Research On Congestion Control Algorithm For Media Streaming Transmission

Along with the rapidly development of the Internet and streaming media technology, the defects of previous Internet which can only dispays texts and images have be completely changed by streaming media which can assemble video, voice, texts and images into one. We actually use UDP/IP for transmission as real-time streaming media transmission, because streaming media has the characteristics of delay sensitive, large amount of data, and need service quality assurance. The UDP/IP for traditional single data transmission business is not longer enough. UDP/IP can't provide congestion control for data transmission, inevitably the bandwidth of other data flow will be invaded limitlessly, and it will result in other data stream "hunger", even cause congestion collapse, and affect the transmission of real-time data stream itself.Analysed the reasons, characters of congestion control, a new TCP-Friendly congestion control algorithm has been proposed. The objective of this paper is to develop a TCP-Friendly and fair congestion control algorithm which regulates the sending rate robustly by inferring the end-to-end available bandwidth. In addition to network stability, we also consider the characteristics of streaming applications, such as the bandwidth resolution in scalable video coding (SVC) which can achieve fine granularity of scalability at bit level to fit the time-vary heterogeneous networks. The congestion control algorithm is mainly composed of two phases: start phase and transmission phase to better utilize the network resource by subscribing SVC layers. In the start phase, we analyze the relationship between the one way delay and the dispersion of packet trains, and then propose an available bandwidth inference algorithm,which makes use of these two features without requiring administrative access to the intermediate routers along the network path. Instead of either binary search or fixed-rate bandwidth adjustment of the probing data as proposed in literature, a top-down approach is proposed to infer the initial available bandwidth robustly and much more efficiently. After acquiring the initial available bandwidth, the missions of the transmission phase include the adaptation of the sending rate fairly by progressive probing and also the accommodation of the network resource to TCP flows.