DSR本地修复算法的改进

对DSR路由协议进行分析,针对路由维护的不足,提出了一种新的本地修复算法.充分利用邻居节点缓存的信息,将修复范围限制在一跳或两跳内,减少了修复时间和降低了路由维护开销,提高了处理失效链路的能力.仿真表明,新的本地修复算法提高了数据递交率,网络吞吐量,降低了控制开销和路由发现频率.     

基于闲时逆寻和路由学习机制的优化AODV路由协议

对AODV协议在不同MANET网络环境中的性能缺陷进行了研究,提出了节点闲时反向路由搜索机制和邻居节点路由监听学习机制,并进一步提出了优化的AODV路由协议O-AODV。利用O-AODV协议在MANET网络中产生多个局部路由,从而增加网络中的路由冗余度,提高路由发现的效率,加快故障路由的本地修复。仿真实验结果表明,O-AODV协议提高了分组投递率,降低了端到端延时,有效地减少了网络中的重路由开销,在大规模和拓扑变化快的网络环境中优于AODV协议。     

一种高能效低时延的LLN路由修复算法

由于低功耗有损网络(LLN)中无线链路的不稳定性和有损性,外部环境的干扰极易导致网络出现故障,从而严重影响网络性能,而LLN网络中现有路由修复算法存在控制开销冗余和修复时延较大等问题。为此,提出了一种高能效低时延的LLN路由修复算法(EELDR-RPL)。该算法通过采用“零额外控制开销通告链路故障及邻居节点信息”机制,使得链路故障节点的子节点能够及时获知链路故障以及链路故障节点的邻居情况;通过采用“自适应调整节点网络深度值”机制,使得链路故障节点能够快速地重新接入网络;通过采用“链路故障节点子节点自适应切换”机制,能够达到优化网络拓扑的目的。仿真结果表明,与现有路由修复算法相比,EELDR-RPL算法能够有效地降低路由修复时延和减少控制开销。     

供给需求关系感知的间断连接无线网络安全路由机制

针对间断连接无线网络中限制消息副本路由机制的低消息投递率与存在恶意节点攻击的问题,提出了一种节点状态实时感知的安全路由机制,采用供给需求模型对节点转发消息的过程进行建模,通过动态感知节点活跃度、邻居节点剩余缓存率和相遇节点声誉值,结合消息生存时间比,建立节点对消息配额的供给需求模型,进而合理分配稀缺的配额资源,并在本地网络状况满足约束条件下,依据消息需求弹性动态更新消息配额,实现可靠的安全路由机制。数值结果表明,所提出的路由机制有效地减小了恶意节点攻击行为的影响,并大幅改善消息投递率和消息平均时延。     

基于节点行为的机会网络路由协议

高移动性、频繁中断、稀疏链接、没有基础设施和有限的资源被认为是机会网络的特点。在这样的网络中路由是最大的挑战,在此提出了一个新的基于节点行为的机会网络路由协议(OPNB),用节点的行为信息预测节点在网络中的移动,为消息路由到目标节点发现和选择更好的下一跳节点。协议还集成了对接收消息的确认,有助于中间节点的缓存管理。通过与epidemic路由协议和Probabilistic路由协议比较,OPNB协议在消息的交付数量、开销比率、平均延迟和缓存时间方面的表现相当不错。     

RSVP-TE CRANKBACK在MPLS网络中的应用

CrankBack是指在建立LSP的过程中如果遇到资源阻塞,或者节点失效时,由资源阻塞的节点向修复节点发起的重新寻找新路由的信令机制.由于LSR所广播的资源信息可能是过期的,因此资源的不足会经常发生并导致LSP建立的不成功,这时CrankBack(回选)路由是非常有用的.采用RSVP-TE信令技术可以实现CrankBack功能.     

