T ypical maintenance functions are T rafficmonitoring, Security management.

b. Authentication Centre : It is defined to protect user identity andtransmission. It contains algorithms for authentication and keys toencrypt.

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GSM SE RVIC ES

GSM services are a standard collection of applications andfeatures available to mobile phone subscribers all over the

world which are defined by the 3GPP.

It allows users to send and receive data at rates up to 9600bytes per second (bps).

T he common standard makes it possible to use the samephones with different companies' services, or even roam intodifferent countries. GSM is the world's most dominant mobilephone standard.

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A DV A NT A GES OF GSM

1. GSM is already used worldwide with over 450 millionsubscribers.

2. International roaming permits subscribers to use onephone throughout Western Europe. C D MA will work in Asia, but not France, Germany, the U.K. and other popularEuropean destinations.

3. T he availability of Subscriber Identity Modules, which aresmart cards that provide secure data encryption give GSMm-commerce advantages.

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CDMA - AR

CHITE

C TURE

CD MA is a channel accessMethod used by various radio

Communication technology.

CD MA employs spread spectrumtechnology and a special codingScheme to allow multiple users to bemultiplexed over the samephysical channel.

CD MA has relatively higher bandwidth compared to others.

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W ORKIN G OF CD M A

CD MA works by converting speech signals into digital signals, which are then transmitted over a wireless network and thendecoded at the receiver's end.

CD MA works by converting speech signals into digital signals, which are then transmitted over a wireless network and thendecoded at the receiver's end.

Each user in a C D MA system uses a different code to modulatetheir signal. Choosing the codes used to modulate the signal is very important in the performance of C D MA systems.

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F EATUR ES OF CD M A

Spread the spectrum using Orthogonal codes.

All the terminals can be active at the same place, atsame moment uninterrupted.

Used in many 3G systems due to higher complexity

and as it is integrated with TD MA/FD MA.

Contains complex receivers, needs more complicatedpower control for senders.

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A DV A NT A GES OF CD M A

y Increased cellular communications security.

y Simultaneous conversations.

y Increased efficiency, meaning that the carrier can servemore subscribers.

y Low power requirements and little cell-to-cell coordinationneeded by operators.

y Extended reach - beneficial to rural users situated far fromcells

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DI S A DV A NT A GES OF CD M A

y D ue to its proprietary nature, all of C D MA's flaws are notknown to the engineering community.

y CD MA is relatively new, and the network is not as matureas GSM.

y

CD MA cannot offer international roaming, a large GSMadvantage.

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C ONCLUSION

y T he wireless world is divided into two camps, GSM (used in alarge part of Western Europe) and C D MA (used in North America and parts of Asia). Just two years before C D MA wasintroduced in Hong Kong in1995, European manufacturers choseto support the earlier technology, GSM's TD MA...

y CD MA poses a threat to GSM. It makes full use of the limitedbandwidth by squeezing in several calls. So handsets that useCD MA technology are smaller and slicker, have better voice anddata quality...

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QUERIES????

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