scispace - formally typeset
Search or ask a question

Showing papers on "Vehicular communication systems published in 2010"


Proceedings ArticleDOI
20 Sep 2010
TL;DR: This work attempts to characterize communication properties of DSRC as well as to analyze the causes of communication loss, and investigates the impact of both uncontrollable environmental factors and controllable radio parameters on DSRC characteristics.
Abstract: IEEE 80211p-based Dedicated Short Range Communications (DSRC) is considered a promising wireless technology for enhancing transportation safety and improving highway efficiency Here, using a large set of empirical measurement data taken in a rich variety of realistic driving environments, we attempt to characterize communication properties of DSRC as well as to analyze the causes of communication loss Specifically, from a perspective of vehicular network engineers, the fundamental characteristic of DSRC communications is Packet Delivery Ratio (PDR) We investigate the impact of both uncontrollable environmental factors and controllable radio parameters on DSRC characteristics Moreover, we also examine temporal correlation, spatial correlation and symmetric correlation of DSRC characteristics under realistic vehicular environments

289 citations


Proceedings ArticleDOI
08 Nov 2010
TL;DR: This paper puts forth a novel vision, namely that advances in vehicular networks, embedded devices, and cloud computing can be used to form what the authors may call Vehicular Cloud Computing, VC2 for short.
Abstract: The past decade has witnessed a growing interest in vehicular networking and its myriad potential applications. The initial view of practitioners and researchers was that radio-equipped vehicles could keep the drivers informed about potential safety risks and increase their awareness of road conditions. The view then expanded to include access to the Internet and associated services. More recently, the availability of bandwidth has seen vehicular peer-to-peer networking and multimedia content delivery.This paper puts forth a novel vision, namely that advances in vehicular networks, embedded devices, and cloud computing can be used to form what we may call Vehicular Cloud Computing, VC2 for short. In VC2, the underutilized vehicles resources such as computing power, Internet connectivity and storage can be shared between drivers or rented over the Internet to various customers, very much like usual cloud resources are.

254 citations


Proceedings ArticleDOI
01 Dec 2010
TL;DR: This work performs experimental measurements in order to collect received signal power and packet delivery ratio information in a multitude of relevant scenarios: parking lot, highway, suburban and urban canyon, and shows that obstructing vehicles cause significant impact on the channel quality.
Abstract: Channel models for vehicular networks typically disregard the effect of vehicles as physical obstructions for the wireless signal. We aim to clarify the validity of this simplification by quantifying the impact of obstructions through a series of wireless experiments. Using two cars equipped with Dedicated Short Range Communications (DSRC) hardware designed for vehicular use, we perform experimental measurements in order to collect received signal power and packet delivery ratio information in a multitude of relevant scenarios: parking lot, highway, suburban and urban canyon. Upon separating the data into line of sight (LOS) and non-line of sight (NLOS) categories, our results show that obstructing vehicles cause significant impact on the channel quality. A single obstacle can cause a drop of over 20 dB in received signal strength when two cars communicate at a distance of 10 m. At longer distances, NLOS conditions affect the usable communication range, effectively halving the distance at which communication can be achieved with 90% chance of success. The presented results motivate the inclusion of vehicles in the radio propagation models used for VANET simulation in order to increase the level of realism.

208 citations


Journal ArticleDOI
TL;DR: This article reviews broadcast communication in vehicular communication networks and mechanisms to alleviate the broadcast storm problem, and introduces vehicular safety applications, network design considerations, and characterize broadcast protocols in Vehicular networks.
Abstract: A primary goal of intelligent transportation systems is to improve road safety. The ability of vehicles to communicate is a promising way to alleviate traffic accidents by reducing the response time associated with human reaction to nearby drivers. Vehicle mobility patterns caused by varying traffic dynamics and travel behavior lead to considerable complexity in the efficiency and reliability of vehicular communication networks. This causes two major routing issues: the broadcast storm problem and the network disconnection problem. In this article we review broadcast communication in vehicular communication networks and mechanisms to alleviate the broadcast storm problem. Moreover, we introduce vehicular safety applications, discuss network design considerations, and characterize broadcast protocols in vehicular networks.

