中文摘要：

在传统的组播策略中,系统总的吞吐量受限于组播组中最差用户的信道增益.为了克服组播系统吞吐量受限的问题,采用基于分层编码的组播策略.在保障组内每个用户的服务质量（QoS）的同时,提出了一个新颖的子载波和比特分配算法,来最大化整个组播组的吞吐量.在下行的正交频分多址无线组播系统中,提出了最优资源分配算法.为了减少最优化算法的计算复杂度,提出了一个2阶段次优化算法.仿真结果显示,次优化算法的系统功效十分接近最优化算法.次优化算法要远远优于传统的组播策略,而且还要优于Tian等所提出的算法.

英文摘要：

In conventional multicast scheme （CMS） , the total throughput of multicast group is constrain- ed by the user with the worst channel quality. In order to overcome the limited throughput problem, a multicast scheduling was considered based on layered coding. A new subcarrier and bit allocation algo- rithm is exploited for targeting the maximum throughput of a whole multicast group while at the same time guaranteeing the quality of services （QoS） requirements of all users. The article proposed an optimal re- source allocation algorithm in the downlink of OFDMA-based wireless multicast group. A two-phase sub- optimal algorithm was proposed as well to reduce the computational complexity. Simulations 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 Tian＇s algo- rithm.