支持QoS的覆盖组播分布式动态路由研究

研究了带度和延时约束的覆盖组播动态路由问题,提出了动态适应性覆盖组播路由协议OMP,给出了一个基于分布式触发重组的组播路由算法——动态覆盖组播路由算法(DDCOMR),最后对该算法的复杂度进行了推证,对协议和算法的有效性进行了网络模拟。     

基于遗传模拟退火算法的多约束QOS组播路由优化算法

组播路由问题在计算机网络中是著名的Steiner树问题,是NP完全问题.通过考虑组播通信服务质量需求与网络资源约束,研究了基于服务质量的组播路由选择算法问题,首次提出了一个基于遗传算法和模拟退火算法的多约束组播路由优化算法,该算法在满足带宽、延时、延时抖动及包丢失率约束条件下寻找代价最小的组播树.     

自组织覆盖网络QoS组播动态路由优化研究

针对覆盖组播节点的动态特性,研究自组织覆盖网络带度和延时约束的组播动态路由问题,提出了动态覆盖组播路由算法AHMQ。组播树由目的节点驱动动态渐近形成,动态路由优化在通信过程中进行。协议是软状态的,仅要求节点维护局部状态信息,同时利用覆盖网络技术和无线媒质的广播能力,降低了网络负载,提高了重构能力。对算法进行了分析研究,通过实验验证了该算法具有较好的性能。     

基于遗传算法的多约束QoS组播路由优化算法

在计算机网络中,随着大量新兴多媒体实时业务的应用,组播路由问题成为越来越重要的课题。组播路由问题在计算机网络中是著名的Steiner树问题,同时也是NP完全问题。目前许多研究者在单约束(特别是延时约束)组播路由中取得了较好的成果,但对于多约束Qos组播路由方面的研究相对比较少。论文提出了一种基于遗传算法的多约束组播路由优化算法,该算法在满足带宽、延时、延时抖动和包丢失率约束条件下寻找代价最小的组播树,文中描述了一种适应于研究Qos组播路由的网络模型。最后通过仿真实验证明该算法操作简单、搜索速度快、效率高且具有较强的实用性和鲁棒性。     

基于暂态混沌神经网络的组播路由算法

讨论了高速包交换计算机网络中具有端到端时延的组播路由问题。首先给出了这类问题的网络模型及其数学描述，然后提出了基于暂态混沌神经网络的组播路由算法。实验结果表明，该算法能够快速有效地实现组播路由优化，并且计算性能及解的质量优于基于Hopfield神经网络的路由算法。     

一种延时约束费用最小分布式动态组播路由算法

多媒体应用一般包含多个组播成员,它消耗大量的网络资源且有严格的端端延时约束.针对这个问题,提出了一种延时约束费用最小的分布式动态组播路由启发算法DDDDCLCMR(distributeddynamicdelay-constrainedleast-costmulticastroutingalgorithm).在DDDDCLCMR算法中,组播源点很少或根本不参与路由计算;即使组播成员发生改变,组播树变化也很小,算法扩展性好.实验结果表明,无论组播成员改变与否,DDDCLCMR算法都能获得满足延时约束且费用很低的组播树.     

基于微粒群算法的QoS组播路由算法

文章研究了带宽、延时、延时抖动约束最小代价的QoS组播路由问题,提出了一种基于微粒群优化(PSO)算法[2,5]来设计路由优化算法。该算法采用一种新的整数编码方案,将路由优化问题转化成准连续优化问题,并采用罚函数处理约束条件。给出了应用微粒群优化算法求解QoS组播路由问题的算例,并与遗传算法和改进后的遗传算法进行了比较。计算机仿真实验证明,该算法可以更有效地求得QoS组播路由问题的优化解,可靠性高。     

一种多受限最小代价的动态组播路由算法

1.引言为确保通信网能提供(QoS)服务质量保证,必须研发有效的基于QoS的路由机制以提供高质量信息传输。一般地,基于QoS的路由要达到两个目标;一是要满足用户的QoS要求,如必须提供足够的带宽、足够小的延时和延时抖动等;二是要优化网络的利用率及代价。近年来,各国学者都开始关注基于QoS的路由问题。由于此类问题属于NP-Complete问题,所以各国学者大都采用启发式方法求解。文[1～3]提出了一些适用于信宿固定情况下的源路由算法。文[4～7]提出了几种动态路由算法,由于求解动态组播树的问题很复杂,大部分学者都将此问题分为两个部分求解:中心点(负责组播树的维护并将会话的状态传给所有网络节点)求解和基于中心点的路由选择,如PIM-SM和CBT算法。本文提出了一种多受限最小代价的动态组播路由算法MDLCMR(Multi-con-strained Dynamic Least Cost Multicast Routing)。该算     

