TABLE OF CONTENTS Over thirty years have passed since the terms spread-spectrum (SS) and noise modulation and correlation (NOMAC) were first used to describe a class of signaling techniques possessing several desirable attributes for communication and navigation applications, especially in an interference environment. What are these techniques? How are they classified? What are those useful properties? How well do they work? Preliminary answers are forthcoming in this introductory chapter.
We will motivate the study of spread-spectrum systems by analyzing a simple game, played on a finite-dimensional signal space by a communications system and a jammer, in which the signal-to-interference energy ratio in the communication receiver s data detection circuitry serves as a payoff function. The reader is hereby forewarned that signal-to-interference ratio calculations alone cannot illustrate many effects which, in subtle ways, degrade more realistic performance ratios, e.g., bit-error-rate in coded digital SS systems. However, the tutorial value of the following simple energy calculations soon will be evident.
The following abstract scenario will be used to illustrate the need for spectrum spreading in a jamming environment, to determine fundamental design characteristics, and to quantify one measure of SS system performance. Consider a synchronous digital communication complex in which the communicator has K transmitters available with which to convey information to a cooperating communicator who possesses K matching receivers (see Figure 1.1 ). Assume for simplicity that the communication signal space has been divided equally among the K ...
