一种时延和时延抖动受约束的启发式多播路由算法

多播路由算法在组播应用中是至关重要的,对视频会议等交互式实时组播业务来说,不仅要考虑时延约束,而且要考虑时延抖动约束。本文提出了一种基于最短时延路径的时延和时延抖动约束的启发式算法,仿真结果表明该算法复杂度较低,而且性能也较好,在算法复杂度和性能之间达到了很好的折中。     

一种新的QoS组播路由算法

针对现有的求解多约束QoS组播路由中存在的问题,结合BP神经网络局部搜索的优势和蚁群算法全局搜索的优势的特点,进行QoS组播路由算法的设计,提出了一种新型的NNAC算法。该算法通过BP神经网络寻找路径的更优解,改善了QoS组播路由路径寻找的方法。通过实验仿真表明,NNAC算法得到最优组播树的总延时为35,总代价费用为21,在完成150个度约束组播路由路径时,NNAC算法在进行最优组播树的寻找成功率上高于AC算法,同时该算法还克服了AC算法易陷入局部最小点的不足。     

改进遗传算法在QoS组播路由选择中的研究

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。     

时延和时延抖动约束的低费用多播路由算法

为了有效支持交互式实时组播业务,不仅要考虑时延约束,而且要考虑时延抖动约束,同时还需高效管理网络资源,以降低多播费用。本文提出了一种新的时延和时延抖动约束的低费用我播路由启发式算法,仿真结果表明该算法复杂度较低,时延抖动较小,又降低了网络费用,是一种快速有效的多播路由算法。     

基于Grover搜索的多约束路由算法

寻找满足多约束条件的QoS路由是网络业务能否顺利实施的关键,在研究和分析了当前多种典型相关算法的基础上,提出了一种基于Grover量子搜索思想的多约束路由算法。算法对路径采用了非线性路径长度的度量方法,分析了Grover搜索的特点和优势,根据Grover迭代的实现过程构建了操作矩阵和概率扩散矩阵,通过选择高概率的节点进行数据转发。仿真表明,该算法在最短路径获取和路由发现成功率方面都有高效的表现。     

基于遗传算法的路由选择问题的研究

为了在一个通信网络中,找到多源点到多目的点的路由总代价最小的符合带宽-时延约束的路由集,根据服务质量组播路由的特点,结合遗传算法的寻优特性,采用一种求解带宽-时延约束的两层遗传算法的方法,进行了理论分析和实验验证,取得了多源点到多目的点组播路由集的代价数据。结果表明,所提出的算法可以有效找到多组播路由问题的优化解。     

一种新的QoS保证的快速组播路由算法

提出了一种新的服务质量保证的组播路由算法。算法使用了一个修改的斯坦利树近似算法来构建时延有界的低代价组播树，再通过最小时延路径与其他尚不在组播树的组内节点连接，并消除环路。理论和仿真表明，新算法与其他一些时延有界组播路由算法一样有较好的性能。并且有较小的复杂度。     

一种时延受限的低代价移动IP组播路由算法

基于固定和移动IP混合网络，针对时延敏感的实时通信业务，建立了网络模型，提出了有时延约束的低代价组播路由问题，给出了一种分布启发式组播路由算法，证明了算法的正确性，分析了算法的复杂度。仿真结果表明，算法是有效的、稳定的。     

一种非精确状态下满足多QoS约束的 动态组播路由算法

提出了一种非精确状态下满足多QoS约束的动态组播路由算法——DMIQ,该算法采用改进的BF算法作为路径搜索算法,WFQ作为分组调度机制,链路延迟不确定且服从均匀分布,能在非精确状态且满足带宽、延迟抖动和丢包率约束的前提下确定具有最小跳数和开销的动态组播路由.仿真实验表明,DMIQ能在非精确状态且满足多QoS约束的前提下建立动态组播路由,在路由请求平均成功率、平均延迟和平均跳数等衡量指标下表现出良好的性能.     

基于位置信息的机会网络高效路由算法

针对现有可用于机会网络的基于地理位置信息的路由算法周期性发布地理位置信息使控制开销偏大的问题,提出一种按需发布地理位置信息的高效路由算法,通过设计和使用一种根据需要发布地理位置信息的新机制,减少路由控制开销,同时使节点在路径断裂时携带数据分组,从而提高数据传送成功率。理论分析和仿真结果表明,文章所提算法与DREAM(Distance Routing Effect Algorithm Mobility)算法和它的改进算法BFDREAM(Boundary Forwarding DREAM)相比,在控制开销、数据传送成功率、分组端到端时延等方面的性能均有所提高。     

QoS multicast routing by using multiple paths/trees in wireless ad hoc networks

In this paper, we investigate the issues of QoS multicast routing in wireless ad hoc networks. Due to limited bandwidth of a wireless node, a QoS multicast call could often be blocked if there does not exist a single multicast tree that has the requested bandwidth, even though there is enough bandwidth in the system to support the call. In this paper, we propose a new multicast routing scheme by using multiple paths or multiple trees to meet the bandwidth requirement of a call. Three multicast routing strategies are studied, SPT (shortest path tree) based multiple-paths (SPTM), least cost tree based multiple-paths (LCTM) and multiple least cost trees (MLCT). The final routing tree(s) can meet the user’s QoS requirements such that the delay from the source to any destination node shall not exceed the required bound and the aggregate bandwidth of the paths or trees shall meet the bandwidth requirement of the call. Extensive simulations have been conducted to evaluate the performance of our three multicast routing strategies. The simulation results show that the new scheme improves the call success ratio and makes a better use of network resources.     

