路由信息的攻击对AODV协议性能的影响分析

AODV协议是移动自组网络中一种按需反应的表驱动路由协议。在移动自组网中，每个节点既是计算机又是路由器，容易遭受基于路由信息的网络攻击，而现今的路由协议基本没有考虑到该问题。本文在分析移动自组网中针对路由信息主要攻击方法的基础上，建立了主动性和自私性两个攻击模型，并且在AODV协议中扩充实现了这两类攻击行为。通过对模拟结果的分析和比较，讨论了路由信息的攻击对AODV协议性能的影响，并进一步探讨了针对基于路由信息攻击的防御措施。     

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.     

AODV_RR: A Maximum Transmission Range Based Ad Hoc on-Demand Distance Vector Routing in MANET

Nodes in a mobile ad hoc network are battery constrained devices and energy efficiency becomes an important consideration. In a multi-hop mobile ad hoc network the most common method to achieve energy efficiency is the transmission power control scheme in which a node transmits the data packets to its nearest neighbor which is at minimum required power level. However this scheme minimizes only the transmission power within the node’s neighborhood and energy efficiency at the link level is possible. With this scheme it is not possible to minimize the overall energy consumption of the network and the communication overhead of the network is not minimized. An analysis has been performed and our results have proved that instead of using low transmission power, the routing strategy needs to be controlled and only certain nodes are to be allowed to receive and process this routing request based on the received signal strength, then the overall energy consumption of the network can be minimized and the communication overhead is also minimized. The modified routing strategy is applied to the basic ad hoc on-demand distance vector (AODV) routing protocol and a maximum transmission range based ad hoc on-demand distance vector routing protocol named AODV range routing (AODV_RR) is proposed and studied under different network sizes. Measurable difference in performance is realized and the proposed AODV_RR perform better than normal AODV with respect to all the selected metrics.     

Study of MANET routing protocols by GloMoSim simulator

This paper compares ad hoc on‐demand distance vector (AODV), dynamic source routing (DSR) and wireless routing protocol (WRP) for MANETs to distance vector protocol to better understand the major characteristics of the three routing protocols, using a parallel discrete event‐driven simulator, GloMoSim. MANET (mobile ad hoc network) is a multi‐hop wireless network without a fixed infrastructure. Following are some of our key findings: (1) AODV is most sensitive to changes in traffic load in the messaging overhead for routing. The number of control packets generated by AODV became 36 times larger when the traffic load was increased. For distance vector, WRP and DSR, their increase was approximately 1.3 times, 1.1 times and 7.6 times, respectively. (2) Two advantages common in the three MANET routing protocols compared to classical distance vector protocol were identified to be scalability for node mobility in end‐to‐end delay and scalability for node density in messaging overhead. (3) WRP resulted in the shortest delay and highest packet delivery rate, implying that WRP will be the best for real‐time applications in the four protocols compared. WRP demonstrated the best traffic scalability; control overhead will not increase much when traffic load increases. Copyright © 2005 John Wiley & Sons, Ltd.     

Optimised relay selection for route discovery in reactive routing

On-demand routing protocols have the potential to provide scalable information delivery in large ad hoc networks. The novelty of these protocols is in their approach to route discovery, where a route is determined only when it is required by initiating a route discovery procedure. Much of the research in this area has focused on reducing the route discovery overhead when prior knowledge of the destination is available at the source or by routing through stable links. Hence, many of the protocols proposed to date still resort to flooding the network when prior knowledge about the destination is un-available. This paper proposes a novel routing protocol for ad hoc networks, called On-demand Tree-based Routing Protocol (OTRP). This protocol combines the idea of hop-by-hop routing (as used by AODV) with an efficient route discovery algorithm called Tree-based Optimised Flooding (TOF) to improve scalability of ad hoc networks when there is no prior knowledge about the destination. To achieve this in OTRP, route discovery overheads are minimised by selectively flooding the network through a limited set of nodes, referred to as branching nodes. The key factors governing the performance of OTRP are theoretically analysed and evaluated, including the number of branch nodes, location of branching nodes and number of Route REQuest (RREQ) retries. It was found that the performance of OTRP (evaluated using a variety of well-known metrics) improves as the number of branching nodes increases and the number of consumed RREQ retries is reduced. Additionally, theoretical analysis and simulation results shows that OTRP outperforms AODV, DYMO, and OLSR with reduced overheads as the number of nodes and traffic load increases.     

