通信 通信系统与通信网、网络管理

0626353Ad Hoc网中链路连通性的概率评估〔刊,中〕/赵红勋//电子科技.—2006,(7).—5-8(D)Ad Hoc网将在未来的商用和军用通信方面起着非常重要的作用。网内节点的随机移动将会导致网络拓扑的动态变化。任一对节点之间链路连通性的分析对提前预测网络拓扑变化起着关键作用。文中基于不同的初始条件通过数学推导的方法来分析任一对节点之间随时间变化的链路连通性空间平均概率。参40626354MANET中的一种新的多路由机制〔刊,中〕/陶开勇//计算机工程与设计.—2006,27(12).—2178-2180(L)在MANET中,DSR和AODV都是按需路由协议,并且都…     

基于无标度网络的车联网连通性研究

移动车辆的连通性是车联网(IoV)的关键指标之一,它会严重影响数据传输的性能。由于车联网的网络拓扑高频动态变化,车辆之间的通信链路容易频繁地断连。如何降低链路建立的随机性和链路断开概率,提高整体网络的连通性一直是急需解决的关键问题。针对上述问题,在视距路径损耗模型和干扰模型下分析网络的连通性,通过对车联网链路在真实世界的表征,设计动态生长(DN)算法。对车辆节点进行增加、删除和链路的偏好连接后,构建无标度车联网。通过仿真结果分析,网络整体的连通性提升了16%。     

基于最小跳数的星座网络拓扑抗毁性分析

随着航天技术的发展与人类对太空的不断探索与利用，大规模低轨星座已成为国内外航天领域的重要热点。星座网络拓扑分析研究对星座运维管控、网络协议开发、业务能力评估等具有重要意义。为评估星座网络拓扑结构发生变化后依然具备网络传输能力，提出了一种基于最小跳数的星座网络拓扑抗毁性分析方法。用邻接矩阵描述星座网络拓扑，并给出邻接矩阵性质判断网络拓扑的连通性；定义最小跳数路由区域，划定网络拓扑分析范围；通过邻接矩阵性质计算节点和链路的介数值，分析部分节点和链路受损对网络拓扑的影响；对网络拓扑中失效过程进行仿真验证，证明了节点或链路的重要性以及对网络拓扑的影响关系。     

基于冲突测度的自组网脆弱点发现算法

在无中心自组织的无线多跳网络中,网络连通性问题作为研究的重点引起广大研究人员的关注。首先介绍了邻近图,并在相关邻近图的基础上引入了冲突测度理论,然后利用基于RNG的冲突测度理论对自组网的链路连通性进行研究,通过仿真说明此方法可以有效评估网络拓扑中节点和边对整个网络的链路连通性的影响。     

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.     

一种基于链路质量的自维护拓扑控制博弈算法

针对无线传感器网络拓扑性能优化单一的问题,本文首先定义了表征双向通信质量的指标.其后将链路质量,节点干扰,剩余能量均衡性等参数融入收益函数,设计了一种基于链路质量的自维护拓扑控制博弈算法SMGLQ.理论证明该算法能保证各节点收敛到帕累托最优.仿真实验表明它能为网络选择通信质量较好的链路,并降低能耗.     

战术Ad Hoc网络中的QoS路由协议设计与仿真

基于TDMA的战术Ad Hoc网络,提出一种分布式的资源预约机制,其中收/发节点采用协商的方式预约时隙,邻居节点通过侦听方式获得时隙被预约的信息,然后依托该机制提出一种QoS路由协议,该协议能够在网络节点之间选择一条满足QoS要求且相时短的路径进行预约时隙,同时对于网络拓扑变化引起的链路故障也能局部修复.仿真表明该协议...     

一种基于缓存技术的改进型AODV路由协议

AODV路由协议是ad hoc网络中一种典型的按需路由协议,但是当网络节点具有高移动性,网络拓扑变化频繁使得路由链路断开频繁时,按需路由协议包括AODV算法都缺乏鲁棒性,各个移动节点在发送数据包时需要不断发起路由请求.文章对AODV算法进行了详细分析,并利用路由缓存技术对AODV算法进行了改进.在缓存中建立了两条备用路由,当活动路由链路断开时,选取一条较好的备用路由作为活动路由.NS2仿真结果表明,这种带缓存功能的AODV算法能降低丢包率、时延,提高路由的稳健性,从而适应网络拓扑结构的频繁变化.     

