QoS Enhancement with Dynamic TXOP Allocation in IEEE 802.11e

The transmission opportunity (TXOP) mechanism defined in the IEEE 802.11 e Hybrid Coordination Function (HCF) is not optimized to meet the QoS requirements of heterogeneous applications, since it is usually allocated by default according to the different Access Categories (AC). In this paper we propose a new algorithm, named DTXOP, for the dynamic assignment of the TXOP maximum duration at the Access Point (AP) of an IEEE 802.lie WLAN. DTXOP is periodically updated according to the current traffic conditions of each specific AC. Simulation experiments show that DTXOP allows to enhance delay and throughput performance and to maintain fairness between upstream and downstream channel access times.