中文摘要：

在基于IEEE 802．11分布协调功能的无线局域网中，为解决每次beacon帧发送后竞争加剧的问题，提出了一种最优省电模式．该机制以成功竞争到信道的站点个数最大化为目标，通过修改beacon帧中的业务指示表域限制过度竞争．该机制定义了下行优先级区分度参数α，以刻画不同业务优先级的差距；建立了使用标准省电模式和最优省电模式时，下行固定速率业务的功耗模型．理论分析和仿真结果表明，该机制能显著改善无线局域网的吞吐量和功耗性能，并可区分优先级．

英文摘要：

In the IEEE 802.11 distributed coordination function based wireless local area network （WLAN）, a new downlink access scheme optimal power saving mode （OPSM） is proposed to solve the problem of over contention after beacon transmissions. To maximize the number of stations which contend the channel successfully, OPSM configures the traffic indication map （TIM） fields in beacon frames to constrain collisions. The downlink priority differentiation degree α is defined to describe the quality of service （QoS） gap between different services. Furthermore, the power consumption of downlink constant bit rate service with standard 802.11 PSM and OPSM are modeled. Analysis and simulation results validate the performance improvement and the priority differentiation by configuring α.