度受限的应用层组播树预先式重构方法

在应用层组播中,如果出现非叶子节点失效或离开,则该节点的所有下游节点都将受到很大的影响。针对该问题提出一种预先式应用层组播树修复方法,即每个非叶子节点提前为它的孩子节点找到一个备用父节点,使得非叶子节点失效或离开后,孩子节点能迅速地从备用父节点接收数据。仿真实验证明,在较小的开销下,该方法在节点离开的修复速度大约是响应式方法的3倍,平均转发延时比其他的预先式方法都要小。     

Ad hoc网络中一种带预测的路由算法

在自组网中,由于网络节点的移动性及拓扑结构的易变性,设计稳定的路由成为最受关注的问题。根据可靠性为多路径路由选择更多的可靠路径,以满足自组网中多路径传输在路径的数量和质量方面的需求,是多路径路由技术中的一个重要研究课题。为此,基于GRID模型和预测模型提出了一种带预测的稳定不相交备用路由算法,其利用有效限制路由查询包的泛洪区域,并结合预测策略和节点不相交路径算法来选择一条最稳定的不相交备用路由,从而进一步提高该路由算法的性能。模拟结果显示,与其他3个多路径路由相比较,该算法是一个有效的自组网路由算法。     

无线Ad Hoc网络中可靠路由的研究

改进了ETX算法,提出了将动态ACK算法与改进的ETX算法相结合的新的链路状况监测算法,以便在选路时忽略质量不好的链路。建议了一种从中间节点开始恢复的备用路由机制以便在链路断时能快速恢复,取代了笔者之前提出的QDSR基于源节点的备用路由机制。NS2仿真实验结果表明,在节点移动速度较小的较大规模移动Ad Hoc网络中,改进后的算法明显减少了路由错误,并且减少了路由发生错误后重新找到一条路径所需要的平均时间。     

结构化对等网Chord路由模型研究

Chord是MIT提出的一个全分布式结构化P2P模型,它能在O（olg2N）时间复杂度实现节点的路由定位。本文分析了Chord的路由模型,重点研究了其路由搜索算法,节点的动态加入、离开及崩溃的处理过程,最后分析了Chord的路由性能。     

WDM网络中考虑Qos约束的动态业务路由算法

路由问题是WDM网络中的一个核心问题。该文研究了WDM网络中受瓶颈带宽Qos和时延Qos约束的动态业务路由算法。算法以链路的延时值作为链路的权值,为网络中所有节点对计算所有代价有限的路由,作为备用路由。当一个连接请求到达时,考察其瓶颈带宽Qos指标与时延Qos指标,在备用路由集中选择满足Qos指标的路由;对所选路由综合考察其跳数、成本以及链路瓶颈带宽,计算目标函数,选择目标函数值最优的路由建立连接。     

基于分段的分布式路由结构

提出一种基于分段的分布式的路由结构,对节点和关键字的ID分级分段处理,每个节点在路由结构中都位于一定的级别,都有到自己兄弟节点路由表和级间路由表。该路由结构的特点是：（1）结合了树结构和流结构,使该路由结构不仅能够快速查找,而且还能够适应动态的节点加入或离开;（2）对于节点的ID,直接使用节点的IP来表示,使下层中地址相近的节点在P2P overlay网络中也是相近的,可以减少许多的网络交通流量。     

基于基本回路的MPLS网络重路由故障恢复机制

研究MPLS网络中的重路由故障恢复机制,提出一种新的计算备用路径的方法,将备用路径的计算分为预处理和在线计算2个过程,给出一种基于基本回路的重路由故障恢复机制(FC-R)。仿真分析表明,FC-R恢复时间较短,可以对抗节点故障或链路故障,大大缩短在线计算时间,减轻节点负担,能够得到性能较优的备用路径,进一步节省网络资源。     

DHT协议设计选项与抖动问题关联分析

因节点加入和离开引起的抖动是增加结构化P2P网络路由表更新代价的主要原因。为了找出影响网络抖动的关键因素,分析了影响抖动的路由方式、邻居选择、节点加入和节点离开以及并行查找等策略因素,发现任意两种DHT网络分别采用的五种策略都至少有两种不同,对两种DHT网络直接进行比较就很难确定哪些策略能更有效地降低抖动。因此,提出在同一网络内用不同的单个策略对网络抖动进行比较和分析的方法,称之为CSP。通过对现有DHT算法进行改进,使用CSP方法对不同的单个策略进行比较,得出以下结论:迭代路由、快速加入和周期性恢复策略和有效的邻居选择算法能更有效地降低网络的抖动。     

基于自律分散系统方法的一种WSNs路由学习算法

本文对随机散播节点的无线传感器网络的路由策略进行探讨,提出了一个通过学习方法计算节点路由的算法。该方法计算路由时,只需要与邻接点交流少量信息,通过深度优先搜索策略,并结合节点路由历史经验,选择路搜索下一节点。该方法体现了分散自律系统方法和分布估计学习算法结合的优越性。仿真结果表明,该算法是一个快速高效的无线传感器网络路由算法。     

