VANETs车联智能网络的紧急消息分发策略研究

围绕城市道路的二维车联网场景,考虑车联网环境内不同车辆节点、邻居节点链路的快速变动性,基于现有车联网广播路由协议、路由ENFLOOD广播策略(Extra Nodes Flood,ENFLOOD)等网络通信方式,由车联网内的每个车辆节点周期性发送HELLO紧急消息的数据报文,其他车辆节点采用自动通告方法主动获取路由协议邻居列表的其他车辆节点信息,每个车辆节点并根据上一跳节点广播规则,决定是否转发邻居节点的广播报文,同时针对车联网接入节点的稠密程度,由车辆节点主动计算自身的覆盖权值、设定合适的权值阈值参数,来调整广播报文的传递策略、传输速率。仿真实验表明,ENFLOOD广播策略在紧急消息转发数、广播时延等方面明显优于其他路由协议的广播策略。

Leveraging Augmented Reality,Semantic-Segmentation,and VANETs for Enhanced Driver’s Safety Assistance

Overtaking is a crucial maneuver in road transportation that requires a clear view of the road ahead.However,limited visibility of ahead vehicles can often make it challenging for drivers to assess the safety of overtaking maneuvers,leading to accidents and fatalities.In this paper,we consider atrous convolution,a powerful tool for explicitly adjusting the field-of-view of a filter as well as controlling the resolution of feature responses generated by Deep Convolutional Neural Networks in the context of semantic image segmentation.This article explores the potential of seeing-through vehicles as a solution to enhance overtaking safety.See-through vehicles leverage advanced technologies such as cameras,sensors,and displays to provide drivers with a real-time view of the vehicle ahead,including the areas hidden from their direct line of sight.To address the problems of safe passing and occlusion by huge vehicles,we designed a see-through vehicle system in this study,we employed a windshield display in the back car together with cameras in both cars.The server within the back car was used to segment the car,and the segmented portion of the car displayed the video from the front car.Our see-through system improves the driver’s field of vision and helps him change lanes,cross a large car that is blocking their view,and safely overtake other vehicles.Our network was trained and tested on the Cityscape dataset using semantic segmentation.This transparent technique will instruct the driver on the concealed traffic situation that the front vehicle has obscured.For our findings,we have achieved 97.1% F1-score.The article also discusses the challenges and opportunities of implementing see-through vehicles in real-world scenarios,including technical,regulatory,and user acceptance factors.

基于车辆运动轨迹的VANETs位置验证

正确的位置信息在维护VANETs的正常运行扮演着重要的角色,恶意节点的位置欺骗将严重影响VANETs诸多应用。通过对节点的位置验证以检测节点的位置欺骗是VANETs重要的研究领域。针对VANETs中车辆移动的相对速度较高,网络拓扑结构频繁变化,传统WSN和MANET中的位置验证方案不再适用于VANETs,提出基于车辆的运动轨迹位置验证方案,采用最小二乘法对车辆进行连续定位跟踪,并绘制其行驶路线,与邻居车辆的行驶路线、速度相比较,计算其吻合度,检测位置欺骗。仿真结果表明,该方案有较低的漏警率和虚警率,当恶意节点的欺骗距离达到30 m时,漏警率和虚警率接近于0。

基于VANETs下的决策树多副本机会路由协议

在车载自组织网络(vehicular Ad hoc networks,VANETs)中,当节点缓存和消息副本数目被限制的情况下,如何合理地选择车载网络的路由节点是实现VANETs高效转发和投递的关键问题。为此提出了一种基于学习方法的决策树理论的多副本VANETs机会路由协议(D-Tree)。D-Tree将VANETs中节点间的传输和连接因素看做多个属性的集合,并与决策树方法得到一个消息转发规则,同时结合多副本路由与机会路由的"存储─携带─转发"优势进行消息投递。真实数据集上的实验结果表明,在场景密集的情况下,D-Tree相比于Bubble和S&W路由算法投递成功率提高了近10%,同时在投递延迟等方面也具有明显优势。

