A multicarrier DS/SSMA system with reduced multiple access interference and higher data rate in Rician fading channels

Abstract

We propose to use multiple signature sequences (instead of one) per user in a multicarrier direct-sequence spread spectrum multiple access system in Rician fading channels. Every user has a distinct set of spreading sequences, with a different spreading sequence for each carrier in each user's set. By analysis and computer simulation, we show that when these sets of sequences are chosen to be mutually orthogonal complementary sets of sequences, multiple access interference (MAI) is reduced in Rician fading channels. We also show that we can pack symbols more closely together, resulting in a higher data rate. The proposed system with a distinct set of deterministic spreading sequences per user has lower MAI and higher data rate than another system with one distinct random spreading sequences per user in Rician fading channels.