Performance optimization of codes DS/SSMA communication systems over a multipath fading channel

Abstract

We consider a coded direct-sequence spread-spectrum multiple access (DS/SSMA) communication system over a multipath Rayleigh fading channel. The relationship among processing gain, code rate, and system transmission bandwidth in maximizing the multiaccess capability is investigated via two approaches. First, we consider convolutionally coded DS/SSMA packet radio system with an ideal RAKE receiver. We analyze the normalized throughput in terms of code rate and processing gain. Second, we analyze the system from an information theoretic point of view. For both cases, it is shown that the multiaccess capability is increased as we decrease the code rate and the processing gain when the overall bandwidth is fixed. It is also shown that there exists an optimum bandwidth which maximizes the throughput.