提出了一种多用户OFDM系统中支持QoS的跨层资源分配策略。在MAC层采用有限长用户缓存模型,推导了丢包率要求引起的用户速率限制条件,将其作为跨层信息指导物理层资源分配过程。根据等待时延对用户进行分级,在保证所有用户QoS的前提下为“高级用户”优先分配子载波和功率。仿真表明,在报文到达率较高的情况下该策略既保证了吞吐量,又降低了系统丢包率。 A cross-layer resource allocation strategy supporting QoS in multi-user OFDM system is proposed. In the MAC layer, a limited length user caching model is adopted to deduce the user rate constraint caused by the packet loss rate requirement as a cross-layer information to guide the physical layer resource allocation process. According to waiting for the delay to classify users, all users are assured QoS under the premise of “Advanced User ” to preferentially allocate subcarriers and power. The simulation results show that the strategy not only guarantees the throughput but also reduces the system packet loss rate when the packet arrival rate is high.