多跳无线Ad hoc网络路由协议的模拟和性能比较

文中采用随机场景的模拟方法对3种多跳无线Ad hoc网络路由协议的性能做了定量性的分析.对网络模拟器NS-2做了更进一步的拓展:增加SASR路由协议、增加AODV的MAC层虚拟HELLO机制,在此基础上对路由协议AODV,DSR和SASR进行了模拟.模拟结果显示:3种路由协议都能适应网络的拓扑结构变化,但是SASR和AODV路由协议在多跳无线Ad Hoc网络仍然具有相对的优越性.     

Improving Bandwidth Utilization of Intermittent Links in Highly Dynamic Ad Hoc Networks

Non-uniform node densities occur and intermittent links exist in highly dynamic ad hoc networks. To fit these networks, researchers usually combine delay tolerant network (DTN) routing protocols and mobile ad hoc network (MANET) routing protocols. The DTN protocol separates end-to-end links into multiple DTN links, which consist of multi-hop MANET links. Determining how to arrange DTN links and MANET links from source to end and dealing with intermittent links are performance issues, because node density ranges from sparse to dense and MANET protocols are much lighter than DTN protocols. This paper presents HMDTN, an application-network cross-layer framework, to solve the previously mentioned issues. The application layer in HMDTN supports disrupt tolerance with a large data buffer while adjusting the routing table on the basis of the connection state of links (link is disrupted or recovered), which are collected by the network layer. As a result, HMDTN increases the bandwidth utilization of intermittent links without compromising the efficiency of the MANET protocol in a reliable network. The HMDTN prototype was implemented based on Bytewalla (a Java version of DTN2) and Netfilter-based AODV. Experiments on Android devices show that unlike AODV and Epidemic, HMDTN increases the bandwidth utilization of intermittent links with a negligible increase of network overhead. In particular, HMDTN maintains the network throughput as high as regular network conditions even if the network undergoes relatively long-term (dozens of seconds or few minutes) data link disruptions.

     

一种基于AODV的链路中断预测和最短路径修复机制

在无线Ad Hoc网络中,为了提高链路质量和通信的稳定性,提出一种基于AODV路由协议的链路中断预测和最短路径修复机制(LIFSR-AODV).通过检测网络中的链接质量,预测和避免链路中断的发生,降低了本地修复过程中控制包的开销和传输延迟.同时,在修复过程中能够通过删除链路中的多余节点来缩短路径长度.通过在IEEE 802.15.4 Matlab模拟器下仿真,验证此路由机制能够提高AODV路由协议的性能和链路的稳定性.     

基于AODV的多度量无线路由算法研究

随着移动自组网络的快速发展,对距离矢量按需路由协议(AODV)的服务质量提出了越来越高的要求.为了提升AODV在无线传感器网络通信中的表现,文章提出了一种新型的基于AODV的多度量无线路由协议(MWR-AODV).MWR-AODV综合考虑了对路由协议性能影响重大的最小跳数、剩余能量、能量流失率和网络节点密度这四个因素,并且引入了一种低成本且高效的本地修复策略.通过Network Simulator-2仿真平台对MWR-AODV与标准AODV、DSDV协议的表现进行了仿真分析.结果表明,所提出的MWR-AODV能为无线传感器网络提供更好的通信服务,并且在均衡能量消耗延长网络寿命和平衡网络通信负载方面也有上佳表现.     