基于蚂蚁算法的组播路由调度方法

探讨了在高速包交换计算机网络中,具有端到端时延及时延拦动限制的组播路由问题,并为这类问题的解决提出了一种新颖的基于蚁算法的组播路由优化方法。仿真实验结果表明,该方法不但能实现具有时延及时延拦动限制的组播路由的全局优化,而且能克服一些现有方法的不足。     

基于改进克隆策略的整体优化组播路由算法

提出一种基于改进克隆策略的整体优化组播路由算法,该算法优先考虑延时,同时在满足延时约束的条件下考虑延时、带宽、代价这三个性能指标,在三者之间进行权衡约束,专门用一个参数Q作为衡量组播路由综合性能的指标,并且对树内路径进行了基因优化从而很快得到最优个体。仿真结果表明,得出的组播树代价和延时较小,带宽较大,大大改善了组播路由的整体服务质量,且该算法收敛速度快,可靠性和稳定性高。     

Fuzzy Logic-Based Multicast Routing in Multiradio Multichannel Wireless Mesh Networks

The availability of bandwidth in wireless mesh networks (WMNs) introduces it as a prominent choice for implementing bandwidth sensitive services. Multicast services such as teleconferencing, push-based systems, multiplayer games, etc., can be implemented in an efficient way in such networks. Moreover, the severe performance degradations that can result from the interference generated by concurrent data transmissions and environmental noises call for the development of interference-aware routing mechanisms. This paper investigates the impact of wireless interference on network performance for multicast transmission in WMNs. We show that by taking wireless interference into consideration in the design of routing mechanisms, better resource usage can be achieved. Hence, a fuzzy logic–based approach is proposed to choose optimal routes from source to the multicast group in multichannel case. Three fuzzy variables are considered in route selection phase, which are interference, available bandwidth, and hop count. Extensive simulations are conducted aiming at verifying the high performance of the proposed algorithm. Simulation results demonstrated that our proposed algorithm outperforms Link-Controlled Multi-Rate Multi-Channel (LC-MRMC) and Channel Assignment with Multiple Factor (CAMF) algorithms in terms of throughput, packet delivery ratio, and end-to-end delay.     

Layered routing in irregular networks

Freedom from deadlock is a key issue in cut-through, wormhole, and store and forward networks, and such freedom is usually obtained through careful design of the routing algorithm. Most existing deadlock-free routing methods for irregular topologies do, however, impose severe limitations on the available routing paths. We present a method called layered routing, which gives rise to a series of routing algorithms, some of which perform considerably better than previous ones. Our method groups virtual channels into network layers and to each layer it assigns a limited set of source/destination address pairs. This separation of traffic yields a significant increase in routing efficiency. We show how the method can be used to improve the performance of irregular networks, both through load balancing and by guaranteeing shortest-path routing. The method is simple to implement, and its application does not require any features in the switches other than the existence of a modest number of virtual channels. The performance of the approach is evaluated through extensive experiments within three classes of technologies. These experiments reveal a need for virtual channels as well as an improvement in throughput for each technology class.     

Torus网络自适应容错路由算法

在应用于大规模并行计算机的互连网络的设计中,容错问题是其中的一个关键问题和难点问题。提出了一种基于Torus虫孔交换网络的容错路由算法,这一算法使用了矩形故障模型,无论故障区域大小多少和如何分布,算法始终是无死锁的,而且具有足够的自适应性,只要故障节点没有断开网络的连接,算法就能够通过选路使消息绕过故障区域,保持路由的连通性。同时,算法仅需要使用3个额外的虚拟通道。最后算法在不同故障率的Torus网络中进行了仿真实验,结果显示这一算法具有良好的平滑降级使用的特性。     

Mesh网络耐故障虫孔路由

耐故障是互连网络设计中的一个重要问题。本文提出了一种新的耐故障路由算法,并将其应用于使用虫孔交换技术的Mesh网络。由于使用了较低的路由限制,这一算法具有很强的自适应性,可以在各种不同故障域的Mesh网络中保持路由的连通性和无死锁性;由于使用了最小限度的虚拟通道,这一算法所需的缓冲器资源很少,非常适宜构建低成本的耐故障互连网络;由于根据本地故障信息进行绕行故障节点的决策,这一算法的路由决策速度较快并且易于在互连网络中实现。最后网络仿真试验显示,这一算法具有良好的平滑降级使用的性能。     

A novel optimization-based bandwidth-aware minimum power multicast routing algorithm in green wireless networks

