Research Of Congestion Control Algorithm Based On The Video Source

Based on the analysis of the causes of congestion, the characteristics of the congestion control and the research significance, this thesis will bring about a new congestion control algorithm in accordance with the characteristics of the data transmission of the current video surveillance system and the present deficiencies of the algorithm mechanism of the congestion control.Through analysis of the existing two congestion control strategy and their characteristics, and for the characteristics of video surveillance system, such as real-time, the volume of data, data traffic emergencies, and so on, we design a congestion control based on the video source. The central idea of the algorithm is: According to the relevant information of the RTCP receive report, we calculate link loop time , transmission delay and the loss of transmission rate , and then calculate the current transmission throughput by using the improved Padhye throughput Model, to dynamic adjust the data sent-rate of the source, that is, when the network loads heavier, the sender decreases the sent rate to make sure it will not have a great deal of data packets into heavier congestion when network is in congestion. And when the network loads less, the sender sends data in higher rate so that the network operates in high-throughput state. Among them, we consider the slow start-up after timeout phase to ensure the accuracy of the model when we derive the TCP throughput model, which make the congestion control mechanisms with this model more reliable. In the calculation of service quality parameters, we only use the relevant information of report that RTCP return and not take feedback into the group, it will not increase the data transmission network additional burden.Finally, by comparing the current mainstream of several simulation software MATLAB, OPNET, SPW, NS2, we choose NS2 to simulation the new algorithm, and the results show that this new algorithm can make sent-rate of the video source more smooth, and make video streaming and TCP flow can fair strive for the bandwidth when they coexist in the network environment, and it won't lead TCP flow to death, that is TCP-friendly.The congestion control algorithm based on the video source which we design apply to the video surveillance system, can cope with and avoid network congestion, reduce latency and packet loss rate, improve the overall performance of the network, and ensure that distributed video surveillance system stability, achieve the anticipated effects of the function.