A Dynamic IEEE 802.11e TXOP Scheme in WLANs under Self-Similar Traffic: Performance Enhancement and Analysis

Transmission opportunity (TXOP) is a new scheme specified in the IEEE 802.11e standard which enables a station to transmit multiple frames consecutively within a burst after it gains the channel. Realistic traffic loads in wireless local area networks (WLANs) with multimedia applications often exhibit the bursty and self-similar properties which imply the frequent occurrence of the large bursts of frame arrivals and thus require the TXOP scheme to be dynamically adapted to the traffic characteristics. This paper presents a dynamic TXOP scheme which adjusts the TXOP limits of mobile stations according to the current status of their transmission queues. We further develop an analytical model to evaluate the performance of this scheme under self-similar traffic. QoS performance metrics in terms of throughput, end-to-end delay, and frame loss probability are derived and validated via NS2 simulation experiments. The numerical results reveal that the dynamic TXOP scheme achieves the better QoS than the original one under self-similar traffic.