A QoS provision multipolling mechanism for IEEE802.11e standard

With flexibility and mobility, Wireless Local Area Network (WLAN) has rapidly become one of the most emergent computer research fields. It attracts significant interests both in academic and industry communities. For applying a higher Quality of Service (Qos) to network applications, the 802.11e Task Group has deployed hybrid coordination function (HCF) to improve the original IEEE 802.11 Medium Access Control (MAC) protocol. Nevertheless, how to choose the right MAC parameters and QoS mechanism so as to achieve a predictable performance still remains unsolved. In this paper, we propose a polling access control scheme which in its PCF mode applies non-preemptive priority in order to transfer voice packets more efficiently. The voice traffic characterized by packet rate of voice source and the maximum tolerable jitter (packet delay variation) is forecasted. We record the scheduling results in a queue, with which AP (Access Point) can poll and then enable mobile users to communicate with their opposite sites. This occurrence also solves the problem that some voice packets do not suit QoS in IEEE 802.11e standard with multipolling. During the time-gap while transmitting no voice packets, the scheme changes to DCF mode to transfer data packets. Furthermore we simulate and analyze the performance of the scheme in a WLAN environment. The experimental results show that our approach can dramatically improve the quality of network service.