AD HOC技术在无线传感器网络中的应用

在介绍两种典型的移动自组织网络中路由算法的基础上，讨论将移动自组织网络路由算法直接运用于无线传感器网络的可行性。从路由性能以及能量的角度进行分析，结果显示，传感器网络以数据为中心的特点约束了移动自组织网络路由算法的直接应用。进一步提出了基于聚类算法的路由，将聚类算法作为移动自组织网络应用的桥梁。仿真结果也显示了基于聚类算法的路由的优越性。     

基于社会环境的一种优化Prophet延迟容忍网络路由算法

在移动智能终端普及的今天,延迟容忍网络作为数据的补充传输方案具有重要的意义。在社会环境中,节点移动规律具有明显周期性,Prophet路由算法在该类场景中效果较好。因此文章提出了一种基于加强传统概率的路由算法,其在工作日模型下对E Prophet算法进行了仿真实验。实验结果表明,所提出的E Prophet算法在该场景下优于传统的Prophet算法。     

基于博弈的协作路由算法

协作虚拟多输入多输出（VMIMO）传输是一种有效的无线传输性能优化技术。将物理层协作VMIMO技术和网络层路由选择技术相结合,设计跨层VMIMO路由选择方案可以利用VMIMO的分集增益,显著地降低网络传输能耗。如何设计VMIMO协作路由协议抵抗无线网络的自私节点和欺骗行为,保证高数据转发率和低传输能耗成为路由设计中的重大挑战。为了提高自私网络的VMIMO路由性能,提出了一种基于重复路由博弈的VMIMO协作路由算法。该算法将网络划分成多个Group、Group间使用VMIMO传输数据。将Group间路由选择过程建模为重复路由博弈过程。为了提高数据转发的成功率,提出适用度函数评估节点参与数据分组转发的信誉。以此为基础,提出基于适用度的路由选择子算法和路由转发子算法。理论证明所提重复路由博弈可达到帕累托最优。仿真实验结果表明本算法可以促进自私节点相互合作,可获得较高的数据转发率,较好地减少数据传输时延以及能量消耗。     

一种面向移动Ad Hoc网络DSR协议的改进泛洪算法

在移动自组织网络中,基于移动节点地理位置辅助信息,提出了一种新的泛洪算法——位置辅助泛洪改进算法（ILFA）,ILFA通过节点位置信息重传广播分组并有效控制网络流量。此外,将ILFA应用于经典MANET源路由（dynamic source routing,DSR）协议中,通过限定请求区域和期望区域等限制路由发现的有效范围,进而通过设置提名广播重传邻居列表限定路由请求分组重传范围,有效减小DSR路由寻路分组的传播次数。仿真结果证明,和传统泛洪方案相比,ILFA能够有效减小DSR路由协议的路由开销并提升MANET吞吐量。     

机会网络中基于摆渡节点与簇节点相互协作的路由机制

机会网络是一种不需要在源节点和目的节点之间存在完整路径,利用节点移动带来的相遇机会实现网络通信的延迟容忍自组织网络,它以“存储-携带-处理-转发”的模式进行.为实现互不相交簇间的信息传输,本文设计了一种带阈值的簇移动模型CMMT,并提出了一种基于摆渡（Ferry）节点与簇节点协作的路由算法（CBSW）.该算法减少了冗余的通信和存储开销,以及在Spray阶段簇节点没有遇到目的节点或摆渡节点,进入Wait阶段携带消息的节点采用直接分发方式只向目的节点传输等问题.仿真实验表明,CBSW算法能够增加传输成功率,减少网络开销和传输延迟.     

基于社会属性的PSN消息路由算法

在PSN（pocket switched network）中实现数据传输成功率与传输延迟的有效平衡是当前有待解决的问题。提出一种基于社会属性的PSN路由算法——BridgingCom算法,该算法使用带有衰退机制的局部社区识别方法,引入桥接中心度（bridging centrality）作为中继节点的选择依据,将社会网络中节点重要性与移动社会网络的特征相结合,考虑了节点社区关系和节点活跃度对路由算法的影响。实验表明,该算法与现有经典算法相比能够获得较高的传输效率和较低的传输延迟。     

BPDSR:基于Chord算法的MANET双向路由模型

为提高移动自组织网络(mobile ad hoc network,MANET)路由查询效率,通过对P2P(peer-to-peer)网络与MANET的交叉研究,在DSR协议基础上引入Chord算法,提出双向路由模型BPDSR.BPDSR双向路由发现算法和路由资源共享算法,降低了查询复杂度,减少了路由失效和绕路问题.通过BPDSR算法性能分析和NS--2仿真实验表明,BPDSR路由模型的路由效率明显提高.     

