加权的基于多播节点的多播路由算法

在许多多播应用中,降低多播树网络费用非常重要.本文提出了加权的基于多播节点的多播路由算法（WDDMC算法）.由于改变了DDMC（Destination-Driven routing for low-cost Multicast ）算法中的指示函数,适当降低了多播节点作为中间节点的优先级,提高非多播节点作为中间节点的优先级,从而使得多播树更接近最小Steiner树.在随机网络上的仿真结果表明,WDDMC算法的多播树网络费用优于DDMC算法.该算法的复杂度与DDMC算法完全相同.     

无线Mesh网络可靠多播路由

无线Mesh网络多播路由是无线路由必须解决的关键技术。部分研究者对网络资源和服务质量（QoS）进行研究,提出了建立最短路径树、最小开销树、负载感知、信道分配多播等多播算法;有的算法考虑链路可靠性,建立备用路径。将结合网络资源和可靠性对多播路由算法进行研究,提出了建立可靠多播树（RT,Reliable Tree）的多播路由算法：可靠多播树是一个多树结构,由一棵首选多播树和一棵多径树构成,多径树提供可靠多路径,以提高网络吞吐量。     

基于传输路径质量的无线mesh网络可靠多播

提出了一种可靠多播网(RM)模型,探讨了无线链路和节点可靠性对多播路径选择的影响。首先,建立了无线链路的相关性和多播路径的可靠性模型,并提出了多播传输的可靠性判据;同时,结合首树算法和多路径树算法提出了构造可靠多播网的算法。可靠多播网具有并行的多播路径,通过在多播源节点和目的节点之间选择多播链路和节点构成了可靠的多播路径,提供了多播路径的"负荷分担"和"热备份"功能,从而支持了多播业务可靠性。     

动态多播最小生成树算法

在IP多播网络中,如何选择合适的路由、优化配置,以减少开支,是IP多播业务推广使用的关键。该文针对IP多播动态路由选择的特点和现有算法的不足,提出了一种新的动态多播最小生成树算法(DMPH),随机网络模型的仿真结果表明:DMPH算法生成的多播树总费用与静态算法基本一致,优于现有的动态算法;计算复杂性较静态算法有很大降低。     

一种节点自分布最优Ad Hoc多播树及其应用

为无线单播模式设计的RTS/CTS信道握手机制不适用于多播模式,导致Ad hoc多播树节点易与隐藏终端发生冲突.通过提出m阶冲突域、节点在冲突域中的分布指标,结合无线网多播数据通信机制分析树节点所在m阶冲突域的冲突概率,进而得到节点自分布最优树的概念,并将它融入多播树的适应函数的设计中,淘汰不良树,优化树节点在m阶冲突域中的分布,在网络层形成一种预防机制,可降低隐藏终端冲突概率;应用于MAODV协议中,提高了MAODV的端到端数据分组平均投递率,这也能够为基于网的和混合式的其他类型MANETs多播路由协议的路由节点分布优化提供有价值的参考.     

基于SimCT的多播路由及故障恢复研究

在数据交换网络中,颜色树是一种通过节点不相交的多路径路由数据报文的有效方法。这种方法中组建两棵以某一节点为根节点的颜色树,即Red树和Blue树,网络中各节点到根节点的路径是节点不相交的。本文在分析和研究SimCT算法的基础上,提出了一种基于颜色树的多播树生成方法及单节点/链路故障的多播通信恢复方案。该方法根据SimCT算法构造的颜色树来组建一棵多播转发树,在多播树中单节点或单链路故障后,故障检测节点本地执行故障恢复方案,将受影响的故障节点的下游子树重新连接到多播树。仿真实验表明,本文所提出的多播树生成方案相比现有方案可以减少网络资源的浪费,并且故障恢复后的代价与原多播通信树相当。     

基于粒子群优化的ad hoc网络最小能耗多播路由算法

在无线ad hoc网络中,设备使用电池提供能量,随着多播应用日益广泛,如何构造最小能耗多播树是一个重要问题。针对选择不同的中继节点集对构造最小能耗多播树的影响,提出了一种优化最小能耗多播树构造的离散粒子群算法。为了避免离散粒子群算法早熟收敛,引入惯性权重策略,以平衡算法的全局搜索能力和局部搜索能力。模拟实验结果表明改进后的离散粒子群算法具有较强的优化能力,有效地优化了最小能耗多播树的构造。     

基于人工神经网络的分簇多播路由算法

为了能够快速有效地求解多播路由模型,融合分簇算法和多播树算法思想,利用神经网络作为计算工具,提出了一种基于分簇思想的多播路由算法:用自组织神经网络来分簇,用Hopfield神经网络来构造一个由簇首节点组成的多播树.该算法不但简单易行,而且具有收敛速度快、效率高、控制开销小的特点.最后,通过仿真从实践上支持了本算法的可行性.     

