Queue Management Strategies to Improve TCP Fairness in IEEE 802.11 Wireless LANs

Wireless Local Area Networks (WLANs) based on the IEEE 802.11 technology have become increasingly popular and ubiquitous. The 802.11 standard allows each station in a WLAN equal opportunity to access the wireless channel, which can result in unfair sharing of network bandwidth between upstream and downstream TCP flows at an AP. In this paper, we propose two different queue management techniques to alleviate the unfairness problem, with one based on Selective Packet Marking (SPM), and the other based on Least Attained Service (LAS) scheduling. We evaluate these proposed solutions using the ns-2 network simulator. The simulation results show that, compared to a conventional DropTail queue mechanism for NewReno TCP sources, the proposed solutions improve the fairness index by 20-40%, while achieving comparable aggregate throughput.