中文摘要：

研究了OFDMA中继下行链路通信系统中的动态资源分配问题，提出了一种可以保证用户最低QoS需求的资源分配算法．首先在简化资源优化问题的过程中，采用等功率分配方法以降低算法复杂度，然后通过拉格朗日松弛优化方法推导出了子载波分配和中继选择最优解，并在此基础上引入用户速率权衡因子，根据速率权衡因子越大的用户，越具有选择子载波和中继的优先权这一准则进行子载波分配和中继选择．仿真结果表明：新算法能够获得较高的系统容量，同时也能很好地保证不同用户的最低速率需求．

英文摘要：

The problem of dynamic resource allocation for downlink orthogonal frequency-division multiple-access （OFDMA） relay systems is studied, and a new resource allocation with quality of service （QoS） constraints is proposed in this paper. Firstly, in order to reduce the complexity, the algorithm uses equal power allocation in the process of simplifying resources optimization problem. Then, the subcarrier allocation and relay selection scheme is derived through Lagrangian relaxation optimization method, based on which each user is assigned a weight factor. The users with higher weight are given higher priority to select their best subcarriers and relays. The simulation re：ults demonstrate that the algorithm can not only obtain high system capacity, but also guarantee the minimum rate requirements of different users.