一种基于折回点重路由的折回机制在ASON中的应用

该文提出了ASON网络中一种基于折回点重路由的折回机制,当连接发生折回时,该机制通过折回点对连接进行重路由,从而省去了折回消息发送的过程。为了实现该机制,扩展了信令消息及处理流程。搭建了15个节点的试验平台,采用了RSVP-TE、OSPF-TE及LMP等协议来实现ASON网络的控制平面。试验数据显示该机制与传统的折回机制相比较,不但节省了信令通信网(SCN)的带宽,而且节省了连接的最终建立时间。     

VANET中基于分布式的分簇的路由机制

车载自组网(VANET)是一种将高速移动车辆作为通信节点的自组网,动态的拓扑结构致使传统的自组网路由机制不再适用。为此,提出基于分布式的分簇路由机制(DCRM)。DCRM首先引用RTB/CTB握手策略,源节点利用RTB/CTB数据包,获取其一跳邻居的信息,然后源节点根据每两个邻近节点间的距离小于门限值的原则,以分布式方式对这些邻居节点进行簇划分。随后,将每个簇中选择一个离源节点最远的节点作为簇头,源节点将消息传输至簇头。接收消息后,簇头成了源节点,重复此过程直至消息传输至目的节点。仿真结果表明,提出的DCRM提高了消息传输效率、降低了消息传输时延。     

AODV路由协议的改进算法

无线Ad hoc网络拓扑结构动态变化的特点,决定了路径断裂是不可避免的。路径断裂会引起源节点路由重建,源节点频繁地发起路由重建过程会降低网络的性能。AODV协议中采用本地修复机制来减少源节点路由重建的次数。基于这一思想,文章提出了一种AODV路由协议改进算法SRP,旨在进一步提高本地修复的成功率。仿真结果表明,在拓扑结构变化迅速的Ad hoc网络中,SRP协议比AODV路由协议有更好的网络性能。     

城市环境VANETS下的基于beacon控制的路由方案

车载网络(Vehicular ad hoc networks,VANETs)是一种特殊形式的网络,具有节点高速移动、拓扑频繁的变化的特性。这些特性为消息的传播带来挑战。路由机制是实现消息传递的关键因素。地理位置路由被广泛地应用于VANETS,要求节点周期广播beacon消息。然而,节点周期地广播beacon消息,降低了路由性能,特别是在城市区域,由于节点密集,每个节点均广播beacon消息,恶化了路由性能。为此,针对城市环境,提出基于beacon控制的路由协议RPBC(Routing protocol with beacon control)。在RPBC中,并非每个节点广播beacon消息,而设置有效的机制选择部分节点广播,从而降低了beacon冗余,同时,采用最短路径算法,减少数据传输跳数。仿真结果表明,提出的RBPC在分组投递率、端到端传输时延以及路由开销方面均有较好的性能。     

RPSF: A Routing Protocol with Selective Forwarding for Mobile Ad-Hoc Networks

Many existing reactive routing algorithms for mobile ad-hoc networks use a simple broadcasting mechanism for route discovery which can lead to a high redundancy of route-request messages, contention, and collision. Position-based routing algorithms address this problem but require every node to know the position and velocity of every other node at some point in time so that route requests can be propagated towards the destination without flooding the entire network. In a general ad-hoc network, each node maintaining the position information of every other node is expensive or impossible. In this paper, we propose a routing algorithm that addresses these drawbacks. Our algorithm, based on one-hop neighborhood information, allows each node to select a subset of its neighbors to forward route requests. This algorithm greatly reduces the number of route-request packets transmitted in the route-discovery process. We compare the performance of our algorithm with the well known Ad-hoc On-demand Distance Vector (AODV) routing algorithm. On average, our algorithm needs less than 12.6% of the routing-control packets needed by AODV. Simulation results also show that our algorithm has a higher packet-delivery ratio and lower average end-to-end delay than AODV.     

Bypass routing: An on-demand local recovery protocol for ad hoc networks

On-demand routing protocols for ad hoc networks reduce the cost of routing in high mobility environments. However, route discovery in on-demand routing is typically performed via network-wide flooding, which consumes a substantial amount of bandwidth. In this paper, we present bypass routing, a local recovery protocol that aims to reduce the frequency of route request floods triggered by broken routes. Specifically, when a broken link is detected, a node patches the affected route using local information, which is acquired on-demand, and thereby bypasses the broken link. We implemented SLR (Source Routing with Local Recovery) as a prototype of our approach. Simulation studies show that SLR achieves efficient and effective local recovery while maintaining acceptable overhead.     

