Achieving airtime fairness of delay-sensitive applications in multirate IEEE 802.11 wireless LANs

In multirate IEEE 802.11 wireless LANs, performance anomaly is a well-studied problem. Most existing solutions try to solve this problem by achieving airtime fairness. However, these solutions tend to increase the frame delay of some stations. If these stations run delay-sensitive applications, e.g., VoIP and video conferences, their quality of service would be seriously degraded. In this article we introduce and classify the existing solutions. The frame delay of each type of approach is illustrated by analytical results. We also propose an adaptive approach to solve this delay issue. The proposed approach could accurately model the condition of each station and concurrently adjust multiple MAC parameters. Simulation results validate that the proposed approach not only achieves airtime fairness but also improves frame delay. Therefore, the proposed approach could be applied to improve the quality of service of multimedia applications over WLAN environments.