An Enhanced EDD QoS Scheduler for IEEE 802.11e WLAN

The IEEE 802.11e standard was proposed to guarantee QoS in the MAC layer. It uses new HCF(Hybrid Coordination Function) protocol, which is composed of two access functions: A distributed contention-based channel access function(EDCA) providing prioritized QoS and a centralized polling-based channel access function(HCCA) providing parameterized QoS. In this paper, we propose a new scheduling algorithm to improve the performance of HCCA. The proposed scheduler guarantees QoS by changing suitably service intervals and transmission opportunities. The service schedule is based not only on the TSPEC parameters of a flow but also on the traffic queueing. Simulation results show that the proposed scheduling algorithm is superior to the reference scheduler and SETT-EDD scheduler in terms of throughput, end-to-end delay and jitter.