泛洪攻击下机会网络典型路由算法健壮性分析

设计了评价方法及指标体系,通过对真实城市场景中带有智能蓝牙设备行人移动行为的仿真,从传输能力、传输效率和节点能耗三个方面定量分析了志愿节点的作用以及在有或没有志愿节点参与情况下泛洪攻击的效果,以此来评价Direct Delivery、Epidemic、Spray and Wait、Prophet和MaxProp共五种机会网络典型路由算法在泛洪攻击下的健壮性。结果表明Direct Delivery算法健壮性最好,能完全抵御泛洪攻击,Spray and Wait算法的健壮性最差,在某些场景下性能会下降80%以上,其他三种算法在泛洪攻击下性能会显著下降。     

路口设施中继辅助车载自组织网络感染路由算法

随着智能交通系统和智慧城市的发展,路旁设施的部署将越来越普遍,城市环境下的车载自组织网络路由算法可以利用路旁设施中继辅助以提高算法的性能。为了解决感染路由算法在高负载场景下由于产生过多的消息副本而引起的路由性能剧烈下降问题,设计了路口设施辅助车载自组织网络感染路由算法IRAER。算法根据道路特点,将车辆的邻居节点划分为不同的区域,且在每个区域中仅选择一个候感节点进行感染,以降低消息副本数量,提高路由性能。另外,建立了随机模型与感染路由算法产生的副本数量进行了对比分析。理论分析和仿真实验结果均表明,所提出路由算法大大降低了在高节点密度场景下的副本数量和投递时延,提高了投递成功率。     

Wait and Spray:一种改进的机会网络路由算法

灾难场景是机会网络重要的应用场景之一,在灾难场景下能量成为稀缺资源,高效转发数据包的同时尽可能减少节点能量消耗成为路由算法追求的目标之一,为此提出了Waitand Spray路由算法,该算法将数据包的转发过程分为Wait和Spray两个阶段,在不同阶段采用不同的路由策略。该算法具有W、K、M参数,恰当的参数设置可控制Spray阶段的泛洪程度,大幅提高算法性能。仿真结果表明,该算法可在获得高传输成功率的同时,大幅降低路由开销,是一种适合在能量稀缺场景下应用的路由算法。     

基于NS2的Ad Hoc网络路由协议性能对比分析

移动Ad Hoc网络是移动节点动态临时组建的自组织网络,路由协议一直都是Ad Hoc网络研究的关键问题。使用NS2网络仿真软件,在不同的场景下分析比较移动Ad Hoc网络的5种路由协议DSDV、OLSR、DSR、AODV和TORA性能,得出不同路由协议在不同场景下的优缺点和适用的网络环境。     

不同合作度下机会网络典型路由算法健壮性分析*

机会网络路由算法在不同合作度下的健壮性是一个重要的但未被充分研究的问题,分析了机会网络中可能存在的节点间不合作的情况,定义了三种适用于不同场景的节点合作度,设计了评价方法及指标体系,通过对真实城市场景中带有智能蓝牙设备行人移动行为的仿真,定量分析了不同节点合作度下Direct Delivery、Epidemic、Spray and Wait、Prophet和MaxProp 五种典型路由算法的健壮性。结果表明Spray and Wait和MaxProp算法健壮性较差,Prophet 和Epidemic算法较     

节点密度感知的容迟网络路由协议*

为适应容迟网络的动态变化,提高路由性能,结合空间节点分布和节点度中心性,提出一种节点密度感知的容迟网络路由协议DAR。该协议引入移动模型的节点分布,通过感知节点当前所处位置的节点密度,动态选择在网络中传播的消息副本数量,并根据节点的度中心性选择中继和分配消息副本数量。仿真结果表明,DAR能够提高传输率、降低传输延迟,在一定程度上降低了资源消耗。     

机会网络中考虑缓存的ProPhet路由算法

机会网络中的ProPhet等路由算法根据机会网络中节点的相遇频率进行节点之间消息的传递,不考虑节点每次相遇的持续时间以及节点中缓存剩余情况。在机会网络内部节点之间的移动速度很快的情况下,采用这些路由算法会使网络内数据的传输效率急剧下降。针对这一不足,结合ProPhet路由算法,计算节点之间的传输概率时充分考虑节点的相遇持续时间以及剩余缓存对节点之间传输概率的影响,使节点之间能更有效地传输数据。仿真结果表明,在给定的移动模型下,该算法能够有效提高消息传递成功率,降低网络中能量消耗等开销。     

移动无线传感器网络中一种新的路由算法

在节点采用RWP移动模型的移动无线传感器网络中,为了提高网络的综合性能,提出了一种新的路由算法LDM.LDM运用节点在RWP模型的运动特点及节点的运动方向与当前位置,推导出节点的传输概率,并使用传输概率来指导路由选择,同时对节点的消息队列进行了有效的管理,提高了网络的综合性能.通过在ONE仿真器上与Epidemic、DT、FAD算法进行比较,结果表明LDM在综合性能上得到了提升.     

