The Research Of TCP Performance Improvement And Multicast Routing Algorithm Optimization

Real time multimedia streaming applications have been a hot topic in the field of multimedia network, including remote education, where real time multimedia streams must be sent to other places of teaching sites with stabilization and high quality. Since the Internet, which mainly depends on the TCP protocol, is a "Best-effort" network, current multimedia streaming applications are still lack of an efficient congestion control mechanism, and then they compete unfairly bandwidth with TCP flows. Thus, research on "TCP-friendly" congestion control mechanisms for multimedia streaming applications is a hotspot of research in the present computer network area. On the other hand, since the wireless network uses the traditional TCP protocol, we focus on how to improve the TCP protocol to suit the characters of wireless networks. Furthermore, how to save resource of network when we use multicast to transmit multimedia streams is also a problem we have to resolve. This paper aims to solve the problems by finding some method to advance the performance of TCP and to guarantee QoS. This paper tries to meet the needs for remote education and other applications by advancing TCP-friendly congestion control, improving performance of TCP for wireless networks, and optimizing multimedia streaming multicast algorithms. Therefore, this paper focuses on the following:First, seeking a mechanism for "end to end" congestion control to guarantee TCP-friendliness and to suit the multimedia streaming characteristics, and paying much attention to balance of TCP-friendliness and those characteristics.Second, improving performance of TCP based on explicit notification mechanism over the traditional TCP protocol for mobile computing;Third, proposing some new multicast routing algorithm satisfying with delay and delay variation constraints, and at the same time satisfying with requisition of service to save network resources, and using an optimized heuristic algorithm to solve a distribution problem for multicast-streams.The main contributions of this thesis are mainly in the following:Since the TFRC(TCP-Friendly Rate Control) mechanism does not fit for the multimedia stream's threshold constrained characteristic, we propose a threshold constrained rate control mechanism for multimedia systems, called TCRC. In addition, on the basis of theory of model-based TCP-friendly congestion control, we propose an improved TCRC version under multiplexing circumstances, called MTCRC...