Research On Congestion Control Mechanism Of Video Data Transmission Over Heterogeneous Network

With the development of network, there are more and more video transmission requirements. Overlapping coverage of heterogeneous networks which is brought by emerging access technologies, and multihoming of hosts, possibly using different technologies and providers, also make it possible for users to enjoy video services on network through one or more access technologies. The dominant transport protocol TCP used for reliable end-to-end data transfer cannot meet the needs of video transmission, primarily using a single end-to-end path. There were some problems like high delay and jitter caused by high packet loss while video transmitting. Meanwhile, those reducing the cost of network access equipment, realizing the diversification of access technology, make that use of multi network interface for concurrent multipath transmission path be possible. Multipath transmission can greatly increase the number of aggregate bandwidth video transmission paths, improve network resource utilization and service reliability.What’s more, congestion control algorithm is the core of the transport layer architecture, efficient congestion control algorithm can greatly improve the utilization of network resources. While video streams in heterogeneous networks transmit through existing multi-path transmission mechanism, packet buffering and ECN marking policy at the intermediate nodes (links) follows the well-known Random Early Detection (RED) scheme. Some inherent characteristics of heterogeneous network, such as high packet loss rate and high delay would limit the performance of RED.More details of our contribution to solve problems proposed above can be described as follows:(1)We deeply study the characteristics of multi-path transmission mechanism, and focus on multi-path congestion control algorithm, also take into account the reliability of the multi-path transmission and packet mapping mechanism. Therefore, we deeply analyze the existing multi-path transmission mechanism, and study its flaws, propose a mathematical model of multi-path transmission mechanism. This model is better than the traditional single TCP transport protocol, it can increase the throughput and reduce the transmission delay and it also can effectively avoid network congestion.(2)This thesis proposes a mechanism for multi-path transmission fluid model combined with the establishment of the mathematical model and typical TCP/RED model. This m odel combines with a single path multipath congestion control mechanisms from the oretical point of view, while taking the reliability of the video transmission into account. The model can dynamically acquire the status of each path and can avoid the congestion before congestion occurs. At the same time, the model can effectively deal with unexpec-ted traffic in the network, and can allow multi-path transmission system which has bee-n stabilized. Simulation shows that this model can dynamically obtain various path conditions, and undertake congestion avoidance before congestion occur. What’s more, it can effectively deal with the attack traffic in the network.(3)The thesis proposes an improved multipath congestion control algorithm to analyze the stability of multi-path congestion control system at the base of the multi-path fluid model, and to establish a relationship network parameters and stability.