Minimum probability of error for asynchronous Gaussian multiple-access channels
IEEE Transactions on Information Theory
Microwave Mobile Communications
Microwave Mobile Communications
Spread spectrum access methods for wireless communications
IEEE Communications Magazine
Wireless Personal Communications: An International Journal
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Since the conventional detector performs poorly inbandwidth-efficient Code Division Multiple Access(CDMA) systems, several multiuser detectors wereproposed recently. In this paper, we compareperformance of the decorrelator, the two-stagedetector (2S), and the decision-feedback detector (DF)for the Rayleigh flat fading synchronous CDMA channel. First, assuming perfect channel estimation, we showthat the 2S and the DF have much lower bit error rate(BER) than the decorrelator, and prove that the idealDF has unity Asymptotic Multiuser Efficiency (AME). Furthermore, we evaluate the performance of thesedetectors in the presence of channel mismatch. Wemodel the Rayleigh flat fading channel as the secondorder Auto Regressive (AR) process, and use the Kalmanfilter as the channel estimator. The lower bounds onthe BER of the 2S and the DF are derived. Theanalytical results and the simulations show that theestimation error accumulated due to cancellation ofother users limits the performance of the 2S and theDF. Therefore, in the presence of channel mismatch,the decorrelator offers comparable or even betterperformance than more complex decision-feedback andtwo-stage detectors.