智能交通自组网的设计与实现

提出了一种智能交通自组网的实现方案,该方案采用适应于车辆移动环境的IEEE 802.1 1p标准,改进车载自组网路由协议,并基于该网络架构实现车辆交通感知与全方位导航等应用.测试结果表明,基于该方案的智能交通自组网的网络性能满足车载通信的要求.     

基于排序的高效交通信息分发算法

提出了一种高效的基于车载自组网的实时交通信息分发算法--ETDAR算法.ETDAR算法中,所有的参与者根据本地信息确定交通信息报告的分发时机及每次广播的报告数,有效地利用了带宽并能很好地适应于各种密度的网络拓扑.算法通过对报告进行排序来解决带宽及节点存储量受限等问题.最后,提出了一种新的算法性能评估标准,并基于此评估标准,通过仿真实验将ETDAR算法与另一种泛洪方式的交通信息分发算法--Grassroots算法进行比较.实验结果显示,ETDAR算法的性能在不同的节点密度、网络带宽下均优于Grassroots算法.     

基于DAB技术的智能交通车载终端

基于数字音频广播(DAB)技术,文章提出了一种交通诱导信息广播系统和一种车载智能终端。交通诱导信息广播系统将高速发展的广播数字化技术与城市交通智能管理相结合,是集信息采编、信息发布、信息移动接收、交通实时导航、娱乐于一体的信息处理平台;车载智能终端基于DAB技术,是用于对车辆现代化管理的设备。交通诱导信息广播系统依托移动网络可以从服务车辆上获得全球定位系统(GPS)定位信息,从而监控和跟踪车辆;车载智能终端可以接收DAB信道的实时广播、动态路况、车辆的导航路径等信息。     

基于OMNET＋＋的VANET无线链路性能仿真

当今车辆运行环境更加复杂,双移动节点,无线链路带宽不稳定以及链路级丢包较多是车载自组网的显著特点之一,而车载自组网无线链路质量,对其网络上层协议的设计具有重要意义。这里分析无线电波在车载自组网中的传播特点,提出一种以无线信道传播模型为基础,通过OMNET＋＋来仿真车载自组网无线链路丢包率的方法。通过该方法可以方便、有效地仿真不同车辆运行环境下车载自组网的无线链路丢包率。     

新的基于变色龙的车载通信安全与隐私保护

在车载自组网（VANET）中许多服务和应用需要保护数据通信的安全,为提高驾驶的安全性和舒适性,一些与交通状况有关的信息就要被周期性地广播并分享给司机,如果用户的身份和信息没有隐私和安全的保证,攻击者就会通过收集和分析交通信息追踪他们感兴趣的车辆,因此,匿名消息身份验证是VANET中不可或缺的要求。另一方面,当车辆参与纠纷事件时,证书颁发机构能够恢复车辆的真实身份。为解决车载通信这一问题,郭等人在传统方案的基础上提出一种基于椭圆曲线的变色龙散列的隐私保护验证协议。虽然此方案较之前方案具有车辆身份可追踪性和高效率性,但分析表明此方案不满足匿名性。对郭等人的方案进行安全性分析并在此基础上做出改进。     

多信道车载网络带宽调制算法

针对固定带宽车载网络频谱利用率低的问题,将半定规划法应用于多信道车载自组网带宽调制问题中,提出了一种车载自组网信道带宽调制算法.该算法首先在有频谱竞争的网络中测量相邻车辆间的距离,以确定网络冲突图;然后通过半定规划松弛来协调频谱的争用,最后以此为基础根据链路负载采用比例压缩策略求得频谱调制方案.仿真分析表明,该算法适用于多信道车载自组网,在动态拓扑环境下表现出较好的性能.     

