Performance of partial parallel interference cancellation for complex spreading CDMA systems in fading channels

Partial parallel interference cancellation (PPIC) for wideband code division multiple access (WCDMA) uplink with complex spreading is investigated in this paper. The channel model assumes independent paths with Rayleigh fading statistics. The effects of the receiving bit error rate (BER) of last stage, interference cancellation weight (ICW), the power ratio of pilot to date channels, multiple access and multipath interference, additive white Gaussian noise (AWGN) and channel estimation error are analyzed. Then, the BER performance of multi-stage PPIC is evaluated through characteristic function method. Results indicate that all factors determining the optimal weight certainly affect the BER performance of PPIC. Optimal weight PPIC (OW-PPIC) have better BER performance than constant weight PPIC (CW-PPIC) utilizing the fixed best weight. It is shown that the power ratio of pilot to data channels has more impact on the performance of the following stage of PIC than that of the previous stage of PIC. Finally, theoretic results are verified by Monte-Carlo simulation.