EVALUATION OF D2D-ASSISTED TWO-STAGE MULTICAST WITH RESOURCE BLOCK REUSE IN LTE ACCESS NETWORKS

摘要

A two-stage multicast scheme in a wireless LTE (Long Term Evolution) or I.TE-Advanced acccss network is considered. The two-stage multicast includes the de-vice-to-device (D2D) communication in the second stage to improve the wireless transmission quality. The D2D communication also reuses CUE (cellular-network user equipment) resource blocks to minimize the resource block usage. There are three steps in the proposed two-stage multicast. First, multicast recipients form clusters and, for each cluster, a cluster head is elected by considering the channel gains between cluster members and the base station. Second, reusable resource blocks are identified and suitable cluster head transmission power is calculated for every cluster by considering the interferences between cluster members and CUEs. The third step is to execute the two-stage multicast, where the base station transmits data to the cluster head in the first stage, and then the cluster head multicasts with the above calculated power to all members in the second stage. Since the first-stage multicast and the second-stage multicast use downlink resource blocks and uplink resource blocks respectively, pipe-lining of the two multicasts is feasible, greatly reducing the multicast delay, which is a more meaningful metric than throughput sum in evaluating the multicast performance. We evaluate the delay time, resource usage, and power consumption, for both two-stage multicast and one-stage multicast by varying the cluster size and the distance between base station and the cluster. Our results show that two-stage multicast is better than one-stage multicast when the cluster is far away from the base station and the cluster size is small.