Direction-based TCP Fairness Enhancement in High speed IEEE 802.11n

Faster and larger transaction concerns in data communication are now an important field of study in academic and commercial research. As the number of users and the size of information to transmit increase, newer technologies should provide facilities to fulfil these needs. IEEE 802.11n is one of them. This high speed wireless standard is designed to guarantee faster delivery and better communication range. One of the most challenging issues in wireless local networks is the unfairness usage of bandwidth when using transport control protocol (TCP) with wireless media access control (MAC) protocols. In this paper we simulate two scenarios on normal and high speed WLANs with Network Simulator 2 (NS-2).The effect of throughput and access point (AP) buffer size on TCP fairness problem are discussed based on simulation outputs. The results show that in 802.11n channel utilization with equal throughput is more robust and both uplink and downlink flows of data can benefit from the channel bandwidth. We also proved that the lower buffer sizes provide better fairness in 802.11n environment. A specific range of buffer size is introduced in which the best fairness index is achieved in such a high speed standard. The main contribution of the paper is to introduce a technique to keep the fairness ideal in heavy loaded 802.11n networks. This modified traffic management technique is described, simulated and its result is compared with theoretically calculated fairness index.