VANET中基于分布式的分簇的路由机制

车载自组网(VANET)是一种将高速移动车辆作为通信节点的自组网,动态的拓扑结构致使传统的自组网路由机制不再适用。为此,提出基于分布式的分簇路由机制(DCRM)。DCRM首先引用RTB/CTB握手策略,源节点利用RTB/CTB数据包,获取其一跳邻居的信息,然后源节点根据每两个邻近节点间的距离小于门限值的原则,以分布式方式对这些邻居节点进行簇划分。随后,将每个簇中选择一个离源节点最远的节点作为簇头,源节点将消息传输至簇头。接收消息后,簇头成了源节点,重复此过程直至消息传输至目的节点。仿真结果表明,提出的DCRM提高了消息传输效率、降低了消息传输时延。     

基于REST风格的混杂感知车载网信息服务设计

实时可靠地获得全面的车载感知服务信息是车载网络发展的"瓶颈"问题。混杂感知车载网(HSVN)兼有无线传感器网络(WSN)和车载自组网(VANET)的特点,为车载用户提供了大量车载信息,是车载网络的发展趋势。表述性状态转移(REST)架构统一了资源格式和交互形式,在服务器和客户端间进行无状态服务,有利于异构问题的解决。文章基于HSVN的信息服务特征,提出一种新型车载网络框架和服务模型,能提高车载感知信息的服务交互能力;基于REST架构理念,采用HSVN中信息服务资源设计方法,为异构网络下的信息交互系统提供一种轻量化的实现途径。     

浅谈无线通信技术在车联网中的应用

车联网是物联网在智能交通领域的典型应用,车联网中的核心关键技术是无线通信技术。无线通信技术决定了车辆的车内网、车际网和车载移动互联网等网络间大范围、大容量数据的交互、共享的实时性和有效性,是当前国内外技术演进的研究热点。随着工业化和信息化在国民生产领域的深度融合,信息化技术不断深入到工业化领域,车联网引导的智能交通越发成熟。     

基于车载自组网的匿名认证机制

车载自组网中,车辆在进行相互通信时需要对收到的信息进行合法性验证,但同时又不希望自己的身份被泄露,从而导致了安全与隐私保护之间的问题。匿名认证是车载自组网中安全和身份隐私保护的关键机制,本文对现有的匿名认证方案进行了分类对比,分析了各个方案的优缺点。     

Toward a secure batch verification with group testing for VANET

Vehicular Ad-Hoc Network (VANET) is an application of Ad-Hoc Network, which can significantly improve the efficiency of transportation systems. The authentication of information is particularly important in the VANET system, because of its significant impact, and the transportation systems may be paralyzed as a result of receiving the wrong traffic information. Hence, a lot of schemes have been proposed to verify the information of VANET. However, most of currently known schemes verify the information on a one by one basis. In real situation, the large amount of traffic flow will generate a lot of information at the same time. If the authentication method is authenticating one by one, it is bound to lead to information delays, and the system will have difficulty to achieve real-time performance. Therefore, we shall propose an improved authentication of the batch scheme based on bilinear pairing to make VANET more secure, efficient, and more suitable for practical use.     

A Framework For Handling Local Broadcast Storm Using Probabilistic Data Aggregation In VANET

Data aggregation is used to combine correlated data items from different vehicles before redistributing to other vehicles in the vehicular ad hoc networks (VANET). The number of retransmissions and the communication overhead can be reduced considerably by using aggregation. It is a prerequisite for applications that require periodic dissemination of information into a large region so that, drivers can be informed well in advance and can take alternative route in case of traffic congestion. Dissemination of information to vehicles through broadcasting creates a broadcast storm problem in VANET. In this paper a novel framework is proposed for handling the local broadcast storm problem using probabilistic data aggregation which reduces the bandwidth consumption and hence improves the information dissemination. This system exploits the knowledge base and stores the decisions for aggregation and is based on a flexible and extensible set of criteria. These criteria’s can be application specific and can enable a dynamic fragmentation of the road according to the various application requirements. The framework is evaluated for VANET based traffic information system through simulation for strictly limited bandwidth and local broadcast problem. The results demonstrate that completely structure-free probabilistic data aggregation reduces the bandwidth consumption by eliminating the local broadcast problem.     