高能量高信号强度节点优先的AODV路由协议

针对AODV协议只选择具有最少跳数路由,而不考虑节点能量即将耗尽或节点即将离开邻节点传送范围,造成路由频繁中断的问题,提出新的改进方案,在路由发现阶段,选择能量较高和信号强度较强的节点作为路由节点,在路由维护阶段,对能量即将耗尽或即将离开邻节点有效传送范围的节点进行路由备份。仿真实验结果表明改进后的协议能够有效增加数据包投递率和减少平均端到端延时,并能有效减缓能耗速度,提高整个网络的生存期。     

分布式超级节点选举算法

基于超级节点的分布式系统中,若超级节点失效或临时离开,希望系统能够自组织地选举出能力最强的节点作为新的超级节点。提出分布式超级节点选举算法,通过洪泛过程构造底层的生成树,叶子节点沿此树进行消息的传递,消息中包含着关于节点和边的信息,根节点根据这些信息构造最小生成树。根节点选出能力最强的节点作为超级节点,并沿着最小生成树广播选举结果。对算法性能从通信复杂度和时间复杂度两方面进行了分析和比较。     

Efficient terrain coverage for deploying wireless sensor nodes on multi-robot system

Coverage and connectivity are the two main functionalities of wireless sensor network. Stochastic node deployment or random deployment almost always cause hole in sensing coverage and cause redundant nodes in area. In the other hand precise deployment of nodes in large area is very time consuming and even impossible in hazardous environment. One of solution for this problem is using mobile robots with concern on exploration algorithm for mobile robot. In this work an autonomous deployment method for wireless sensor nodes is proposed via multi-robot system which robots are considered as node carrier. Developing an exploration algorithm based on spanning tree is the main contribution and this exploration algorithm is performing fast localization of sensor nodes in energy efficient manner. Employing multi-robot system and path planning with spanning tree algorithm is a strategy for speeding up sensor nodes deployment. A novel improvement of this technique in deployment of nodes is having obstacle avoidance mechanism without concern on shape and size of obstacle. The results show using spanning tree exploration along with multi-robot system helps to have fast deployment behind efficiency in energy.     

基于节点运动信息的链路稳定路由设计及其仿真分析

为MANETs路由构建了通过节点运动数据来实现的链路稳定路由LDPR,利用节点运动信息对链路生存时间进行初步预测,同时加入了双路由结构。采用LDPR路由来估计二个节点的链路连通时间时需考虑二个节点相对速度矢量。LDPR路由先对链路生存时间进行预测,确保链路发生断开前使备份路由处于工作状态。在路由被建立后,利用源节点来计算路由生存时间。参数优化结果得到:当节点数上升后,路由的开销率也不断增大,吞吐量发生了减小,传输时延也更大。相比较AODV路由,LDPR路由的开销率以及传输时延都较低,吞吐量较高,可见提出的LDPR路由运行效率更高。     

基于蚁群算法的Ad hoc多径路由协议

针对无线移动自组织网中网络拓扑结构变化迅速,节点间移动速率快的特点,提出一种采用备份路径修复断裂链路的基于蚁群算法的无线移动自组织网路由协议-antPro协议.和传统的路由协议相比,对同一目的节点,新路由协议在源节点建立多条路由,在路由的中间节点缓存有备份路径.协议具有较好的鲁棒性,在链路断裂时采用备份路径及时恢复数据分组的传送,能很好地适应Ad hoc网络环境.     

A backup path routing for guaranteeing bandwidth in mobile ad hoc networks for multimedia applications

This paper suggests a backup path routing scheme in ad hoc networks for multimedia applications. A data path is established in an on-demand manner when there is a need to send data. A primary and a backup path are created as a result of a route control message exchange process. Each control message has additional information for guaranteeing the service quality. A backup path is configured around the primary path in multi-hop wireless networks. After detecting a failure when sending data, a repairing procedure occurs near the failed node of the primary path. The proposed scheme exploits the route request and reply information exchanged between nodes to create a backup path. Proposed backup routing scheme uses a one-hop search method, and the rerouted path length is two-hop at maximum. The service quality as measured by the error rate and delay is considered when establishing and repairing a route by making an allowance for the required bandwidth. Simulation results show that the proposed backup path routing scheme has a better data delivery ratio and an improved end-to-end data delay while guaranteeing the requested bandwidth for multimedia application.     

