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UBC Theses and Dissertations

Dynamic congestion control methods to improve performance of TCP split connections over satellite networks Wu, Lijuan


Satellites play important roles in global telecommunications. However, the performance of Transmission Control Protocol (TCP) for reliable data transfer over the Internet suffers significant degradation over satellite networks due to high bit error rate and the long latency of satellite links. Among the methods proposed for alleviating the impact of satellite link characteristics on TCP performance, the split TCP connection separated by performance enhancement proxies between the satellite and terrestrial Internet segments proves to be attractive for improving endto- end TCP performance while keeping the TCP configurations in end systems unchanged. In this thesis, we propose a dynamic TCP congestion control mechanism for the satellite segment in a split TCP connection scenario. This scheme uncouples the TCP congestion control and error recovery operations, which benefits error-prone channels, and allows immediate congestion feedback from underlying layer, which benefits long delay channels. We model a satellite network with two gateways, which is widely studied in the literature, and contribute a new system architecture with a single gateway, which employs a medium access control protocol for very small aperture terminals accessing a shared satellite uplink. Different from other approaches, the random early detection queue is deployed in the gateway. Based on these two models, the performance between the proposed mechanism and other ubiquitous TCP versions is compared under a number of network scenarios. Simulation results show that our proposed mechanism improves TCP performance significantly, and is more robust when the traffic load is heavy.

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