TABLE OF CONTENTS Mobile phones are now such an everyday feature of life throughout the World that in total they outnumber the population of fixed telephone lines. For many, the mobile phone is the preferred means of communication. This chapter explains how a mobile phone system works and the relationship between mobile and fixed networks. We begin by considering the nature of a mobile system. After a simple review of how a telephone call can be carried over a radio link, we examine the various cellular mobile network systems, and conclude by looking at how the mobile and fixed networks in the future may begin to merge.
Most people would characterise a mobile phone as something that uniquely relies on the use of radio. Indeed, mobile phones do use radio but, not all systems using radio are actually mobile. An example of non-mobile usage of radio is the point-to-point radio links between exchanges and users' premises, as described in Chapter 5. There are, in fact, several characteristics in addition to the use of radio that together distinguish mobile from fixed telecommunications systems. The key characteristics are described below.
A so-called tetherless link is used between the mobile handset and the exchange to enable the required freedom of movement. Whilst in theory there are several technologies that could provide a tetherless link, including infra-red, laser light, etc., invariably a radio link is used. In effect, this radio link performs the role of...
