| With the rapid development of the Internet, more services have required by people, they need access Internet more quickly, wider area being covered by network and higher band-width. At the same time, satellite communication has the advantage that large area to cover and high-speed communication, so the satellite-based Internet will become an important research direction in future. However, the inherent features of satellite networks such as large propagation delay, high bit error rates and network asymmetry that impact the per-formance of traditional TCP based in terrestrial environment. Hereby, how to enhance TCP performance over the satellite-based Internet is an important research topic.The dissertation first gives a top view of satellite communication and the background of this thesis, secondly gives a deep understanding of the TCP mechanism. The different char-acteristics between satellite networks and terrestrial networks are compared. Then the short-comings of standard TCP over satellite network are pointed out and this paper analyzes three existing popularity improved methods. Thirdly an arithmetic called TCP acknowl-edgement agent is put forward to improve TCP performance over satellite networks, also two types of the network architecture which the arithmetic supports are introduced and de-scribed in detail.By the way of theoretical analysis, the thesis compares the Round-Trip Time between the standard TCP and the TCP with the acknowledgement agent. The result indicates that ac-knowledgment agent arithmetic can remarkably reduce Round-Trip Time.Finally, this dissertation builds an OPNET model for improved TCP Protocol, the per-formances of improved TCP and standard TCP are compared, including Congestion Win-dow Size, RTT and Throughput. This dissertation proves again that the arithmetic with End-end protocol is able to enhance the TCP performance over the satellite-based Internet and ensures that the available bandwidth resources of the satellite link are fully utilized. |
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