Wireless Communications & Networking

CHAPTER 4 An Overview of Digital Communication and Transmission

4.1 Introduction

The basic part of any digital communication system is the communication channel. This is the physical medium that carries information bearing signals from the source of the information to the sink. In a radio system the communication channel is the propagation of radio waves in free space (see Figure 4.1). As discussed in Chapter 3, radio waves in free space are subjected to fading. In nearly all communication systems some equipment is required to convert the information-bearing signal into a suitable form for transmission over the communication channel and then back into a form that is comprehensible to the end-user. This equipment is the transmitter and receiver ...