Multi-User Joint Tx/Iterative Rx MMSE-FDE and Successive MUI Cancellation for Uplink DS-CDMA

Uplink multi-user direct sequence-code division multi-access (DS-CDMA) suffers from strong multi-user interference (MUI) and self inter-chip interference (ICI) caused by severe frequency-selective fading. In this paper, we propose a joint Tx/iterative Rx frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion and successive MUI cancellation (MUIC) for DS-CDMA uplink. In the proposed scheme, each user applies one-tap Tx FDE before transmitting signal. At the base station, joint one-tap Rx FDE and successive MUIC is iteratively performed. The FDE weights of users and base station are jointly optimized based on the MMSE criterion in order to reduce MUI and ICI while exploiting channel frequency-selectivity. Computer simulation results show that the proposed scheme provides much improved bit error rate (BER) performance than the conventional iterative Rx MMSE-FDE with successive MUIC.