网络多播路由的改进编码软件设计与实现

传统网络多播路由编码方法采用多播分布树进行编码,但链路容量遭遇瓶颈,致使编码节点较多,导致浪费带宽资源的问题。在此提出基于Koetter指数时间的网络多播路由改进编码算法对编码软件进行设计,分析多播路由的总体设计,通过数据包编码转发模块在多播拓扑不相交路径上进行编码和转发多播数据包,利用输入模块实现网络多播路由和上游节点的信息交换,通过开关仲裁模块判断能够向特定输出端口传输信息的输入端口,利用死锁控制模块对出现死锁现象的路由节点进行检测,一段时间后使多播路由恢复正常的数据交换,通过输出模块对数据的输出进行管理。以降低带宽资源为目的,采用Koetter指数时间算法实现网络多播路由编码,并给出编码的详细代码。实验结果表明,所提方法不仅节省网络资源,而且显著降低多播路由时延,增强网络吞吐量。     

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。     

基于时延约束的改进型实时QoS多播路由算法

多播技术是将特定数据选择性地传送至多个客户端的方法,因而其服务质量是评价其优劣的关键.结合FLSPT算法和贪婪法思想,提出一种基于时延约束的改进型实时QoS多播路由算法,它利用启发式策略,使得节点在多播树时能满足时延约束的条件下建立最小代价路径.测试结果表明,采用该算法可获得较小的端到端时延,能改善网络服务质量,适用于成员数目变化频繁的多播应用.     

基于网络编码的多播路由算法性能分析

多播传输是目前通信系统中的一项关键技术,可以将相同的信息同时传向多个接收节点。该文提出一种基于网络编码的新的多播路由算法,该算法利用Dijkstra约简网络搜索源节点到各接收节点的路径族。仿真结果表明,该算法在资源消耗和负载均衡方面较传统的多播路由算法有更好的表现,同时性能也更接近基于网络编码的最小费用多播算法。最后,数学分析表明该算法具有较低的计算复杂度。     

多播群组通信中服务质量受限的Core Placement算法

与面向源节点的路由算法不同，Ｃｏｒｅ Ｂａｓｅｄ多播路由算法在网络中为一个多播组上 的多个多播连接只建立一棵共享树，从而实现了提高了网络资源利用率的目的。本文针对 Ｃｏｒｅ Ｂａｓｅｄ多播路由中 ｃｏｒｅ节点的定位问题，提出了一个同时最小化多播时延及目标节点间时延抖动的 ｃｏｒｅ节点定位算法 ＱＯＣＰ。由仿真结果可知，这里提出的方法在优化服务质量性能指标方面明显优 于文中涉及的其他算法。     

一种基于拉格朗日松弛的时延约束多播路由算法

提出了一种基于拉格朗日松弛方法的时延约束最小代价多播路由算法(LR-DLMA)。该算法充分利用拉格朗日松弛方法的特点，通过构建封闭图，对封闭图进行拉格朗日松弛求得满足条件的多播树。仿真实验结果表明本算法性能稳定，其代价性能接近性能最好的BSMA算法，并具有快速、低时延的特点。     

一种传感器网络的分布式多播路由优化算法

传感器感知的信息需要通过网络传送给感兴趣目标节点,传统网络中的多播技术往往能耗高、实时性不够理想,不利于在传感器网络中使用。针对 WSN中节点对网络拓扑未知,该文先将多播路由问题演化为最优多播路径问题,通过启发式算法求解分布式最优路径,并通过一种基于贪婪思想的裁剪合并策略优化多播路由树,直至整个网络得到最优路径,最后并结合了节点区域集中以及无线多播特性,提出了 DCast 路由算法。最后通过仿真实验与uCast, SenCast等经典的传感器网络的多播路由算法仿真比较,可以得出其算法在时延性以及能耗等方面性能有优势。     

分光器稀疏配置的WDM光网络多播路由算法

针对分光器稀疏配置条件下的WDM光网络多播路由分配问题,提出了一种路由分配算法.详细阐述了算法的实现步骤.通过大量仿真实验,结果表明:该算法具有寻找目标节点时间短、建立动态链路快等优点;与其它算法相比,该算法在多播路由分配中使用的平均波长代价最小,在单条链路上使用的波长数最少.     