多跳无线网网络拓扑控制优化目标研究

研究了多跳无线网中网络性能与网络拓扑结构关系的问题。数值计算结果表明网络节点只与“最邻近”的节点建立链路时形成的拓扑结构节点的吞吐量最大,这样的拓扑结构同时能满足网络的低功耗、低截获概率和可靠性要求。计算机仿真结果验证了上述结论。因而,网络拓扑控制的目标就转化为节点在邻节点中选择“最邻近”节点,继而建立逻辑链路的问题。     

无线网状网射频链路的信道分配算法

研究了无线网状网络节点的接口异构对网络容量的影响.提出了一种新颖的以射频链路为信道分配对象的接口和信道联合分配的分布式贪婪最大算法.该算法以队列长度为权的射频链路吞吐量之和最大为目标,寻找自适应于网络拓扑和流量变化的分布式接口与信道联合分配方案.算法分析指出本算法与非接口异构的Dist. Greedy算法的时间复杂度相当,NS2仿真结果表明网络容量有明显提升.     

A distributed routing algorithm for multihop packet radio networkswith uni- and bi-directional links

Multihop packet radio networks require routing algorithms which are distributed in nature and which have the ability to timely detect changes in the network topology. These changes are mostly changes in connectivity caused by link or node failures and by the relative motion of the nodes. This paper describes and analyzes an adaptive decentralized routing algorithm for packet radio networks. The network connectivity, as perceived by each node, is translated into a graph representation of the network. The proposed routing mechanism then uses a breadth-first search algorithm along the inbound links of such a graph. Unlike most of the algorithms found in the open literature the one proposed here can be used in networks having both uni- and bi-directional radio links. Examples are shown to illustrate the methodology     

LSCR:一种Mobile Ad hoc网络链路状态分组路由算法

本文提出了一种Mobile Ad hoc网络(Manet)链路状态分组路由算法(Link State-hased Cluster Routing Algo-rithm-LSCR)，该算法对Manet节点进行动态分组，每一组选举出一个具有最大度数的头结点(CH-Cluster Header)，该cH负责本组信息的管理、组内结点与组外结点之间的通信以及与其他组的CH之间交换链路状态信息等工作．本算法将改进的链路状态协议与分组路由协议有机结合，有效提高了Manet网络的路由效率．分析和实验结果表明，这种算法具有路由收敛速度快、维护成本相对较低，数据包发送成功率高，发送等待时间短等特点。     

Distributed Topology Construction in ZigBee Wireless Networks

Topology control is one of the important techniques in wireless multi-hop networks to preserve connectivity and extend the network lifetime. This is more significant in ZigBee, since the address assignment scheme is tightly coupled with topology construction. For example, there can be orphan nodes that cannot receive the network address and isolated from the network due to predefined network configurations. In this paper, we propose a distributed topology construction algorithm that controls the association time of each node in order to solve the orphan node problem in ZigBee as well as construct an efficient routing tree topology. The main idea of the distributed topology construction algorithm is to construct primary backbone nodes by propagating the invitation packets and controlling the association time based on the link quality. Since the dynamically selected primary nodes are spread throughout the network, they can provide backbone to accept the association requests from the remaining secondary nodes which are majority in a network. In the performance evaluation, we show that the proposed topology construction algorithm effectively solves the orphan node problem regardless of network density as well as provides efficient tree routing cost comparable to the approximation algorithm for degree constrained minimum routing cost tree (DC-MRCT) problem.     

