Analysis of a Hybrid Frequency - Time Hopping Random-Access Satellite Communication System

Abstract

This paper analyzes the multiple-access performance of a satellite communications network, in which each subscriber employs a hybrid frequency-time hopping random-access technique for the transmittal of binary information by means of a linear average power limited satellite repeater. The information is repetitively encoded into a number of binary chips. Individual mark and space chips are matched filter envelope detected and pairwise compared; the final binary decision is based upon a majority vote. The present analysis extends previous results by simultaneously taking into account RF phase cancellation effects at the satellite as well as up- and down-link noise. Some numerical results are presented using system parameters typical of a small subscriber net. The multiple-access performance of the frequency-time hopping system is (for the assumed parameters and a bit error rate of 10-5) found to be about 6.6 dB poorer than that of a comparable orthogonal multiple-access system.