无线ad hoc网络技术研究

无线ad hoe网络是随着无线通信技术的快速发展而出现的一种新型网络。详细介绍了无线ad hoc网络的定义及发展,对其体系结构、主要特点和关键技术进行了分析。最后,展望了网络防火墙的发展趋势。     

移动ad hoc网络中DOS攻击及其防御机制

移动ad hoc网络由于其动态拓扑、无线信道以及各种资源有限的特点,特别容易遭受拒绝服务(DOS)攻击．提出了移动ad hoc网络中一种新的DOS攻击模型——ad hoc flooding攻击及其防御策略．该攻击主要针对移动ad hoc网络中的按需路由协议,如AODV,DSR等．ad hoc flooding攻击是通过在网络中泛洪发送超量路由查询报文及数据报文,大量地占用网络通信及节点资源,以至于阻塞节点正常的通信．分析ad hoc flooding攻击之后,提出了两种防御策略：其一是邻居阻止,即当入侵者发送大量路由查询报文时,邻居节点降低对其报文的处理优先级,直至不再接收其报文．其二是路径删除,即目标节点将入侵者发送攻击报文的路径删除,以阻止其继续发送攻击报文．模拟实验证实,通过这两种方法的结合．能够有效地阻止网络中的ad hoc flooding攻击行为．     

ad hoc网络AODV协议在Windows CE上的实现

为给无线网络的应用提供研究平台,用Windows CE模拟器平台和IEEE 802.11b无线网络接口搭建真实的移动网络环境,通过调用API和增加功能模块的方式实现ad hoc路由协议,使用模拟器编写相关应用程序,实现AODV(Ad hoc on-demand Distance Vector)路由算法模块. 对该模块进行初步的验证和测试,结果表明:所设计的路由协议不仅在1跳范围内具有良好的通信性能,而且具备多跳通信能力;可以按需建立路由并实时启动路由维护过程. 该路由协议的实现为编写其他ad hoc网络路由协议提供1种实用框架.     

移动ad hoc网络安全路由协议综述

移动adhoc网络路由协议对于各种针对路由协议的攻击无能为力,因为路由协议并未考虑安全因素,攻击者肆意利用路由协议中的安全隐患来破坏网络。论文综述了移动adhoc网络安全路由协议研究方面的一些最新工作,对该领域各种安全路由协议进行了研究分析,并描述了移动adhoc网络安全路由协议所面临的安全挑战。     

一种新的移动ad hoc网络中带宽保证的路由算法

移动adhoc网络(Mobileadhocnetworks)是一种由无线移动主机/节点组成的动态自治网络。移动adhoc网络在军事和民用方面都有很大的应用前景。在移动adhoc网络中进行有QoS保证的路由选择有重要的意义。论文讨论了移动adhoc网络中的路由选择、QoS保证,并提出了一种新的带宽保证的路由算法ABGR。ABGR以受限扩散路由方法为基础,采用多种机制避免在全网中进行扩散,同时在路由选择的过程中考虑路径稳定性和节点的电能受限问题。     

MIMO下行链路中的多用户调度与功率分配

分析了MIMO下行链路中的多用户调度和功率分配方法,讨论了各种功率分配方法的多用户调度性能,并通过仿真实验对性能进行了比较。实验结果表明,在低信噪比条件下,二维注水功率分配的性能最佳,而在高信噪比条件下,各种功率分配方法的性能差别很小。     

移动ad hoc网络的安全漏洞及对策

移动ad hoc网络是一种新型的无线移动网络，因其特有的路由多跳性、无中心的控制分布性以及拓扑动态性，使得现有网络中的安全机制不能完全应用于移动ad hoc网络。文中探讨了移动ad hoc网络特有的各种安全漏洞以及相应的对策中存在的各种不足，并与现有网络中的安全对策进行了较深入的比较，从而总结出该领域研究的发展趋势，并指出了几个值得重视的研究方向。     