低开销的MANET网络按需路由协议

针对简单泛洪效率低的问题,提出了一个限制洪泛的高效的路由广播算法,通过Euclidean距离来限制路由发现过程中请求分组被转发的次数;研究了减少路由维护开销,并降低路由发现的频率的方法,提出了一个基于节点高度的路由修复与优化算法,该算法使用节点监听来对链路断裂的路由进行修复与优化.基于限制泛洪的高效的路由广播算法和路由修复优化算法,提出了一种新的低开销的MANET网络按需路由协议LOOR(low overhead on-demand routing).仿真结果表明,新协议增强了路由的顽健性,减少了路由跳数,降低了路由发现的频率,提高了数据分组递送率,并显著地降低了路由控制开销.     

A hop‐by‐hop delay‐constrained routing algorithm with explicit loop avoidance and backup routing information

QoS Routing is crucial for QoS provisioning in high‐speed networks. In general, QoS routing can be classified into two paradigms: source routing and hop‐by‐hop routing. In source routing, the entire path to the destination node of a communication request is locally computed at the source node based on the global state that it maintains, which does not scale well to large networks. In hop‐by‐hop routing, a path‐selecting process is shared among intermediate nodes between the source node and the destination node, which can largely improve the protocol scalability. In this paper, we present the design of hop‐by‐hop routing with backup route information such that each intermediate node can recursively update the best known feasible path, if possible, by collectively utilizing the routing information gathered thus far and the information that it locally stores. Such a route is kept as a backup route and its path cost is used as a reference to guide the subsequent routing process to search for a lower‐cost constrained path and avoid performance degradation. In this way, the information gathered is maximally utilized for improved performance. We prove the correctness of our presented algorithm and deduce its worst message complexity to be O(∣V∣²), where ∣V∣ is the number of network nodes. Simulation results indicate that, however, the designed algorithm requires much fewer messages on average. Therefore it scales well with respect to the network size. Moreover, simulation results demonstrate that the cost performance of our algorithm is near‐optimal. Copyright © 2004 John Wiley & Sons, Ltd.     

Void traversal for efficient non-planar geometric routing

Geometric routing provides a scalable and efficient way to route messages in ad hoc networks if extensive routing information is unavailable. Such algorithms require a planar graph to guarantee message delivery. The routing techniques for such guarantee usually center around the traversal of planar faces of the graph. However, in realistic wireless networks existing planarization methods, if at all applicable, tend to require extensive local storage or result in suboptimal route selection. In this paper we study an alternative approach of translating the algorithms themselves to be able to route messages over voids in non-planar graphs. We prove sufficient memory requirements for such translations. We then translate several well-known planar geometric routing algorithms and evaluate their performance in both static and mobile networks.     

Integrated Routing and Storage for Messaging Applications in Mobile Ad Hoc Networks

This paper is motivated by the observation that traditional ad hoc routing protocols are not an adequate solution for messaging applications (e.g., e-mail) in mobile ad hoc networks. Routing in ad hoc mobile networks is challenging mainly because of node mobility – the more rapid the rate of movement, the greater the fraction of bad routes and undelivered messages. For applications that can tolerate delays beyond conventional forwarding delays, we advocate a relay-based approach to be used in conjunction with traditional ad hoc routing protocols. This approach takes advantage of node mobility to disseminate messages to mobile nodes. The result is the Mobile Relay Protocol (MRP), which integrates message routing and storage in the network; the basic idea is that if a route to a destination is unavailable, a node performs a controlled local broadcast (a relay) to its immediate neighbors. In a network with sufficient mobility – precisely the situation when conventional routes are likely to be non-existent or broken – it is quite likely that one of the relay nodes to which the packet has been relayed will encounter a node that has a valid, short (conventional) route to the eventual destination, thereby increasing the likelihood that the message will be successfully delivered. Our simulation results under a variety of node movement models demonstrate that this idea can work well for applications that prefer reliability over latency.     

