Combination of adaptive multiuser detection and parallel interference cancellation technique for DS-CDMA systems

Abstract

Two kinds of the adaptive multi-stage multiuser detectors are implemented for DS-CDMA. One is the adaptive MMSE/PIC multiuser detector and the other is the adaptive decorrelating/PIC multiuser detector. These detectors can be implemented by combining the adaptive multiuser detection schemes with the parallel interference canceller (PIC). From the simulation results and numerical calculation results, it is apparent the performance of the adaptive MMSE/PIC and the adaptive decorrelating/PIC detectors are very closed to that of the non-adaptive MMSE/PIC and nonadaptive decorrelating/PIC detectors. Also it was shown that the performance of these detectors is much better than that of the conventional detector and decorrelating multiuser detector and that they are near-far resistant. As the power of the interference increases the performance of MMSE/PIC and decorrelating/PIC approaches a single user bound. In addition, the adaptive algorithm does not require calculation of the cross-correlation and the inversion of the cross-correlation. Therefore, it is efficient to use the adaptive multiuser detectors instead of non-adaptive multiuser detectors it view of the system complexity.