Decision Threshold Controlled in Both Receivers of a Communication System with Information Feedback

Abstract

In this work the efficiency of a coded Communication System with Information Feedback (CSIF) is analyzed when its direct and feedback channels are affected by white Gaussian noise. The configuration of the system under consideration is constructed on the basis of two recent patents. These patents are related with the control of detection thresholds in the receivers of both direct and feedback channels. Expressions for calculating the a priori probabilities of the received redundancy symbols in a linear systematic code are obtained. An easy technique to improve the performance of the CSIF direct channel based in the use of optimized detection thresholds for the redundancy symbols in a linear systematic is suggested. The method of using optimized detection thresholds in the feedback channel receiver is also considered. The use of this method on both channels of the CSIF makes this communication system more efficient, because of the energy saving when the signal to noise ratio on both direct and feedback channels is significantly small. A main application area of this improved CSIF scheme is in satellite communications. Keywords: Coded communication system with information feedback, error probability, feedback communication systems, Gaussian white noise, linear systematic codes