一种多约束QoS多播路由算法

提出了带宽时延约束、代价最小的QoS多播路由模型,并提出了一种启发式算法求解该问题,分析了算法的复杂度。仿真试验证明,该算法是稳定有效的。它能够在满足两种约束的情况下,使多播树的代价优化。     

多媒体通信的多播路由算法

在多媒体通信网的实际应用中,多播(multicasting)技术日显重要,在实际网络中,网络节点具备不同的多播能力,有些节点不具备多播能力,而具备多播能力的节点要限制其复制信息的数量,即节点多播能力受限,该文用节点的度约束来表示每个节点的多播能力;此外网络中的很多业务要求信息从源节点传送到目的节点的时延受限;因此该文研究带度约束和时延约束的多播路由问题,给出了一种Lagrange松弛法,能够较好地解决这类问题。     

High-throughput multicast routing metrics in wireless mesh networks

The stationary nature of nodes in a mesh network has shifted the main design goal of routing protocols from maintaining connectivity between source and destination nodes to finding high-throughput paths between them. Numerous link-quality-based routing metrics have been proposed for choosing high-throughput routing paths in recent years. In this paper, we study routing metrics for high-throughput tree or mesh construction in multicast protocols. We show that there is a fundamental difference between unicast and multicast routing in how data packets are transmitted at the link layer, and accordingly how the routing metrics for unicast routing should be adapted for high-throughput multicast routing. We propose a low-overhead adaptive online algorithm to incorporate link-quality metrics to a representative multicast routing protocol. We then study the performance improvement achieved by using different link-quality-based routing metrics via extensive simulation and experiments on a mesh-network testbed, using ODMRP as a representative multicast protocol.Our extensive simulation studies show that: (1) ODMRP equipped with any of the link-quality-based routing metrics can achieve higher throughput than the original ODMRP. In particular, under a tree topology, on average, ODMRP enhanced with link-quality routing metrics achieve up to 34% higher throughput than the original ODMRP under low multicast sending rate; (2) the improvement reduces to 21% under high multicast sending rate due to higher interference experienced by the data packets from the probe packets; (3) heavily penalizing lossy links is an effective way in the link-quality metric design to avoid low-throughput paths; and (4) the path redundancy from a mesh data dissemination topology in mesh-based multicast protocols provides another degree of robustness to link characteristics and reduces the additional throughput gain achieved by using link-quality-based routing metrics. Finally, our experiments on an eight-node testbed show that on average, ODMRP using SPP and PP achieves 14% and 17% higher throughput over ODMRP, respectively, validating the simulation results.     

无线mesh网络中编码感知且负载均衡的组播路由

提出一种新的基于网络编码的负载均衡路由量度CRM-LB(coding-aware routing metric with load balancing),CRM-LB在CRM(coding-aware routing metric)的基础上增加了对路径p上所有节点通信密集程度与网络拥塞程度的考虑。进一步提出了基于CRM-LB的无线mesh网络多播路由CLR(coding and load-balancing routing)。该协议可以增加网络编码机会,同时考虑到网络中的负载均衡。通过性能分析和仿真实验表明,该协议在提高多播吞吐量的前提下,不仅能更好地支持网络编码,而且网络负载基本均衡。     

Avoidance of multicast incapable branching nodes for multicast routing in WDM networks

In this article we study the multicast routing problem in all-optical WDM networks under the spare light splitting constraint. To implement a multicast session, several light-trees may have to be used due to the limited fanouts of network nodes. Although many multicast routing algorithms have been proposed in order to reduce the total number of wavelength channels used (total cost) for a multicast session, the maximum number of wavelengths required in one fiber link (link stress) and the end-to-end delay are two parameters which are not always taken into consideration. It is known that the shortest path tree (SPT) results in the optimal end-to-end delay, but it can not be employed directly for multicast routing in sparse light splitting WDM networks. Hence, we propose a novel wavelength routing algorithm which tries to avoid the multicast incapable branching nodes (MIBs, branching nodes without splitting capability) in the shortest-path-based multicast tree to diminish the link stress. Good parts of the shortest-path-tree are retained by the algorithm to reduce the end-to-end delay. The algorithm consists of tree steps: (1) a DijkstraPro algorithm with priority assignment and node adoption is introduced to produce a SPT with up to 38% fewer MIB nodes in the NSF topology and 46% fewer MIB nodes in the USA Longhaul topology, (2) critical articulation and deepest branch heuristics are used to process the MIB nodes, (3) a distance-based light-tree reconnection algorithm is proposed to create the multicast light-trees. Extensive simulations demonstrate the algorithm’s efficiency in terms of link stress and end-to-end delay.     