基于斯坦纳树和泰森多边形的连通恢复算法

针对无线传感器网络容易遭受恶劣环境破坏,连通恢复后各关键节点的能量损耗远大于其他节点从而导致网络断连的问题,提出基于斯坦纳树和泰森多边形的连通恢复算法（CRAST）。首先,将被分割的节点分区抽象为离散点,枚举出离散点区域内的所有非退化四边形,再使用四边形斯坦纳树结构对这些非退化四边形部署中继节点以达到连通恢复。然后,用关键节点构建Delaunay三角网,通过Delaunay三角网构建出整个无线传感器网络的泰森多边形拓扑结构。最后,在泰森多边形所有顶点部署可移动的备用中继节点,在关键节点损坏时通过比较备用节点所占关键节点对应的所有备用节点比重选择要移动的备用节点,移动备用中继节点替换损坏的关键节点。整个算法能使传感器网络以最少的代价实现连通恢复,并且拥有较强的高效性和健壮性。     

Embedding and reconfiguration of spanning trees in faultyhypercubes

The problem of tolerating faulty nodes in hypercubes has been studied by many researchers either by using spares or by reconfiguration. Algorithms for tolerating faulty nodes and links in hypercubes are presented. The algorithms are based on using general spanning trees (GST), complete unbalanced spanning trees (CUST), and balanced spanning trees (BST) for reconfiguring the hypercube to avoid faulty nodes and links. The algorithms contain two phases: the first phase involves the construction of the spanning tree and the second one is for reconfiguring the hypercube should a faulty node be detected. The reconfiguration process consists of two basic steps. First, the faulty node is disconnected from the spanning tree. Then, a new spanning tree is constructed by reconnecting the children of the faulty node to the spanning tree. One hundred percent single fault correction (avoidance) and almost 100 percent fault correction (avoidance) of double and triple faults are achieved by the proposed algorithms for hypercubes having a dimension of n⩾6. Simulation results for the algorithm under more than three faults also are presented. For any k faulty nodes (1⩽k⩽2ⁿ-1), the reconfiguration algorithm may be applied k times to avoid these k faulty nodes as long as no combination of any two of the faults results in a blocking situation. The proposed reconfiguration algorithms tolerate all possible single-link faults. The reconfiguration algorithms are extended to tolerate (k⩽n-1) multiple faults, causing blocking situation, with a backtracking     

能量高效的传感器网络数据查询路由*

提出一种能量高效的传感器网络数据查询路由EEDQ(energy-efficient data query),EEDQ以sink节点为根节点,构造最小路由生成树,由sink节点发出查询任务,查询结果由叶子节点向sink节点传输,传输过程中进行数据汇聚.实验表明,EEDQ相比direct transmission,大大提高了传感器网络的生命周期.     

多媒体通信中带度约束的多播路由算法

随着多媒体业务的发展,多播技术应用日益广泛,多播路由是要寻找连接源节点和一组目的节点的一棵多播树,这个问题在数学上归结为Steiner树问题,它是一个NPC问题。在实际网络中,网络节点具备不同的多播能力,有些节点不支持多播,有些节点支持多播,但为了保证网络速度和节点负载平衡,支持多播的节点要限制其复制信息的数量,即节点的多播能力受限。在这种情况下,寻找多播树变得更加困难,该文用节点的约束来表示敏个节点具备的多播能力,节点多播能力受限情况下的多播路由问题被称为带度约束的多播路由问题,其仍是一个NPC问题。该文提出了一种求解带度的约束多播路由问题的双层遗传算法。算法的基本思想是最优多播树应是一棵满足度约束的最小生成树,因此问题的关键在于如何找到包括在最优生成树中的Steiner节点。遗传算法 采用二进制编码方式,内层算法用于求解满足度约束的最小生成树;外层算法进行全局搜索。该文将算法在稀疏图上进行实验,为了更好地模拟真实网络,稀疏图中每个节点具有不同的多播能力,并且多播目的节点数目相比于网络节点数要小。实验对算法进行了三方面比较：（1）解的质量;（2）计算时间;（3）算法的收敛性。实验结果表明,文中提出的遗传算法能够找到费用较小的多播树,但是当网络规模增大时,算法的求解时间也较长。     

Rendezvous based routing protocol for wireless sensor networks with mobile sink

In wireless sensor networks, the sensor nodes find the route towards the sink to transmit data. Data transmission happens either directly to the sink node or through the intermediate nodes. As the sensor node has limited energy, it is very important to develop efficient routing technique to prolong network life time. In this paper we proposed rendezvous-based routing protocol, which creates a rendezvous region in the middle of the network and constructs a tree within that region. There are two different modes of data transmission in the proposed protocol. In Method 1, the tree is directed towards the sink and the source node transmits the data to the sink via this tree, whereas in Method 2, the sink transmits its location to the tree, and the source node gets the sink’s location from the tree and transmits the data directly to the sink. The proposed protocol is validated through experiment and compared with the existing protocols using some metrics such as packet delivery ratio, energy consumption, end-to-end latency, network life time.