Adaptive receivers for DS/CDMA multiuser communication in multipath fading channels

In direct-sequence code division multiple access (DS/CDMA) multiuser communication systems with multipath channels, both intersymbol interference (ISI) and multiple-access interference (MAI) must be considered. The multipath effect usually changes the characteristics of the spreading codes. Modification of the conventional receiver structure is needed to account for the interference of the multipath fading. This paper proposes four adaptive receivers for such multiuser DS/CDMA systems in multipath fading channels. We employ least mean square (LMS) and recursive least squares (RLS) algorithms for both finite impulse response (FIR) and infinite impulse response (IIR) receiver structures. Mean square error (MSE) and convergence analysis are also given in this paper. Simulation results show the performance comparisons of the four proposed receivers.