168 citations


Proceedings ArticleDOI
16 Jun 2010
TL;DR: The results show that the traffic prioritization schemes selected for the standards work well, and even in the presence of multi-channel operation implemented by the IEEE 1609.4 the delay of control messages of highest priority remains on the order of tens of milliseconds.
Abstract: In this paper we study the performance of the IEEE 1609 WAVE and IEEE 802.11p trial standards for vehicular communications. We have implemented key components of these standards in a simulation environment also supporting realistic vehicular mobility simulation. We study both the overall capacity of vehicular networks utilizing the said standards, as well as delay performance, which is an extremely important performance metric especially for safety applications. Our results show that the traffic prioritization schemes selected for the standards work well, and even in the presence of multi-channel operation implemented by the IEEE 1609.4 the delay of control messages of highest priority remains on the order of tens of milliseconds. Thus even with high densities of vehicles these standards should yield a stable platform a variety of vehicular applications can be built on.

158 citations


Journal ArticleDOI
TL;DR: The ITS technologies for energy saving and CO2 emission reduction, which include traffic signal control, ETC, route guidance, cruise control, and automated driving, are surveyed.
Abstract: Recent annual CO2 emission from Japan sums up to 1.2 billion ton, and about 17 percent of it is from automobile traffic. There are many approaches to reduce CO2 emission and to prevent the global warming, and one of the important approaches is the Intelligent Transport Systems. This article surveys the effects of the ITS on the energy saving and global warming prevention based on the data in Japan, focusing on the applications of vehicular communication technologies. The ITS could contribute to the energy saving on two aspects: one is to eliminate the congestion, which enables each automobile to drive at the fuel optimal speeds, and the other is to provide means for modal shift, which reduces the traffic. This article surveys the ITS technologies for energy saving and CO2 emission reduction, which include traffic signal control, ETC, route guidance, cruise control, and automated driving. The road-to-vehicle and vehicle-to-vehicle communications play an essential role in energy saving as well as in the safety of automobiles and road transportation.

95 citations


Proceedings ArticleDOI
14 Mar 2010
TL;DR: A novel routing protocol, based on opportunistic vehicle to vehicle communication, to enable efficient multi-hop routing capabilities between mobile vehicles and APs and fully supports two- way communication.
Abstract: -Nowadays, the navigation systems available on cars are becoming more and more sophisticated. They greatly improve the experience of drivers and passengers by enabling them to receive map and traffic updates, news feeds, advertisements, media files, etc. Unfortunately, the bandwidth available to each vehicle with the current technology is severely limited. There have been many reports on the inability of 3G networks to cope with large size file downloads, especially in dense and mobile settings. A possible alternative is provided by WiFi access points (APs) that are being installed in several countries along the main routes and in popular areas. Although this approach significantly increases the available bandwidth, it still does not provide a fully satisfactory solution due to the limited transmission range (usually a few hundred meters). In this paper we present a novel routing protocol, based on opportunistic vehicle to vehicle communication, to enable efficient multi-hop routing capabilities between mobile vehicles and APs. Unlike prior work, this protocol fully supports two- way communication, i.e., the traditional vehicle-to-AP as well as the more challenging AP-to-vehicle. We leverage the information offered by the navigation system in terms of final destination and path, to i) route packets to the closest AP and ii) to route replies back to the moving vehicle efficiently.

72 citations


Proceedings ArticleDOI
10 Oct 2010
TL;DR: The authors' measurements indicate a quite problematic LOS sensitivity that strongly influences the performance of V2V-based applications and how the awareness of these context-based connectivity problems can be used to improve the design of possible future cooperative ITS safety applications.
Abstract: Future cooperative Intelligent Transport Systems (ITS) applications aimed to improve safety, efficiency and comfort on our roads put high demands on the underlying wireless communication system. To gain better understanding of the limitations of the 5.9 GHz frequency band and the set of communication protocols for medium range vehicle to vehicle (V2V) communication, a set of field trials with CALM M5 enabled prototypes has been conducted. This paper describes five different real vehicle traffic scenarios covering both urban and rural settings at varying vehicle speeds and under varying line-of-sight (LOS) conditions and discusses the connectivity (measured as Packet Reception Ratio) that could be achieved between the two test vehicles. Our measurements indicate a quite problematic LOS sensitivity that strongly influences the performance of V2V-based applications. We further discuss how the awareness of these context-based connectivity problems can be used to improve the design of possible future cooperative ITS safety applications.

