基于M/G/1/K排队模型的IEEE802.11e EDCA性能研究

Performance Investigation of IEEE 802.11e EDCA Based on the M/G/1/K Queue Model

该文利用二维Markov链分析方法,提出了一种新的IEEE802.11e EDCA网络分析模型,该模型引入了空闲状态和不同接入等级的仲裁帧间隔(AIFS)的使用;利用Markov链状态转移图的Z域信号传递函数推导了MAC层平均服务时间的概率分布;结合M/G/1/K排队模型分析了增强分布式信道接入(EDCA)在非饱和和饱和负载下的性能。经过访真实验结果与数值分析结果的对比,验证了分析模型的准确性。分析结果表明:EDCA接入机制只为不同优先级业务提供QoS区分;不同优先级业务信道接入的不公平性是EDCA接入机制的特点。

A new Markov chain model for the IEEE 802.11e EDCA is presented. The model takes into account both the idle state and differentiation based on different AIFS-value for different traffic. The signal transfer function of the generalized state transition diagram can be used to derive a probability distribution of the MAC layer service time and the performance of EDCA from a non-saturated channel to a saturated medium by using presented M/G/1/K queuing model is analyzed. A good match between the analytical model and simulation which conforms the veracity of proposed model is observed. Simulation shows that despite providing prioritized QoS, the EDCA still can not support strict QoS for real-time application. It is inevitable that there is unfairness of channel access to prioritized traffic due to EDCA.