9 DIGITAL MOBILE RADIO COMMUNICATION SYSTEMS

This chapter describes digital mobile radio communication systems. Some basic concepts are discussed first, followed by system descriptions. At the time of writing the first edition of this book, the situation on digital mobile system had been changing rapidly and new systems were appearing. However, in my opinion, the new system evolution rush has passed its peak now. For further description of mobile radio communication systems, the reader may refer to references [1–11] for rather old systems and [12] and [13] for the latest ones.

9.1 FUNDAMENTAL CONCEPTS

This section introduces some basic concepts of digital mobile communication systems: cellular systems, multiple access, channel allocation, multiplexing, intercell interference suppression and repeating system are described.

9.1.1 The Cellular Concept

In a cellular system, a service area is covered with many small zones or cells (Fig. 9.1). A zone is illuminated by a base station. With this system, the system capacity, that is, the number of subscribers that can be accommodated, can be increased through reuse of radio channels at different cells where cochannel interference can be neglected. Thus, a cell group is repeated to cover the total service area. In addition, a lower transmit power is possible because of the smaller coverage of a base station compared to a single-cell system with a large coverage area. On the other hand, the cellular system needs sophisticated procedures ...

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