【作者】 黄珂；

【导师】 吕锋；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 随着网络技术的飞速发展,当前通信网络带宽和处理能力的提高使网络能够提供更多的多媒体业务,也使得支持“点到多点”或“多点到多点”的组播通信方式成为网络支持多媒体业务的必要形式。组播路由是网络层具备的功能,组播问题的关键在于组播路由的确定,寻找简单、高效、健壮的组播路由算法一直是网络界致力研究但未完全解决的问题。另一方面,许多分布式的多媒体应用对时延、时延抖动、带宽以及包丢失率有不同的要求,这需要当前网络能够传送具有这些QoS要求的实时多媒体信息。因此,作为QoS为中心的网络体系结构中不可缺少的组成部分,基于QoS约束的组播路由算法的研究成为网络研究领域的重要内容和热点问题。本文主要研究基于QoS约束的组播路由算法,针对时延和时延抖动约束的最小代价组播路由问题,提出了一种有效、实用的组播路由算法。主要研究工作和取得的成果如下:(1)在介绍组播路由技术背景知识的基础上,研究了QoS路由的网络模型和QoS度量的定义,重点对组播路由问题进行分类讨论,分析了QoS组播路由的特性,并归纳了相关算法的优缺点;(2)将模拟退火的优化思想引入组播路由计算中,提出一种基于模拟退火方法的时延及时延抖动约束的最小代价组播路由算法。该算法采用“路径交换”策略在可行解范围内构造邻域集,避免了搜索区域的扩大和计算时间的增加。(3)对提出的改进算法进行仿真,并与改进前进行比较,仿真结果表明算法的可行性、有效性和稳定性,并验证了算法具有代价低、收敛快的特点。更多还原

【Abstract】 With fast development of network technologies,increase of network bandwidth and processing power makes the network provide more multimedia applications,and also makes the multicast communication that supports "one-to-many" or "many-to-many" become a necessary mode of multimedia services.A fundamental issue in multicast communication is how to determine an efficient multicast routing, and finding simple,effective and robust multicast routing algorithms.This is unsolved problem in network fields.In addition,many distributed multimedia applications have various demands on delay,delay variation,bandwidth and packet loss,which requires current network to transmit real-time multimedia information with these quality-of-service(QoS)constraints.So,as an indispensable component in a QoS-centric network architecture,research on multicast routing algorithms based on IP QoS constraint becomes an important part and hotspot issue of network research fields.This paper researches the structure,typical service model and mechanism of QoS based on network,and introduces the key technology about it;then classifies the multicast routing algorithms with QoS constraints which have been put forward.By analyzing the simulated annealing algorithm and importing the conception of paths-switching,the paper presents a kind of improved simulated annealing algorithm: SAD_DVMA.The simulative result illustrates SAD_DVMA is better than traditional algorithm in solving the least cost multicast routing problem with delay and delay variation constraint.Generally,the main achievements in this paper are as follows:(1)Concentrates on researching multicast routing algorithms with QoS constraints,proposes several simple,effective and practical QoS multicast routing heuristic algorithm to solve some classical multicast routing problems with NP difficulty;(2)Apply the simulated annealing to multicast routing,and propose a multicast routing algorithm(SAD_DVMA)based on simulated annealing to solve delay and delay variation constrained least-cost multicast routing problem.To avoid enlargement of search area and increase of computing time,SAD_DVMA uses "paths-switching" strategy,which constructs neighbor set in the range of feasible solutions according to the relationship between delay and delay variation;(3)Simulations demonstrate that the algorithm has characteristics of feasibility, stability and rapid convergence,and it can effectively construct multicast tree with lower cost according to QoS request,and has better real-time property.更多还原