1˳ Introduction
There are various cellular systems in the world, such as the GSM and CDMA˳ The design of these cellular systems are complicated but the architecture of most cellular systems can be broken down into six basic components˳
In this article, I will illustrate the six basic components that can be found in most cellular systems˳
2˳ Six basic components of Cellular Systems
The architecture of most cellular systems can be broken down into the following six components:
a) Mobile Station (MS)
A mobile station is basically a mobile/wireless device that contains a control unit, a transceiver and an antenna system for data and voice transmission˳ For example, in GSM networks, the mobile station will consist of the mobile equipment (ME) and the SIM card˳
b) Air Interface Standard
There are three main air interface protocols or standards: frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA)˳ These standards are basically the medium access control (MAC) protocols that define the rules for entities to access the communication medium˳
These air interface standards allow many mobile user to share simultaneously the finite amount of radio channels˳
c) Base Station (BS)
A base station is a fixed station in a mobile cellular system used for radio communications with mobile units˳ They consist of radio channels and transmitter and receiver antenna mounted on a tower˳
d) Databases
Another integral component of a cellular system is the databases˳ Databases are used to keep track of information like billing, caller location, subscriber data, etc˳ There are two main databases called the Home Location Register (HLR) and Visitor Location Register (VLR)˳ The HLR contains the information of each subscriber who resides in the same city as the mobile switching center (MSC)˳ The VLR temporarily stores the information for each visiting subscriber in the coverage area of a MSC˳ Thus, the VLR is the database that supports roaming capability˳
e) Security Mechanism
The security mechanism is to confirm that a particular subscriber is allowed to access the network and also to authenticate the billing˳
There are two databases used for security mechanism: Equipment Identify Register (EIR) and Authentication Center (AuC)˳ The EIR identifies stolen or fraudulently altered phones that transmit identity data that does not match with information contained in either the HLR or VLR˳ The AuC, on the other hand, manages the actual encryption and verification of each subscriber˳
f) Gateway
The final basic component of a cellular system is the Gateway˳ The gateway is the communication links between two wireless systems or between wireless and wired systems˳ There are two logical components inside the Gateway: mobile switching center (MSC) and interworking function (IWF)˳
The MSC connects the cellular base stations and the mobile stations to the public switched telephone network (PSTN) or other MSC˳ It contains the EIR database˳
The IWF connects the cellular base stations and the mobile stations to Internet and perform protocol translation if needed˳
3˳ Conclusion
This article aims to provide an introductory guide to the architecture of a typical cellular system and identify the six basic components found in most cellular systems˳ This article offers an insight towards how a cellular system is designed although different cellular systems may have variations in their own implementations˳
Source by https://ezinearticles˳com/?Basic-Components-of-Cellular-Systems&id=1752247
