Location-Aware Services over Vehicular Ad-Hoc Networks using Car-to-Car Communication

Recent advances in wireless inter-vehicle communication systems enable the establishment of vehicular ad-hoc networks (VANET) and create significant opportunities for the deployment of a wide variety of applications and services to vehicles. In this work, we investigate the problem of developing services that can provide car drivers with time-sensitive information about traffic conditions and roadside facilities. We introduce the vehicular information transfer protocol (VITP), a location- aware, application-layer, communication protocol designed to support a distributed service infrastructure over vehicular ad- hoc networks. We describe the key design concepts of the VITP protocol and infrastructure. We provide an extensive simulation study of VITP performance on large-scale vehicular networks under realistic highway and city traffic conditions. Our results demonstrate the viability and effectiveness of VITP in providing location-aware services over VANETs.     

Extending Vehicular CAN Fieldbuses With Delay-Tolerant Networks

In this paper, we propose and evaluate the possibility of extending vehicular controller-area network (CAN) fieldbuses with delay-tolerant networks (DTNs) based on the multihop car2car (C2C)—or vehicle2vehicle—paradigm. Previous research has focused on single-hop wireless communications, which are inadequate in many real-life scenarios . We demonstrate that efficient network layers, such as DTNs, are necessary to overcome those limitations. As a proof of concept, we present a working prototype of a system that extends the standard diagnostics interface of a CAN bus.      

无线车联网WAVE车-车通信中的一种路由算法实现

车载网络WAVE中车与车之间能够通信靠的是移动过程中车与车之间建立起来的网络连接，路由是实现网络连接的一个关键问题。基于行车速度与距离的快速多跳路由算法FMHR是以中间车辆与目标车辆之间通信时间值最小为策略来选择信息传递的下一跳。提出的保持最大通信时间KMCT路由算法与FMHR不同，KMCT 是以中间车辆与发送信息车辆之间通信时间的最大值为策略来选择信息传递的下一跳，实验结果表明，当车辆速度较高时，KMCT性能要优于FMHR。     

Vehicular Networks

Vehicular networks have attracted a lot of attention in recent years.Manyprojects have been initiated by government,industry,and academia toimprove driving safety,provide travel assistance,improve traffic flow,and decrease fuel consumption.These projects exploit vehicular com-munications and networking technologies,generally referred to as vehicular     

一维车载Ad Hoc网络连接度分析

In this paper we analyze connectivity of one-dimensional Vehicular Ad Hoc Networks where vehicle gap distribution can be approximated by an exponential distribution. The probabilities of Vehicular Ad Hoc Network connectivity for difference cases are derived. Furthermore we proof that the nodes in a sub-interval [z1,z1 +Δz] of interval [0, z], z>0 where all the nodes are independently uniform distributed is a Poisson process and the relationship of Vehicle Ad hoc Networks and one-dimensional Ad Hoc networks ...     

稀疏城市车载网络中的静态结构动态权重路由

以上海市4 000辆出租车为期两年的GPS数据为依托,设计仅存在于理论意义上的车载网络路由最优算法并对其进行仿真,一方面,最优路由算法的结果揭示了现有路由算法的不足;另一方面,根据最优路由算法的宴际路径特点,设计了基于地图的静态结构动态权重的路由策略来逼近车载网络路由的理论最优性能,这一路由算法相对干传统的地理路由和其变种算法在性能方面有超过50%的提升.     

车辆传感器网络研究

随着无线通信技术的快速发展和车辆在日常生活中的不断普及,车辆传感器网络作为新一代的网络技术越来越被重视。文章基于无线车辆传感器网络的基本概念和体系结构,讨论了车辆传感器网络与传统无线传感器网络的主要区别,以及由此引入的各种设计上的挑战。对车辆传感器网络中的关键技术,包括媒体访问控制（MAC）协议、路由协议和移动模型,文章进行了研讨,并介绍了世界上已建立的车辆传感器网络试验床。文章还介绍了行车安全、城市监控、路况监测、交通流量监测等几种典型的车辆传感器网络的应用。     