A peer-to-peer zone-based two-level link state routing for mobilead hoc networks

A new global positioning system (GPS)-based routing protocol for ad hoc networks, called zone-based hierarchical link state (ZHLS) routing protocol, is proposed. In this protocol, the network is divided into nonoverlapping zones. Each node only knows the node connectivity within its zone and the zone connectivity of the whole network. The link state routing is performed on two levels: focal node and global zone levels. Unlike other hierarchical protocols, there is no cluster head in this protocol. The zone level topological information is distributed to all nodes. This “peer-to-peer” manner mitigates traffic bottleneck, avoids single point of failure, and simplifies mobility management. Since only zone ID and node ID of a destination are needed for routing, the route from a source to a destination is adaptable to changing topology. The zone ID of the destination is found by sending one location request to every zone. Simulation results show that our location search scheme generates less overhead than the schemes based on flooding. The results also confirm that the communication overhead for creating and maintaining the topology in the proposed protocol is smaller than that in the flat LSR protocol. This new routing protocol provides a flexible, efficient, and effective approach to accommodate the changing topology in a wireless network environment     

基于拓扑重构的水下移动无线传感器网络拓扑优化

针对水下移动无线传感器网络（MUWSN, mobile underwater wireless sensor networks）拓扑随洋流动态演化对其网络性能会产生很大影响,提出了一种基于拓扑重构的水下移动无线传感器网络拓扑优化方法,首先通过模拟鱼群行为对传感器节点位置进行调整,优化网络覆盖度;其次,利用冗余节点修复网络中不连通位置,消除关键节点,优化网络连通性,最后,通过仿真对比实验验证了该方法的合理性和有效性。实验结果表明,所提算法能在较低能耗下,保证网络覆盖度长期维持在97%左右,连通率达到89%以上。     

The rich-club phenomenon in the Internet topology

We show that the Internet topology at the autonomous system (AS) level has a rich-club phenomenon. The rich nodes, which are a small number of nodes with large numbers of links, are very well connected to each other. The rich-club is a core tier that we measured using the rich-club connectivity and the node-node link distribution. We obtained this core tier without any heuristic assumption between the ASs. The rich-club phenomenon is a simple qualitative way to differentiate between power law topologies and provides a criterion for new network models. To show this, we compared the measured rich-club of the AS graph with networks obtained using the Baraba/spl acute/si-Albert (BA) scale-free network model, the Fitness BA model and the Inet-3.0 model.     

一维Ad Hoc网络二连通性研究

无线Ad Hoc网络拓扑结构的连通性是成功实现网络端到端数据通信的基本前提,而二连通性是网络在有节点失效的情况下保持拓扑连通的基本条件.为了有效构建具有容错能力的网络拓扑结构,本文针对节点随机均匀分布的一维Ad Hoc网络模型,基于割点概率,分析了一维Ad Hoc网络的二连通性,给出了网络的二连通性与网络分布区域大小、节点数目、通信半径间的解析关系.利用该结论,合理配置网络参数,能够有效优化网络的拓扑结构.仿真实验结果表明,理论值与仿真值吻合良好,验证了所得结论的正确性.     

A design technique for reliable networks under a nonuniform trafficdistribution

Many network-reliability analysis techniques define and compute a variety of reliability measures. Most techniques assume that network connectivity is the only determining factor in network reliability; and merely analyze an existing network structure but do not provide any methodology for reliable design. This paper presents a heuristic design algorithm to enhance the reliability of existing communication networks by modifying their topology. This algorithm improves the reliability of the least reliable node (reliability is the probability that messages transmitted from a given node reach their destination). To use this algorithm on large networks, a reliability analysis method is developed which determines approximate network reliability values in linear-time when an upper bound is placed upon the in-degree of all network nodes. The heuristic network design algorithm uses this approximate reliability analysis technique to place additional links. The goal of this link placement is to improve the reliability of the least-reliable node. The placement of additional links is a function of both the traffic distribution and the connectivity of the network. This process continues until either a desired level of network reliability is achieved or a maximum number of additional links has been added. A unique feature of this design strategy is that it has quadratic time-complexity when the maximum in-degree of all network nodes is limited     

自组网容错拓扑控制的研究

为省能而提出的拓扑控制若未考虑容错易造成自组网无法面对节点和无线信道失效.本文针对一般的原始平面图G0提出了保持两点之间最大限度K点、K边和K路径容错连通能力的概念.设计了一种基于K条内部节点互不相交路径的分布式拓扑控制算法LKINDP,能够保持G0内任意两点之间最大限度K连通容错能力,并给出了证明.仿真结果表明,LKINDP能够显著减小平均电台半径,简化网络拓扑结构,并且能够通过改变K值来调整网络的容错能力.