Multi-Level Hierarchies for Scalable Ad hoc Routing

Ad hoc networks have the notable capability of enabling spontaneous networks. These networks are self-initializing, self-configuring, and self-maintaining, even though the underlying topology is often continually changing. Because research has only begun to scratch the surface of the potential applications of this technology, it is important to prepare for the widespread use of these networks. In anticipation of their ubiquity, the protocols designed for these networks must be scalable. This includes scaling to both networks with many nodes, and networks with rapidly changing topologies. This paper presents two hierarchical clustering protocols that improve the scalability of ad hoc routing protocols. The Adaptive Routing using Clusters (ARC) protocol creates a one-level clustered hierarchy across an ad hoc network, while the Adaptive Routing using Clustered Hierarchies (ARCH) protocol creates a multi-level hierarchy which is able to dynamically adjust the depth of the hierarchy in response to the changing network topology. It is experimentally shown that these protocols, when coupled with an ad hoc routing protocol, produce throughput improvements of up to 80% over the ad hoc routing protocol alone.     

无线自组织网络中一种拥塞意识的多径路由算法

提出了无线自组织网络中一种拥塞意识的多径路由算法。该算法在路由发现过程中,综合节点的队列长度和路径跳数来动态确定路由请求消息的转发概率,可以在保证路由请求消息有一定送达率的条件下,降低路由开销;在路径选择和流量分配过程中,综合考虑节点的队列长度和路径质量作为路由度量,发现流量高吞吐量低拥塞路径,并基于该度量值进行流量分配。仿真结果显示,所提出的多径路由算法能有效提高网络性能。     

Performance of Multipath Routing for On-Demand Protocols in Mobile Ad Hoc Networks

Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently found attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called Dynamic Source Routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Our modeling effort shows that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long path lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths. We perform some simulation experiments which validate these findings.     

移动Ad hoc网络按需路由协议中的虫洞问题研究

由于移动Ad hoc网络具有动态变化的特性以及自组织和多跳性的特点,更容易遭受多种恶意攻击。其中虫洞攻击就是最严重的一种攻击。本文详细剖析了虫洞问题,在总结已有解决方案的基础上提出了一种简洁的解决方案。此方案利用路由发现过程中中间结点计算的MAC值以及邻居维护机制提供的认证信息一起能够很好的抵抗虫洞攻击,提高了路由协议的安全性。     

电力通信PCM组网方式研究

基于64k通道的PCM业务,是现有电力通信网最常见的接入层业务,结合地区PCM组网情况,提出应用VPN技术进行组网,解决了基于HDLC组网时故障无法监测定位的问题,为PCM业务的可靠运行奠定了坚实的基础。     

在ad hoc网络中一种新的节能路由切换模型

提出了一种基于能量消耗的路由切换模型(ERHM),它在路由维护中利用切换技术来使路由的能量消耗最小.仿真结果表明采用切换技术的ERHM模型的能量节省量要比不采用切换技术节约1.5～7.5倍,且节点的移动性越大,能量节约越多.     

一种新的移动Ad hoc网络的安全路由策略

本文从各网络节点易受攻击、俘获，各网络节点之间不可信赖的角度出发，引入了可信任第三方的信任分散策略并结合Diffie-Hellman密钥交换算法，提出了一种新的移动Adhoc网络的安全路由策略。     

Channel Adaptive Shortest Path Routing for Ad Hoc Networks

1　IntroductionAdhocnetworksareformedwithoutrequiringthepreexistinginfrastructureorcentralizedadminis tration ,incontrasttocellularnetworks.Asidefromtheoriginalmilitaryapplication ,ithasapplicationinpublicsafetyandcommercialareas,butadaptiveprotocolsarerequiredinorderforthemtodoso .Twoimportantcharacteristicsofacommunicationlinkinadhocnetworksareitsunreliabilityanditsvariability .Thelinksinsuchanetworkareunreli ablebecauseoffading ,interference,noise,andper hapsthefailureofthetransmittingorrec…     

移动Ad hoc网络路由协议标准

通过重点说明互联网工程任务组(IETF)已通过的两个移动Ad hoc网络路由协议标准,使得相关工程人员在对应用于此种网络的路由协议有一个整体认识基础之上,进一步加深对移动Ad hoc网络原理的理解.     

