Coherent decorrelating detector with imperfect channel estimates for CDMA Rayleigh fading channels

A coherent multiuser decorrelating detector for an asynchronous CDMA, time-varying Rayleigh fading channel is proposed and analyzed. The detector employs fractionally sampled correlators´ outputs at time instants corresponding to users´ relative delays to simultaneously achieve two goals: the novel realization of a one-shot decorrelator with lower computational complexity; and to exploit a form of the time diversity for improved error performance compared to symbol spaced sampling. The decision statistics are formed from the decorrelator output according to the maximal ratio combining rule. The proposed detector performance is compared to that of a conventional symbol-spaced receiver in a single-user environment, and the impact of the channel estimation error is illustrated