Multipath interference canceller for orthogonal code-multiplexed channels and its performance in W-CDMA forward link

This paper proposes a multipath interference canceller (MPIC) for orthogonal code multiplexed channels in the W-CDMA forward link and evaluates by computer simulation the improvement in BER performance owing to the multipath interference (MPI) suppression effect obtained by the MPIC. The simulation results show that a one-stage MPIC, which removes the MPI from the common pilot channel (PICH), common control channel (CCH), and synchronization channel (SCH), achieves a sufficient MPI suppression effect, and that the required received E-b/N-0 of the traffic channel (TCH) at the average BER of 10(-3) using the MPIC for the common channels is decreased by approximately 6.5 dB compared to that with a matched filter (MF)-based Rake receiver (the transmit power ratio of each common channel to TCH: Delta(PICH/TCH) = 0dB, Delta(CCH/TCH) = 5dB Delta(SCH/TCH) = 3 dB, without fast transmit power control (TPC) and antenna diversity reception). We also show that by using MPIC, the required transmit E-b/N-0 at the average BER of 10(-3), when the ratio of the target E-b/I-0 of the 9-interfering users to desired user is Delta(Int)/(Des) = 6 dB with fast TPC, is increased by only approximately 0.6 dB compared to that when Delta(Int)/(Des) = 0dB. This implies that the preferential MPI suppression from high-rate TCHs that abates the increase in complexity in a mobile terminal is effective in increasing the link capacity in the forward link.