动态QoS多播路由协议

本文主要研讨了具有QoS约束的动态多播路由问题.文中描述了一种适用于QoS多播路由的网络模型,提出了一种动态QoS多播路由协议(DQMRP),该协议能操作在单播路由协议的顶层,它只要求网络链路(或节点)的局部状态信息,不需要维护全局状态信息.DQMRP可有效地减少构造一棵多播树的开销,多播组成员可动态地加入／退出多播会晤.该协议可搜索多条可行树枝,并能选择一条最优(或近优)树枝将新成员连接到多播树.文中给出了DQMRP的正确性证明和复杂性分析,并通过仿真实验验证了该协议的可用性和有效性.     

QUASIMODO: quality of service-aware multicasting over DiffServ and overlay networks

Efficient delivery of real-time multicast traffic imposes on the underlying network infrastructure the burden of supporting quality of service. This can be quite a complex issue in a differentiated services IP network, especially if multicast users are allowed to join and leave the multicast tree dynamically. In fact, since DiffServ lacks explicit reservation states, a replicating node cannot test whether a corresponding reservation exists on an output link, and upon a dynamic join of a QoS multicast user, the DiffServ network lacks control functions to verify whether resources are available along the new path. We present a solution to support dynamic multicast with QoS over a DiffServ network. Our solution combines two ideas. First, resource availability along a new QoS path is verified via a probe-based approach. Second, QoS is maintained by marking replicated packets with a special DSCP (differentiated service code point) value before forwarding them on the QoS path.     

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     

面向绿色互联网的低功耗多播路由算法

基于路径节点驱动策略,提出了一种绿色互联网中的一对多组播路由算法,充分利用路径节点共享路径,生成低功耗最短路径树,提高用户QoS满意度。基于CERNET2拓扑仿真实现了该算法,通过与现有的能量感知启发式路由算法在网络功耗、路由成功率和运行时间等方面的性能对比,表明本文提出的算法具有更好的性能。     

一种改进的多播路由算法

低代价最短路径树是一种广泛使用的多播树,它能够在保证传送时延最小的同时尽量降低带宽消耗。DDSP(Destination-Driven Shortest Path)算法是一个性能较好,计算效率较高的低代价最短路径树算法,在该算法基础上,通过改进结点的搜索过程,提出一种改进的快速低代价最短路径树算法。由算法分析和实验比较得出,改进算法的计算效率高于DDSP算法,且算法构造的最短路径树的性能也优于DDSP算法构造的树．     

Multi-Constrained Dynamic QoS Multicast Routing Design Using Ant Colony System

1IntroductionThe objective of Dynamic QoS Multicast Routing(DQMR) is to find the opti mal routing trees in the fu-ture real-ti me communication network, where informa-tion or messages are sent fromthe source nodeto all des-tination nodes , while meeting all QoS requirements forevery admitted connection and achieving global efficien-cy in resource utilization. Different applications haverather diverse QoS constraints on bandwidth, delay,delayjitter and so on. Multiple constraints often mak…     

A new delay‐constrained algorithm for multicast routing tree construction

New multimedia applications provide guaranteed end‐to‐end quality of service (QoS) and have stringent constraints on delay, delay‐jitter, bandwidth, cost, etc. The main task of QoS routing is to find a route in the network, with sufficient resources to satisfy the constraints. Most multicast routing algorithms are not fast enough for large‐scale networks and where the source node uses global cost information to construct a multicast tree. We propose a fast and simple heuristic algorithm (EPDT) for delay‐constrained routing problem for multicast tree construction. This algorithm uses a greedy strategy based on shortest‐path and minimal spanning trees. It combines the minimum cost and the minimum radius objectives by combining respectively optimal Prim's and Dijkstra's algorithms. It biases routes through destinations. Besides, it uses cost information only from neighbouring nodes as it proceeds, which makes it more practical, from an implementation point of view. Copyright © 2004 John Wiley & Sons, Ltd.     

Two algorithms for multi‐constrained optimal multicast routing

Multimedia applications, such as video‐conferencing and video‐on‐demand, often require quality of service (QoS) guarantees from the network, typically in the form of minimum bandwidth, maximum delay, jitter and packet loss constraints, among others. The problem of multicast routing subject to various forms of QoS constraints has been studied extensively. However, most previous efforts have focused on special situations where a single or a pair of constraints is considered. In general, routing under multiple constraints, even in the unicast case is an NP‐complete problem. We present in this paper two practical and efficient algorithms, called multi‐constrained QoS dependent multicast routing (M_QDMR) and (multicasting routing with multi‐constrained optimal path selection (M_MCOP)), for QoS‐based multicast routing under multiple constraints with cost optimization. We provide proof in the paper that our algorithms are correct. Furthermore, through extensive simulations, we illustrate the effectiveness and efficiency of our proposals and demonstrate their significant performance improvement in creating multicast trees with lower cost and higher success probability. Copyright © 2003 John Wiley & Sons, Ltd.