基于信誉值的ad hoc网络节点自私类型检测

在ad hoc网络中,节点间的合作是一个重要的问题,不相邻节点的信息传递只能依靠中间节点的转发来完成,若中间节点存在自私行为则会较大地影响网络的性能。节点自私类型有不同,对网络功能造成的影响也各不一样,有些自私节点在一定数量上对网络整体性能影响不大,可以容忍;而有些自私节点则必须得采取强硬的惩戒措施,将其驱逐出网络或降低它的信誉值并公布。该文采用基于信誉值的算法检测出ad hoc网络中的问题节点,并对其进行类型定义,仿真查看其对网络性能的影响,方便下一步根据不同自私节点进行机制设计。     

一种ad hoc多路径安全路由算法

移动ad hoc网络无中心、拓扑结构动态变化等特点,以及节点能源和计算能力有限,使其安全路由设计面临巨大挑战.在按需路由的基础上提出了一种多路径安全路由算法,采用高效的分布式密钥管理策略,路由过程中隐藏通信节点的地址信息,节点之间逐跳认证保证信息的完整性,能够抵御单路径协议不能抵抗的多恶意节点的合谋攻击,同时能平衡负载,具有更好的安全性能和网络性能.     

一种ad hoc网络中的密钥管理

ad hoc网络是一种新型的无线移动自组织网络,内部节点相互合作信任,没有中心控制节点,节点计算能力有限。针对如何在这种自组织群体中进行密钥管理,保证安全的通信,本文提出建立可信第三方CA(certificate authority),发放CA证书,并进行证书更新和证书撤消的操作,从而实现安全而有效的分布式密钥管理。     

Transmission scheduling algorithm for MIMO link ad hoc networks

Most reported works on transmission scheduling algorithm for multiple input multiple output (MIMO) link ad hoc networks do not fully exploit the spatial multiplexing potential inherent to multiple an-tennas system.In this paper,a novel transmission scheduling algorithm is proposed to further enhance the performance of MIMO link ad hoc networks.By utilizing the MIMO multi-stream reception capabilities and ordering the nodes’ allocation sequence,the proposed algorithm can dramatically shorten the scheduling frame length and more evenly distribute the data streams allocated to the network nodes.Meanwhile,allowing the nodes to transmit multiple streams in a slot,the algorithm can fully exploit the MIMO spatial multiplexing potential.Additionally,we give the theoretical analysis to quantify the throughput and delay performance with respect to this scheme.Numerical results demonstrate that the proposed algorithm can efficiently enhance the network throughput and reduce the average and maximum delay.     

An evolutionary computation approach for designing mobile ad hoc networks

This paper presents the topological design of ad hoc networks in terms of distances among static nodes and speeds of mobiles nodes. Due to the complexity of the problem and the number of parameters to be considered, a genetic algorithm combined with the simulation environment NS-2 is proposed to find the optimum solution. More specifically, NS-2 provides the fitness function guiding the genetic search. The proposed framework has been tested using a railway scenario in which several static and mobile nodes are interacting. Results show the feasibility of the proposed framework and illustrate the possibility of genetic approach for solving similar application scenarios.     

一种新的多路径自组网路由算法

传统的单路径路由使自组网路由性能一直不能获得太大的突破。因此,设计有效的和稳定的多路径路由成为最受关注的问题。为此提出了一种新的多路径路由算法,其在路由发现阶段使用了一种新的多路径转发策略。在基于稳定性因子的基础上,该算法计算路径间海明距离并据此选择多条相似的稳定不相交多路由,从而进一步提高该路由算法的性能。模拟结果显示,与经典的多路径路由相比较,该算法是一个有效的多路径自组网路由算法。     

TCP-aware network coding with opportunistic scheduling in wireless mobile ad hoc networks

This paper presents a scheme that employs TCP-aware network coding with opportunistic scheduling to enhance TCP throughput in wireless mobile ad hoc networks. Specifically, it considers a TCP parameter, congestion window size, and wireless channel conditions simultaneously to improve TCP throughput performance. Evaluation of this scheme is carried out by using ns2 simulations in different scenarios. The results show that the proposed scheme gives approximately 35% throughput improvement in a high mobility environment and about 33% throughput increase in no or low mobility environment as compared to traditional network coding with opportunistic scheduling. This paper also proposes a new adaptive-W (i.e., adaptive Waiting time) scheme whose objective is to adaptively control waiting time of overheard packets that are stored in a buffer to achieve tradeoff between throughput and overhead.     

