Uplink TCP traffic control with monitoring downlink buffer for throughput fairness over wireless LANs

TCP uplink flow over wireless LANs is well known to cause two serious throughput-unfairness issues. The first is TCP throughput unfairness among uplink flows. The second is unfairness between uplink and downlink flows. Several approaches addressing these serious issues have been proposed. While they improve performance, there are difficulties in cases of legacy wireless LAN MAC stations, large numbers of stations, and encrypted packets. In this paper, we propose a simple and scalable traffic control method that can easily be applied to all of the above cases. The main idea is for access points to discard TCP uplink packets, with the discard probability determined on the basis of downlink buffer occupancy. Our proposal has the advantage that only access points require modification, not wireless stations. Simulation results show that proposed method can improve two kinds of fairness with small degradation of aggregated throughput due to the intentional uplink packet discard.