A two-stage adaptive MMSE detector for synchronous DS-CDMA system in a Rayleigh fading channel

In this paper, a two-stage adaptive minimum mean-squared error (MMSE) detector for synchronous DS-CDMA system is considered in a Rayleigh fading channel. The near-far effect causes performance degradation of a DS-CDMA system. To improve performance of the adaptive MMSE detector in a near-far environment, a near-far resistant decorrelating decision-feedback detector (DDFD) is combined with the adaptive MMSE detector in which a normalized least mean square (NLMS) algorithm is utilized as an adaptive algorithm. The performance of the proposed receiver is evaluated by simulation and compared with that of other suboptimum multiuser detectors. Through the numerical results, it is shown that the proposed receiver achieves significant performance improvement at the expense of a modest increase in computational complexity.