Multicast routing in wireless networks that possess the wireless multicast advantage could significantly reduce the power and energy consumption. However, this kind of multicast routing that only addresses the transmission radius coverage might not be able to meet the bandwidth requirement of the users. As a result, additional transmissions are required to incur more energy consumption and carbon dioxide emissions that make existing algorithms not applicable to bandwidth constrained applications. In this paper, for the first time, we address the bandwidth aware minimum power multicast routing problem in wireless networks where the objective function is to minimize the total power consumption subject to the users?? bandwidth requirements. This problem is a challenging cross-layer design problem that requires seamless and sophisticated integrated design in the network layer (multicast routing) and physical layer (bandwidth-aware wireless transmission and power control). We first formulate this problem as a mixed integer linear programming problem and then propose a Lagrangian relaxation based algorithm to solve this problem. Numerical results demonstrate that the proposed approach is a sound green networking algorithm that outperforms the existing power efficient multicast routing approaches under all tested cases, especially in large bandwidth request, fine radius granularity, large group size and sparse network.     

Towards the fast and robust optimal design of wireless body area networks

Wireless body area networks are wireless sensor networks whose adoption has recently emerged and spread in important healthcare applications, such as the remote monitoring of health conditions of patients. A major issue associated with the deployment of such networks is represented by energy consumption: in general, the batteries of the sensors cannot be easily replaced and recharged, so containing the usage of energy by a rational design of the network and of the routing is crucial. Another issue is represented by traffic uncertainty: body sensors may produce data at a variable rate that is not exactly known in advance, for example because the generation of data is event-driven. Neglecting traffic uncertainty may lead to wrong design and routing decisions, which may compromise the functionality of the network and have very bad effects on the health of the patients. In order to address these issues, in this work we propose the first robust optimization model for jointly optimizing the topology and the routing in body area networks under traffic uncertainty. Since the problem may result challenging even for a state-of-the-art optimization solver, we propose an original optimization algorithm that exploits suitable linear relaxations to guide a randomized fixing of the variables, supported by an exact large variable neighborhood search. Experiments on realistic instances indicate that our algorithm performs better than a state-of-the-art solver, fast producing solutions associated with improved optimality gaps.     

QoS routing optimization strategy using genetic algorithm in optical fiber communication networks

This paper describes the routing problems in optical fiber networks, defines five constraints, induces and simplifies the evaluation function and fitness function, and proposes a routing approach based on the genetic algorithm, which includes an operator [OMO] to solve the QoS routing problem in optical fiber communication networks. The simulation results show that the proposed routing method by using this optimal maintain operator genetic algorithm (OMOGA) is superior to the common genetic algorithms (CGA). It not only is robust and efficient but also converges quickly and can be carried out simply, that makes it better than other complicated GA.     

微分方法在路由优化中的应用研究

通过引入势函数，使用微分方法设计了一个流量路由优化算法．讨论了如何设计势函数和调节虚拟链路利用率来加快算法收敛的速度，降低可能引入的误差．在初始可行解的计算上，给出了一个能够适应苛刻带宽和流量矩阵的更加有效的方法．试验结果表明，该算法同其他方法相比，能够在更短的时间内取得更好的优化结果，可以有效的应用于网络的优化设计．     

带度约束的最小直径应用层多播路由问题的启发式遗传算法

由于IP多播难以在因特网环境中配置,应用层多播作为IP多播的一种替代方案得到越来越多的研究。从网络设计的角度来看,应用层多播在网络代价模型及路由策略方面与传统的IP多播有很大区别。本文研究了带度约束的最小直径应用层网络多播路由问题,提出了解决该问题的启发式遗传算法。通过大量仿真实验,我们对比分析了两种贪婪算法法和遗传算法的性能。实验显示,启发式遗传算法具有较好的性能。     

Adaptive TCP congestion control and routing schemes using cross-layer information for mobile ad hoc networks

Compared with traditional networks, ad hoc networks possess many unique characteristics. For example, ad hoc networks can drop a packet due to network events other than buffer overflow. Unfortunately, the current layered network architecture makes it impossible to pass the information specific to one layer to other layers. As a result, if a packet is lost due to reasons other than buffer overflow, TCP adversely invokes its congestion control procedure. Similarly, the routing algorithm may misinterpret that a path is broken and adversely invoke the route recovery procedure.This study addresses the limitations of the current layered network architecture by adopting a cross-layer protocol design for TCP and routing algorithms in ad hoc networks. The objective of this approach is to enable the lower-layered ad hoc network to detect and differentiate all possible network events, including disconnections, channel errors, buffer overflow, and link-layer contention, that may cause packet loss. Using the information exploited by lower layers, the upper layer-3 routing algorithm, and the layer-4 TCP can take various actions according to the types of network events. Simulation results demonstrate that the combination of the cross-layer optimized TCP and routing algorithms can effectively improve the performance of TCP and DSR, regardless of whether it is in a stationary or a mobile ad hoc network.