Information Theory, Coding and Cryptography

Chapter 1

Probability, Random Processes, And Noise

1.1  INTRODUCTION

Any signal that can be uniquely described by an explicit mathematical expression, a well-defined rule or a table look-up, is called a deterministic signal. The value of such signals is known or determined precisely at every instant of time. In many practical applications, however, some signals are generated in a random fashion and cannot be explicitly described prior to their occurrence. Such signals are referred to as nondeterministic or random signals. An example of random signal is noise, an ever-present undesirable signal that contaminates the message signal during its passage through a communication link and makes the information erroneous. The composite signal, the desired ...