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随着无线自组网络技术的发展,多播应用日益广泛。文章研究无线自组网络多插路由问题,针对已有算法在时延约束多播路由树费用优化方面的不足,提出基于遗传算法的多播路由算法。该算法首先通过Dijkstra算法得到源节点到每个接收节点间的最多K条路径;其次给这些路径编号,进行编码,设计遗传操作;最后,进行遗传迭代运算找到费用全局优... 相似文献
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基于AdHoc网络的特殊性,固定网络中已有的多播路由协议已经难以有较好的适应度,怎样在移动无线自组织网络中实现效率较高的多播路由已成为一个极具挑战性的问题。分析了移动无线自组织网络中多播路由协议所具有的问题以及相应的设计要求;详细阐述了现有的移动无线自组织网络多播路由协议,并对该网络中不同多播路由的方法进行了分析和比较;对移动无线自组织网络中的多播路由协议的使用进行了总结。 相似文献
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网络编码被应用于多播、广播和单播中。而把网络编码应用于无线传感网汇播的研究还处于理论和仿真阶段。把网络编码应用于实际环境中,需要考虑节点同步、开销控制、线性独立的编码系数等问题。为了研究网络编码对传统汇播的影响,文中在真实无线传感网中实现了一种基于网络编码的汇播机制。文中基于TDMA实现同步和开销控制,采用线性网络编码来进行编码,采用高斯消除来进行解码。文中以收集率为参考,实验结果表明,网络编码能给传统汇播带来可靠性增益。 相似文献
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在WDM网络中有两种全光多播方式,一种是OCS(光电路交换)网络中基于光树的多播,另一种就是在OBS(光突发分组交换)网络中基于突发分组的多播。这两种方式都有各自的优缺点。在分析这两种交换技术优缺点的同时,提出了一种采用混合交换技术的新型光交换网络(c-HyLabs),并提出了在此网络上实现光多播的机制。通过OPNET的仿真表明,该混合光交换网络在相同条件下其延时及丢包率等性能均优于OBS网络多播。 相似文献
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无线自组织网络由于节点能量受限、无线链路可靠性较差等特性使得在设计数据可靠传输方案时必须考虑上述问题.提出了一个无线自组织中基于网络编码的可靠中继多播方案,本方案让一部分接收节点担当信源节点的发送任务,以中继的形式完成链路失效率较高的节点的传输.理论分析和数值分析结果表明,所提出的方案是可行的,在一定程度上提高了无线自... 相似文献
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考虑到在无线多跳网络中存在多个相互独立的多播流的调度问题,首先提出了一个基于网络编码的动态多源多播模型,并根据该模型设计了一个适用于802.11DCF MAC的多播算法MulSrc。MulSrc以队列积压作为流调度的主要依据,以网络编码作为数据传输和本地恢复的主要手段,无固定的传输路径,在无线网络中实现以丰富的多路径来克服相关丢失、降低延迟的目标,适用于无线网络中大量存在的随机丢包情况。实验证明,在存在多个多播流的网络上,MulSrc可以取得比同类协议CodeCast和MMForests更好的性能。 相似文献
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研究了对多播网络进行网络编码的方法,提出了一种基于网络编码的应用层多播算法.该算法在计算网络拓扑时考虑了链路的花费.源端和-中间节点使用随机线性编码方法进行编码,在目的端进行解码操作使得目的端能从乱序的信息和部分丢失的信息中恢复出原始数据,提高了网络的可靠性.通过对ns-2的扩展并进行仿真实验,结果证明了基于网络编码的应用层多播算法是可以提高网络的吞吐量,并且和网络中最大的吞吐量比较接近.在信息块不是很大的情况下,编码延迟率的增长是在一定的范围内的. 相似文献
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本文提出了一种网络计算环境下的I/O加速方法:iSCSI透明可靠多播(iTRM)。通过在iSCSI网络计算系统中设计双路径:共享数据的多播传送路径和iSCSI协议数据包传递路径,来加速网络计算数据加载性能。并且在iSCSI启动器端对多播数据进行丢包检测和请求重传,由iSCSI会话重传丢失的数据包来保证I/O数据的可靠性。扩展了iSCSI协议以支持多播会话通告,设计了一种基于数据感知实现I/O路由选择的透明多播监控代理。测试结果表明,基于iTRM的iSCSI网络计算系统显著提升了多个客户主机的并发I/O性能,并对客户主机数量的增加具有良好的系统扩容性。 相似文献
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研究航天器部署在火星表面的无线传感器节点,首次提出了外层空间无线传感器网络(outer space wireless sensor network,OSWSN)的概念,指出该网络的节点以自组织方式组网。基于已有的地面无线传感器网络经典组播路由协议,结合无线自组织网络组播协议建树思想,设计应用于外层空间无线传感器网络的OSWSNMP(OSWSN multicast protocol)。与已有的MAODV组播路由协议以及应用于地面无线传感器网络的EMRS组播路由协议进行比较,在NS2上搭建OSWSNMP仿真环 相似文献
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提出了一种可以无阻塞地传输其输入与输出间任意多播信号的新型自路由无阻塞多级网。该网络采用了循环重建法,以二进制扩散概念为基础。它由一个二进制扩散网络和两个二分之一大小的多播路由网络循环构建而成。多播信号由第一个Omega网复制并二分扩散到输出端口,进入N×N的Omega×Omega-1网络,再进入紧随其后的N/2×N/2的Omega×Omega-1网络……。每个Omega×Omega-1网络负责依照目的地址的有效标志位将输入置换到输出的上半部分和下半部分,再分别进入上下两个子Omega×Omega-1网络中做同样的处理,如此类推,直到全部地址有效位处理完毕,从而完成自路由无阻塞的多播传输。由于各大小不等的Omega×Omega-1网络皆可并行设置和并行路由,故此种新型多Omega网络的设置时间为O(NlogN),路由时间为O(log2N),硬件代价则为O(Nlog2N)。它比现行已知的多播网络设计具有较优的代价。 相似文献
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This paper considers wireless multicast networks where network coding (NC) is applied to improve network throughput. A novel joint topology and cross-layer design is proposed to maximise the network throughput subject to various quality-of-service constraints, such as: wireless multicast rate, wireless link capacity, energy supply and network lifetime. Specifically, a heuristic NC-based link-controlled routing tree algorithm is developed to reduce the number of required intermediate nodes. The proposed algorithm facilitates the optimisation of the wireless multicast rate, data flow of wireless links, energy supply and lifetime of nodes through a novel cross-layer design. The proposed joint topology and cross-layer design is evaluated and compared against other schemes from the literature. The results show that the proposed scheme can achieve up to 50% increase in the system throughput when compared to a classic approach. 相似文献