An optimized trusted‐cluster–based routing in disruption‐tolerant network using experiential learning model

Disruption‐tolerant network (DTN) implementation is subject to many routing constraints like limited knowledge of the network and intermittent connections with no end‐to‐end path existence. In this paper, the researchers propose trusted‐cluster–based routing protocol (TCR) for routing in DTN. TCR uses the experiential learning model that integrates neural network‐based bipolar sigmoid activation function to form trusted‐cluster DTN. TCR works in two phases: firstly to form a trusted‐cluster and secondly to identify cluster heads to direct network traffic through them. After the formation of the trusted‐cluster, a cluster head is chosen for a set period, thus instigating stability in the network. These trust values are attached to the node's route cache to make competitive routing decisions by relaying a message to the other trusted intermediate nodes only. With negative trust value, any node is deprived of participation in the network. This way, TCR eliminates malicious or selfish nodes to participate in the DTN network and minimizes the number of messages forwarded in a densely populated DTN. Also, this implementation conserves sufficient buffer memory to reach the destined node. The TCR's performance with other DTN routing schemes, namely, epidemic and trust‐based routing, is compared using multiple simulations runs. The proposed work is verified using mobility traces from Community Resource for Archiving Wireless Data At Dartmouth, and the experimental result shows the elimination of selfish nodes participating in the DTN. The simulation result shows an increase of 19% in message delivery by forwarding only to a trusted intermediate node possible.     

A routing layer based approach for energy efficient service discovery in mobile ad hoc networks

Service discovery can be greatly enhanced in terms of efficiency, both regarding service discoverability and energy consumption, by piggybacking service information into routing messages. Thus, service discovery does not generate additional messages and a node requesting a service, in addition to discovering that service, it is simultaneously informed of the route to the service provider. We extended the Zone Routing Protocol in order to encapsulate service information in its routing messages. Our extended protocol, E‐ZRP, may be seen as a representative of routing layer protocols providing service discovery functionality. Simulations demonstrate the superiority of this routing layer‐based service discovery scheme over that of a similar, but application layer based service discovery scheme. In order to have a thorough evaluation of our approach we introduced a new metric, called Service Availability Duration (SAD), which characterizes the ‘quality’ of discovered services and experimentally examines the implications of network density and node mobility on the availability of services discovered with E‐ZRP, as a typical representative of routing layer based service discovery protocols. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis of MANET dynamic source routing and its performance enhancements

Since the inception of the dynamic source routing (DSR) protocol for mobile ad hoc networks, several enhancements have been proposed, along with other competing routing protocols. All of them provide different degrees of throughput improvement under different scenarios. In this paper, we use DSR as a base, diagnose the contribution of its constituent components, and provide the reason why certain routing enhancements can increase the throughput and under what conditions. A major finding of the study is that the broadcast mechanism used in propagating route request and route error messages has a significant impact on how routing behaves. We also show that unicast route error report and preventive cache update improve throughput at different sides of the mobility spectrum. Finally, we show that aggressive buffer combined with route management provides the best performance improvement on the entire mobility and loading spectrum. Copyright © 2013 John Wiley & Sons, Ltd.     

Reliable Distributed Local Repair Approach for Maximizing Reliability and Packet Delivery Rate in Wireless on Demand AODV Networks

The most used protocol in Mobile Ad hoc Networks (MANETs) uses the Ad hoc On-Demand Distance Vector (AODV) routing protocol for achieving dynamic, self-organizing, and on-demand multihop routing. In AODV, wireless links may be lost occasionally because the nodes on the routing path are unreachable. Such a problem causes AODV inefficient and unreliable. For solving the problem, AODV provides a local repair mechanism for an intermediate node to find an alternative route to destination when the node detects links broken. The repair mechanism uses the broadcast-type RREQ message for discovering a repair route, which results in a large number of repair control messages and requires a large amount of power consumption for sending these messages. Therefore, in this paper we propose a unicast-type distributed local repair protocol for repairing breaks expeditiously, i.e., achieving high network reliability and utilization, less the number of control messages, and less the repair delay. Furthermore, the optimal number of hops in a neighbor table is analyzed. Numerical results indicate that the proposed approach is superior to other repair approaches in terms of successful fixing rate, control message overhead, and network utilization.