Impact of a simple load balancing approach and an incentive-based scheme on MANET performance

Most reactive mobile ad hoc network (MANET) routing protocols such as AODV and DSR do not perform search for new routes until the network topology changes. But, low node mobility does not affect the MANET connectivity and the same routes may be used for a long time. This may cause concentration of traffic on few mobile stations (MSs), which results in congestion and hence longer end-to-end delay. In addition, continuous use of MSs may cause their battery power to get exhausted rapidly. Expiration of MS energy causes disruption of connections traversing through the MSs and could generate many simultaneous new routing requests. Therefore, we propose a load balancing approach called Simple Load Balancing Approach (SLBA), which can be transparently added to any current reactive routing protocol such as AODV and DSR. SLBA minimizes the traffic concentration by allowing each MS to drop RREQ or to give up packet forwarding depending on its own traffic load. Meanwhile, MSs may deliberately give up forwarding packets to save their own energy. For encouraging MSs to volunteer in forwarding packets, we introduce a reward scheme for packet forwarding, named Protocol-Independent Fairness Algorithm (PIFA). We compare the performance of AODV and DSR with and without SLBA and PIFA. Simulation results indicate that SLBA can distribute traffic very well and improve the MANET performance. PIFA is also observed to prevent MANET partitioning and any performance degradation due to selfish nodes.     

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).     

MANET中一种新的多路由机制

在MANET中，DSR和AODV都是按需路由协议，并且都是单路径的协议，即只能发现一条路由。然而，在AdHoe中，因为节点的移动性和通信链路的不稳定性，多条路由是必须的。目前，有一些多路由协议，如AOMDV和MNH等。提出了一种新颖的多路由协议AMODV。在这种协议当中，分散的和相反的路径碎片被连接起来从而获得了另外的路由，能找到比其它多路由协议更多的路由。     

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.     

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。     

MANET环境下AODV协议的研究和改进

MANET网络就是移动Ad—Hoc网络，它是由若干节点所组成的一个移动自治系统，在一个无线Ad—Hoc网络中，节点之间通过多跳无线链路相互通信，所有的节点利用共享的无线媒质相互联系。这样节点之间路由问题就成为一个重点要解决的问题。目前，在这方面普遍采用DSR和AODV路由协议。但是，这两种路由协议对于要求QoS的网络来说还是力不从心的。文中主要讨论的是基于AODV路由协议的一些改进方案。     

MANET中带自愈功能的路由优化机制

MANET中，现有的按需路有协议解决了包传送路由的问题。但是，因为节点的移动，这些协议都缺乏对全局节点拓扑的认识，因而不是最优的。路由是否优化影响着网络的性能，特别是当网络负载很重的时候。越长的路由耗费的带宽会更多，连不通的可能性就越大。提出了一种带自愈功能的路由优化机制（ORMS）来监视路由，如果一条较短的路由存在，就尽可能使其变短。ORMS在现有的带宽和反应时间内提高了网络的性能而没有增加任何额外的资源耗费.     

Ad Hoc网络中按需路由协议的仿真与性能分析

对Ad Hoc网络中两种典型的按需路由协议AODV和DSR协议进行了介绍,对两种协议的路由发现和路由维护过程进行了分析与比较。对两种路由协议在不同的运动场景中进行了比较系统的仿真研究。仿真中选取了数据包的传输率、端到端的平均时延、路由开销这三个指标对AODV和DSR路由协议进行了性能评估,并通过改变节点的个数、分组速率和节点暂停时间来分析比较这些参数的改变对这两个协议性能的影响。     

A learning automata-based fault-tolerant routing algorithm for mobile ad hoc networks

