Performance Management of 802.11 Wireless LANs
November 15, 2004
Yigal Bejerano, Lucent Technologies - Bell Labs
In recent years, IEEE 802.11 wireless LANs (WLANs) have been rapidly deployed all over the world. In the U.S. alone, several companies, such as SBC and T-mobile, plan to build nationwide WLAN networks. Recently, Philadelphia, San Francisco as well as other cites announced their intention to deploy citywide WLANs with thousands of access-points. Additionally, equipment vendors such as Cisco and SpectraLink have introduced 802.11 phones aimed at providing wireless phone services in these networks. To make such efforts successful, however, certain serious shortcomings of 802.11 WLANs must be overcome. These include the lack of fair service for data users and the inability to provide any kind of quality of service (QoS) guarantees for real-time (RT) services, such as voice. Several schemes for providing fairness and supporting RT services in wireless networks have been proposed. However, most such proposals require modification of the standard and/or assume that all stations are within the transmission ranges of each other, making them hard to deploy in large-scale WLANs.
In this talk, we address the challenges of providing fairness and QoS support in large WLANs without changing the standard. We start with a short description of the IEEE 802.11 MAC standard and the obstacles that it raises for providing fairness and QoS support. We then give a brief description of some proposals that address these needs. Finally, we describe two management schemes for providing fair service to mobile user that were developed in Bell-Labs. The presented results are based on two studies that have been published this year. The first is MiFi: A Framework for Fairness and QoS Assurance in Current IEEE 802.11 Networks with Multiple Access Points. This is a joint work with Randeep Bhatia and it was published at the Infocom 2004 conference. The second study is Fairness and Load Balancing in Wireless LANs Using Association Control. This is a joint work with Seung-Jae Han and Li (Erran) Li, and it was presented at Mobicom 2004 conference.