基于区域分组的城市VANETs的安全信息广播协议

为提高城市车辆自组织网络(VANETs)安全信息广播的有效性,提出了一种基于区域分组的安全信息广播协议(AGBP)。该协议采用正三角形法或正六边形法给中继节点每跳覆盖的区域平均分割,节点按照所在的区域分组。正三角形和正六边形顶点为中继节点的最佳位置,每一组内所有的节点根据自己和中继节点最佳位置的距离计算等待时延,由等待时延决定每一组内的中继节点并转发信息,因此信息可以同时沿着多个方向多条路转发。与传统的沿着一条道路转发信息的广播协议相比,该协议能够避免因分组不当造成信息冗余和碰撞,致使信息的传输效率下降,从而能够降低网络开销、链路时延和转发节点率,提高覆盖率。

基于3G的VANETs数据传输的技术研究

在车载自组织VANETs中,为解决车辆间通信数据传输不流畅的问题。提出采用3G辅助VANETs的数据传输技术。在无法利用VANETs多跳通信传输数据时,启动3G传输,将此方案命名为3GDD,首先建立数据传输率和数据传输时延的效用函数,利用3G辅助VANETs数据传输实现最大化效用;其次,为了避开优化问题的复杂性,将原始的优化问题变换成整数线性规范问题ILP(integer linear programming problem);最后通过解决ILP,在不同时刻分配3G预算,并选择最不可能通过VANETs传输的数据用于3G传输。实验结果表明,提出的3GDD与同类的方案相比具有良好的性能。

人工蜂与K-means混合算法在VANETs的应用

针对车载自组织网(Vehicular Ad Hoc Networks,VANETs)拓扑结构经常变化导致通信链路容易断裂而通信质量不可靠的问题,将人工蜂与K-means混合算法应用在VANETs中。在成簇阶段,该混合算法利用人工蜂算法较强的全局搜索能力确定初始聚类中心,代替传统的K-means对初始聚类中心的选择,这样就消除了K-means对随机初始聚类中心的依赖。在簇头选取阶段,类内具有最小的速度方差以及到其他节点最小平均距离的车辆节点被选择为簇头。在簇的维护阶段,当最优节点即簇头有变化时,次优节点被选为临时簇头,直至更新为最优节点的簇头信息。为测试该混合算法的性能,将其和PSO与K-means混合算法、经典Kmeans算法进行实验对比,结果表明,该混合算法能够更加稳定VANETs通信链路,具有更高成簇质量和更高通信质量。

一种基于伪距离的VANETs的节点位置安全算法

由于VANETs的车辆的快速移动,基于地理位置的路由协议广泛应用于VANETs。车辆周期广播位置信息来建立路由,导致车辆的位置信息容易遭受泄露。为此,提出基于伪距离的位置隐私保护(false-based location pri-vacy protection,FLPP)路由协议。在FLPP中,通过转发节点到目标节点的伪距离而不是真实距离来建立路由,通过巧妙地设置节点的定时器来保护节点的位置信息,同时采用别名策略隐藏身份信息。仿真结果表明,FLPP具有较高的数据传输率以及位置隐私保护力度。

基于启发式算法的VANETs性能优化研究

车载自组织网络(VANETs)是驾驶员在路上进行沟通和确保安全的革命性飞跃。针对VANETs的数据包传输问题,提出了一种改进的启发式算法,该算法考虑了干扰因素,基于碰撞丢包率,SINR和队列溢出,根据网络和交通情况优化传输功率和竞争窗尺寸。用Vanet Mobi Sim交通仿真软件构建VAENTs网络场景。结果表明,与传统的启发式算法比较,改进的启发式算法在端到端延迟影响较小的情况下,能够有效地降低数据包丢包率,提高数据包传递率和可靠性,进而提高吞吐量、降低端到端延迟和提高数据包传输的可靠性。

基于混合信息和冗余传输的VANETs路由协议

车辆节点的快速移动导致网络拓扑频繁变化和无线链路质量不稳定,这为车载自组织网络(vehicular ad-hoc networks,VANETs)路由协议的研究带来挑战。为了应对这些挑战,文章提出了基于混合信息和冗余传输的VANETs路由协议。针对城市环境下道路的特点抽象出一个以交叉路口为顶点,以路段为边的无向图,并依托部署在路口的固定节点收集交通和网络的实时信息为每条边赋予权值,然后运用Dijkstra算法计算任意2个交叉路口间的最短路径;针对路段内的数据传输,综合考虑距离、速度和链路可靠性等因素来选择下一跳节点,并通过冗余传输技术提高数据传输的成功率。通过仿真实验对比现有协议,验证了该路由协议在性能上的优越性。

