Decision Feedback Equalizer Based Multiuser Detection in DS-CDMA Systems

Abstract—In this paper, we investigate the architecture and performance of a decision feedback equalizer (DFE) based multiuser receiver for asynchronous direct sequence code division multiple access (DS-CDMA) systems. The DFE consists of a feedforward filter (FFF) and a feedback filter (FBF) to combat the intersymbol interference (ISI) and multiple access interference (MAI). We use an adaptive, centralized decision feedback scheme where, in addition to the feed forward estimates, the previous and current decisions of the interfering users’ data are taken into account. We evaluate the performance of the DFE based receiver on both AWGN as well as Rayleigh fading channels in a near-far scenario. The proposed DFE receiver structure is shown to exhibit good near-far resistance and offer significant performance advantage over linear adaptive receivers which use only feedforward filters.