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Reliable multicast, the lossless dissemination of data from one sender to a group of receivers, has a wide range of important applications in wireless networks. In this paper, we are interested in the reliable single-hop wireless multicast. As the wireless channel is inherently error prone, it is challenging to achieve high channel utilization in reliable wireless multicast. Most schemes proposed by now for reliable single-hop wireless multicast share the same weakness in that an entire frame will be retransmitted even if it has single error bit. To alleviate this problem, this paper presents an efficient reliable multicast scheme based on block-level ARQ and network coding technique. The new scheme breaks the data stream into blocks and retransmits only erroneous blocks (rather than the entire corrupted frame), where the novel network coding technique is further adopted to minimize the total number of block retransmissions. The theoretical analysis and simulation are conducted to demonstrate the performance of the new scheme and also some typical available schemes in terms of their bandwidth efficiency. The simulation and theoretical results indicate that new reliable wireless multicast scheme can significantly enhance the channel utilization, especially in the scenarios where bit error rate is high and the number of receivers is large. 相似文献
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In this paper, we discuss the energy efficient multicast problem in ad hoc wireless networks. Each node in the network is assumed to have a fixed level of transmission power. The problem of our concern is: given an ad hoc wireless network and a multicast request, how to find a multicast tree such that the total energy cost of the multicast tree is minimized. We first prove this problem is NP-hard and it is unlikely to have an approximation algorithm with a constant performance ratio of the number of nodes in the network. We then propose an algorithm based on the directed Steiner tree method that has a theoretically guaranteed approximation performance ratio. We also propose two efficient heuristics, node-join-tree (NJT) and tree-join-tree (TJT) algorithms. The NJT algorithm can be easily implemented in a distributed fashion. Extensive simulations have been conducted to compare with other methods and the results have shown significant improvement on energy efficiency of the proposed algorithms. 相似文献
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网络容量度量了网络的最大信息传输率,计算网络容量是网络信息论的基本任务。网络容量可以分为编码容量和路由容量,一重组播网络的编码容量已被证明等于信源和各个信宿之间最小割的最小值,但路由容量却由于受到网络拓扑、信源信宿的数目和位置等因素的影响不存在这样简单和一般化的结论,对具体网络需要做出具体分析。组播路由网络容量分析可建模为Packing Steiner Trees问题,但该问题是NP-hard的,目前尚缺乏计算组播路由网络容量的有效方法。讨论分数组播路由网络的容量分析问题,分数网络的信源消息和边容量都是整数维的,在这个范畴内,把组播路由网络的容量分析建模为组合设计问题并提出一种方法加以解决,该方法的关键点在于通过子树分解技术大大缩减了网络规模,由此降低了组合设计的复杂度,并通过对三层网络的分析演示了该方法的使用。 相似文献
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针对现有组播拥塞控制算法应用到无线网络中存在的性能下降问题,提出一种基于新的智能组播拥塞控制机制ECMCC。ECMCC机制根据网络相对队列时延和数据包丢失检测网络的拥塞状态,采用代表集合机制反馈信息,利用专家控制器的推理判断区分丢包原因和当前的网络状态,进而采取不同的控制策略调节组播源端发送速率。仿真结果表明,ECMCC机制收敛速度快、灵敏性好、速率变化平滑,在有线网络中具有良好的TCP友好性。同时,ECMCC能有效区分网络拥塞和随机差错,提高了网络的吞吐量,适用于无线网络环境,且在无线网络较低误码率时具有一定的TCP友好性。 相似文献
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Hong-Hsu Yen Steven S. W. Lee Florence G. H. Yap 《The Journal of supercomputing》2012,62(3):1119-1138
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. 相似文献