On Detecting Spectrum Opportunities for Cognitive Vehicular Networks in the TV White Space

We overview the challenges related to spectrum awareness in the vehicular environment, with emphasis on awareness in the TV licensed band. In the vehicular environment the cognitive radio can help to: 1) satisfy capacity demand for Intelligent Transportation Systems (ITS) applications; and 2) offload time insensitive applications from the ITS dedicated spectrum. However, using simple propagation models we show that neither sensing, nor geolocation database lookup alone can provide sufficient incumbent protection. Collaboration among the sensors to take advantage of spatial diversity is difficult due to the rapidly changing network topology. Nevertheless, mobility provides the opportunity to use time diversity at each sensor. We also discuss the influence of sensing subsystem design on the vehicular cognitive network medium access (MAC) sublayer. Whenever appropriate, we evaluate applicability of the requirements imposed by the Federal Communications Commission (FCC) and the IEEE 802.22 standard to the cognitive vehicular networks.     

车辆无线通信网络及其应用

文章介绍了车辆通信网的基本概念、网络架构、国际标准及关键技术,分析了其在物理层、媒体接入层、路由层、安全技术的研究热点问题,并讨论了其在智能交通、安全行车、导航和智能驾驶等方面的应用前景。     

车辆网络告警信息的自适应发送策略

对节点之间的距离与告警信息寿命关系进行了研究,研究结果表明在车辆的速度给定的情况下,节点之间的距离与告警信息寿命成正比。为了减少车辆网络中告警信息的延迟,提高告警信息的递送率,提出了一种适应于车辆网络节点密度变化的、利用重复发送结合大范围忙音[1]来提高告警信息发送的可靠性与有效性的策略。仿真结果表明提出的方法能够显著提高告警信息成功接收率。     

A Mobicast Routing Protocol in Vehicular Ad-Hoc Networks

In this paper, we present a “spatiotemporal multicast”, called a “mobicast”, protocol for supporting applications which require spatiotemporal coordination in vehicular ad hoc networks (VANETs). The spatiotemporal character of a mobicast is to forward a mobicast message to vehicles located in some geographic zone at time t, where the geographic zone is denoted as zone of relevance (ZOR). Vehicles located in ZOR at the time t must keep the connectivity to maintain the real-time data communication between all vehicles in ZOR. The connectivity is kept of all vehicles in ZOR through the vehicular ad hoc networks (VANETs). The connectivity of ZOR is lost if any vehicle in ZOR suddenly accelerates or decelerates its velocity. The temporal network fragmentation problem is occurred such that vehicle in ZOR cannot successfully receive the mobicast messages. To solve the problem, a new mobicast protocol is presented in this work to successfully disseminate mobicast messages to all vehicles in ZOR via a special geographic zone, called as zone of forwarding (ZOF). The main contribution of this work is to develop a new mobicast routing protocol to dynamically estimate the accurate ZOF to successfully disseminate mobicast messages to all vehicles in ZOR. To illustrate the performance achievement, simulation results are examined in terms of dissemination successful rate, packet overhead multiplication, packet delivery delay, and throughput.     

Wireless Location Privacy Protection in Vehicular Ad-Hoc Networks

Advances in mobile networks and positioning technologies have made location information a valuable asset in vehicular ad-hoc networks (VANETs). However, the availability of such information must be weighted against the potential for abuse. In this paper, we investigate the problem of alleviating unauthorized tracking of target vehicles by adversaries in VANETs. We propose a vehicle density-based location privacy (DLP) scheme which can provide location privacy by utilizing the neighboring vehicle density as a threshold to change the pseudonyms. We derive the delay distribution and the average total delay of a vehicle within a density zone. Given the delay information, an adversary may still be available to track the target vehicle by some selection rules. We investigate the effectiveness of DLP based on extensive simulation study. Simulation results show that the probability of successful location tracking of a target vehicle by an adversary is inversely proportional to both the traffic arrival rate and the variance of vehicles’ speed. Our proposed DLP scheme also has a better performance than both Mix-Zone scheme and AMOEBA with random silent period.     

