A low-overhead fault-tolerant routing algorithm for mobile ad hoc networks: A scheme and its simulation analysis

The fault-prone nodes in a mobile ad hoc network (MANET) degrade the performance of any routing protocol. Using greedy routing mechanisms that tend to choose a single path every time, may cause major data losses, if there is a breakdown of such a path in a fault-prone environment. On the other hand, using all the available paths causes an undesirable amount of overhead on the system. Designing an effective and efficient fault-tolerant routing protocol is inherently hard, since the problem is NP-complete because of the unavailability of precise path information in adversarial environments [1].To address the above mentioned problem, we present a fault-tolerant routing algorithm (FTAR), which bases on the ideas of foraging in natural ants [2]. The algorithm is divided into six stages, namely, initialization, path selection, pheromone deposition, confidence calculation, evaporation and negative reinforcement. Simulation results show that FTAR achieves high packet delivery ratio and throughput as compared to some of the key protocols which do not address fault-tolerance at all. Most importantly, FTAR is established to supersede the performance of one of the best fault-tolerant MANET routing schemes [1] known currently, with respect to the amount of routing overhead incurred – it is an important achievement for ad hoc networks.     

Routing with adaptive path and limited flooding for mobile ad hoc networks

In MANET, each mobile host can freely move around and the network topology is dynamically changing. To send a datagram, a source host broadcasts a route discovery packet to the network. All neighboring nodes receiving this packet will rebroadcast this packet until it reaches the destination. It will have large flooding overhead, poor network performance and undesirable battery power consumption. To improve network performance, we design a novel routing protocol called RAPLF (Routing with Adaptive Path and Limited Flooding) for mobile ad hoc networks. Simulation results show that our protocol has better performance especially in packet delivery rate and flooding overhead when compared to similar protocols.     

Randomized dynamic route maintenance for adaptive routing in multihop mobile ad hoc networks

Several approaches have been proposed for designing multihop routing protocols in mobile ad hoc networks (MANET). Many of them adopt a method, called flooding, to discover a routing path. Due to the time-varying nature of the route in MANET, the discovered route needs to be dynamically maintained for optimality in terms of traffic load, hop-distance, and resource usage. It is easy to see that flooding incurs significant overhead and hence is inappropriate for the dynamic route maintenance. In this paper we propose a randomized, dynamic route maintenance scheme for adaptive routing in MANET. The scheme makes use of a nomadic control packet (NCP) which travels through the network based on a random walk, and collects its stopovers as a traversal record. The NCP uses the traversal record to probabilistically provide the nodes with clue for routing path updates. From the clue, the nodes can find the routing path update information that is up-to-date and optimal (less-loaded and shorter), thereby adapting to the dynamic network topology and traffic load conditions. We present an analytical model for measuring the effectiveness of NCP in terms of its frequency of visits and probability of finding the clue from the NCP traversal record. The proposed randomized scheme serves as a routing protocol supporting layer and can be easily applied with minimum modifications to the existing on-demand routing protocols such as AODV and DSR. In our experimental study, we modified the AODV protocol to maintain routing paths using NCPs’ traversal record. Simulation results show that NCPs help the routing protocol to notably reduce average end-to-end packet delay with increased route optimality and better control on traffic congestion.     

一种基于改进RTS/CTS的MANET高效报文转发策略

MANET网络由可自主移动的无线节点组成。节点的自主移动导致了链路路由的改变,因此需要有一个机制维护和发现路由信息。目前人们已经针对MANET网络提出了几种路由协议,但这些路由协议都是基于IP的且路由维护的代价高,这严重影响了MANET网络的稳定性、可扩展性和用户有效带宽。本文提出了一种基于改进RTS/CTS的MANET高效报文转发策略。该策略对标准IEEE 802.11协议进行了修改,利用改进的RTS/CTS报文信息,进行报文转发,从而避免了使用MANET网络路由协议给网络性能带来的影响。使用改进的NS-2模拟了基于改进RTS/CTS的MANET高效报文转发策略。模拟结果表明:该策略可以有效地降低路由维护的开销并降低报文传输的延迟。     

井下无线传感器网络AODV和DSDV协议的仿真对比

通过分析当前煤矿安全监测无线传感器网络的路由特点及其对应的掘进工作面典型的系统方案,比较当前无线传感网络中比较经典的AODV和DSDV路由协议,为了考察这两种路由协议在矿井下的性能,使用NS2网络仿真软件的Shadowing模式,选取包成功投递端到端的平均延时、包成功投递率、路由协议负载这三个衡量指标对AODV与DSDV路由协议进行了性能评估,研究结果表明在节点相对少的掘进巷道场景下DSDV协议表现出较好的特点和很好的鲁棒性,为满足井下实时监测网络的应用需求提供一种方案.     

