Research Of Congestion Control Protocol In High Bandwidth Delay Product Networks

With the development of network-based applications, a variety of network environments, such as high-speed networks, wireless networks, satellite networks, developed gradually. Since the traditional congestion control protocol cannot adapt to these networks, researchers have proposed various improved TCP protocols for certain network environment. However, it is difficult for users to choose the appropriate protocol under unknown network environment, so the adaptability of protocol needs to be studied. Not only that, these TCP variants also faces tremendous challenges in High Bandwidth-Delay Product Networks.Firstly, the thesis reviews the researches of TCP under different network environment in recent years, mainly focuses on development of protocols under High Bandwidth-Delay Product Networks. Based on this study, the thesis presented a comprehensive adaptability evaluation of various TCP variants under different network environments by simulations. Then the influences of network characters on protocols are analyzed. Lastly, the thesis gives the analysis of advantages and disadvantages of protocols.In the following, this thesis presents a novel explicit congestion control protocol (VCP-BE) under High Bandwidth-Delay Product Networks, which uses two existing ECN bits for explicit feedback and the end-to-end bandwidth estimation algorithm to obtain high resolution congestion estimates. Simulations also have shown that the proposed protocol outperforms VCP and MLCP, and achieves high efficiency, reasonable fairness, fast convergence speed, low persistent queue length, and negligible packet loss rate.Finally, the thesis summarizes the current existing open issues, and provides some further interesting directions.