基于移动预测的VANETs广播路由协议

针对车载自组织网络（VANETs）的通信特点,基于移动预测的广播路由协议（MPBP）可以有效的提高网络的性能。MPBP的核心思想是根据车辆的位置信息和相对速度来预测节点和的链的路生存期,即连接的持续时间,由此来选择可靠高效的下一跳,即为选择了最稳定的路由路径,由此提高路由性能。仿真结果表明,无论在低速或高速场景下,MPBP协议能够实现可靠的数据递交率和较小的数据传榆时延。     

机会网络视频数据的分块渐进传输新方法

各类移动多媒体智能终端的普及使得设备间的自组织机会通信成为国际研究热点,而移动节点间的机会通信方式已无法满足日益增长的多媒体传输需求.面向机会组网与视频内容传输问题,基于机会网络实际通信能力计算,提出了一种视频分块大小最优化计算方法,使机会网络通信能力得到最大化利用;提出了一种能够实现渐进式接收视频分块的路由调度算法,建立分块紧缺度模型,引导分块在目标节点趋于均匀分布.实验结果表明,该方法能在恶劣通信环境下实现高效的视频数据预览与传输,可为相关视频内容的无线移动传输提供支持.     

车载时延容忍网络路由协议研究

基于移动模型相似度评价机制（MMSE, movement model similarity evaluation scheme）,提出一种面向移动范围转发动态多副本车载时延容忍网络路由协议（MROFDM, movement range oriented forwarding and dynamic multi-copies routing protocol）。该协议利用移动模型间的相似度和车辆的本地实时信息,将数据向目的节点的移动范围转发,同时采用副本均衡策略,动态调整不同类型数据分组的副本数目。通过仿真实验对比现有多副本协议,验证了MROFDM在性能上的优越性以及在不同比例移动模型下的适应性。     

Performance Analysis with Traffic Accident for Cooperative Active Safety Driving in VANET/ITS

Recently, by using vehicle-to-vehicle and vehicle-to-infrastructure communications for VANET/ITS, the cooperative active safety driving (ASD) providing vehicular traffic information sharing among vehicles significantly prevents accidents. Clearly, the performance analysis of ASD becomes difficult because of high vehicle mobility, diverse road topologies, and high wireless interference. An inaccurate analysis of packet connectivity probability significantly affects and degrades the VANET/ITS performance. Especially, most of related studies seldom concern the impact factors of vehicular accidents for the performance analyses of VANET/ITS. Thus, this paper proposes a two-phase approach to model a distributed VANET/ITS network with considering accidents happening on roads and to analyze the connectivity probability. Phase 1 proposes a reliable packet routing and then analyzes an analytical model of packet connectivity. Moreover, the analysis is extended to the cases with and without exhibiting transportation accidents. In phase 2, by applying the analysis results of phase 1 to phase 2, an adaptive vehicle routing, namely adaptive vehicle routing (AVR), is proposed for accomplishing dynamic vehicular navigation, in which the cost of a road link is defined in terms of several critical factors: traffic density, vehicle velocity, road class, etc. Finally, the path with the least path cost is selected as the optimal vehicle routing path. Numerical results demonstrate that the analytical packet connectivity probability and packet delay are close to that of simulations. The yielded supreme features justify the analytical model. In evaluations, the proposed approach outperforms the compared approaches in packet connectivity probability, average travel time, average exhausted gasoline. However, the proposed approach may lead to a longer travel distance because it enables the navigated vehicle to avoid traversing via the roads with a higher traffic density.     

AGP: an anchor-geography based routing protocol with mobility prediction for VANET in city scenarios

Vehicular ad-hoc networks (VANET) routing is a key technology for efficient data forwarding in intelligent transport system (ITS). A novel routing scheme, Anchor-Geography based routing protocol (AGP), designed specifically for VANET communication in city environment is proposed in this paper. The reactive broadcasting is used for both getting destination location and routing discovery. Connectivity status and load balancing is considered in routing decision. In addition, the map information and the kinematics parameters are used for the vehicle trajectory prediction. Such a mobility prediction can provide a solution for the situation in which the destination moves away from the location in the routing discovery procedure. In simulation, VanetMobiSim is used as the traffic generator for more realistic traffic scenarios in VANETs than simple mobility model definition. Simulation results in NS2 show that AGP protocol gains obvious improvement in packet delivery ratio and average hops.     

