1. Introduction

There are several cellular systems in the world, such as GSM and CDMA. The design of these cellular systems is complicated, but the architecture of most cellular systems can be divided 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 divided 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 the transmission of data and voice. 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 media access control (MAC) protocols that define the rules for entities to access the media.

These air interface standards allow many mobile users to simultaneously share the finite number of radio channels.

c) Base station (BS)

A base station is a fixed station in a mobile cellular system that is used for radio communication with mobile units. They consist of radio channels and a transmitting and receiving antenna mounted on a tower.

d) Databases

Another integral component of a cellular system is databases. The databases are used to keep track of information such as billing, the location of the caller, subscriber data, etc. There are two main databases called Home Location Record (HLR) and Visitor Location Record (VLR). The HLR contains the information of each subscriber residing in the same city as the mobile switching center (MSC). The VLR temporarily stores the information of each visiting subscriber in the coverage area of ​​an MSC. Therefore, the VLR is the database that supports roaming capability.

e) Security mechanism

The security mechanism consists of confirming that a particular subscriber has permission to access the network and also to authenticate billing.

There are two databases that are used for the security mechanism: Equipment Identification Registry (EIR) and Authentication Center (AuC). The EIR identifies stolen or fraudulently altered phones that transmit identity data that does not match the information contained in the HLR or VLR. The AuC, on the other hand, handles the actual encryption and verification for each subscriber.

f) Gateway

The last 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 within the gateway: mobile switching center (MSC) and interworking function (IWF).

The MSC connects cellular base stations and mobile stations to the public switched telephone network (PSTN) or another MSC. Contains the EIR database.

The IWF connects cellular base stations and mobile stations to the Internet and performs protocol translation if necessary.

3. Conclusion

This article aims to provide an introductory guide to the architecture of a typical cellular system and to identify the six basic components found in most cellular systems. This article offers an idea of ​​how a cellular system is designed, although different cellular systems may have variations in their own implementations.