Novel Metrics and Experimentation Insights for Dynamic Frequency Selection in Wireless LANs

Authors: Giannis Kazdaridis, Stratos Keranidis, Adamantios Fiamegkos, Thanasis Korakis, Iordanis Koutsopoulos and Leandros Tassiulas

Conference: WiNTECH - MobiCom 2011, Las Vegas, Nevada, USA, September 2011

The rapidly increasing popularity of IEEE 802.11 WLANs has led the unlicensed frequency bands to unprecedented levels of congestion, especially in densely populated urban areas. Performance experienced by end-users, in such deployments, is significantly degraded due to contention and interference among adjacent cells. In this paper, we develop novel metrics and insights that we use for dynamic frequency selection, incorporating the various features that affect total network interference. The proposed scheme features a novel client feedback mechanism, which enables the nodes of the cell, as well as nodes belonging to different cells, to contribute to interference measurements. Furthermore, we incorporate a traffic monitoring scheme that makes the system aware of prevailing traffic conditions. We design a distributed protocol, through which messages containing the information above are passed by the stations to the access points, where the frequency selection is performed in a dynamic form. The proposed algorithm is implemented using the MADWiFi open source driver and is validated through extensive testbed experiments in both an indoor RF-Isolated environment, as well as in a rich interference, large-scale wireless testbed. Results obtained under a wide range of settings, indicate that our algorithm improves total network throughput, up to a factor of 7.5, compared to static approaches followed by wireless vendors.

Download paper: DFS_WinTECH_2011_paper.pdf