基于共享树的能量优化多播路由算法

为了延长多播中共享树的工作时间,要求尽量减少节点的能量消耗。利用基于共享树的能量优化的分布式多播路由算法D-REMiT,能够降低共享树的总能耗和延长共享树的使用寿命。模拟结果显示,D-REMiT算法付出很少的共享树总能耗代价,大大提高了共享树的生存时间,有较好的收敛性,比已有的算法G-REMiT更适用于自组网环境。     

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。     

移动Ad hoc网络基于链路可用时间的动态源路由协议

为了提高链路的稳定性,增加路径可用时间,提出一种应用于移动Ad hoc网络的基于链路可用时间的动态源路由协议(LARP).该协议以路径可用时间作为路径评价的参数,优先选择具有最大路径可用时间的路径进行数据包传递.路径可用时间反映了当前节点移动对路径稳定性的影响,其数值取决于路径中的最小链路可用时间.仿真结果表明该协议相...     

移动Ad hoc网络安全路由协议综述

Ad hoc网络的安全性问题越来越引起人们的关注,如何确保Ad hoc网络路由协议的安全成为Ad hoc研究的一项关键技术。本文介绍了安全协议的目标以及针对Ad hoc网络路由协议的恶意攻击,接着详细分析了目前比较典型的几种Ad hoc网络安全路由的研究现状,在对他们进行综合比较的基础上指出了存在的问题。     

自组网路由协议综述

自组网路由协议用于监控网络拓扑结构变化,交换路由信息,定位目的节点位置,产生、维护和选择路由,并根据选择的路由转发数据。本文综述了自组网路由协议研究方面的一些最新工作,描述了设计自组网路由协议所面临的问题,并着重对该研究开展以来所提出的各种主要协议进行了对比、分析和分类阐述,为进一步的研究提出了新的课题。     

Performance Evaluation of Routing Protocols for Ad Hoc Wireless Networks

A mobile ad hoc network is a collection of autonomous mobile nodes that communicate with each other over wireless links. Such networks are expected to play an increasingly important role in future civilian and military settings, being useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable and movement of communicating parties is possible. However, since there is no stationary infrastructure such as base stations, mobile hosts need to operate as routers in order to maintain the information about the network connectivity. Therefore, a number of routing protocols have been proposed for ad hoc wireless networks. In this paper, we study and compare the performance of the following routing protocols AODV, PAODV (preemptive AODV), CBRP, DSR, and DSDV. A variety of workload and scenarios, as characterized by mobility, load and size of the ad hoc network were simulated. Our results indicate that despite its improvement in reducing route request packets, CBRP has a higher overhead than DSR because of its periodic hello messages while AODV's end-to-end packet delay is the shortest when compared to DSR and CBRP. PAODV has shown little improvements over AODV.     

Stimulating Node Cooperation in Mobile Ad hoc Networks

Mobile Ad hoc Networks (MANETs) rely on the cooperation of nodes for packet routing and forwarding. Much of the existing work in MANETs assume that mobile nodes (possibly owned by selfish users) will follow prescribed protocols without deviation. However, a user may misbehave due to several advantages resulting from noncooperation, the most obvious being power saving. As such, the network availability is severely endangered. Hence, enforcing the cooperation among nodes becomes a very important issue. Several different approaches have been developed to detect non-cooperative nodes or deal with the non-cooperative behavior of mobile nodes in MANETs. These protocols are first surveyed in details in this paper. It is found that the proposed approaches have several concerns that prevent them from really enforcing the node cooperation in MANETs. Thus, a new scheme that can stimulate and also enforce nodes to cooperate in a selfish ad hoc environment is presented. We also present a mechanism to detect and exclude potential threats of selfish mobile nodes. The simulation results indicate that by using the proposed scheme, MANETs can be robust against nodes’ misbehaving and the performance of the network is enhanced many folds when compared to other existing schemes.