自助学习路由协议(SL-AODV)及GloMoSim仿真

一个移动Ad Hoc网络是由一群无线移动主机组成的自治网络,不需要固定的基础设施和集中管理,针对这种网络人们提出了许多路由算法.自助学习路由协议(SL-AODV)是在AODV基础上的改进,通过修改控制报文的结构,节点能在转发报文和路由发现同时进行路由学习,减少了路由开销和延时.对协议的有效仿真和验证是必要的,全球移动信息系统仿真库在移动自组网的仿真研究中得到广泛应用,尤其是对大规模网络的仿真支持.充分应用GloMoSim仿真工具对该协议在不同场景参数下的数据传输率、平均端到端延时、路由开销性能进行测试,得出了对路由改进的最好方案,并和AODV作比较,仿真结果表明SL-AODV的路由性能相对于AODV有明显提高.     

基于平均传递概率的容迟网络路由算法的设计

本文简要总结了容迟网络(DTN)的特点及其体系结构,分析了目前比较常用的容迟网络路由算法,并比较它们的优劣。为了实现提高传递率、降低传输延迟、对节点缓存区进行更加有效地管理的目的,采用ONE模拟器对设计的路由算法和已有的几种常见的DTN路由算法进行了基于特定场景的比较。仿真结果表明,该算法在节点的缓存区大小不同以及网络中节点的数目不同两种情况下,传递率和路由开销比率的性能均优于本文中用于比较的其它路由算法。     

Testbed results of an opportunistic routing for multi-robot wireless networks

Opportunistic routing is a candidate for multihop wireless routing where the network topology and radio channels vary rapidly. However, there are not many opportunistic routing algorithms that can be implemented in a real multihop wireless network while exploiting the node mobility. It motivates us to implement an opportunistic routing, random basketball routing (BR), in a real multi-robot network to see if it can enhance the capacity of the multihop network as mobility increases. For implementation purposes, we added some features, such as destination RSSI measuring, a loop-free procedure and distributed relay probability updating, to the original BR. We carried out the experiments on a real multi-robot network and compared BR with AODV combined with CSMA/CA (routing + MAC protocol). We considered both static and dynamic scenarios. Our experiments are encouraging in that BR outperforms AODV + CSMA/CA, particularly in dynamic cases; the throughput of BR is 6.6 times higher than that of AODV + CSMA/CA. BR with dynamic networks shows 1.4 times higher throughput performance than BR with static networks. We investigate the performance of BR in the large-scale network using NS-2 simulation. We verify the effect of node density, speed, destination beacon signal and loop-free procedure. According to the large-scale simulation, the end-to-end throughput grows with the node speed.     

基于连通度的Ad hoc网络路由协议研究与仿真*

对Ad hoc网络各种路由协议进行仿真评估,分析它们在不同约束条件下不同度量的相对性能,是了解与学习路由协议性能的重要手段.目前的度量标准主要集中在吞吐量、延时、抖动、丢包率等QoS因子或路由负载、寻路时间等外部特性上,还没有以Ad hoc网络系统本身的连通度作为度量标准进行仿真,评价各种路由协议在不同试验条件下对于同一网络系统连通度的影响的相关研究.基于能量模型、节点密度、停留时间及移动速率四种约束条件对MANET提出的四种路由协议进行了关于网络连通度的仿真与评估,给出了这方面的初步结论.     

Spray and forward:Efficient routing based on the Markov location prediction model for DTNs

Typical delay tolerant networks(DTNs)often suffer from long and variable delays,frequent connectivity disruptions,and high bit error rates.In DTNs,the design of an efficient routing algorithm is one of the key issues.The existing methods improve the accessibility probability of the data transmission by transmitting many copies of the packet to the network,but they may cause a high network overhead.To address the tradeoff between a successful delivery ratio and the network overhead,we propose a DTN routing algorithm based on the Markov location prediction model,called the spray and forward routing algorithm(SFR).Based on historical information of the nodes,the algorithm uses the second-order Markov forecasting mechanism to predict the location of the destination node,and then forwards the data by greedy routing,which reduces the copies of packets by spraying the packets in a particular direction.In contrast to a fixed mode where a successful-delivery ratio and routing overhead are contradictory,a hybrid strategy with multi-copy forwarding is able to reduce the copies of the packets efficiently and at the same time maintain an acceptable successful-delivery ratio.The simulation results show that the proposed SFR is efficient enough to provide better network performance than the spray and wait routing algorithm,in scenarios with sparse node density and fast mobility of the nodes.     