Design and Performance of PRAN: A System for Physical Implementation of Ad Hoc Network Routing Protocols

Simulation and physical implementation are both valuable tools in evaluating ad hoc network routing protocols, but neither alone is sufficient. In this paper, we present the design and performance of PRAN, a new system for the physical implementation of ad hoc network routing protocols that unifies these two types of evaluation methodologies. PRAN (physical realization of ad hoc networks) allows existing simulation models of ad hoc network routing protocols to be used - without modification - to create a physical implementation of the same protocol. We have evaluated the simplicity and portability of our approach across multiple protocols and multiple operating systems through example implementations in PRAN of the DSR and AODV routing protocols in FreeBSD and Linux using the standard existing, unmodified ns-2 simulation model of each. We illustrate the ability of the resulting protocol implementations to handle real, demanding applications by describing a demonstration with this DSR implementation transmitting real-time video streams over a multihop mobile ad hoc network; the demonstration features mobile robots being remotely operated based on the real-time video stream transmitted from the robot over the network. We also present a detailed performance evaluation of PRAN to show the feasibility of our architecture     

移动Ad Hoc网络中AODV路由协议的改进

移动Ad Hoc网络研究中,路由协议是一个关键问题。鉴于Ad Hoc网络的高移动性,通信路径的稳定性显得尤为重要。本文在基于AODV（Ad Hoc On-Demand Distance Vector）按需距离矢量路由的思想上,提出一种新的双径路由改进方案。旨在提高协议的健壮性,增强网络对拓扑变化的适应能力。性能分析和仿真结果表明,改进后的AODV路由协议,降低了端到端时延,减少了数据包的丢失,提高了网络的吞吐量,使得网络的性能得到了提升。     

Efficient on-demand routing for mobile ad hoc wireless access networks

In this paper, we consider a mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Mobile nodes outside the transmission range of the gateway can continue to communicate with the gateway via their neighboring nodes over multihop paths. On-demand routing schemes are appealing because of their low routing overhead in bandwidth restricted mobile ad hoc networks, however, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the ad hoc on-demand distance vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Simulation results show that as traffic increases, our proposed LB-AODV routing protocol has a significantly higher packet delivery fraction, a lower end-to-end delay and a reduced routing overhead when compared with both AODV and gossip-based routing protocols.     

一种蜂窝辅助的AODV路由协议

首先提出了一种新的融合AdHoe和蜂窝网络体系结构。接着在这种融合网络结构下,对传统AODV路由协议进行了改进,设计了一种蜂窝辅助的AODV路由协议（CA-AODV）。CA-AODV路由协议利用蜂窝系统中代理节点所保存的移动adhoe节点位置信息,来维护、更新节点中的路由,这种主动维护路由信息的方法从而可以提高传统AODV协议的性能。最后文中通过NS-2仿真表明：在数据发送率较高的情况下,CA-AODV路由协议能显著提高传统AODV协议的系统参数性能。     

RMRPTS: a reliable multi-level routing protocol with tabu search in VANET

Vehicular ad hoc network (VANET), a subclass of mobile ad hoc networks (MANETs), is a promising approach for the intelligent transportation system (ITS). One of the main challenges in VANETs is establishment of vehicular communication and stable routing. Another problem of VANETs is their tendency of being trapped in a local optimum. In this paper, a reliable multi-level routing protocol based on clustering, RMRPTS has been introduced in VANETs. Even if this topology constantly changes, clustering based multi-level routing will create the possibility of self-organization and route maintaining; moreover, it will solve the problem of developing a trap in the local optimum using tabu search. At the first level, the proposed protocol is an extension of AODV routing protocol that has been improved using fuzzy logic in order to create reliable routing between cluster members. Tabu search has been used at a higher level for routing between cluster heads and destination. Tabu search is a meta-heuristic improved learning method used for solving hybrid optimization problems, and it uses cost function to select a solution among a set of possible solutions. The effective parameters used in the proposed method to select the best path include nodes distance, the velocity of nodes, node’s angle, link stability, and link reliability. The proposed protocol was simulated using an NS-2 simulator, and the results of its performance showed increased average packet delivery rate and decreased average end to end delays, number of packet losses compared with earlier protocols.     

基于改进蚁群算法的Ad hoc路由协议的研究

现有Ad hoc网络路由协议技术研究中,路由稳定性和可靠性问题尚未得到很好解决,不能很好地适应Adhoc网络.针对已有Ad hoc路由技术中存在的开销大以及网络稳定性较低的问题,该文引入蚁群算法,并对其进行改进.研究基于改进蚂蚁算法的Ad hoc路由协议,并与比较成熟的AODV(Ad hoc On-Demand Distance Vector)进行对比.仿真实验结果表明,通过发挥网络中结点群体功能,新协议减小了端对端传输延时,改善了数据包传输成功率与协议开销,有效地提高了网络的稳定性和通信效率.     

