Performance analysis of MMSE based adaptive multiuser detection of DS-CDMA signals in dispersive and non-dispersive channels

The performance of the minimum mean squared error (MMSE) based adaptive multiuser detection (MUD) of direct-sequence code-division multiple access (DS-CDMA) signals in dispersive and non-dispersive channels is considered. DS-CDMA is a popular multiple-access technology for wireless communication. However its performance is limited by multiple-access interference (MAI) and multipath distortion. Adaptive techniques for detection of DS-CDMA signals improves the performance of the CDMA system by reducing interference among users by employing two major types of adaptive technique called least mean squares (LMS) and recursive least square (RLS) in non-dispersive channels. In this paper the diversity scheme called maximum ratio combining (MRC) as preprocessor to the adaptive MMSE detector of DS-CDMA system in dispersive channel is introduced. Simulations have proved its better performance compared with the conventional Match Filter detector, performing nearly as well as single user case.