移动自组网络中一种有效的选播路由协议

移动自组网是一种特殊的无线移动通信网络，它由一系列带有无线收发装置的动态节点临时形成一个多跳的自治系统，因此传统网络中的路由协议不适合于移动自组网络．选播作为一类新的通信协议，能有效平衡网络负载分布和提高网络性能．本文首先描述了移动自组网络的特点及该环境下的路由协议，在此基础上提出了一种有效的选播路由协议．通过平均分组传送成功概率和平均控制字节数指标的测试表明了算法的有效性．     

Malicious node prevention and mitigation in MANETs using a hybrid security model

Mobile ad-hoc network (MANET) has got tremendous success and attention due to its self-maintenance and self-configuration properties or behavior. Based on wired and wireless networks, the network topology of MANETs changes rapidly by means of routing attacks. Hence, providing security to this infrastructure-less network is a major issue. The routing protocols for ad-hoc networks cope well with the dynamically changing topology but are not designed to accommodate defense against malicious attacker. Malicious nodes have opportunities to modify or discard routing information or advertise fake routes to attract user data to go through themselves. In this article, we discuss a hybrid technique using anonymity, one-way trapdoor protocol, hash functions, and elliptic curve cryptographic to mitigate attacks in the MANET. The simulation is carried on NS-2 and the simulation results are dissected on different system execution measurements, for example, packet send and received, packet dropped, average network throughput, end-to-end delay, and packet delivery ratio.     

E-ODMRP: Enhanced ODMRP with motion adaptive refresh

On-Demand Multicast Routing Protocol (ODMRP) is a multicast routing protocol for mobile ad hoc networks. Its efficiency, simplicity, and robustness to mobility render it one of the most widely used MANET multicast protocols. At the heart of the ODMRP’s robustness is the periodic route refreshing. ODMRP rebuilds the data forwarding “mesh” on a fixed interval and thus the route refresh interval is a key parameter that has critical impact on the network performance. If the route refresh rate is too high, the network will undergo too much routing overhead, wasting valuable resources. If it is too low, ODMRP cannot keep up with network dynamics, resulting in packet losses due to route breakages. In this paper, we present an enhancement of ODMRP with the refresh rate dynamically adapted to the environment. Simulation results show that the Enhanced ODMRP (E-ODMRP) reduces the packet overhead by up to a half yet keeping a packet delivery ratio comparable to that of the original ODMRP. E-ODMRP compares favorably with other published multicast schemes.     

An Energy-Aware Geographic Routing Protocol for Mobile Ad Hoc Networks

Mobile ad hoc networks (MANET) are characterized by multi-hop wireless links and resource constrained nodes. To improve network lifetime, energy balance is an important concern in such networks. Geographic routing has been widely regarded as efficient and scalable. However, it cannot guarantee packet delivery in some cases, such as faulty location services. Moreover, greedy forwarding always takes the shortest local path so that it has a tendency of depleting the energy of nodes on the shortest path. The matter gets even worse when the nodes on the boundaries of routing holes suffer from excessive energy consumption, since geographic routing tends to deliver data packets along the boundaries by perimeter routing. In this paper, we present an Energy-Aware Geographic Routing (EGR) protocol for MANET that combines local position information and residual energy levels to make routing decisions. In addition, we use the prediction of the range of a destination''s movement to improve the delivery ratio. The simulation shows that EGR exhibits a noticeably longer network lifetime and a higher delivery rate than some non-energy-aware geographic routing algorithms, such as GPSR, while not compromising too much on end-to-end delivery delay.     

移动自组网路由局部修复算法的研究

移动自组织网(mobile ad hoc networks,MANET)的多跳的无线连接、动态拓扑和有限的带宽等特征,给其路由协议带来了很多挑战.当多跳路径失效时,路由协议需要对其进行修复.已有的修复机制需要很多的开销和很长的端到端时延.在此修复机制的基础上,提出了一种新的路由局部修复算法,将修复尽量限制在断链的局部范围内,以减少对链路断裂的反应时间和降低路由维护的开销,而且不用考虑失效链路在整个路由上的相对位置,都可以对其进行修复,提高了处理失效链路的能力,有利于提高MANET的可扩展性.仿真表明,这种新的路由局部修复算法明显地提高了网络多方面的性能.     

基于群组移动模型的OLSR协议性能仿真与评估

在研究移动自组网移动模型和无线路由协议的基础上,选取移动自组网中具有代表性的参考点群移动模型,基于ns2网络模拟平台,以参考点群组移动模型生成移动场景文件,应用层使用cbr数据流量,对OLSR无线路由协议在不同参数条件下的性能进行了模拟测试。通过对测试结果数据的详细分析,总结得出了OLSR无线路由协议在参考点群移动模型下端到端时延、报文交付率和路由负载三个方面的特点。为进一步研究移动自组网下基于OLSR协议的各种应用提供参考。     

多跳无线移动Ad Hoc网络路由协议的研究分析

无线移动Ad Hoe网络(MANET)作为可移动分布式多跳无线网络，没有预先确定的网络拓扑或网络基础设施以及集中控制．为了在如此的网络中促进通信，路由协议主要用于在节点之间发现路径．Ad Hoe网络路由协议的主要目的是网络拓扑的动态变化、任意两个节点之间建立一个使得通信总费用和带宽消费最少的正确和有效的通信路径．描述了设计移动Ad Hoe网络路由协议所面临的问题以及对它们的评价，详细比较了七种典型无线移动AdHoe网络路由协议的特性和功能，即DSDV，CGSR，WRP，AODV，DSR，TORA和ABR，为进一步的研究提出了新的课题．     

