The Research Of Network Congestion Control Based On QoS

The congestion control is one of essential technology about solving the quality of service in computer network multimedia application. This paper is about the research and analysis of current congestion control algorithm performance, and it brings up the ideas of improving the TCP congestion control algorithms in light of the problem that slow start in congestion control algorithms based on TCP has rapid growth in the latter part. In view of the problem that it lacks friendness between the UDP flows and TCP flows in the network application, it brings up the mixed-driven network congestion control mechanism of receiving end and intermediate nodes.Improved TCP congestion control algorithms use to increase the proportion of the adjustment factor and reduce slow the sending rate of packets in the late phase of slow start-up. The congested controlling mechanism of mixed-driven between receiving end and middle node adopts returning the losing package rate of the middle node and uses TCP model of throughput for calculating the speed of sending date in send end and returns a speed suitable for multimedia transmit in receive end. And then it get the speed of the network sending date by doing plus average of the two speed to realize the congested controlling of UDP flow in multimedia application.The simulation result of the above study by the NS2 network simulator showed that the improved TCP congestion control algorithm are improved in lowing the losing package rates, and in increasing the link utilization. RED algorithm has better network performance than Droptail algorithm. The mixed reception-driven mechanism of receiving end and intermediate nodes make the relationship between network UDP flow and TCP flow friendly to some extent.