71 citations


Journal ArticleDOI
TL;DR: An innovative system called wireless local danger warning (WILLWARN), which is based on recent and future trends of cooperative driving, enables an electronic safety horizon for foresighted driving by implementing onboard vehicle-hazard detection and V2V communication.
Abstract: Vehicle collision mitigation, cooperative driving, and vehicle-to-vehicle (V2V) and/or vehicle-to-infrastructure (V2I) communication constitute a broad multidisciplinary research field that focuses on improving road safety. Statistics indicate that the primary cause of most road accidents is vehicles' excessive speed and delayed drivers reaction. Thus, road safety can be improved by early warning based on V2V communication. An innovative system called wireless local danger warning (WILLWARN), which is based on recent and future trends of cooperative driving, enables an electronic safety horizon for foresighted driving by implementing onboard vehicle-hazard detection and V2V communication. One of the key innovative features of the proposed system is the focus on low penetration levels in rural traffic by a new message-management strategy that is based on storing warning information in the vehicle and distributing warnings through communication, particularly with oncoming traffic. The system timely warns the driver about a dangerous situation ahead by decentralized distribution of warnings and incident messages via ad hoc intervehicle communication. The WILLWARN system is based on a modular object-oriented architecture consisting of the V2V communication module (VVC), the warning message-management module (WMM), the hazard-detection-management module (HDM), the hazard-warning-management module (HWM), a Global Positioning System (GPS) receiver, and various onboard sensors. In this paper, all system modules, as well as their interoperability, are presented in detail.

66 citations


Journal ArticleDOI
TL;DR: The simulation results showed that the proposed V2R2 algorithm can effectively find better paths with less travel time than the shortest path, and it can bypass void areas when collecting real-time traffic information.
Abstract: With advances in wireless communications and global position system-enabled devices (such as cellular phones, PDAs and car PCs), vehicle route guidance systems gradually become indispensable equipments for more and more automobile drivers because of its great convenience. Conventional route guidance systems are designed to direct a vehicle along the shortest path from the origin to the destination. However, usually, the shortest path does not result in the smallest travel time because of the dynamic traffic conditions on roadways. Therefore the state-of-the-art route guidance systems incorporate real-time traffic information to find better paths. There are two types of approaches to collecting real-time traffic information: infrastructure-based approach and infrastructure-free approach. The authors adopt infrastructure-free approach to develop a real-time route guidance algorithm, called V2R2 (Vehicle-to-Vehicle Real-time Routing). Our simulation results showed that V2R2 algorithm can effectively find better paths with less travel time than the shortest path. In addition, it can bypass void areas (i.e. the areas containing empty roads) when collecting real-time traffic information. The simulation results validate the efficiency and robustness of the proposed V2R2 algorithm.

57 citations


Proceedings ArticleDOI
12 Apr 2010
TL;DR: This paper argues that the cooperation of pure ad-hoc vehicle-to-vehicle communications and roadside infrastructure is fundamental to broaden the supported applications of the ”Vehicle Grid”.
Abstract: Vehicular communications are becoming a reality under the push of increased transportation safety requirements and huge investments of several actors in the field like car manufacturers and Public Transport Authorities. As a consequence, the building blocks of the ”Vehicle Grid” (radios, Access Points, spectrum, standards, etc.) will soon be in place enabling a broad gamut of applications ranging from automatic safety systems, intelligent transport, entertainment, urban sensing and environmental protection/monitoring. In this paper, we take a visionary look at ”Vehicular Grid” and we argue that the cooperation of pure ad-hoc vehicle-to-vehicle communications and roadside infrastructure is fundamental to broaden the supported applications. The paper further describes the activities carried out at UCLA to deploy an open testbed integrating ad hoc vehicle-to-vehicle communications and a wireless mesh backhaul based on MobiMESH hardware/software solutions.