QoS-aware multi-path video streaming for urban VANETs using ACO algorithm

Drivers can be provided with several beneficial services associated with video streaming in a vehicular ad-hoc network (VANET). Given the dynamic topology and high mobility of VANETs, a single path cannot support the required quality of service (QoS). To maximize global QoS metrics, a two-path model is proposed based on a disjoint algorithm to forward sub-streams over diverse paths from the transmitter to the receiver vehicle. In this solution, the video information spread in separate paths is categorized based on their priority. For this purpose, the protocol for transmitting each kind of video data should be selected cautiously. The present study aims to propose an ant colony optimization-based technique to establish the primary and secondary paths and enhance the QoS of routing paths. To achieve this goal, the QoS routing issue is formulated mathematically as a problem of constrained optimization. Moreover, to achieve high-quality video streaming, inter-frames are transmitted over the user datagram protocol and intra-frames are transmitted over the transmission control protocol (TCP). TCP transmission delays are also minimized using a TCP-ETX algorithm for selecting appropriate paths. According to the simulation results, the proposed two-path solution can be used to improve the quality of video streaming and to enhance the performance in terms of end-to-end delay, packet delivery ratio, and overhead. In this way, the proposed method can outperform several prominent routing algorithms such as adaptive QoS-based routing for VANETs, geographic source routing (GSR), intersection-based geographical routing protocol, and efficient GSR.

     

Location prediction algorithm for a nonlinear vehicular movement in VANET using extended Kalman filter

Vehicular ad-hoc network (VANET) is an essential component of the intelligent transportation system, that facilitates the road transportation by giving a prior alert on traffic condition, collision detection warning, automatic parking and cruise control using vehicle to vehicle (V2V) and vehicle to roadside unit (V2R) communication. The accuracy of location prediction of the vehicle is a prime concern in VANET which enhances the application performance such as automatic parking, cooperative driving, routing etc. to give some examples. Generally, in a developed country, vehicle speed varies between 0 and 60 km/h in a city due to traffic rules, driving skills and traffic density. Likewise, the movement of the vehicle with steady speed is highly impractical. Subsequently, the relationship between time and speed to reach the destination is nonlinear. With reference to the previous work on location prediction in VANET, nonlinear movement of the vehicle was not considered. Thus, a location prediction algorithm should be designed by considering nonlinear movement. This paper proposes a location prediction algorithm for a nonlinear vehicular movement using extended Kalman filter (EKF). EKF is more appropriate contrasted with the Kalman filter (KF), as it is designed to work with the nonlinear system. The proposed prediction algorithm performance is measured with the real and model based mobility traces for the city and highway scenarios. Also, EKF based prediction performance is compared with KF based prediction on average Euclidean distance error (AEDE), distance error (DE), root mean square error (RMSE) and velocity error (VE).     

一种基于区域广播的VANET机会路由协议

对VANET网络中现有的路由协议进行了系统的分析和研究,提出了一种基于区域广播的VANET机会路由协议。基于安全消息在网络割裂情况下的传播需求,新协议结合地理信息和机会转发算法,提出了不同于点对点的新的基于区域广播的消息传播模式,以实现安全消息在稀疏车辆环境下的有效传播。理论分析和仿真实验表明,该协议相比传统路由协议具有更优异的网络性能和可靠性。     

Trade-off between accuracy,cost, and QoS using a beacon-on-demand strategy and Kalman filtering over a VANET

Vehicular Ad-hoc Networks (VANETs) have been suggested as an active and powerful field of research to mitigate environmental problems and challenges. The main challenge in a VANET is to ensure routing with a good Quality of Service (QoS). The Greedy Perimeter Stateless Routing (GPSR) protocol is one of the most promising position-based routing mechanisms used to overcome this challenge. Its effectiveness depends entirely on the information on a node's mobility and the precision of this information. By broadcasting periodic beaconing within transmission boundary ranges, GPSR can manage neighbors' mobility information and maintain up-to-date lists of neighbours. Nevertheless, information on the position of a neighboring vehicle quickly becomes outdated, which negatively influences the efficiency of the routing. In order to monitor information mobility and to increase the QoS in this challenging area, position estimation needs to be considered.Thus, in this study, we examine the position estimation problem, and propose an improvement to the GPSR protocol, named KF-GPSR, where each vehicle estimates in real time the position of its neighbors using the Kalman filter algorithm. Indeed, by employing this strong estimation technique, it is possible to reduce considerably the frequency of exchanged beacon packets, while maintaining high position accuracy. For greater reliability, we also propose an extension to KF-GPSR, called BOD-KF-GPSR, that uses the “beacon-on-demand” process only if a node needs to rediscover its neighborhood. Simulation experiments using the network simulator NS-2 are presented to demonstrate the ability and usefulness of our two proposals. Here, we compare the proposed protocols against diverse common protocols: GPSR, AODV, DSR, and ZRP. The results show that BOD-KF-GPSR achieves a significant enhancement in terms of its packet delivery ratio, routing cost, normalized routing load, end-to-end delay, and throughput.     

