Optimization of Signature Ensembles for SI DS CDMA using Random Search

Performance of direct sequence code division multiple access system (DS CDMA) in a multipath channel can be severely impaired due to high level of multiple access interference (MAI). Usage of signature interleaved (SI) DS CDMA mitigates this problem, reducing dependence of MAI to easily controllable correlations of non-shifted or just one-chip-shifted signatures independently of the maximal multipath delay. In the article selection criterion for signature ensembles for SI DS CDMA is considered. Using random search, correlation properties of the latter can be significantly improved, providing a visible gain in terms of bit error rate (BER).