We consider the use of multistage parallel interference cancellation at the base station of a code-division multiple-access (CDMA) wireless system. Previous work in this area has demonstrated the potential for significant improvements in capacity and near-far resistance. However, most previous work has assumed perfect synchronization with the signals of interest. Practical systems will experience phase jitter and timing errors. We undertake an analysis of the effects of phase and timing errors, obtaining a closed form result for bit-error rate (BER) performance after an arbitrary number of stages of cancellation in an additive white Gaussian noise (AWGN) channel. This result is shown to agree well with simulations. Simulation results are also presented for the important case of frequency selective Rayleigh fading. The results from both analysis and simulations demonstrate that interference cancellation is fairly robust to phase and timing errors.

This paper presents a multistage receiver for code division multiple access (CDMA) systems. Previous multistage receivers have lead to improved multiple access (MA) performance, but require knowledge of received signal powers. This paper proposes a "multistage RAKE" receiver which does not require a priori knowledge of the signal powers or the channel. Performance of the multistage RAKE is simulated for Gaussian and multipath channel models, and for the case of imperfect power control.>