基于声信号处理的交通事故自动检测算法

建立交通事故应急救援系统具有很强的现实意义,关键技术是对交通事故进行自动检测。为了保证检测的实时性与准确性,提出一种基于声信号处理的方法,采集车辆周围的声音并进行预处理,使用Harr小波变换提取声信号的频域特征,采用单类支持向量机进行异常点检测,实现了分类判别。按上述方法对交通事故发生时的碰撞信号与正常行驶时的非碰撞信号做了分析,准确的识别出交通事故。仿真实验结果表明与常用的线性判别分析方法相比准确率有了显著提高,而且计算复杂度低,易于在DSP系统上实现,算法的判别性能达到了实用化的程度。     

基于元数据的电力客户流量数据实时监测设计

为了提高电力客户流量数据实时监测能力,提出基于元数据的电力客户流量数据实时监测系统设计方法。构建电力客户流量数据的分布式采集和存储结构模型,采用多分布的传感器阵列进行电力客户流量数据采样,对采集的电力客户流量数据进行特征重组,提取电力客户流量数据的元数据结构特征,根据元数据的结构分布进行电力客户流量数据的模糊信息聚类处理,建立电力客户流量数据的多分布特征检测和属性聚类模型,采用模糊融合方法进行电力客户流量数据的多元信息重构,在重构的特征空间中实现电力客户流量数据实时监测。仿真结果表明,采用该方法进行电力客户流量数据监测的实时性较好,识别精度高,特征分辨能力较强,具有很好的电力客户流量信息检测和识别能力。     

DESCV—A Secure Wireless Communication Scheme for Vehicle ad hoc Networking

As an indispensable part of intelligent transportation system (ITS), inter-vehicle communication (IVC) emerges as an important research topic. The inter-vehicle communication works based on vehicular ad hoc networking (VANET), and provides communications among different vehicles. The wide applications of VANET helps to improve driving safety with the help of traffic information updates. To ensure that messages can be delivered effectively, the security in VANET becomes a critical issue. Conventional security systems rely heavily on centralized infrastructure to perform security operations such as key assignment and management, which may not suit well for VANET due to its high mobility and ad hoc links. Some works suggested that vehicles should be connected to fixed devices such as road side units (RSUs), but this requires deployment of a large number of costly RSUs in a specific area. This paper is focused on the issues on decentralized IVC without fixed infrastructure and proposes a method for Dynamic Establishment of Secure Communications in VANET (DESCV), which works in particular well for VANET communication key management when centralistic infrastructure or RSU is not available. We will demonstrate through synergy analysis and simulations that DESCV performs well in providing secure communications among vehicles traveling at a relative velocity as high as 240 km/h.     

VANET: A novel service for predicting and disseminating vehicle traffic information

The arrival of cloud computing technology promises innovative solutions to the problems inherent in existing vehicular ad hoc network (VANET) networks. Because of the highly dynamic nature of these networks in crowded conditions, some network performance improvements are needed to anticipate and disseminate reliable traffic information. Although several approaches have been proposed for the dissemination of data in the vehicular clouds, these approaches rely on the dissemination of data from conventional clouds to vehicles, or vice versa. However, anticipating and delivering data, in a proactive way, based on query message or an event driven has not been defined so far by these approaches. Therefore, in this paper, a VANET‐Cloud layer is proposed for traffic management and network performance improvements during congested conditions. For the traffic management, the proposed layer integrates the benefits of the connected sensor network (CSN) to collect traffic data and the cloud infrastructure to provide on‐demand and automatic cloud services. In this work, traffic services use a data exchange mechanism to propagate the predicted data using a fuzzy aggregation technique. In the evaluation phase, simulation results demonstrate the effectiveness of the proposed VANET‐Cloud layer to dramatically improve traffic safety and network performance as compared with recent works.     