基于路口的VANETs路由道路连通性预测方法综述

车辆自组织网络(VANETs)路由中,基于路口的地理路由协议能很好的适应城市VANETs的环境,其中道路连通性预测在路由协议中具有决定性的作用,本文分析并比较了经典VANETs路由协议中采取的各种道路连通性预测方法的工作机制和优缺点,最后进行总结和展望。

VANETs中基于群签名的假名交换位置隐私保护方案

针对车载自组织网络(vehicular ad-hoc networks, VANETs)中增强道路安全的应用频繁收集车辆位置数据导致的位置隐私泄露,以及现有位置隐私保护方案假名混淆程度较低、计算开销较大等不足,采用群签名技术,通过选取与自身行驶状态最相似的车辆进行假名交换,提高车辆假名的混淆程度,降低攻击者成功链接车辆新旧假名的概率,有效阻断攻击者的跟踪,保护车辆用户的真实位置。仿真结果表明,所提方案能有效保护车辆的位置隐私,同时降低了权威机构的计算开销和攻击者的跟踪成功率。

基于VANETs的交叉口车辆碰撞预警系统

针对道路交叉口处交通流复杂、事故频发,及现有事故预警系统成本较高的问题,设计了一种基于VANETs的交叉口车辆碰撞预警系统。首先,结合交叉口场景搭建了碰撞预警系统的体系架构,设计了系统的工作流程;然后,给出了车辆碰撞的检测方案和不同危险等级的消息发布方案;最后,在分析了不同碰撞预警系统影响因素的基础上,从影响因素和系统有效性两方面,对系统的性能进行了仿真测试。测试结果表明,系统能够较为准确的完成事故检测和预警。

Performance of beacon safety message dissemination in Vehicular Ad hoc NETworks (VANETs)

Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications.

A Fair Blind Signature Scheme to Revoke Malicious Vehicles in VANETs

With the rapid development of IoT(Internet of Things),VANETs(Vehicular Ad-Hoc Networks)have become an attractive ad-hoc network that brings convenience into people’s lives.Vehicles can be informed of the position,direction,speed and other real-time information of nearby vehicles to avoid traffic jams and accidents.However,VANET environments could be dangerous in the absence of security protection.Because of the openness and self-organization of VANETs,there are plenty of malicious pathways.To guarantee vehicle security,the research aims to provide an effective VANET security mechanism that can track malicious vehicles as necessary.Therefore,this work focuses on malicious vehicles and proposes an anonymous authentication scheme in VANETs based on the fair blind signature to protect vehicle security.

A Greedy Traffic Light and Queue Aware Routing Protocol for Urban VANETs

Vehicular Ad-hoc Networks(VANETs) require reliable data dissemination for time-sensitive public safety applications. An efficient routing protocol plays a vital role to achieve satisfactory network performance. It is well known that routing is a challenging problem in VANETs due to the fast-changing network typology caused by high mobility at both ends of transmission. Moreover, under urban environment, there are two non-negligible factors in routing protocol design, the non-uniform vehicle distribution caused by traffic lights, and the network congestion due to high traffic demand in rush hours. In this paper, we propose a greedy traffic light and queue aware routing protocol(GTLQR) which jointly considers the street connectivity, channel quality, relative distance, and queuing delay to alleviate the packet loss caused by vehicle clustering at the intersection and balance the traffic load among vehicles. Through performance evaluation, we show that our proposed protocol outperforms both TLRC and GLSR-L in terms of packet delivery ratio and end-to-end delay.

