Research On Fairness Of IEEE 802.11e

Among standards of WLAN, IEEE 802.11 shows most extensivion. With the emergence of audio and video, IEEE 802.11e which can provide various priorties of Qos to multimedia service is proposed. With the worldwide applications of wireless local area network, the improvement of performance has become the focus of related researchers.Fairness, as the primary parameter of performance measurement, if of each node there will be an optimization of network. In this paper, on focus of improvement of fairness, after the analysis of reasons of unfairness, the development direction of research on unfairness and classification of algorithm of fairness have been introduced.Two reasons of unfairness have been analysed in this paper:firstly, unfairness caused by hidden terminal; secondly, ratio unfairness after priorty. Meanwhile perspective improved schemes are proposed.1. Propose mechanism of DelayCTS on resolution of unfairness of hided node.Mechanism of DelayCTS allow two-hop transmission of node, note its neighbor nodes within two hops its own information of data, and then reply to CTS with relay, thus prolong the time of handshake, which avoid the conflict of continuas data sending of hidden terminal caused by non-collection of CTS.2. Propose scheme of "Coarseâ†'Fine-tuningâ†'Tuning" on resolution of ratio unfairness.Dynamic configuration of parameters of "Coarseâ†'Fine-tuningâ†'Tuning" change AIFS with coarse, change CWmin with fine-tuning, finally interger of CWmin with tuning, thus "ratio fairness" of throughput of different priorities is achieved after the dynamic adjustment. availability assurance of each scheme, the feasibility of schemes being proved. And then conclusion of the paper, pointing out the defects of the scheme, meanwhile directions of further research.