时延受限低代价的一种组播路由动态算法

提出了一种适合目的节点动态加入的、时延受限低代价多播路由的启发式算法DLHMA算法。该算法基于MPH算法的基本思想进行扩展,在满足时延限制条件和多播树代价增加最小的基础上,逐步将目的节点添加到多播树上。最后,证明了算法的正确性,分析了算法的动态性,并进行了仿真实验。结果表明,该算法可以实现新加目的节点的动态加入,并保证所获得多播树的低代价。     

一种路径对约束下构造最低代价我播树的探索算法

提出了一种新的探索算法,它根据源与目的节点的时延约束,构造最低代价的多播树。并且可以在网络节点请求加入或离开时,通过更新现有的多播树,实现多播的动态维护。对该算法进行了仿真,并与现有的一些算法进行了比较。     

Optical multicast provisioning with differentiated leaf availability guarantee in WDM networks

As multicast applications become more and more popular, implementing multicast in the optical domain has attracted increased attention due to its more efficient bandwidth usage. And also these services have quality-of-service requirements. In this article, the problem of cost-effective optical multicast provisioning to satisfy the differentiated leaf availability requirements is formally stated. A Mixed Integer Linear Program formulation is proposed for provisioning dedicated light-tree protection with differentiated leaf availability guarantee. The algorithm is so complex and infeasible that we also propose a feasible two-step approximate approach to solve the problem. Different from the previous schemes, our scheme finds out the primary light-trees and backup paths for destination nodes whose availability is not satisfied. Because of taking the different leaf availability requirements into account, the proposed algorithm obtains a more efficient feasible solution requiring less network resources.     

Dynamic agent-based hierarchical multicast for wireless mesh networks

We propose and analyze a multicast algorithm named Dynamic Agent-based Hierarchical Multicast (DAHM) for wireless mesh networks that supports user mobility and dynamic group membership. The objective of DAHM is to minimize the overall network cost incurred. DAHM dynamically selects multicast routers serving as multicast agents for integrated mobility and multicast service management, effectively combining backbone multicast routing and local unicast routing into an integrated algorithm. As the name suggests, DAHM employs a two-level hierarchical multicast structure. At the upper level is a backbone multicast tree consisting of mesh routers with multicast agents being the leaves. At the lower level, each multicast agent services those multicast group members within its service region. A multicast group member changes its multicast agent when it moves out of the service region of the current multicast agent. The optimal service region size of a multicast agent is a critical system parameter. We propose a model-based approach to dynamically determine the optimal service region size that achieves network cost minimization. Through a comparative performance study, we show that DAHM significantly outperforms two existing baseline multicast algorithms based on multicast tree structures with dynamic updates upon member movement and group membership changes.     

A rearrangeable algorithm for the construction of delay-constraineddynamic multicast trees

With the proliferation of multimedia group applications, the construction of multicast trees satisfying quality of service (QoS) requirements is becoming a problem of prime importance. Many of the multicast applications (such as video broadcasts and teleconferencing) require the network to support dynamic multicast sessions wherein the membership of the multicast group changes with time. In this paper, we propose and evaluate an algorithm called CRCDM (controlled rearrangement for constrained dynamic multicasting) for on-line update of multicast trees to adjust to changes in group membership. The CRCDM algorithm is based on a concept called quality factor (QF) that represents the usefulness of a portion of the multicast tree to the overall multicast session. When the usefulness of a particular region of the tree drops below a threshold, a rearrangement technique is used to suitably modify the tree. Our algorithm aims to satisfy the delay constraints of all current group members, at the same time minimizing the cost of the constructed tree. We compare the performance of our algorithm, by simulation, with that of an off-line Steiner heuristic; with ARIES, a previously published algorithm for on-line update of unconstrained trees; and with the algorithm proposed by Hong, Lee and Park (see Proc. IEEE INFOCOM, p.1433-40, 1998) for on-line update of delay-constrained trees. The simulation results indicate that our algorithm provides excellent cost-competitiveness that is better than that provided by the algorithm described by Hong et al., minimizes changes in the multicast tree after each update, and performs favorably even when compared with the unconstrained ARIES heuristic     

