A new packet scheduling algorithm for access points in crowded WLANs

Nowadays, Wireless LANs (WLANs) have been densely deployed to provide the last mile delivery of Internet access to mobile clients. As the population of WLAN clients who carry WiFi-enabled devices keeps increasing, WLANs are often crowded and WLAN clients may thus encounter serious performance degradation due to channel contention and interference. Therefore, in this paper we present a new packet scheduling algorithm, named DAT, for access points (APs) in a crowded 802.11 WLAN. Our goal is to improve the performance of efficiency (measured by packet response time or throughput) and fairness which often conflict with each other. To meet this goal, our solution is to aggregate and balance both performance metrics by enabling an AP to automatically adjust time windows for serving each active WLAN client. Specifically, our algorithm leverages the knowledge of the observed traffic to dynamically shift the weight between efficiency and fairness and strikes to improve the preferred performance metric without excessively degrading the other one. A valid queuing model is designed in this work to evaluate the performance of our new scheduling algorithm. Trace-driven simulations demonstrate that the proposed algorithm successfully balances the trade off between efficiency and fairness in crowded WLANs.