基于车载自组织网络的消息发送时机研究

车载自组织网络(VANET)是一种节点迅速移动的无线自组织网络,网络的动态密度变化具有明显的特征,呈现出疏密相间的"手风琴"现象。利用汽车之间相遇的机会进行通信需要考虑到网络动态变化对传输的影响。文章利用仿真软件SUMO生成的跟踪轨迹文件,在仿真软件ONE下做网络参数的对比实验。通过模拟道路交通的网络动态密度变化,文章得到结论:最佳发送时机随网络参数不同而变化。     

Routing in Sparse Vehicular Ad Hoc Wireless Networks

A vehicular ad hoc network (VANET) may exhibit a bipolar behavior, i.e., the network can either be fully connected or sparsely connected depending on the time of day or on the market penetration rate of the wireless communication devices. In this paper, we use empirical vehicle traffic data measured on 1-80 freeway in California to develop a comprehensive analytical framework to study the disconnected network phenomenon and its network characteristics. These characteristics shed light on the key routing performance metrics of interest in disconnected VANETs, such as the average time taken to propagate a packet to disconnected nodes (i.e., the re-healing time). Our results show that, depending on the sparsity of vehicles or the market penetration rate of cars using Dedicated Short Range Communication (DSRC) technology, the network re-healing time can vary from a few seconds to several minutes. This suggests that, for vehicular safety applications, a new ad hoc routing protocol will be needed as the conventional ad hoc routing protocols such as Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing (AODV) will not work with such long re-healing times. In addition, the developed analytical framework and its predictions provide valuable insights into the VANET routing performance in the disconnected network regime.     

Trajectory-Based Data Forwarding Schemes for Vehicular Networks

This paper explains trajectory-based data forwarding schemes for multihop data delivery in vehicular networks where the trajectory isthe GPS navigation path for driving in a road network. Nowadays, GPS-based navigation is popular with drivers either for efficient driv-ing in unfamiliar road networks or for a better route, even in familiar road networks with heavy traffic. In this paper, we describe howto take advantage of vehicle trajectories in order to design data-forwarding schemes for information exchange in vehicular networks.The design of data-forwarding schemes takes into account not only the macro-scoped mobility of vehicular traffic statistics in road net-works, but also the micro-scoped mobility of individual vehicle trajectories. This paper addresses the importance of vehicle trajectoryin the design of multihop vehicle-to-infrastructure, infrastructure-to-vehicle, and vehicle-to-vehicle data forwarding schemes. First, weexplain the modeling of packet delivery delay and vehicle travel delay in both a road segment and an end-to-end path in a road net-work. Second, we describe a state-of-the-art data forwarding scheme using vehicular traffic statistics for the estimation of the end-to-end delivery delay as a forwarding metric. Last, we describe two data forwarding schemes based on both vehicle trajectory and vehicu-lar traffic statistics in a privacy-preserving manner.     

车载移动异构无线网络架构及关键技术

传统的车辆通信网络通常只是针对于公路计费等用途设计的封闭式通信网络,新近的发展使得车辆支持车间自主通信从而互通安全信息。但是由于在网络架构方面的缺陷,现有的系统只能对高速行驶中的车辆提供局部区域内的信息交互,无法实现车辆与智能交通控制中心进行实时数据服务和接入宽带无线网络。文章提出了基于车辆环境下无线接入（WAVE）（IEEE802.11p）和全球微波接入互操作性（WiMAX）（IEEE802.16e）融合的车载移动异构无线网络体系,建立了新型车载异构网络通信架构及体系模型,并分别对WAVE网络中的多信道自适应协调机制和分布式多信道调度算法和基于移动预测的路由及服务质量、WiMAX网络中的群组切换机制和两级资源调度等关键技术进行了研究和探讨。     

Segmented OTA Platform Over ICN Vehicular Networks

Mobile Networks and Applications - The Internet Protocol (IP) architecture could not fully satisfy the Vehicular Ad-hoc Networks (VANETs) needed efficiency, due to their dynamic topology and high...