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.     

一种Ad Hoc网络中路由软切换策略的研究

提出了一种新的Ad Hoc网络中对路由的维护方法,即基于局部多路径路由维护的路由软切换技术。在当前路由中某段或某几段链路出现问题时,通过建立局部的多路径路由,分担问题链路中的负载,维护网络保持通信连接不被中断;当路由稳定时,从局部多路径路由中寻找一条满足当前主路由通信需要的子路径,并且将数据传输切换到此子路径上,达到路由抢先维护和软切换的目的。该方法能够缩短路由重建的时间,延长单路径路由的寿命,使用多路径维护,避免了网络拥塞出现造成路由中断,能够很好地提高网络性能。     

基于AODV的无线多媒体传感器网络路由协议

研究了AODV路由协议,分析了多路径路由实现机制,提出了一种可应用于无线多媒体传感器网络的能量均衡多路径AODV路由协议。该协议建立从源节点到目的节点的多条路径,在路径的选择上综合考虑了路径跳数和节点剩余能量,用以保证负载均衡,延长网络生存期,该算法使用了分流的方式避免拥塞。通过使用NS2仿真软件对EEMP-AODV路由协议进行仿真,结果显示其在拥塞避免、实时性、吞吐量和网络生存期方面的性能有明显提升。     

基于异构无线网络的多路径传输

针对异构无线网络环境中,大容量业务传输质量不可靠、网络资源利用率低的问题,提出了一种基于异构无线自组织网络的多路径传输路由算法。该算法有效避免了单路通信方式下的传输链路拥塞、吞吐量低等问题,并结合大容量业务的特点,通过一定的法则合理表征网络环境信息,依据表征结果提出发端到终端的多路径策略,使得重要性不同的业务可选择相应链路质量的路径进行并行传输,避免了网络中的每个自组网节点独立寻找路由导致的源节点难以获得中间节点路由信息的现象。仿真结果表明,该算法可实现整个网络负载均衡,缓解网络链路拥塞,有效降低传输中的丢包率,降低传输时延。     

基于IEEE802.11 DCF的链路预先修复AODV路由协议

基于无线自组织网络中普遍使用的底层通信协议IEEE802.11 DCF,针对广泛应用于无线自组织网络中的路由协议(AODV),提出了一种链路预先修复算法。该算法首先推算了DCF协议中的不稳定传输范围,然后通过MAC层与路由层的跨层协作,在下一跳节点移动在不稳定传输范围时就事先采取相应的路由修复措施。相对于AODV中采用节点周期性地发送HELLO消息来监测邻居节点变化的方法,该算法更为高效及时。仿真结果表明,该算法能够有效的减小端到端时延,保障了投递率。     

机动突击中的自组网多路径路由技术

随着作战样式的变化和武器装备的变革,装甲车辆机动突击作战中协同控制的重要性不断增强,对网络通信的各项性能指标提出了更高要求,而自组织网络所具备的一些优良特性能够较好地适应这一需求。在网络通信中,稳定性是衡量网络路由性能的重要因素。机动突击作战中,车辆移动、障碍物阻挡等因素将导致网络拓扑变化迅速,给路由稳定性带来严重影响,极大地降低了网络通信质量。基于AODV协议,设计并仿真了一种链路不相交的多路径被动式路由协议,以路由回复消息中携带的路由信息为基础,实现两条不相交链路作为通信路由并互为备份。仿真结果表明,该协议在数据包到达率及平均时延方面较AODV协议均有一定提高。     

多跳无线Ad Hoc网络中AODV路由协议的改进研究

本文提出了一种E-AODV,对AODV做了两大改进:设计了一种邻节点发现程序(NDP),该程序为AODV设计而独立于AODV,可以被移植到其他路由协议中,它为路由协议提供了一种检测链路状态和邻节点发现的底层支持,并避免了单向链路和不稳定链路的产生.基于NS的仿真结果显示,E-AODV在增加分组开销不大的情况下,分组投递延时和分组递交率均有了明显的提高.     

基于SimCT的多播路由及故障恢复研究

在数据交换网络中,颜色树是一种通过节点不相交的多路径路由数据报文的有效方法。这种方法中组建两棵以某一节点为根节点的颜色树,即Red树和Blue树,网络中各节点到根节点的路径是节点不相交的。本文在分析和研究SimCT算法的基础上,提出了一种基于颜色树的多播树生成方法及单节点/链路故障的多播通信恢复方案。该方法根据SimCT算法构造的颜色树来组建一棵多播转发树,在多播树中单节点或单链路故障后,故障检测节点本地执行故障恢复方案,将受影响的故障节点的下游子树重新连接到多播树。仿真实验表明,本文所提出的多播树生成方案相比现有方案可以减少网络资源的浪费,并且故障恢复后的代价与原多播通信树相当。     