A statistical approach for enhancing security in VANETs with efficient rogue node detection using fog computing

Rogue nodes broadcasting false information in beacon messages may lead to catastrophic consequences in Vehicular Ad Hoc Networks(VANETs).Previous researchers used cryptography,trust scores,or past vehicle data to detect rogue nodes;however,these methods suffer from high processing delay,overhead,and False–Positive Rate(FPR).We propose herein Greenshield's traffic model–based fog computing scheme called Fog–based Rogue Node Detection(F–RouND),which dynamically utilizes the On–Board Units(OBUs)of all vehicles in the region for rogue node detection.We aim to reduce the data processing delays and FPR in detecting rogue nodes at high vehicle densities.The performance of the F–RouND framework was evaluated via simulations.Results show that the F–RouND framework ensures 45%lower processing delays,12%lower overhead,and 36%lower FPR at the urban scenario than the existing rogue node detection schemes even when the number of rogue nodes increases by up to 40%in the region.

基于代理重加密的VANETs中安全位置服务

提供车辆位置服务是车载网络(vehicle ad hoc networks,VANETs)的重要应用。而用户(车辆行驶人)希望他的位置信息只能暴露于他授权的消息发送者,这就涉及位置隐私问题。提出基于代理重加密的安全位置服务算法(proxy re-encryption-based secure location service,PRESLS)。PRESLS算法采用中心管理模式,并由交通信息港(traffic information center,TIC)扮演中心管理者,且由TIC维持车辆轨迹数据,同时,TIC作为车辆与路边设施单元的中介,使得路边设施单元能安全地共享轨迹数据。利用代理重加密算法,使得轨迹数据不仅对未授权的实体,而且对TIC也是隐匿的,进而实现了位置数据所保密性。通过安全性能分析和基于地图位置服务(map-based location service,MBLS)的实验评估PRESLS算法的性能。分析表明,车辆能够控制仅由车辆允可的路边设施单元才能接入车辆的轨迹数据。同时,基于MBLS的实验数据表明,PRESLS算法在维持车辆轨迹数据安全的同时,并没有降低位置查询成功率。

Cross-Layer Safety-Critical Broadcast Service Architecture Integrating VANETs with 3G Networks in loT Environments

As Vehicle Ad Hoc Networks (VANETs) is part of the applications of the Internet of Things (IoT), and Vehicles in VANETs periodically broadcast the beacon message for status advertisement to provide public safety, the impacts of the network parameters on the reliability of broadcast messages are investigated and discussed; meanwhile, a cross-layer safety-critical broadcast service architecture is proposed to obtain an optimized set of packet loss rate and delay based on the Neural Networks (NN) and Back Propagation (BP) algorithm to dynamically adjust the transmission rate-power pairs. Simulation results illustrate that the proposed mechanism can effectively improve the reliability performance while maintaining the fairness among vehicles.

Performance Comparison between Delay-Tolerant and Non-Delay-Tolerant Position-Based Routing Protocols in VANETs

Vehicular ad hoc networks (VANETs) are a new emerging recently developed advanced technology that allows a wide group of applications related to providing more safety on roads, more convenience for passengers, self-driven vehicles, and intelligent transportation systems (ITS). There are various routing protocol categories used in VANETs, like unicast, multicast, and broadcast protocols. In unicast position-based protocols, the routing decisions are based on the geographic position of the vehicles. This does not require establishment or maintenance of routes but needs location services to determine the position of the destination. Non-delay-tolerant network protocols (non-DTN), also identified as minimum delay protocols, are aimed at minimizing the delivery time of the information. Delay-tolerant protocols (DTN) are used in a variety of operating environments, including those that are subject to failures and interruptions and those with high delay, such as VANETs. This paper discusses the comparison between non-DTN and DTN routing protocols belonging to the unicast delay-tolerant position-based category. The comparison was conducted using the NS2 simulator, and the simulations of three non-DTN routing protocols and three DTN routing protocols were recorded. Simulation results show that the DTN routing protocols outperform in delivery ratio compared to the non-DTN routing protocols, but they lead to more average delay due to buffering, the processing algorithm, and priority calculation. In conclusion, non-DTN protocols are more suitable for the city environment since the distance between nodes is relatively smaller and the variations in the network topology are slower than they are on highways. On the other hand, DTN protocols are more suitable for highways due to the buffering of packets until a clear route to destination is available.