Patent
09 Aug 2010
TL;DR: In this paper, a distributed traffic navigation in a vehicular network is presented, where information associated with the vehicular networks is acquired and stored, and destination addresses are broadcasted as route requests.
Abstract: A method for distributed traffic navigation in a vehicular network is presented. At each vehicle entering the network, information associated with the vehicular network is acquired and stored, and destination addresses are broadcasted as route requests. At each vehicle in the network, the stored information is updated through vehicle to vehicle communication. At each junction, a header vehicle is selected for listening for broadcasts to determine the presence of a matrix. If the matrix is not present, the matrix is initialized based on the stored information of the header vehicle. The header vehicle further estimates travel time on the road segments based on the matrix, calculates a backlog indicator based on the segment travel time and the route requests. The header vehicle further updates the matrix and generates a route based on the matrix. The matrix is broadcasted from the header vehicle.

Journal ArticleDOI
01 Jul 2010
TL;DR: This paper proposes a cross-layer position-based delay-aware communication protocol called PROMPT that outperforms existing routing protocols proposed for vehicular networks in terms of end-to-end packet delay, packet loss rate, and fairness of service.
Abstract: Vehicular communication systems facilitate communication devices for exchange of information among vehicles and between vehicles and roadside equipment. These systems are used to provide a myriad of services ranging from traffic safety application to convenience applications for drivers and passengers. In this paper, we focus on the design of communication protocols for vehicular access networks where vehicles access a wired backbone network by means of a multi-hop data delivery service. Key challenges in designing protocols for vehicular access networks include quick adaptability to frequent changes in the network topology due to vehicular mobility and delay awareness in data delivery. To address these challenges, we propose a cross-layer position-based delay-aware communication protocol called PROMPT. It adopts a source routing mechanism that relies on positions independent of vehicle movement rather than on specific vehicle addresses. Vehicles monitor information exchange in their reception range to obtain data flow statistics, which are then used in estimating the delay and selecting best available paths. Through a detailed simulation study using ns-2, we empirically show that PROMPT outperforms existing routing protocols proposed for vehicular networks in terms of end-to-end packet delay, packet loss rate, and fairness of service.

Journal ArticleDOI
TL;DR: A new technique based on the concept of Encounter Probability is proposed for vehicles to share information using vehicle-to-vehicle communications, which is to facilitate the dissemination of information between vehicles when they meet each other, taking into account the relevance of the data to the drivers.
Abstract: In vehicular ad hoc networks (VANETs), different types of information can be useful to drivers. Such networks are highly dynamic due to both the movements of the vehicles and the short range of the wireless communications. Thus, the information exchanges between vehicles about relevant information can only rely on short interactions. Therefore, an efficient mechanism to manage and disseminate the relevant information is required. Specifically, we present in this paper a system for data sharing in vehicular networks, which we call Vehicular Event Sharing with a mobile Peer-to-peer Architecture (VESPA). In this system, a new technique based on the concept of Encounter Probability is proposed for vehicles to share information using vehicle-to-vehicle communications. The objective is to facilitate the dissemination of information between vehicles when they meet each other, taking into account the relevance of the data to the drivers. Besides, the relevance must also be considered to inform a driver about the interesting events. Moreover, our proposal takes into account any type of event (e.g., available parking spaces, obstacles in the road, information relative to the coordination of vehicles in emergency situations, etc.) in the network. An experimental evaluation and the implemented prototype show the interest of the system.

Journal ArticleDOI
TL;DR: The simulation results demonstrate that by using the 3G-based solution to disseminate connectivity information, vehicular ad hoc routing protocols improve their route selections, which results in a higher packet delivery ratio in urban scenarios.
Abstract: Cellular networks have gained a lot of popularity in the context of vehicular communication within the last few years. Existing reference architectures such as CALM already consider them to provide enhanced connectivity to vehicles for data communication. Their capabilities, especially 3G and next-generation, translate into great potential in the vehicular environment, far beyond the provision of data connectivity. In this context we present a solution that uses 3G cellular networks not only as a backup for data communication among vehicles, but also and especially as an efficient mechanism for the dissemination of relevant control information for multiple applications, services, and protocols. Our simulation results demonstrate that by using our 3G-based solution to disseminate connectivity information, vehicular ad hoc routing protocols improve their route selections, which results in a higher packet delivery ratio in urban scenarios.

