Chapter 4 - Cellular basics

Abstract

There are many different cellular radios or cellular telecommunication systems in use around the world. Naturally, they have many differences in the way they operate. Not only are there different implementations of similar technologies but there have also been developments in the technologies that are used. One of the key requirements for any radio-based telecommunication system is the efficient use of the frequencies that are available. Any cellular telecommunications system needs to have a method to allow multiple subscribers access to the system. These are called multiple access schemes, and there are three main methods that are in use: frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). The concept of a cellular phone system is that it has a large number of base stations, each covering a small area of cells. A as a result, frequencies can be reused. Cell-phone systems also provide mobility. It is therefore a basic requirement of the system that as the mobile handset moves out of one cell and into the next, it must be possible to hand the call over from the base station of the first cell to that of the second with no discernable disruption to the call. There are two terms for this process: “handover” is used within Europe and “handoff” in North America. The first analogue systems gave way to digital systems, and in turn, these are being migrated to technologies that are able to carry much higher data-rate signals to cope with the new applications that are being found.