A Chase Based Multistage Parallel Interference Cancellation Scheme for Asynchronous Fading Channels

A key issue in a multistage parallel interference cancellation (PIC) scheme is to improve the hard decision accuracy after matched filters (MFs). For achieving this purpose, one category of PIC schemes keeps the hard decision values after MFs intact and focuses on choosing the suitable weight for each user in current stage so that the hard decision accuracy is improved as much as possible in the next stage. Another category of PIC focuses on optimizing the hard decision values in current stage. Rather than directly using the hard decision values after MFs to do the interference cancellation, this approach reviews the possible hard decision combinations and selects the one minimizing a cost function as the final hard decision result to do the interference cancellation. In Liu Feng et al. (2006), a new PIC scheme using the normalized least-mean-square (NLMS) at the earlier stages and Chase in the later stages for synchronous Rayleigh fading channels is proposed. In this paper, the proposed technique is applied to asynchronous Rayleigh fading channels. Simulation shows that the proposed scheme can achieve a better performance than multistage NLMS-PIC but with complexity reduction.