中文摘要：

随着无线网络应用的不断发展，为了适应网络中不同类型业务的区分服务需要，IEEE802．11工作组在IEEE802．11DCF（distributed coordination function）的基础上推出了支持QoS的IEEE802．11EDCA协议．针对EDCA（enhanced distributed channelaccess）协议的优先级区分信道接入特性，提出了一种基于Markov链的协议性能模型分析方法．与已有文献不同，该模型分析同时包含了EDCA主要的3个关键区分信道接入机制：Wmin／Wmax，AIFS（arbitration inter-frame space），TXOP（transmission opportunity）逼过模型分析，获得了EDCA协议各优先级接入的传输吞吐量、信道接入延迟、数据丢失率等性能分析．不仅分析了饱和情形下的EDCA性能，而且还对非饱和情形下的EDCA性能进行了分析．仿真验证结果表明，模型分析结果和仿真结果取得了很好的一致性，利用给出的模型分析方法，提出了一种基于TXOP动态调整的D．TXOP（dynamic TXOP）接纳控制算法．算法根据网络中业务流的QoS要求，在动态调整各优先级的TXOP参数设置的基础上，对网络中新到业务流进行接纳控制，达到提高网络的业务承载能力的目的．

英文摘要：

With the rapid development of wireless applications, the IEEE 802.11 task group proposed the QoS- supporting enhanced distributed channel access （EDCA） MAC mechanism, which is based on the legacy IEEE 802.11 DCF, to provide service differentiation for different types of traffic flows in the networks. This paper proposes a novel Markov chain-based analytical model for the IEEE 802.11 EDCA. Unlike the existing analytical models for the EDCA, the proposed model incorporates all the three major features of the EDCA, i.e., Wmin/Wmax , AIFS （arbitration inter-frame space）, and TXOP （transmission opportunity）. With this model, the paper presents the performance evaluations of the EDCA analytically, including each priority＇s transmission throughput, media access delay, packet loss rate, etc. It dose not only analyze the saturated EDCA operation case, but also analyze the non-saturated EDCA operation case. Simulation results confirm the accuracy of the model analysis. Based on the model analysis, this paper proposes an admission control scheme D-TXOP （dynamic TXOP）. While making admission decision, the scheme adjusts different priorities＇ TXOP parameter settings adaptively according to their QoS requirements, which greatly enhances the network capacity.