VDNet: an infrastructure‐less UAV‐assisted sparse VANET system with vehicle location prediction

Vehicular Ad Hoc Network (VANET) has been a hot topic in the past few years. Compared with vehicular networks where vehicles are densely distributed, sparse VANET have more realistic significance. The first challenge of a sparse VANET system is that the network suffers from frequent disconnections. The second challenge is to adapt the transmission route to the dynamic mobility pattern of the vehicles. Also, some infrastructural requirements are hard to meet when deploying a VANET widely. Facing these challenges, we devise an infrastructure‐less unmanned aerial vehicle (UAV) assisted VANET system called V ehicle‐D rone hybrid vehicular ad hoc Net work (VDNet), which utilizes UAVs, particularly quadrotor drones, to boost vehicle‐to‐vehicle data message transmission under instructions conducted by our distributed vehicle location prediction algorithm. VDNet takes the geographic information into consideration. Vehicles in VDNet observe the location information of other vehicles to construct a transmission route and predict the location of a destination vehicle. Some vehicles in VDNet equips an on‐board UAV, which can deliver data message directly to destination, relay messages in a multi‐hop route, and collect location information while flying above the traffic. The performance evaluation shows that VDNet achieves high efficiency and low end‐to‐end delay with controlled communication overhead. Copyright © 2016 John Wiley & Sons, Ltd.     

Communication framework for vehicle ad hoc network on?freeways

Providing an efficient and stable communication framework of Vehicular Ad hoc Network (VANET) is an emerging issue. Most of conventional VANET communication schemes only support short range transmission, vehicles need to relay traffic data or frequently switch to different roadside units. Such an ad hoc-based method suffers a high jitter delay and makes it difficult to develop travel and real-time multimedia services, such as traffic information dissemination and fleet management. Fortunately, existing novel wireless technologies, e.g. WiMAX mobile multi-relay (MMR), provide long transmission range and high transmission rate in mobile environments. This study presents a Safety/Vehicular Information Delivery (SVID) framework, an application-layer VANET communication protocol. A power-abundant, large size vehicle, called SIP-based relay vehicle (SRV), e.g. long distance transportation bus, plays as a relay station (RS) providing the connectivity to other small vehicles around it. To provide VANET services in SVID, this work adopts a SIP-based mechanism. The proposed scheme can provide more efficient communication than conventional VANET ad hoc mode. Simulation results show that the proposed scheme achieves a low SIP transaction time, jitter delay, frame loss rate while avoiding the broadcast storm problem.     

数据融合技术在高速公路异常事件检测中的应用

交通异常事件的检测一直以来都是高速公路监控系统的难点和重点。现有的交通异常事件检测系统在实际应用中检测效果不很理想。而数据融合技术是近年来发展起来的一种新的信息综合处理方法，目前已经在ITS中有许多尝试。本文简述了交通异常事件检测的基本原理，并通过对数据融合基本理论的总结与剖析，重点阐述了数据融合的3个层次（数据级融合、特征级融合、决策级融合）在交通异常检测中的具体应用以及交通异常事件检测的数据融合系统模型。应用数据融合技术的交通事件检测系统能提高系统的有效性，得到最佳协同作用的结果。     

面向资源节省的传感网动态目标自适应获取系统

针对图像传感网动态目标监测问题,搭建了面向资源节省的动态目标自适应获取系统Easi RS。利用存储空间复用技术减少存储资源需求;提出图像完整性自适应实时检测方法,解决由于目标动态性导致的连续图像的实时处理问题;在图像完整性实时检测的基础上,对获取的信息进行选择性传输,以减少传输数据量和传输能耗。通过室内和室外环境对该方法进行实验,结果表明,该系统不仅可以有效保证系统的感知性能,而且降低了存储开销和传输能耗。