Performance Analysis and Optimization of the 802.11e EDCA Transmission Opportunity (TXOP) Mechanism

The IEEE 802.11 Task Group E is working on a QoS-aware MAC protocol involving Enhanced Distributed Channel Access (EDCA). This scheme was developed to offer QoS capabilities to WLAN, offering significant improvements to multimedia traffic. MANETs will also benefit from this new technology since the most widely deployed and used wireless cards are those based on IEEE 802.11. The use of transmission opportunity (TXOP) EDCA differentiation parameter, received a little attention in the previous analytical studies in contrast to the contention window size-based differentiation mechanism. In this paper, an analytical model is proposed to study and optimize the TXOP bursting transmission scheme. We expose formulates for saturation throughput, delay, and frame-dropping of different priority classes. The analysis allows us to derive the optimal durations of the packet bursting regarding application and network load parameters. We validate the accuracy of our model through ns-2 simulations.