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...     

k元n方网络中的优化多播策略

该文提出了一种在基于虫孔交换的k元n方网络中实现并发多播通信的有效策略。该策略通过引入分区的概念,把整个网络划分成多个通信区域而提高了多播的并行性。在该策略下,结合自适应单播路由生成的多播路由算法能够实现低延迟,低标准差和高吞吐率的多播通信,且不需要引入任何附加硬件需求。该文给出了在512个节点的三维torus网络中的仿真结果,验证了该策略的有效性。     

A ring-based multicast routing topology with QoS support in wireless mesh networks

Wireless mesh networking (WMN) is an emerging technology for future broadband wireless access. The proliferation of the mobile computing devices that are equipped with cameras and ad hoc communication mode creates the possibility of exchanging real-time data between mobile users in wireless mesh networks. In this paper, we argue for a ring-based multicast routing topology with support from infrastructure nodes for group communications in WMNs. We study the performance of multicast communication over a ring routing topology when 802.11 with RTS/CTS scheme is used at the MAC layer to enable reliable multicast services in WMNs. We propose an algorithm to enhance the IP multicast routing on the ring topology. We show that when mesh routers on a ring topology support group communications by employing our proposed algorithms, a significant performance enhancement is realized. We analytically compute the end-to-end delay on a ring multicast routing topology. Our results show that the end-to-end delay is reduced about 33 %, and the capacity of multicast network (i.e., maximum group size that the ring can serve with QoS guarantees) is increased about 50 % as compared to conventional schemes. We also use our analytical results to develop heuristic algorithms for constructing an efficient ring-based multicast routing topology with QoS guarantees. The proposed algorithms take into account all possible traffic interference when constructing the multicast ring topology. Thus, the constructed ring topology provides QoS guarantees for the multicast traffic and minimizes the cost of group communications in WMNs.     

Multicast Routing in Wireless Mesh Networks: Minimum Cost Trees or Shortest Path Trees?

There exist two fundamental approaches to multicast routing: shortest path trees (SPTs) and minimum cost trees (MCTs). The SPT algorithms minimize the distance (or cost) from the sender to each receiver, whereas the MCT algorithms minimize the overall cost of the multicast tree. Due to the very large scale and unknown topology of the Internet, computing MCTs for multicast routing in the Internet is a very complex problem. As a result, the SPT approach is the more commonly used method for multicast routing in the Internet, because it is easy to implement and gives minimum delay from the sender to each receiver, a property favored by many real-life applications. Unlike the Internet, a wireless mesh network (WMN) has a much smaller size, and its topology can be made known to all nodes in the network. This makes the MCT approach an equally viable candidate for multicast routing in WMNs. However, it is not clear how the two types of trees compare when used in WMNs. In this article we present a simulation-based performance comparison of SPTs and MCTs in WMNs, using performance metrics, such as packet delivery ratio, end-to-end delay, and traffic impacts on unicast flows in the same network.     

图压缩优化光组播最小网络编码路由

将网络编码和光网络相结合可以有效解决光网络的 带宽资源利用率等问题。然而,在光网络中进行编码操作,又将增加光网的光域运算开销、 复杂度和缓存需求。为了减少光网络中网络编码的操作次数,本文提出一种基于图压缩的方 法优化光网络拓扑结构, 结合智能优化遗传算法(GA)实现组播最大速率的光组播最小编码节点,通过对光网络拓扑结 构中的一类特殊潜在编码节点 进行压缩处理,达到缩小算法搜索空间、排除大量非最优解的目的。仿真结果表明,通过本 文图压缩优化后的光网络拓扑结 构,可以使得现有的智能优化GA在求解光组播最小网络编码路由问题时效率更高,寻找到的 解更优。     

Improved Shuffled Frog-Leaping Algorithm Based QoS Constrained Multicast Routing for Vanets

Prompt and reliable communication between vehicular nodes are essential as its limited coverage and dynamic mobility rate introduces frequent change of network topology. The key feature of vehicular communication that establishes direct connectivity or Road Side Unit-based data transfer among vehicular nodes is responsible for sharing emergency information during critical situations. Multicast routing data dissemination among vehicular nodes is considered to be the potential method of parallel data transfer as they facilitate the option of determining an optimal multicast tree from feasible number of multicast trees established between the source and destinations. This estimation of optimal multicast tree using meta-heuristic techniques is confirmed to improve the throughput and reliability of the network when QoS-based constraints are imposed during multicast routing. An Improved Shuffled Frog-Leaping Algorithm-Based QoS Constrained Multicast Routing (ISFLABMR) is proposed for estimating an optimal multicast tree that confirms effective multi-constrained applied multicast routing between vehicular nodes. ISFLABMR minimizes the cost of transmission to 22% by reducing the number of multicast clusters formed during multicasting through the utilization of local and global-based optimizations. The simulation results of ISFLABMR proveits predominant reduction rate of 24% and 21% in average packet latency and energy consumptions incurred under multicast routing.     

片上网络节点编码的设计和在路由方面的应用

网络拓扑选择和路由算法设计是片上网络设计的关键问题.在比较现有的三种网络拓扑结构的基础上,提出了一种隐含着相邻节点以及节点之间链路关系并适合二维Torus拓扑结构的节点编码方法.该编码和Torus结构的结合能拓扑结果够简化路由算法的设计和实现,改善了网络路由性能.实验结果表明,提出的编码方法与二维Torus拓扑结构的结合有效地提高了片上网络通信性能.