A New Congestion Control Mechanism Based On COS-Slow-Start

With the further development of the Internet, both the number of consumers and the applied scale of the Internet are rapidly expanding. A serious problem of this kind of burst growth is the network congestion. Now, the congestion has already become a very sensitive and important topic, and its control mechanism has also been the key factor of assuring the Internet's stability and robustness.We analyzed the basic principle of the current TCP congestion control mechanism. To mainly aim at the shortage of the slow-start strategy in the source algorithm, we put forward the improvement in the composing of round-trip time, the differential model of the congestion control and the tantamount bandwidth estimate of the network etc., which minishes the error of the RTT and the dynamic ssthresh obviously.This paper investigates the current standard slow-start algorithm of TCP congestion control mechanism and its actual problem. A new variant slow-start scheme which is based on the cosine function, and called"COS-Slow-Start"is presented. At the same time, an appropriate generalizing to the initial window is further given. Mathematics theory analyses and proves that this new scheme can obviously improve the stability, efficiency and fairness of the network. Finally, NS2 simulation results demonstrate that it can significantly reduce both packet losses and traffic burstiness, and increase the bandwidth utilization ratio. It also provides a better granularity control over the congestion window, and still contributes to improving a system throughput.It must be pointed out that the traditional congestion control mechanism can't adapt the multimedia services which are rapidly developing. Because it needs better smooth sending window to the velocity variety, we improve the original AIMD rule, and put forward a kind of adjustable parameter mechanism named A-AIMD in this paper. It can carry out the self-adapting selection of the parameter according to the traffic object, and make the new congestion control mechanism together with COS-Slow-Start. The result of the comparative simulation shows this new mechanism can improve the performance of the TCP connection and have amity of satisfaction. Furthermore, it is clear that the new slow-start strategy also contributes to the management performance of the router buffer, and elevates the network service quality.