A unified QoS-inspired load optimization framework for multiple access points based wireless LANs

The extensive deployment of 802.11 WLAN has positioned itself as the de-facto wireless access network for the 'last mile' connections. The potential for WLAN to deliver multimedia contents such as VoIP, video conferencing, streaming and data services will become a reality with the advent of 802.11n standard, promising data rate of up to 600 Mbps. Although these QoS demanding multimedia applications can be supported by the 802.11e standard, it offers limited QoS guarantee. Further, its possible adoption by the industry remains unclear due to high cost of hardware replacements. In this paper, we give a solution to provision QoS support for multimedia traffic in commercially deployed 802.11 a/b/g WLAN operating with fundamental distributed coordination function (DCF) access mechanism in a unifying QoS-inspired load optimization framework. We further postulate the notion of QoS balance as load criterion in heterogeneous WLANs where data rates and channel conditions are radically different. In practice, link adaptation employed to combat diverse channel conditions could lead to multirate operation and consequently the long-term throughput of stations are penalized by the lowest data rate peer. We argue that such rate anomaly can be mitigated by maintaining a QoS-balanced system. Simulations show that our solution provides service QoS guarantee for both real-time and non real-time traffic as well as achieves both throughput and QoS fairness under dynamic network conditions in a self-adjusting manner.