SDR: A Stable Direction-Based Routing for Vehicular Ad Hoc Networks

A stable and reliable routing mechanism for vehicular ad hoc networks (VANETs) is an important step toward the provision of long data transmission applications, such as file sharing and music download. Traditional mobile ad hoc network (MANET) routing protocols are not suitable for VANET because the mobility model and environment of VANET are different from those of traditional MANET. To solve this problem, we proposed a new stable routing algorithm, called stable directional forward routing. The novelty of the proposed routing protocol is its combining direction broadcast and path duration prediction into ad hoc on-demand distance vector routing protocols, which including: (1) Nodes in VANET are grouped based on the position, only nodes in a given direction range participating in the route discovery process to reduce the frequency of flood requests, (2) Route selection is based on the link duration while not the hops or other metrics to increase the path duration, (3) Route discovery is executed before the path expiration in order to decrease the end to end delay. The performance of the new scheme is evaluated through extensive simulations with Qualnet. Simulation results indicate the benefits of the proposed routing strategy in terms of decreasing routing control packet, reducing the number of link-breakage events, improving the packet delivery ratio and decreasing the end-to-end delay.     

FGWSO‐TAR: Fractional glowworm swarm optimization for traffic aware routing in urban VANET

In mobile distributed applications, such as traffic alert dissemination, dynamic route planning, file sharing, and so on, vehicular ad hoc network (VANET) has emerged as a feasible solution in recent years. However, the performance of the VANET depends on the routing protocol in accord with the delay and throughput requirements. Many of the routing protocols have been extensively studied in the literature. Although there are exemptions, they escalate research challenges in traffic aware routing (TAR) protocol of VANET. This paper introduces the fractional glowworm swarm optimization (FGWSO) for the TAR protocol of VANET in an urban scenario that can identify the optimal path for the vehicle with less traffic density and delay time. The proposed FGWSO searches the optimal routing path based on the fitness function formulated in this paper. Fractional glowworm swarm optimization is the combination of the GWSO and fractional theory. Moreover, exponential weighted moving average is utilized to predict the traffic density and the speed of the vehicle, which is utilized as the major constraints in the fitness function of the optimization algorithm to find the optimal traffic aware path. Simulation of FGWSO shows the significant improvement with a minimal end‐to‐end delay of 6.6395 seconds and distance of 17.3962 m, respectively, in comparison with the other existing routing approaches. The simulation also validates the optimality of the proposed TAR protocol.     

VANET中路由协议分析

分析目前大多数VANET路由算法,将其归类为基于位置的贪婪路由算法、基于锚节点路由算法、基于街道集路由算法和基于簇路由算法,并着重于这些特点设计每类算法,通过NS2仿真实验对比和分析,为进一步的研究提出新的课题。     

RVCloud: a routing protocol for vehicular ad hoc network in city environment using cloud computing

Routing in Vehicular Ad hoc Network (VANET) is a challenging task due to high mobility of vehicles. In this paper, a RVCloud routing protocol is proposed for VANET to send the data efficiently to the destination vehicle using cloud computing technology. In this protocol, vehicle beacon information is send to the cloud storage through the Road Side Unit (RSU). As vehicles have less storage and computing facility, the information of all the vehicles moving in the city is maintained by the cloud. Source vehicle sends the data to the destination by sending the data to the nearby RSU. After receiving the data, RSU sends a request to the cloud for an optimal RSU information, that takes minimum packet forwarding delay to send the data to the destination. Cloud provides location service by providing destination location and optimal RSU information. Then RSU sends the data to the optimal RSU using internet. By using the internet facility, packet forwarding delay and link disruption problem are reduced. Simulation results show that, RVCloud performs better than VehiCloud, P-GEDIR, GyTAR, A-STAR, and GSR routing protocols.