Research On Mechanism And Technology Of Synchronized Video Multicast On Converged Gateway

The multicast technology is practiced by more and more applications because it has the communication pattern of one to many, and high utilization of network resources. With the emerge and development of integration network, the ubiquitous network provides services such as video conference, stock online system, online game, e-business, database synchronize to users without the limits of network, client and space. The next generation internet is featured by the integration of heterogenous networks and full ip network. In this network (?)aviroment, the multicast service should be studied in two layers:the network layer and the application layer.Firstly, to solve the problems such as bad practicability, high complexity and costly reconstruction in the constructing of delay and delay-variation bounded multicast tree, we present a fast multicast tree constructing algorithm in this dissertation, which is based on the novel plain structure of multi-cores tree and using the sliding delay-variation window for multiple cores selection mechanism. The algorithm provides a large solution seeking space for initial multicast tree and the tightest delay-variation bounded constraint for the result tree. In theory, the time complexity of this algorithm is equal to Delay and Delay Variation Constraint Algorithm (DDVCA), which has the best performance in time complexity. In simulated experiments to construct the large-scale multicast tree, the execution time of our algorithm is at most60%shorter than DDVCA under the same constraints on delay and delay-variation bounds. Extensive experiments also show that, comparing with Chains algorithm that has the tightest delay-variation constraint so far as I know, the tightest delay-variation constaint could be obtained by the algorithm presented in this dissertation.Secondly, with the development of Internet, especially the development of mobile Internet, ubiquitous multicast services have become the focus of attention. The robust multicast routing algorithm is the most important feature and key point of the multicast service system, but also the most important part of the algorithm towards the application. The multicast tree recovery mechanism plays a role in the condition of the multicast tree unusual failure (such as path failure, node failure, etc.). Multicast tree proactive recovery technology uses a backup strategy which including three levels:link, path, and tree. How to make the multicast tree construction algorithm have the optimal robustness property has became an important research filed:how to pave the way for the recovery of the multicast tree at the initial multicast tree construction process, and how to implement recovery strategies and so on.Multicast application services are based on top of a variety of access networks. The cost of data transmission path determines the cost of the service operators. Especially for those applications who take a long time for data transmission, Steiner multicast tree becomes the primary concern of the operators. Steiner tree multicast as a classic NP-hard problem cannot find the optimal solution in polynomial time. In this dissertation, the heuristic algorithm with polynomial time complexity based on multi-core tree topology can find the global optimal solution. At the same time, the algorithm has serval characteristics such as dismantled, concurrent and asynchronous computation. The algorithm reduces the amount of computation through filtering with delay variation constraint candidate windows, and achieves fast convergence in the solution finding process.Finally, mice flow should dominate the next generation of ubiquitous wireless networks because the frequent and important communications would be mice flow certainly due to the limits of terminals and networks. The most important factor which affects the performance of applications is the duration time of mice flow. The natural reasons for the duration time of mice flow are that the slow pace of ACK-based transmission and the conservative packet transmission strategy of windows-based. This dissertation proposes a delay-sensitive Fast-Pacing TCP (FP-TCP) transmission mechanism for mice flow:the transmitting pace is speeded up by the tighter intervals base on the measurements of packets’RTT, the transmitting packets is considered by the CWND and the batch index of transmission, the definite network status and RTO can be obtained by the measurements of total packets in the mice flow. The simulations comparing to the modified TCP show that in the condition of network is not busy, the loss of flows keep almostly the same, the during time of mice flow can shorten by FP-TCP up to about22%at most; in the condition of network is busy, the duration time can be also shorten obviously, only little growth is taken to the loss of flows.