短波Ad Hoc路由协议仿真与性能分析

为找到一种适合短波Ad hoc网络使用的路由协议,通过OPNET仿真软件对短波信道进行建模,在该模型的基础上对无线Ad Hoc常用的3种路由协议:优化链路状态路由(Optimized Link State Routing,OLSR)、反应式路由中的动态源路由(Dynamic Source Routing,DSR)和按需距离矢量(Ad hoc On Demand Distance Vector,AODV)进行仿真分析。仿真结果表明,OLSR路由协议网络时延最小、吞吐量最高和数据丢失率最低,其整体性能优于AODV及DSR路由协议,更适合于短波信道,但是OLSR路由协议也存在着开销高的不足,下一步可以针对降低路由开销进行研究。     

无线传感器网络路由协议的设计与实现

针对传统路由协议端到端时延长、丢包率过高的现实问题,提出了一种基于贪婪转发的能量感知多路径路由协议(Greedy Forward Energy-aware Multipath Routing Protocol,GFEMRP)。GFEMRP从传感器起始结点出发,如果遇到网络黑洞则选择周边转发方式,否则将选择吞吐量大、且更接近于目的结点的结点作为下一跳结点。利用了OMNET++5.0和INET框架对包括无线自组网按需平面距离向量路由协议(Ad hoc on-demand distance vector routing protocol,AODV),动态按需无线自组织网络(Dynamic MANET On-demand,DYMO),贪婪周边无状态路由无线网络(Greedy Perimeter Stateless Routing for Wireless Networks,GPSR)和GFEMRP协议在内的四种路由协议进行了仿真和比较,实验结果表明GFEMRP协议具有良好的端到端时延、丢包率等性能。     

Performance Evaluation of Improved Directional Ad Hoc on Demand Distance Vector Routing Protocol

Mobile ad hoc networks (MANET’s) popularly uses ad hoc on-demand distance vector (AODV) routing protocol. Past research has identified certain limitations on performance on AODV. This work discusses the results of a new protocol, improved directional AODV (ID-AODV) routing protocol; that has succeeded in improving the performance of MANET’s for energy, delay, packet delivery ratio and overheads as compared with networks using AODV. In ID-AODV, improvements are carried out in both network layer, and data link layer. The directionality is introduced based on hop count of its position from the source. The dual sensing directional media access control protocol is used to eliminate the hidden terminal, exposed terminal, and deafness issue. Participation of nodes in forming route is decided by checking remaining energy level of the node and also checking its load. A modified algorithm is used to reduce the delay. This algorithm reduces the delay by changing the time to live, wait time, and using expanded ring search technique. The simulation results show that the ID-AODV offers improved performance on average Energy consumption in the range of 17–20%, average end to end delay is lower by 61 to 95%, Overheads improved in the range of 10–13%, Jitter 6–21%, link break 43–52%, packet delivery ratio is 6–21% lower as compared to MANETS deploying AODV.     

Probabilistic analysis of routes on mobile ad hoc networks

The ad hoc network is comprised of mobile nodes without wires or any infrastructures. All data are transmitted from source node to destination node through wireless channels. The ad hoc network is self-organized by ad hoc network routing protocols. Due to the mobility of nodes, the route which is constructed from many proposed ad hoc network routing protocols and comprised of several direct node-to-node links exists only for a certain period. That also means the route is subject to frequent breakages. In this letter, the probabilistic behavior of a constructed route is investigated through simulation and curve fitting. The simulation results show that the probability density function of a route is exponential distribution. The simulation also shows how the time proportion is distributed among different route lengths under a certain scenario. The route is a basic factor in the ad hoc network which operates without any central controller. The characteristics of the route have much influence on the performance of the ad hoc network. Thus the probabilistic analysis provides important implications when we are designing ad hoc network routing protocols and deploying ad hoc networks.     

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.