Research Of TCP-Friendly Congestion Control Protocols

TCP is currently the most popular end-to-end congestion control mechanism used on the Internet. But networked multimedia applications usually employ non-TCP protocols such as UDP to transmit continuous media data such as audio and video to avoid the oscillation of TCP. As these applications become widespread, it becomes increasingly important to ensure that they are able to co-exist with each other and with current TCP-based applications. A key requirement of such a co-existence is the implementation of some form of congestion control that results in a reduction of transmission rate in the face of network congestion. In this paper, we present a brief background on the TCP-Friendly congestion control protocols especially put emphasis on TFRC. Using the NS simulator, we perform a detailed study of the fairness, smoothness and other properties of TFRC. At the end of this paper, we propose one approach to improve TFRC with the slow-start congestion avoid, then we modify the equation TFRC used for rate adaptation to improve the fairness, smoothness properties of TFRC. All results of these attempts are shown by comparison.