改进遗传算法在QoS组播路由选择中的研究

摘要

The essence of the QoS multicast routing problem is to find the transmission path from the source node to the destination node,although there are a lot of literature on the use of genetic algorithm for multicast routing,but the cost of multicast routing is relatively high,and the execution time is too long,and encoding is more difficult,the optimization efficiency is low.To solve these problems,an improved genetic algorithm was proposed in this paper,the algorithm takes the bandwidth constraint,delay constraint,delay variation constraints,loss constraints and routing cost into account,based on the traditional genetic algorithm,a kind of self-fitness function based on application layer is designed.It improved genetic encoding method,and designed a variety of optimization functions such as adaptive crossover function and adaptive mutation function.The simulation results show that the improved genetic algorithm greatly reduces the cost and execution time of QoS multicast routing,and it can quickly find the optimal QoS multicast path.%QoS组播路由的选择问题本质是从源节点至目的节点间找到满足QoS要求的传输路径,尽管现在有许多文献利用遗传算法对组播路由问题做了研究,但其组播路由费用都比较大,执行时间过长,并且编码难度都比较大,优化效率低.针对这些问题,文中提出了一种改进的遗传算法,该算法综合考虑了带宽约束、时延约束、时延抖动约束、丢包率约束以及路由费用等度量指标,在传统遗传算法的基础上,设计了一种基于应用层业务的自适度函数,改进了染色体编码方式,并且设计了自适应交叉函数与自适应变异函数等多种优化函数.通过仿真结果表明,该改进的遗传算法很大程度上降低了QoS组播路由的费用和执行时间,并且能快速地找到最优QoS组播路径.