Adaptive Variable-Rate Communication System for Fading Channels

Abstract

Diversity techniques have been in use since long for communication over fading channels. Alternatively, adaptive feedback techniques have been suggested to improve the performance of communication systems in the presence of fading. Either the transmitter power or the transmission rate can be varied adaptively, depending on the channel condition, the information about which is sent on the feedback channel.

A variable-rate communication system has been described and the results of the study of a generalized adaptive system have been presented in this paper. Adaptation strategies for different systems have been discussed. A comparison of the systems based on the optimum power adaptation, optimum rate adaptation and the diversity reception has been made. A technique has been proposed which would eliminate the necessity of a large buffer storage, as required in adaptive rate systems.

Indexing terms:

• Adaptive communication
• Variable-rate communication system
• Fading channels