Adaptive Multi-polling Scheduler for QoS Support of Video Transmission in IEEE 802.11e WLANs

摘要

The 802.11E Task Group has been established to enhance Quality of Service(QoS) provision for time-bounded services in the current IEEE 802.11 MediumAccess Control (MAC) protocol. The QoS is introduced throughout HybridCoordination Function Controlled Channel Access (HCCA) for the rigorous QoSprovision. In HCCA, the station is allocated a fixed Transmission Opportunity(TXOP) based on its TSPEC parameters so that it is efficient for Constant BitRate streams. However, as the profile of Variable Bit Rate (VBR) traffics isinconstant, they are liable to experience a higher delay especially in burstytraffic case. In this paper, we present a dynamic TXOP assignment algorithmcalled Adaptive Multi-polling TXOP scheduling algorithm (AMTXOP) for supportingthe video traffics transmission over IEEE 802.11e wireless networks. Thisscheme invests a piggybacked information about the size of the subsequent videoframes of the uplink streams to assist the Hybrid Coordinator accurately assignthe TXOP according to actual change in the traffic profile. The proposedscheduler is powered by integrating multi-polling scheme to further reduce thedelay and polling overhead. Extensive simulation experiments have been carriedout to show the efficiency of the AMTXOP over the existing schemes in terms ofthe packet delay and the channel utilization.