ABRP: Anchor-based Routing Protocol for Mobile Ad Hoc Networks

Ad hoc networks, which do not rely on any infrastructure such as access points or base stations, can be deployed rapidly and inexpensively even in situations with geographical or time constraints. Ad hoc networks are attractive in both military and disaster situations and also in commercial uses like sensor networks or conferencing. In ad hoc networks, each node acts both as a router and as a host. The topology of an ad hoc network may change dynamically, which makes it difficult to design an efficient routing protocol. As more and more wireless devices connect to the network, it is important to design a scalable routing protocol for ad hoc networks. In this paper, we present Anchor-based Routing Protocol (ABRP), a scalable routing protocol for ad hoc networks. It is a hybrid routing protocol, which combines the table-based routing strategy with the geographic routing strategy. However, GPS (Global Positioning System) (Kaplan, Understanding GPS principles and Applications, Boston: Artech House publishers, 1996) support is not needed. ABRP consists of a location-based clustering protocol, an intra-cell routing protocol and an inter-cell routing protocol. The location-based clustering protocol divides the network region into different cells. The intra-cell routing protocol routes packets within one cell. The inter-cell routing protocol is used to route packets between nodes in different cells. The combination of intra-cell and inter-cell routing protocol makes ABRP highly scalable, since each node needs to only maintain routes within a cell. The inter-cell routing protocol establishes multiple routes between different cells, which makes ABRP reliable and efficient. We evaluate the performance of ABRP using ns2 simulator. We simulated different size of networks from 200 nodes to 1600 nodes. Simulation results show that ABRP is efficient and scales well to large networks. ABRP combines the advantages of multi-path routing strategy and geographic routing strategy—efficiency and scalability, and avoids the burden—GPS support.     

Supporting multicasting in mobile ad‐hoc wireless networks: issues,challenges, and current protocols

The basic philosophy of personal communication services is to provide user‐to‐user, location independent communication services. The emerging group communication wireless applications, such as multipoint data dissemination and multiparty conferencing tools have made the design and development of efficient multicast techniques in mobile ad‐hoc networking environments a necessity and not just a desire. Multicast protocols in mobile ad‐hoc networks have been an area of active research for the past couple of years. This paper summarizes the activities and recent advances in this work‐in‐progress area by identifying the main issues and challenges that multicast protocols are facing in mobile ad‐hoc networking environments, and by surveying several existing multicasting protocols. This article presents a classification of the current multicast protocols, discusses the functionality of the individual existing protocols, and provides a qualitative comparison of their characteristics according to several distinct features and performance parameters. Furthermore, since many of the additional issues and constraints associated with the mobile ad‐hoc networks are due, to a large extent, to the attribute of user mobility, we also present an overview of research and development efforts in the area of group mobility modeling in mobile ad‐hoc networks. Copyright © 2001 John Wiley & Sons, Ltd.     

Querying time indexed information in mobile Ad hoc networks

Time indexed information refers to information whose instance producing time is used as the search key for its access. One common scenario of querying time indexed information is to discover the information instance whose producing time is the closest to a given queried time. However, in the context of mobile ad hoc networks (MANETs), lack of infrastructure support, node mobility, and potential packet loss in wireless communications make querying time indexed information a challenging task. This paper describes a Self-Organizing Mechanism for querying Time indexed Information in MANETs, termed SOMTI. Using SOMTI, each instance producer h discovers routes to a set of instance producers whose instance producing times are the closest to a set of computed time points both before and after h’s instance producing time. These routes form a web of search indices, which allow queries received by any instance producer to be forwarded in the manner of n-ary search for the instance producer whose instance producing time is the closest to the queried time. Both mathematical analysis and simulation study show that SOMTI is scalable with the number of nodes and the query producing rate. In addition, simulations results demonstrate that the goodness, in terms of the closeness to the queried time, of the discovered instance is always better than competing approaches under various node mobility speeds, query generation rates, and the number of nodes in the network, which demonstrates the effectiveness of SOMTI.     

移动Ad hoc网络基于干扰和连通度的路由协议

移动Ad hoc网络中,节点随机移动会引起通信链路频繁断开,从而导致路由失效,带来大量的路由重建与路由发现,耗费了有限的网络资源。传统按需路由中,采用简单的洪泛进行路由发现,路由请求包的盲目转发会带来大量不必要的冗余转发,造成广播风暴问题。此外,大量的数据包同时发送也会对彼此的传输造成干扰,增加数据包冲突概率。针对这种情况,本文提出一种基于干扰和连通度的路由协议,该协议结合节点的连通度和潜在干扰设计转发概率,不仅减少了路由请求包的传播范围,还减少了路由请求包的冲突概率,提高了传输成功率。仿真结果表明,本文设计的方案在减少路由开销的同时,有效提高了数据包投递率,从而提高了路由性能。