层状 Ad Hoc 网络的信息传播路由算法研究

讨论了层状移动AdHoc网络的一个信息传播路由算法和基于半马尔可夫过程的节点移动跟踪模型,通过该路由算法可以有效地解决层状子网络间的通信和信息交换。通过路由算法得到的中继节点的移动跟踪模型和计算机仿真,分析了层状移动AdHoc网络的传播性能和路由开销,并得出:当 0≤ρ≤ 1时,层状AdHoc网络的传播性能显著地受到移动呼叫率ρ的影响,当ρ>1时,层状AdHoc网络的传播性能主要取决于移动网络的节点总数、节点移动速度和加速度的结论。     

Triangle-based routing for mobile ad hoc networks

Routing protocols for Mobile ad hoc networks (MANETs) have been studied extensively in the past decade. Routing protocols for MANETs can be broadly classified as reactive (on-demand), proactive, hybrid and position-based. Reactive routing protocols are attractive because a route between a source and a destination is established only when it is needed. Such protocols, unlike proactive protocols, do not have high overhead for route maintenance and are especially suitable for networks in which not all nodes communicate frequently. One problem with existing reactive routing protocols is the propagation of redundant route request messages during route discovery. In this paper, we present a low-overhead reactive routing protocol which reduces propagation of redundant route request messages. We also compare its performance with the well-known reactive routing protocol AODV.     

基于移动状态的车载自组织网络路由算法

传统的AODV协议应用于车载自组织网络,尽管分组投递率比较高,但在数据分组需要发送时才建立路由,网络延迟较大。而DSDV中通过周期性的路由更新机制,网络延迟小,但需维护大量不必要的路由,并且拓扑结构变化使许多路由无效,导致分组投递率非常低。为了综合满足VANET分组投递率和网络延迟的要求,将AODV和DSDV两种路由建立机制相互融合,形成混合式路由协议。首先,根据车辆节点的位置、速度和方向等移动状态周期性地选择稳定且距离适中的链路,形成网络主干并更新路由;其次,当数据分组目的节点路由不存在时,发起路由发现过程建立路由,在路由请求报文前进和路由应答报文回溯过程中求出路由过期时间。仿真实验表明,尽管路由开销有所增大,分组投递率略低于AODV,但是网络延迟显著降低。     

Cost-effective mobile ad hoc networks management

As there are more and more mobile devices in use, different mobile networking models such as ad hoc or mesh are attracting a large research interest. Self-organizing mobile ad hoc networks (MANET) allow devices to share their services and resources without any central administration or Internet support. In this respect they can become the backbone of the wireless grid or the gateway to existing grids. To achieve these goals, MANET management must be as effective as that of wired networks. This is, however, a challenging task due to network features like mobility, heterogeneity, limited resources of hosts and feeble communication. This paper presents a set of simple, cost-effective and resilient procedures for the basic tasks of MANET creation and management.     

A clique-based secure admission control scheme for mobile ad hoc networks (MANETs)

Wireless mobile ad hoc networks (MANETs) do not have centralized infrastructure and it is difficult to provide authentication services. In this paper, we apply Certificate Graph (CG) and identity-based security in designing an admission control scheme for MANETs. We first use one-hop message exchange to build CG at each mobile node. Then we select maximum clique nodes in CG as distributed Certificate Authorities (CAs). We use identity-based key agreement from pairings to protect each session. Then we prove the security by Canetti–Krawczyk (CK) model-based analysis. We demonstrate the effectiveness and feasibility of our protocol through computer simulations.