A study of adaptive communication systems

Three types of adaptive communication systems are studied. These are the receiver-only systems, the transmitter-only system, and the feedback systems. The theoretical performance of a multi-receiver, operating in a Rayleigh fading medium, is analyzed. Successive transformations of a multi-variate random function are used to derive the probability density functions needed to predict the performance of the multi-receiver. This method is advantageous when the joint probability density function of the multi-variate random variable is difficult to obtain by a more direct method. The transmitter-only type of adaptive system is studied and a feasible method of data compression is proposed by using finite difference table computers. The zero entries in the table are shown to be significant in being able to predict successive values of a periodically sampled function. An intermittent feedback adaptive system is analyzed in a Rayleigh fading medium. Performance predictions for the intermittent system are given to illustrate the advantage of such a system over the conventional systems. The similarity, in terms of system performance, is noted between the intermittent system and the multi-receiver. The comparison shows the intermittent system performance better or at least equal to the multi-receiver when the multi-receiver measures one propagation path. The general performance of a binary PCM telemetry system operating in a free space medium is investigated. The analysis is one of a parametric study of variations in transmitter power and system bandwidth along with their influence on system performance. The Apollo Communications System is briefly discussed and the adaptive aspects of the system are shown. Using the Apollo system as a guide, a self-adaptive communications system employing a model-reference is proposed along with a discussion of the communication system philosophy implied by such a system.