移动自组网基于路径维持概率的按需路由协议

在移动自组网(mobile ad hoc networks,简称MANET)中,节点的移动使无线链路经常发生断裂,从而导致路由无效.为了提高路由的稳定性,在分析单跳链路的t-时间维持概率的基础上,提出了一种基于路径t-时间维持概率的按需路由协议.该协议通过目的节点对路由请求的二次应答和中间节点对路由的反向优化来选择具有最大t-时间维持概率的路径,从而延长了路由的维持时间.仿真结果表明:与AODV(ad hoc on-demand distance vector)和DSR(dynamic source ro     

MANET典型路由协议的性能分析与仿真

移动Ad Hoc网络(MANET)是由一组无线移动主机组成的一个没有任何事先建立好的基础设施或集中管理设备的临时网络,其特点是网络拓扑易变,带宽、能源有限及容易受到攻击等。该文对AODV, DSR, DSDV这几种典型的路由协议进行分析比较,指出它们的优缺点及适用场合。通过2个场景的配置,从路由开销、分组投递率、端到端的平均时延3个方面进行实验。仿真结果表明,按需路由协议在3个方面都表现出较好的性能。     

三种Ad Hoc网络组播协议的性能分析与比较

近年来,Ad hoc网络的组播路由协议研究受到广泛关注,但已经提出的各种组播协议中还没有一种在MANET定义的各种性能指标方面都处于领先,因此对不同协议的分析和比较能帮助人们在不同的应用环境下选择和设计更适合的组播协议。本文首先分别介绍了3种典型的组播路由协议：ODMRP、ADMR、DRMR,然后对其控制开销进行了计算分析,最后利用NS2仿真软件对3种协议进行仿真,分析与比较了它们在各种网络环境下的性能。     

基于OLSR的MANET地址自动配置机制

为了解决现有无线自组织网络地址自动配置协议过于复杂、开销大、可实现性不强的问题,利用OLSR在全网拓扑信息维护、低开销消息洪泛等方面的优势,提出一种以OLSR为基础的地址自动配置方案。实现IP地址的快速分配,并只需对OLSR协议消息作简单修改即可在网络运行过程中维护地址的唯一性。所提出的方案具有开销低、实现简单的特点,适合大型网络地址分配需要。     

一种能量感知的无线移动自组网路由协议

无线移动自组网中的大多数节点都是由有限寿命的电池来提供的,能量保护策略就成为设计网络协议的一个重要条件。提出一种能量感知的无线移动自组网路由协议,综合考虑了节点的剩余能量和路由跳数,有效保护网络中能量低的节点,减少了节点能量损耗,延长了网络的使用时间。该路由协议中采用了局部路由修复机制,减少了数据包丢失,提高了数据传输率。最后,仿真结果证明了协议的有效性。     

Applying link stability estimation mechanism to multicast routing in MANETs

Mobile ad hoc networks are self-organizing network architectures of mobile nodes. Node mobility causes network topologies to change dynamically over time, which complicated important tasks such as routing. In this paper, a novel link stability estimation model based on received signal strength indication is proposed. We have integrated this model into MAODV and present a stability-based multicast routing protocol termed as SMR. SMR can discover more available stable routes and better adapt to network topology changes. Simulation results show the superiority of SMR over the existing methods in terms of packet delivery ratio, average end-to-end delay and routing packet overhead.     

Link stability based multicast routing scheme in MANET

The group-oriented services are one of the primary application classes that are addressed by Mobile Ad hoc Networks (MANETs) in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for MANETs to ensure better packet delivery ratio, lower delays and reduced overheads. In this paper, we propose a mesh based multicast routing scheme that finds stable multicast path from source to receivers. The multicast mesh is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. The stable paths are found based on selection of stable forwarding nodes that have high stability of link connectivity. The link stability is computed by using the parameters such as received power, distance between neighboring nodes and the link quality that is assessed using bit errors in a packet. The proposed scheme is simulated over a large number of MANET nodes with wide range of mobility and the performance is evaluated. Performance of the proposed scheme is compared with two well known mesh-based multicast routing protocols, i.e., on-demand multicast routing protocol (ODMRP) and enhanced on-demand multicast routing protocol (EODMRP). It is observed that the proposed scheme produces better packet delivery ratio, reduced packet delay and reduced overheads (such as control, memory, computation, and message overheads).     

Ad Hoc移动网络多路径研究

在Ad Hoc移动网络中,由于结点的移动性,网络拓扑结构的易变性,路由成为研究的热点和难点。当前AdHoc路由协议一般都是单路径协议。然而由于多路径路由方式可以大大减少路由开销,提高数据传输率,减少网络拥塞,越来越多的研究表明,它将是未来Ad Hoc网络路由的主要方式。本文介绍了几种典型的多路径路由协议,并对这些多路径协议进行评价,对其性能进行比较,然后介绍多路径协议在QoS、能源和安全方面的应用,最后指出未来多路径研究的关键问题。