Research On Performance Of TCP In Manet

The research background of the work presented in this dissertation is the research on UAS-TN (Unmanned Aerial System Tactic Network), undertaking at Sichuan Network Communication Key Laboratory(SC-Netcom Lab). UAS-TN is a special type of Mobile Ad hoc network (MANET), except that the moving speed of nodes is faster than that in traditional MANETs and it demands higher degree of security working in a hostile space. However, the work presented in this dissertation is generally applicable for MANET.The topic of this dissertation is pertainent to performance of TCP in MANET as it is the dominant transport protocol. The congestion control mechanism in TCP is triggered by heavy data losses. However, this may not be true since bad channel or link failur bit enor may also cause data loss in wireless networks. This implies that a better triggering criterion for congestion control is needed. Moreover, observation has also shown that with IEEE802.11 DCF, some TCP streams may overtake channel resources for existence of exposed terminals.In this dissertation, the author has made the following contributions:A. Provided a comprehensive study to TCP performance in MANET;B. Introduced an improved algorithmat MAC layer to solve unfairness problem between TCP streams;C. Provided a cross-layer mechanism to improve TCP congestion control and demonstrated its advantage through simulation.Finally, the author has briefly discussed the advantages of future SOA (Service Oriented Architecture) and layerless architecture based on the necessity and merits of cross-layer operation in improving TCP performance.