Adaptive multiuser receivers with diversity reception for nonselective Rayleigh fading asynchronous CDMA channels

We investigate the performance of low-complexity decorrelating multiuser receivers with diversity reception in frequency-nonselective Rayleigh fading asynchronous CDMA channels. The impact of fading dynamics on the differentially coherent receiver with equal-gain combining is quantified. We also analyze an adaptive coherent multiuser receiver utilizing decision-directed carrier recovery and maximal ratio combining, and bound its error probability showing the impact of imperfect channel estimates and multiple-access interference. Both multiuser receivers have superior performance compared to their conventional counterparts. The comparison of two receiver structures indicates that the coherent decorrelating detector with diversity reception is preferable in nonselective fading CDMA channels with memory