Study On TCP Flow Fairness In Ad Hoc Network

Ad Hoc network is a kind of new network which is different from all other traditional networks.Unfairness will be arised when TCP is running over the Ad Hoc network. Fairness is the basic demand for networks, so it is important to solve the unfairness problem.The TCP flow's unfairness problem was deeply analyzed by quantitive manner, and then a new scheme was proposed to improve the TCP flow's fairness in the paper.The factors that lead to TCP unfairness were analyzed and concluded, and the basic factors were pointed out. Then a mathematical model was built to analyze TCP fairness quantitively.A new scheme F-MAC with low overhead cost was proposed to improve TCP fairness. In this scheme, the backoff window at MAC layer was controlled by detecting the basic factors that lead to TCP unfairness ,so that the TCP fairness was improved.Fianally, the rationality of the model and the validity of the F-MAC was validated by simulation under NS2. The result shows that:(l) the mathematical model is universal;(2)F-MAC can improve the TCP fairness remarkably in 802.11 based Ad Hoc networks.