中文摘要：

以多业务蜂窝中继系统已接入用户的服务质量（QoS）指标、中继负载大小为约束条件，在正交频分多址（OFDMA）方式下，将接入控制问题转化为最大化中继传输下所减少使用的子载波数的问题，并进一步考虑了用户对中继的选择、用户间竞争接入等情况，设计了几种改进的接入控制算法。同时，把这些算法推广到多业务的应用场景中，研究了不同速率业务比例对系统性能的影响。仿真结果表明，所提出的接入算法能支持更多接入用户、降低接入阻塞率和增加节省的子载波数，从而有效地提高了系统容量和资源利用率。

英文摘要：

The admission control problem in multi-service cellular relay systems with orthogonal frequency division multiplexing access （OFDMA） was investigated. Taking the quality-of-service （QoS） requirements and the capability of relay as the constraints, the admission control problem was formulated to maximize the amount of subcarriers decreased by relaying transmission. With further consideration of users＇ selection of relays and the competence among users, several new algorithms were proposed. Meanwhile, the application in multi-service scenario was taken into account, and the effect caused by the ratios of service with different transmission rates was studied. The simulation results verify that the proposed algorithms can support more admitted users, decrease the blocking probability and increase the total number of saved subcartiers, thus effectively improving the system capacity and resource utilization.