TCP performance in multihop wireless networks

Abstract

IEEE 802.11 MAC is a standard protocol for most of the wireless network. Although it can be used in some ad hoc network architecture, there are some problems when used in multihop ad hoc network. Since the interference range larger than transmission range, when one node is sending data, not only the nearby nodes defer their transmission, but also other nodes in the network cannot send packets due to the interference. As the result, the TCP throughput will become instable (because sometime drop many packets). And this protocol also have link contention problem, some node will have unfairness in transmission due to dominate the medium by one transmission. In this project, the IEEE 802.11 MAC protocol problem is analyzed first by using the network simulator to simulate the multi-hop wireless network. Then some methods that proposed by other scholars is investigated. Finally, a enhanced solution is used to store the local information for each of the node and use an update mechanism to achieve fairness. This solution solved the stated problems of IEEE 802.11 MAC in various simulated topologies of multi-hop wireless network.