Reliable routing of packets in a Mobile Ad Hoc Network (MANET) has always been a major concern. The open medium and the susceptibility of the nodes of being fault-prone make the design of protocols for these networks a challenging task. The faults in these networks, which occur either due to the failure of nodes or due to reorganization, can eventuate to packet loss. Such losses degrade the performance of the routing protocols running on them. In this paper, we propose a routing algorithm, named as learning automata based fault-tolerant routing algorithm (LAFTRA), which is capable of routing in the presence of faulty nodes in MANETs using multipath routing. We have used the theory of Learning Automata (LA) for optimizing the selection of paths, reducing the overhead in the network, and for learning about the faulty nodes present in the network. The proposed algorithm can be juxtaposed to any existing routing protocol in a MANET. The results of simulation of our protocol using network simulator 2 (ns-2) shows the increase in packet delivery ratio and decrease in overhead compared to the existing protocols. The proposed protocol gains an edge over FTAR, E2FT by nearly 2% and by more than 10% when compared with AODV in terms of packet delivery ratio with nearly 30% faulty nodes in the network. The overhead generated by our protocol is lesser by 1% as compared to FTAR and by nearly 17% as compared to E2FT when there are nearly 30% faulty nodes.     

一种改进的基于能量效率的AODV路由协议

传统的按需距离矢量路由协议（AODV）使用基本的路由发现算法建立从源节点到目的节点的路由,不考虑节点当前的剩余能量大小,整个网络的生存期受到影响。提出了一种改进的按需距离矢量路由协议（EM-AODV）。它在建立路由的过程中使用了一种考虑节点剩余能量的算法,来确定路由请求报文的转发时延,选取剩余能量较多的节点建立路由。仿真结果表明：EM-AODV较AODV提高了能量使用效率,延长了网络生存期。     

基于AODV的能量优化路由协议

对AODV路由协议进行改进,提出了基于AODV的能量优化路由协议(EO-AODV).进行了节点的剩余能量的考虑,根据节点的剩余能量对RREQ延迟进行了调节,并采用了避免路由失效算法,利用节点最近一次传递过数据分组的时间作为约束条件对RREQ的洪泛广播进行了优化.仿真结果表明,和AODV路由协议相比,降低了网络的能量消耗并减少了耗尽能量的节点数,延长了网络的生存时间.     

基于位置信息的改进AODV路由算法

针对AODV协议路由开销较大的问题,提出一种基于位置信息的改进路由协议(GAODV).GAODV利用中间节点重新计算转发角度,保证转发角度内邻居节点数不小于预设门限值,同时还引入基于位置信息的计数器方案,使距离目的节点近的中间节点优先转发路由请求消息,有利于减少转发冗余路由请求信息和降低寻路失败概率.OPNET仿真实验结果表明,GAODV在数据分组投递率、路由开销、总丢包数、端到端时延和平均路由跳数等方面都优于已有算法.     

MANET路由子层微移动管理

在采用无线自组网按需平面距离矢量(AODV)路由协议的移动自组网(MANET)网关设计中,针对MANET节点的微移动特性,提出应用于MANET路由子层的微移动管理策略,并在AODV路由协议中进行实现。在NS2平台上的仿真结果表明,采用微移动管理策略的MANET网关可有效降低MANET网络访问Internet的时延,并能减少MANET内控制报文的开销。     

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     

按需式ad hoc移动网络路由协议的研究进展

Ad hoc移动网络是一种完全由移动主机构成的网络，网络拓扑易变，带宽，能源有限是ad hoc移动网络的主要特点，针对这些特点，目前设计的ad hoc路由协议大多采用按需查找方式，该文介绍了这方面研究的最新进展，对几种典型的按需路由协议进行了说明，分析和综合比较，文中分析了目前协议存在的一些问题并提出了相应的改进方法，最后指出了下一步研究方向。     