一种可部署在重路由光网络中实现有效连接管理的策略——基于分布式代理与蚁群算法

在大型骨干光网络中, 建立一条从源节点到宿节点的路由至关重要。在集中式网络管理系统体系下, 网络中动态路由信息以及故障状态信息, 通过路由的“泛洪”机制, 被传送到其他节点上实现资源信息共享,这对于连接的迅速建立, 恢复路由的快速启动将是不利的。尝试采用一种启发式算法-蚁群策略, 快速提高光网络中故障恢复的速度。该路由算法平台采用了分布式蚁群算法自动修复故障点, 解决了重路由的快速收敛问题; 依靠分布式代理机制构建管理平面和数据平面相互通信的机制, 完成诸如链路信息素的更新等功能。设计了一个网络故障的场景, 通过实验数据表明, 采用蚁群的分布式路由策略, 可以更快地实现路由信息的汇聚, 找到最佳的恢复路由。     

基于跨层设计的AODV路由算法研究

为了提高移动Ad Hoc网络中AODV路由算法的性能,提出了一种基于两跳邻居信息的高效AODV路由算法-TNAODV,文中采用两跳邻居信息机制,减少了建立路由所耗的时间;同时通过在网络层、MAC层与物理层三层之间的跨层协同,实现了及时的感知链路的连接状态,减少了因链路断裂而增加的路由开销。性能分析和仿真结果均表明,该路由算法在端到端时延、成功率等性能优于经典的AODV路由算法。     

SMORT: Scalable multipath on-demand routing for mobile ad hoc networks

Increasing popularity and availability of portable wireless devices, which constitute mobile ad hoc networks, calls for scalable ad hoc routing protocols. On-demand routing protocols adapt well with dynamic topologies of ad hoc networks, because of their lower control overhead and quick response to route breaks. But, as the size of the network increases, these protocols cease to perform due to large routing overhead generated while repairing route breaks. We propose a multipath on-demand routing protocol (SMORT), which reduces the routing overhead incurred in recovering from route breaks, by using secondary paths. SMORT computes fail-safe multiple paths, which provide all the intermediate nodes on the primary path with multiple routes (if exists) to destination. Exhaustive simulations using GloMoSim with large networks (2000 nodes) confirm that SMORT is scalable, and performs better even at higher mobility and traffic loads, when compared to the disjoint multipath routing protocol (DMRP) and ad hoc on-demand distance vector (AODV) routing protocol.     

Improving protocol robustness in ad hoc networks through cooperative packet caching and shortest multipath routing

A mobile ad hoc network is an autonomous system of infrastructure-less, multihop, wireless mobile nodes. Reactive routing protocols perform well in this environment due to their ability to cope quickly against topological changes. This paper proposes a new routing protocol named CHAMP (caching and multiple path) routing protocol. CHAMP uses cooperative packet caching and shortest multipath routing to reduce packet loss due to frequent route failures. We show through extensive simulation results that these two techniques yield significant improvement in terms of packet delivery, end-to-end delay and routing overhead. We also show that existing protocol optimizations employed to reduce packet loss due to frequent route failures, namely local repair in AODV and packet salvaging in DSR, are not effective at high mobility rates and high network traffic.     

基于移动性的AODV路由协议改进

介绍了Ad Hoc网络路由协议（Ad Hoc On-Demand Distance Vector Routing,AODV）的路由机制和特点,提出了一种基于AODV的改进协议V-AODV。V-AODV改进了AODV的路由测度,用量化的节点移动性代替跳数作为路由代价的度量,在动态网络中能够选取到更加稳定的路由。仿真表明,V-AODV比AODV在时延和重传次数等性能上都有一定程度的提升。     

基于第一跳节点累积的AODV协议改进

利用DSR协议的源路由策略,对AODV协议进行修改——在其路由发现过程中,将第一跳节点的地址信息添加到路由消息中。中间节点接收路由消息后,建立或者更新到达第一跳节点的路由。将修改后的协议称为AODV-FA协议,并在ns2中模拟仿真其路由性能。结果表明:相较于AODV协议,AODV-FA在分组传输率、平均端到端时延和归一化路由负载3个路由性能上均有提升。     

DOA: DSR over AODV Routing for Mobile Ad Hoc Networks

We present a lightweight hierarchical routing model, Way Point Routing (WPR), in which a number of intermediate nodes on a route are selected as waypoints and the route is divided into segments by the waypoints. Waypoints, including the source and the destination, run a high-level intersegment routing protocol, while the nodes on each segment run a low-level intrasegment routing protocol. One distinct advantage of our model is that when a node on the route moves out or fails, instead of discarding the whole original route and discovering a new route from the source to the destination, only the two waypoint nodes of the broken segment have to find a new segment. In addition, our model is lightweight because it maintains a hierarchy only for nodes on active routes. On the other hand, existing hierarchical routing protocols such as CGSR and ZRP maintain hierarchies for the entire network. We present an instantiation of WPR, where we use DSR as the intersegment routing protocol and AODV as the intrasegment routing protocol. This instantiation is termed DSR over AODV (DOA) routing protocol. Thus, DSR and AODV—two well-known on-demand routing protocols for MANETs—are combined into one hierarchical routing protocol and become two special cases of our protocol. Furthermore, we present two novel techniques for DOA: one is an efficient loop detection method and the other is a multitarget route discovery. Simulation results show that DOA scales well for large networks with more than 1,000 nodes, incurring about 60 percent-80 percent less overhead than AODV, while other metrics are better than or comparable to AODV and DSR.     

