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Dynamic polling mechanism for enhancing voice transmission in IEEE 802.11e wireless LANs

In this paper, we propose a Dynamic Polling Mechanism (DPM) to enhance the system capacity in supported voice stations over IEEE 802.11e based WLANs, which employs Hybrid Co-ordination Function (HCF) to detect the silence and talkspurt alternation of voice stations and dynamically adds and removes the voice station IDs in the polling list. Apart from the existing dynamic polling mechanisms, the DPM detects the silence-to-talkspurt alternation by the reception of the first packet of each talkspurt, which contends to access channel with high Enhanced Distributed Co-ordination Function (EDCF) priority in Contention Period (CP). An analytical model is presented to investigate the access delay of the voice packets transmitted in CP and the system capacity in supported voice stations. The numerical and simulation results show that the performance of the DPM significantly outperforms that of conventional static polling mechanism. In addition, through exploring the impact of the DPM on the throughput of data stations, we conclude that the performance of the DPM can be optimised by configuring the first packet of each talkspurt with the highest EDCF priority.