Introduction

Communication systems, in their most primitive form, are systems that enable or improve the transmission and dissemination of useful information among people in different locations. Technically speaking, the purpose of a communication system is to transmit messages from an information source to one or more destinations. In general, we can identify four basic components in a communication system, as represented by the functional block diagram shown in Fig. 1.1, namely, information source, transmitter, channel, and receiver [Proakis and Salehi (1994); Wozencraft and Jacobs (1965)].