一种适用于无线网络的AODV-MPR协议研究

为了降低无线自组网按需平面距离矢量路由(AODV)协议在维护路由时广播参数中源地址和目的地址均为本节点地址的路由应答报文(HELLO消息)时的网络开销,提出了一种基于广播中继(MPR)的AODV路由协议改进方案,对AODV的HELLO消息机制进行了改进,并在NS2中对改进协议和原AODV协议进行了对比仿真。仿真结果证明:改进的AODV协议在网络吞吐量、端到端时延和丢包率方面均优于原AODV协议。     

移动Ad hoc网络中AODV路由协议的研究与改进

针对移动Ad hoc网络AODV路由协议存在的一些缺点,提出了一个改进的路由协议。在改进方案中增加了备份路由和电池电量门阀值,可以有效避免路由的重新发现。性能分析与仿真结果表明,改进后的AODV路由协议更能适应网络拓扑结构的变化,并能在链路中断后迅速找到可用的路由。     

A highly topology adaptable ad hoc routing protocol with complementary preemptive link breaking avoidance and path shortening mechanisms

Ad-hoc on-demand distance vector routing (AODV) is a well-known routing protocol for mobile ad hoc networks. The original AODV protocol works in a semi-dynamic fashion, by establishing a route on demand and using that route until it breaks. However, to suit the changing network topology of ad hoc networks, more aggressive and adaptable routing strategies are required. A number of researches have proposed improving AODV performance by locally repairing broken links, predicting and replacing potentially vulnerable links, or shortening a link through removing redundant nodes from the transmission path. Although local repair may relieve some problems, it usually results in longer paths and thus a considerable performance drop in heavy traffic conditions. There are also issues regarding packet loss and communication delay due to route rebuilding once the link is broken. Predicting and replacing potentially vulnerable links may require special hardware, additional tables to maintain, or other extra overhead. Finally, path shortening may result in shorter and more efficient routes, but there is no guarantee that the new paths will be robust. This paper proposes integrating preemptive link breaking avoidance and path shortening mechanisms into a modified AODV protocol. However, the difficult issue lies in determining the right timing to initiate the two independent mechanisms so that the two dynamically and complementarily operating mechanisms can work together to improve the routing performance. Through numerical analysis and simulation, we have arranged a simple parameter setting for controlling the activation of each mechanism at the appropriate time. The proposed combination is a highly dynamic ad hoc routing protocol that is capable of adapting itself to the changing network topology and achieving extremely good performance in various routing performance metrics. Extensive simulations show that each of the two schemes alone improves AODV performance. More importantly, the integrated protocol performs even better in terms of data delivery rate, average delay time, and network overhead. To be more specific, in the best cases our protocol can reduce up to 82% in control overhead and 66% in delay time, while achieving 12% more in data delivery rate comparing to AODV.     

Security upgrade against RREQ flooding attack by using balance index on vehicular ad hoc network

VANET is an ad hoc network that formed between vehicles. Security in VANET plays vital role. AODV routing protocol is a reactive or on-demand routing protocol which means if there is data to be send then the path will create. AODV is the most commonly used topology based routing protocol for VANET. Using of broadcast packets in the AODV route discovery phase caused it is extremely vulnerable against DOS and DDOS flooding attacks. Flooding attack is type of a denial of service attack that causes loss of network bandwidth and imposes high overhead to the network. The method proposed in this paper called Balanced AODV (B-AODV) because it expects all network node behave normally. If network nodes are out of the normal behavior (too much route request) then they identified as malicious node. B-AODV is designed with following feature: (1) The use of adaptive threshold according to network conditions and nodes behavior (balance index) (2) Not using additional routing packets to detect malicious nodes (3) Perform detection and prevention operations independently on each node (4) Perform detection and prevention operations in real time (5) No need for promiscuous mode. This method for detection and prevention flooding attack uses average and standard deviation. In this method each node is employing balance index for acceptation or rejection RREQ packets. The results of the simulation in NS2 indicates B-AODV is resilience against flooding attack and prevent loss of network bandwidth. Comparing between AODV with B-AODV in normal state (non-attacker) shows B-AODV is exactly match with AODV in network performance, this means that the B-AODV algorithm does not impose any overhead and false positive to AODV.