Performance of Frequency-Hopped Spread-Spectrum Multiple Access Communication Systems with Readable Erasures

Abstract

As a way to improve user capacity, we introduce and evaluate in this paper the readable-erasure channel for frequency-hopped spread-spectrum multiple access systems using MFSK modulation scheme (FH/MFSK). For an MFSK scheme, in contrast to the erasure-only channel having M +1 outputs, the readable-erasure channel has 2M outputs, M of which correspond to the outputs when no hits occur and M of which represent the outputs when channel is hit. For comparison purposes, the performances of readable-erasure and erasure-only channels both using Reed-Solomon codes and using BCH codes are evaluated. It is shown that the readable-erasure outputs can help to improve user capacity. By taking the spectral efficiency into consideration, we point out that directly applying RS codes to the FH/MFSK systems is very inefficient in spectrum utilization. Instead, the channel with readable-erasure outputs using BCH codes and 4-ary FSK is suggested for FH/MFSK systems.