Multiuser interference suppression is considered for direct-sequence code-division multiple-access(DS-CDMA) system assuming that the spreading waveforms of all users are known. Among various detection schemes for DS-CDMA systems, decorrelating detectors have been studied extensively by many researchers because they significantly outperform the conventional receiver when multiple access interference(MAI) is high or near-far effect is dominant. The application of the decorrelating detectors to synchronous DS-CDMA systems when the signal timing is known but the signal energy is not known at the receiver has been addressed by several researchers and is the problem we address in this dissertation work.
Previously proposed decorrelating detection schemes exhibit high computational complexity because the inverse of the cross-correlation matrix is difficult to compute in real time when the number of active users and the cross-correlations between the users are time-varying in real systems. Hence, the trade-off between the complexity and the performance of the decorrelating detector has been considered and the practical near-decorrelating detectors which have very low computational complexity by approximating the cross-correlation matrix has been proposed.
Simulation results show that the proposed methods have similar performance to the decorrelating detector as the stage increases.
