Performance of multistage weight-optimized parallel interference cancellation with imperfect channel estimation

In this paper, we derive closed-form expressions of the optimal interference cancellation weight (OICW) and evaluate bit error rate (BER) performance for multistage partial parallel interference cancellation (PPIC) over multipath fading channels in the case of perfect and imperfect channel estimation. The channel model assumes independent path with Rayleigh fading statistics. The effects of receiving BER of last stage, power ratio of pilot to date channels, multiple access and multi-path interference, additive white Gaussian noise (AWGN) and the factors affecting channel estimation error are analyzed. Then, the BER performance for multistage PPIC with complex spreading is evaluated by characteristic function method, indicating that all factors determining the optimal weight certainly affect the BER performance of PPIC. Performance of optimal weight PPIC (OW-PPIC), constant weight PPIC (CW-PPIC) and PPIC with perfect channel estimation (PCE-PPIC) is compared by analysis and simulation, indicating that OW-PPIC employing two stages achieves the performance near to PCE-PPIC with one stage.