A QoS-aware multicast routing protocol

The future Internet is expected to support multicast applications with quality of service (QoS) requirements. To facilitate this, QoS multicast routing protocols are pivotal in enabling new receivers to join a multicast group. However, current routing protocols are either too restrictive in their search for a feasible path between a new receiver and the multicast tree, or burden the network with excessive overhead. We propose QMRP, a new QoS-aware multicast routing protocol. QMRP achieves scalability by significantly reducing the communication overhead of constructing a multicast tree, yet it retains a high chance of success. This is achieved by switching between single-path routing and multiple-path routing according to the current network conditions. The high level design of QMRP makes it operable on top of any unicast routing algorithm in both intradomain and interdomain. Its responsiveness is improved by using a termination mechanism which detects the failure as well as the success of routing without the use of timeout. In addition, QMRP always constructs loop-free multicast trees     

Penalty function approach in heuristic algorithms for constrained redundancy reliability optimization

To solve the problem of constrained redundancy reliability optimization, several heuristic algorithms have been developed in the literature. Most of these algorithms search for the solutions remaining within the feasible boundary e.g. [15], [20]. Perhaps the most interesting & efficient heuristic algorithm in terms of solution quality is that given by KYA, in which the search is made not only in the feasible region but also into the bounded infeasible region by making an excursion, which returns to the feasible region with a possibly improved solution. In this paper, a heuristic algorithm based on the penalty function approach is proposed to solve the constrained redundancy optimization problem for complex systems. An excursion is made into the infeasible region, but an adaptive penalty function helps the search not to go too far into the infeasible region. Thus, promising feasible & infeasible regions of the search space are explored efficiently & effectively to identify finally an optimal or near optimal solution. Computational experiments are conducted on 11 sets of problems (10 with linear constraints, and 1 with nonlinear constraints); each with 10 different randomly generated initial solutions. Comparison is made between the proposed algorithm P-Alg, N-N algorithm [15], Shi algorithm [20], and KYA [9] . It is observed that P-Alg performs consistently better than others, showing an overall improvement in various measures of performance. Besides, as P-Alg does not require any assumptions on the nature of the objective & constraint functions, it can solve a wide variety of problems.     

基于灰狼算法的无线网络组播路由优化

针对无线网络中资源受限的组播路由问题,考虑网络节点的节点度限制和网络链路的带宽约束,以最小化组播路由开销为目标,提出了一种二进制编码方式的基于灰狼优化算法的组播路由策略.在给定的网络拓扑下,基于灰狼优化算法的组播路由策略可以迅速找到一棵包含源和目的节点的最小开销组播树.仿真结果表明,相比于遗传算法,所提出的基于灰狼优化...     

支持空间迷你时槽重用的IEEE 802.16Mesh网络多播调度算法

In this paper, we propose a mechanism for multicast data transmission in IEEE 802.16 mesh networks aimed at increasing the throughput by incorporating mini-slot spatial reuse. The proposed mechanism includes two novel algorithms: a source-based multicast tree topology construction algorithm followed by an interference-aware multicast scheduling algorithm. The proposed multicast interfer-ence-aware scheduling algorithm can be ap-plied to both source-based and rendez-vous-based multicast tree topologies. Results of our simulation study show that in compari-son to the mechanism used for the IEEE 802.16’s standard, the proposed multicast tree generation algorithm reduces the number of consumed mini-slots by 64% on average. Moreover, using the proposed interfer-ence-aware scheduling algorithm decreases the number of required mini-slots by a further 22% on average. Therefore, the proposed multicast scheduling mechanism shows a higher throughput than the previous ap-proaches and it is more scalable with respect to increasing the number of multicast groups as well as increasing the number of members inside each multicast group.     

基于多条件约束的ASON动态组播路由算法

在将自动交换光网络(ASON)建模成着色多重图的基础上采用综合成本策略,设计了一种新的最小综合成本路径计算算法,并结合组播成员的动态变化特性提出一种满足多条件约束的动态组播路由(DMRMC)算法,使组播路由和波长分配在同一过程内完成,且尽可能使组播树的综合总成本最小,同时局部优化波长转换次数、分光次数和不同波长的使用数量。仿真实验表明,本文算法有效可行,与采用单成本策略的组播算法相比,其取得了更低的综合成本和更好的连接阻塞性能。     

QoS multicast routing in cognitive radio ad hoc networks

In this paper, we discussed the issues of QoS multicast routing in cognitive radio ad hoc networks. The problem of our concern was: given a cognitive radio ad hoc network and a QoS multicast request, how to find a multicast tree so that the total bandwidth consumption of the multicast is minimized while the QoS requirements are met. We proposed two methods to solve it. One is a two‐phase method. In this method, we first employed a minimal spanning tree‐based algorithm to construct a multicast tree and then proposed a slot assignment algorithm to assign timeslots to the tree links such that the bandwidth consumption of the tree is minimized. The other is an integrated method that considers the multicast routing together with the slot assignment. Extensive simulations were conducted to show the performance of our proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.