一种路点受限的移动传感器网络移动模型

提出了一种基于随机路点移动模型的路点受限移动模型。在模型设计中,对节点的路点选择和暂停时间进行了设置,从而保持节点移动的规律性,满足特定场景的需要。利用仿真工具模拟模型的节点移动轨迹与其它移动模型进行比较,并从路由协议方面进行评估。仿真结果证明:该模型对集体搜索等特定场景具有较好的适用性。     

OPNET-based modeling and simulation of mobile Zigbee sensor networks

Modeling and simulation can help to validate and evaluate the performance of wireless sensor networks (WSNs) within specific applications. In order to resolve the issue of the restriction on node mobility in existing Zigbee WSN simulation models, this paper proposes a Zigbee compliant new simulation model using the OPNET simulator. Based on the Zigbee MAC layer model in OPNET Modeler, we develop a network layer model and propose an improved AODV routing algorithm to support node mobility, both of which are compatible with Zigbee protocols. We further present in details the structure of the network layer process model and the implementation procedures of its kernel functions. Comprehensive performance comparisons are performed between the proposed model and the Zigbee model in OPNET standard libraries. In order to evaluate the effectiveness of the proposed model in the aspect of node mobility support, time intervals between route failure occurrence and route recovery are measured as well. The experimental results show that the proposed simulation model achieves better performance, compared to the original one. In addition, when node mobility causes routing failures, alternative routes can be established quickly by the proposed model.     

车联网城市交通移动多场景建模仿真及分析

本文针对车载自组织网络环境中的城市交通车辆移动应用场景进行了分析,在VanetMobiSim交通仿真器和NS-2网络仿真器协同仿真环境中,对城市智能交通中的两类典型应用场景交叉路口和双向快速四车道进行了模型构建,同时在这两类应用场景中对AODV和DSDV路由协议进行了仿真和分析.通过端到端时延、抖动率、丢包率和控制包开销四个评价指标对比不同协议在同一场景下的表现效果.此外,针对AODV协议,分析了车辆速度、车辆密度、最大联机数和单位时间内发送封包数等环境因子对协议通信效果的影响.仿真结果表明,选取合适的移动场景模型有助于客观评价协议性能,不同的协议对不同的场景的表现性和适应性不同.DSDV应用于简单稳定的移动场景时表现较优,而AODV面对复杂多变的移动场景时有更好的适应性,且AODV协议受网络拓扑复杂程度和结构变化频率影响较大.     

An encounter-based multicast scheme for disruption tolerant networks

Some ad hoc network scenarios are characterized by frequent partitions and intermittent connectivity. Hence, existing ad hoc routing schemes that assume that an end-to-end path exists from a source to a destination do not work in such challenging environment. A store-and-forward network architecture known as the disruption tolerant network (DTN) has been designed for such challenging network environments. Several unicast and multicast routing schemes have been designed for DTNs. However, the existing multicast routing schemes assume a route discovery process that is similar to the existing ad hoc network routing approach. Thus, in this paper, we design an encounter-based multicast routing (EBMR) scheme for DTNs which uses fewer hops for message delivery. We first describe how the EBMR scheme works and then present an analytical framework to estimate the delivery performance of the EBMR scheme. Next, we present some comparisons of the analytical and simulation results to show that our analytical framework provides delivery performance estimates that match closely the observed simulation results. Last but not least, we present simulation results to study the delivery performance of EBMR in different scenarios, e.g. different mobility models, different multicast group size, different number of multicast groups and different node speed. We also compare the performance of the EBMR scheme with other DTN multicast strategies. Our simulation results indicate that the EBMR scheme can achieve higher delivery ratio while maintaining high data transmission efficiency compared to other multicast strategies.     

基于最近社交圈的社交时延容忍网络路由策略

无稳定拓扑使时延容忍网络(delay tolerant networks,DTN)路由协议主要通过增加冗余数据包副本提高路由性能.社交网络是DTN的一种典型应用场景,但由于其网络规模相对较大,当网络负载高时,通常的DTN路由不能有效控制数据包副本的数量,从而产生大量丢包导致性能下降.借鉴MANET网络中利用分簇结构控制网络冗余路由数据包的思想,通过分析社交网络中节点的移动模型,定义了在社交关系的约束下,聚合移动规律相近的节点构成最近社交圈的节点簇组成策略.提出了一种基于该分簇结构的分为簇外喷射、簇间转发和簇内传染3个阶段的社交时延网络路由协议.实验证明,这种基于最近社交圈分簇结构的路由能有效地控制冗余数据包副本的产生,并在高网络负载的情况下仍然能够达到较好的性能.