Multipath interference canceller using soft-decision replica combined with hybrid ARQ in W-CDMA forward link

This paper proposes a multipath interference canceller (MPIC) that employs soft-decision replica generation combined with hybrid ARQ (HARQ) to achieve a peak throughput of more than 10 Mbps in a multipath-fading environment in the W-CDMA forward link. In the proposed scheme, more accurate multipath interference (MPI) replica generation is possible by decreasing the influence of data-decoding errors associated with the reliability of the originally transmitted and retransmitted packets. Simulation results elucidate that by applying the soft-decision replica, a four-stage MPIC improves the peak throughput by approximately 300 kbps and I Mbps with 64QAM data modulation in an average equal level 2- and 3-path Rayleigh fading channel compared with the MPIC using the hard-decision replica, respectively. In addition, by effectively combining the originally transmitted packet with the identical retransmitted one in soft-decision MPI replica generation, the throughput performance is further improved by approximately 300 kbps in a 3-path environment. Consequently, we clarify that the maximum peak throughput using the proposed MPIC achieves approximately 11.8 and 10.4 Mbps with 64QAM data modulation in a 2- and 3-path Rayleigh fading channel, respectively, within a 5-MHz bandwidth.