MULTIUSER DETECTION IN MISMATCHED MULTIPLE-ACCESS CHANNELS

In this paper we consider an additive white Gaussian noise multiple-ac cess channel and investigate the performance degradation of several mu ltiuser detectors due to imperfect knowledge of channel parameters, in duced by either estimation errors or sampling/quantization of the rece iver's sufficient statistics. The symbol error rates and the asymptoti c multiuser efficiencies (AME's) of these detectors are examined as fu nctions of both true and approximated channel parameters for 2 asynchr onous users. The results quantify the loss of near-far resistance due to parameter estimation errors and demonstrate that detectors which ar e optimal for ideal conditions are often more sensitive to parameter m ismatch. Examples are given which illustrate a reverse ordering of the symbol error rates for these detectors in the high signal-to-noise re gime, and also illustrate cases when the conventional matched-filter d etector exhibits superior performance over multiuser detectors.