Research And Implementation Of Adaptive Congestion Control Algorithm Based On The Heterogeneous Networks

With the development of computer network technologies, methods of communication have witnessed enormous reforms. Packet switched technology eventually made the traditional voice networks and digital networks convergence together into a unified multimedia network, whose scope expands further with wired networks, wireless networks, high-speed networks and the satellite networks as the bearer network.The end-to-end communications are no longer in a single mode, and the messages during the period of transmission may experience several different network environments.TCP/IP is the most important communication protocol suite in current networks, and most of the network transmissions are done by the TCP protocol. However, the TCP protocol is designed for general wired networks and cannot reach the best performance in the heterogeneous networks, especially in non-traditional wired network environments such as the satellite networks. So it is necessary to carry on the researches on the improvement and designs direct for the TCP protocol to meet the challenges brought by the heterogeneous network environments.In this paper, based on the TCP transport protocol, we design a self-adaptive congestion control algorithm named ATCP (adaptive TCP) with the convergence of the typical optimization mechanisms of different networks. Using ATCP instead of the standard TCP and Vegas protocol in heterogeneous networks we can obtain better performance, fairness and friendliness.The main contributions of this paper are as follows:1. Key mechanisms for congestion control are researched, and congestion control improving schemes in specific network environments are analyzed in detail, providing a certain foundation for further optimizations of network transmissions in specific network environments.2. Using the simulation software to change the key control parameters of the transport protocol and observing the performances obtained in different combinations of parameter settings, a reasonable value or range set of the parameters fully enhancing the performance of the transport protocol are got.3. Typical optimization mechanisms for different networks are merged deeply, and ATCP algorithm is implemented. ATCP is then implemented in Linux as a kernel module,with which we can change the TCP congestion control machenism dynamically even though the Linux OS is online,which makes the improved algorithm gets better adaptability and flexibility in heterogeneous networks.This paper is supported by National 863 Program (2010AA7010203) and National 973 Program (613118) and some research results have been applied to the subject, achieving good results. The support of the projects will played a significant promoting role in the long-term and effective researches on the network transmission under the harsh environment in the future.