Channel-estimator-aided parallel interference cancellation for CDMA systems in multipath fading channels

This paper introduces an improved multistage parallel interference cancellation (PIC) whose weights are optimized by processing information from channel estimators. An expression determining the optimal interference cancellation weight (OICW) for partial parallel interference cancellation (PPIC) in multipath fading channels is derived and then a new weight-optimizing scheme for PPIC is proposed. Stage by stage, the proposed scheme can make the variance of residual interference less and less and is applicable to multi-rate CDMA systems. The simulation results in single-rate and multi-rate CDMA systems validate our reasonable assumption and show that the proposed scheme makes bit error rate (BER) at the following stage less than that at the previous stage. It is indicated that the proposed PPIC performs better than CW-PPIC with best interference cancellation weight (ICW), still more conventional PIC. Moreover, at a BER of 0.01. the performance loss of the proposed PPIC stage 2 is only 1.5dB, compared to PPIC with channel-known interference of one stage.