Enhanced AODV routing protocol for Bluetooth scatternet

Bluetooth is one of the most widespread technologies for personal area networks that allow portable devices to form multi-hop Bluetooth ad hoc networks, so called scatternets. Routing is one of the challenges in scatternets because of its impact on the performance of the network. It should focus on reducing the power consumption in the network because most of the nodes are battery-operated portable devices. In this paper, we propose a routing protocol for Bluetooth scatternets that customizes the Ad hoc On-Demand Distance Vector (AODV) routing protocol by making it power-aware and suitable for scatternets. It enhances the AODV flooding mechanism by excluding all non-bridge slaves from taking apart in the AODV route discovery process. In addition, it improves the AODV route discovery phase by considering the hop count, the predicated node’s power, and the average traffic intensity for each node as metrics for best route selection. By removing HELLO packets, our protocol reduces the control packets overhead and the power consumption in network devices. Simulation results show that the proposed protocol achieved considerable improvements over other enhanced AODV protocols by increasing the data delivery ratio by 10.78%, reducing the average end-to-end delay by 8.11%, and reducing the average energy consumption by 7.92%.     

Scalability of MANET routing protocols for heterogeneous and homogenous networks

In Mobile Ad hoc Network (MANET), mobility, traffic and node density are main network conditions that significantly affect performance of routing protocols. Much of the previous research in MANET routing have focused on developing strategies, which suit one specific networking scenario. Therefore, there is no existing protocol that can work well in all different networking scenarios. This paper reviews characteristics of several different classes of routing protocols. Moreover, most of current routing protocols assume homogeneous networking conditions where all nodes have the same capabilities and resources. This paper presents extensive studies simulations for DSR, AODV, LAR1, FSR and WRP in homogenous and heterogeneous networks that consist of different nodes with different resources. The results showed that while all protocols perform reasonably well in homogenous networking conditions, their performance suffer significantly over heterogonous networks.     

无线移动自组织网路由协议性能研究

路由是无线移动自组织网的关键技术之一。目前已经提出的MANET路由协议有很多种，因此如何针对一定应用场景选择一个最佳的路由协议，是人们十分关心的一个问题。该文对已经通过IETF认可的三种MANET路由协议：DSR、AODV和OLSR进行了仿真对比分析。设计了大量的场景，通过对路由协议的分组传送率、端到端时延和所选路径长度等指标的比较，得出了在不同的网络环境下MANET最佳路由协议选择方案。仿真中发现同是采用按需的路由发现策略的DSR和AODV在高移动、高负荷的网络环境下的性能存在较大差异，对此原因进行了深入分析，并根据分析对DSR提出了改进方案。     

Security threats and solutions in MANETs: A case study using AODV and SAODV

Mobile ad hoc network (MANET) security has become the focus of prolific research efforts. Driven by the unique and considerable difficulties of providing security arising from the dynamic nature of MANETs, many security schemes have been proposed. Rather than trying to encompass the entire field of MANET security, this paper focuses on networks using the popular Ad-hoc On-demand Distance Vector (AODV) protocol and a secure extension to AODV, the Secure AODV (SAODV) protocol. SAODV is representative of a number of secure versions of the AODV protocol in that it relies upon the use of cryptographic mechanisms to protect the routing control messages of AODV from being forged and/or altered by attackers. We conduct a vulnerability analysis of SAODV to identify unresolved threats to the algorithm, such as medium access control layer misbehaviour, resources depletion, blackholes, wormholes, jellyfish and rushing attacks. We then compare this vulnerability analysis to schemes that have been proposed to combat the identified threats. These proposals include multipath routing, incentive schemes, directional antennae, packet leashes, randomized route requests, localized self-healing communities and a reactive intrusion detection node blacklisting scheme.     

基于NS2的Ad Hoc网络AODV协议研究与改进

无线自组网是由一组无线移动主机组成的无基础设施的临时网络,在与其相关的网络协议的研究中常涉及到修改及扩展问题。文章分析了经典按需路由协议AODV的路由发现和建立过程,通过NS2仿真软件的内核扩展及重编译,在控制台输出相关的扩展内容,包括RREQ和RREP包的传送、正反向路由表的建立和节点路由表的更新等信息。结果表明,在NS2仿真软件下对无线自组网路由协议的研究和调试分析是一种科学有效的方法。最后对AODV协议本身提出了几种改进的思路和方法。