Revealing TCP unfairness behavior in 802.11 based wireless multi-hop networks

Abstract

In this paper, we report and reveal an unfairness problem among TCP connections in an IEEE 802.11-based wireless multi-hop network. This problem is not the same as those unfairness problems reported before. In each of the cases we identified, the one TCP connection is completely shut down, even if it starts much earlier than the competing TCP traffic. By illustrating the TCP layer and MAC layer traces, we show that this kind of unfairness problem is rooted in the IEEE 802.11 MAC layer. The hidden node problem and the exposed node problem along with the exponential back-off scheme in the MAC layer are the major causes for that problem.