Modeling of Communication Systems

The simulation of a communication system requires a software-representable description of the system. The standard description of a system is a block diagram, where each block represents a signal-processing operation. The block diagram, as such, is really only a signal flow diagram in the sense that it merely indicates the generic type of operations that the signal(s) and noise(s) that drive the system are subjected to. While there are many different types of communication systems using a wide range of technologies, information transmission in all communication systems takes place through a series of basic (or “generic”) signal-processing operations. The following operations are fundamental to all communication systems (although, in a given system, not all operations need appear): source encoding and decoding, modulation and demodulation, multiplexing, error control coding/decoding, filtering (fixed and adaptive), and synchronization. Although many of these terms are usually associated with digital transmission, they can in some cases also be given a meaningful interpretation for analog signals. Figure 4.1 (adapted from Ref. 1) shows a block diagram of a “generic” communication system in the sense that virtually any communication system can be specified as a particular case of this block diagram.