Architecture of GSM Technology

Table of contents

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INTRODUCTION

GSM (pronounced GEE – ESS –EM) is the most popular cell phone standard, especially when compare to CDMA .The origins of GSM can be traced back to 1982.

When the Group Global System for Mobile communications was one of the second generation mobile .There signal convert Analog to Digital .

According to the “GSM Association(GSMA)” In 2010 GSM achieving 90% market share and operate in 212 country and 5 billion people used .

GSM System provide various feature some of them as follow , Encryption to make calling more secure Short message service.(SMS),Call forwarding ,Caller ID etc. Feature of GSM System.

GSM HISTORY

1982 GSM establish by the developer of European cellular mobile system standard.

1987 TDMA approach adopted as a main access method for GSM by FDM is used between channel and TDM for each individual frequency channel.

1989 European telecommunications takes some responsibility for managing the GSM network.

1990 Phase 1 of the GSM specifications released.

1991 Commercial launch of the GSM service. It was first deployed in Finland .

1993 Coverage of main roads GSM services start outside Europe

1995 Phase 2 of the GSM specifications released

2004 GSM subscriptions reach 1 billion. Announcement made at 3G GSM in Cane.

GSM Architecture

The architecture are divided into 4 block:

Mobile Station.
Base-Station Subsystem (BSS).
Network and Switching Subsystem (NSS)
Operation and Support Subsystem (OSS)

1. Mobile Station:

It consists 2 equipment:

a. Mobile Equipment (ME) : it consist a mobile with sim .Or without sim and every mobile have a unique id i.e. IMEI number because identify done by the IMEI number when mobile are without sim. when ever we want to go mobile in the network the service provider check your IMEI number is in database or not

b. SIM (SUBSCRIBER IDENTITY MODULE) : The sim are (jio, airtel,BSNL etc ). its contains a secret key for authentication or other purpose and there also a pin no.it consist a mobile with sim .Or without sim and every mobile have a unique id i.e. IMEI number because identify done by the IMEI number when mobile are without sim. when ever we want to go mobile in the network the service provider check your IMEI number is in database or not

Whenever any call made. Its connect BTS by A (AIR) interface .

2. Base Station Subsystem (BSS)

It consists of two elements:

a.Base Transceiver Station(BTS ):

The BTS used in a GSM network comprises the radio transmitter receivers.

And Release the signal .and also do signal processing .After its encrypt the signal and also modulation & Demodulation. Its is connect the BSCA VIA Um interface with its associated protocols. After BTS CALL to the BSC.

b. Base Station Controller (BSC)

It controls a group of BTSs. BSC is connected by the BTS and MSC .Its reserve the radio frequency & channel’s and also handle the one BTS to another BTS which are in the BSS .There are many BTS in a BSC .. A BSC connects to the BTS over a Abis interface .Then after BSC send to MSC (mobile switching center ) . For any particular area there is only one MSC . In one MSC there are many BTS.

3.Network Switching Subsystem (NSS)

The GSM system architecture contains a variety of different elements .its also consists home location and visitor location register which provides the call routing and roaming capabilities of GSM .

a. Mobile Services Switching Centre (MSC):

The main element within the core networking area of the overall GSM network architecture is the Mobile switching Services Centre (MSC). Its is the heart of GSM network architecture .

It manage the VLR and BSC for any particular area there are only one MSC also particular MSC there are particular BSC. and it connect the BSS other MSC ,VLR via A interface .

It also handle the mobile subscribers (Registration , Authentication ,Location, routing)

Home Location Register (HLR): This is a Warehouse which stores data belonging to large number of subscribers . it is basically a large database while we purchase a SIM then its fetch the details and update the detail (Customer id , ,bill).

Visitor Location Register (VLR): This contains similar information to the HLR but difference that it store temporary information regarding the individual subscriber data when the subscriber In active state.

Equipment Identity Register (EIR): The EIR is the entity that decides whether a given mobile equipment may be allowed onto the network. Each mobile equipment has a number known as the IMEI (International Mobile Equipment) it checked by the network during registration. access, or monitored in case its problems.

Authentication Centre (AUC): The AUC is for security purpose when we purchase a SIM that contains the secret key also contained in the user’s SIM card. It is used for authentication and for encryption on the radio channel which can remove the fraud call.