Receivers for CDMA communication over time-varying Rayleigh fading channels

We study multiuser receiver design and analysis for synchronous CDMA channels with time-varying Rayleigh fading. Starting from an error probability criterion, we first derive a receiver for this channel that admits a detector-estimator decomposition, has certain asymptotic optimality properties and a complexity which is horizon independent. The performance of this detector is analytically characterised and contrasted with that of the single-user (or conventional) detector as well as the optimal multiuser detector for the time-invariant CDMA Rayleigh fading channel when it is implemented over the time-varying channel. Notable among our conclusions is the fact that, unlike the time-invariant channel multiuser detector, the time-varying channel detector is able to withstand not only the estimated interference from the other system users, but also, the residual (unestimatable) interference arising out of imperfect estimation of the interferer fading parameters