Fast Shared Feedback Methods for Uplink CoMP with H-ARQ

Abstract

An efficient direct feedback method from coordinated base stations (BSs) to a mobile station (MS) for an uplink (UL) coordinated multipoint (CoMP) reception with supporting hybrid automatic-repeat-request (H-ARQ) transmission is proposed. Acknowledgement (ACK)/negative acknowledgement (NACK) feedback based on local detection at each BS in the CoMP set is directly transmitted from the BSs using shared-feedback resources. Therefore, an MS can obtain global ACK/NACK information without experiencing extra backhaul delay with a small feedback overhead, and we can reduce the H-ARQ retransmission latency for the inter-cell UL-CoMP operation. To minimize the ACK/NACK detection error at the MS, we investigate the optimized design methods for shared-feedback resources. We derived the analytical detection error probability of the proposed feedback method and the optimum sub-block size to minimize misdetection probability for a fixed overhead and false alarm rate. Based on the analytical and computer simulation results, we have verified that the proposed feedback method can provide a reliable detection performance with a small feedback overhead. In addition, system level simulation results show the proposed fast feedback based inter-cell UL-CoMP system increases the system throughput compared to the conventional intra-cell UL-CoMP without increasing the feedback latency.