Research On Multicast Routing Algorithm Based On Improved Ant Colony Optimization

With fast development of network technologies, increasing of network bandwidth and processing power make the network provide various multimedia applications, such as video on demand, video conference, VoIP, online games, distance learning, distributed multimedia databases and so on. Such applications sensitive to bandwidth, delay, delay jitter, packet loss rate, fees etc and have a higher quality of service requirements. The current rapid development of Internet makes network nodes exponential growth, large-capacity, high-speed, multimedia-oriented development. The traditional "best effort service" can not meet these new business requirements.Multicast is a mechanism which can supports multi-point communication efficiently, and it consists of concurrently sending the same information from a source to a subset of all possible destinations in a computer network. As a result of the multicast tree router copy and forward, compared with unicast, multicast data stream is transmitted to a destination node source node only needs to have sent a stream of data, so the multicast technology have the characteristics of alleviating the bottleneck of network transmission and reducing the host processing pressure and effectively improving the efficiency of transmission characteristics, widely used. Multicast issue is critical for determining multicast routing, QoS multicast routing is how to select multicast routes trees with sufficient resources to meet the requirement of QoS parameters, which is proved to be a NP complete problem, so the conventional algorithms are too difficult to solve. That requires by using heuristic algorithms. Ant colony algorithm is a novel simulating evolutionary algorithm with inherent advantage such as robustness, positive feedback, parallelism of and combining easily with other heuristic algorithms. So it is one of the best algorithms for solving the multicast routing problem with multi-QoS constraint.In this paper, I first listed multicast routing protocol and algorithm’s classification, analyzed several classical QoS routing algorithms in details, and presented some problems existing in the study of QoS multicast routing. Then this paper analyzed the basic theory and model of ACA, selects some key parameters value of ant colony algorithm by simulations of Oliver30city TSP. The ant colony algorithm is improved on in view of problem that its premature partial restrain and convergence. We designs the self-adaptive ant colony algorithm which adjusts parameters with the iteration outcome, modifies the rule of updating pheromones in ant colony algorithm, so that after every round of search, the increment of pheromones can better reflect the quality of a solution to quicken the convergence, to determine the next node that being selected in order to prevent the source node to the destination nodes formed in the loop.Considering the ant colony species differences and differences in behavior, we introduced the improvement strategy that the mixing ants having multiple behaviors to extend the solution search space.Finally, the improved ant colony algorithm is applied to solve the QoS multicast routing problem. Simulation results demonstrate that the improved algorithm is feasibility and validity for solving QoS multicast routing problem with multiple constraints.