An Analytical Model for EDCA Mechanism
一种EDCA机制分析模型

Priority classification and two-level collision being adopted, Enhanced Distributed Channel Access (EDCA)mechanism of IEEE 802.11e protocol is quite difficult to be modeled and analyzed. According to the characteristics of EDCA mechanism, an effective and simple model for two-level collision is proposed. The probabilities of inner virtual collision and outer collision are calculated based on the formula of sending probability deduced from simple EDCA model, and then integrated. Finally, the simulation of throughput and delay of complicated EDCA under saturation is conducted. The simulation demonstrates that EDCA mechanism, which adopts priority classification and two-level collision, can not only preferentially guarantee the throughput of voice and video, but also greatly decrease the average delay of the system.