A layered-based resource allocation algorithm for multicast services in OFDMA system

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, we consider an opportunistic multicast scheduling (OMS) based on layered coding. A novel subcarrier and bit allocation algorithm is exploited for targeting the maximum throughput (MT) of a whole multicast group while at the same time guaranteeing the quality of services (QoS) requirements of all users. In this paper, we propose an optimal resource allocation algorithm in the downlink of OFDMA-based wireless multicast group. A two-phase suboptimal algorithm is proposed to reduce the computational complexity. Simulation results show that the performance gap between the optimal algorithm and the proposed suboptimal algorithm is quite small. The proposed algorithm significantly outperforms CMS. Moreover, it obtains more throughput than another existing algorithm.