Journal ArticleDOI
TL;DR: An analytic model with linear time complexity is developed to compute the optimal number of active roadside units under a connectivity constraint and guidelines for applying a power-saving model in a vehicular network are provided.
Abstract: In this letter, we investigate the impact on connectivity metric when a power-saving model is applied to a vehicular network. An analytic model with linear time complexity is developed to compute the optimal number of active roadside units under a connectivity constraint. We provide guidelines for applying a power-saving model in a vehicular network. The results are very useful for the ministry of transportation.

Proceedings ArticleDOI
05 May 2010
TL;DR: The implementation of a wireless access in vehicular environment (WAVE)/ dedicated short-range communication system (DSRC) is presented and the performance of the implemented system is evaluated via on-road testing with the WAVE short-message protocol (WSMP), which shows the efficiency of the system in Vehicular environments.
Abstract: The IEEE 802.11p and IEEE 1609-family standards are developed for vehicular communications in telematics. Based on these standards, the implementation of a wireless access in vehicular environment (WAVE)/ dedicated short-range communication system (DSRC) is presented. The performance of the implemented system is evaluated via on-road testing with the WAVE short-message protocol (WSMP), which shows the efficiency of the system in vehicular environments.

Journal ArticleDOI
TL;DR: The methods and algorithms developed in this paper provide detailed insights into location privacy and thus contribute to the development of future-proof, privacy-preserving vehicular communication systems.

Proceedings ArticleDOI
13 Jul 2010
TL;DR: The main goals of this paper are to motivate communications researchers to design EEFG protocols, demonstrate the ability to integrate fuel and emission models with vehicular networks, and illustrate the benefit of transmitting the traffic light signal information to vehicles for fuel consumption and emission reduction.
Abstract: With recent advances in the development of wireless communication networks, vehicular networks have been receiving considerable research interest. One of the major applications of vehicular networks is Intelligent Transportation Systems (ITS). To exchange and distribute messages, geocast routing protocols have been proposed for ITS applications. Almost all of these protocols evaluate network-centric performance measures, instead of evaluating the impact of the protocol on the vehicular system. Nowadays, rising fuel costs and the harmful effects of air pollutants have been the subject of considerable public debate. Therefore, it is desirable to create new economical and environmentally friendly geocast (EEFG) protocols, which focus on minimizing vehicle fuel consumption and emissions. The main goals of this paper are to motivate communications researchers to design EEFG protocols, demonstrate the ability to integrate fuel and emission models with vehicular networks, and illustrate the benefit of transmitting the traffic light signal information to vehicles for fuel consumption and emission reduction. By means of an example, we show how vehicular networks can be used to reduce fuel consumption and carbon dioxide (CO 2 ) emission in a city environment. Simulation results demonstrate that vehicle fuel consumption and CO 2 emission will be reduced if such an EEFG protocol is used.

DOI
01 Jan 2010
TL;DR: In this article, the authors proposed a new algorithm that can be used by navigation systems to calculate routes circumnavigating congested roads, which can improve the traffic efficiency of future transport systems.
Abstract: Finding a way to improve traffic efficiency is a high-frequented problem to be solved. One new promising approach is the use of decentralized wireless vehicle to vehicle communication based on the Vehicle-2-X (V2X) technology. The underlying idea is that vehicles share information about their current local traffic situation and use this information to optimize their routes. In this paper, we introduce a new algorithm that can be used by navigation systems to calculate routes circumnavigating congested roads. To evaluate the improvements that can be achieved by our algorithm, simulations have been carried out which show that navigation systems using the V2X technology for a more intelligent route calculation can improve the traffic efficiency of future transport systems. For the simulation of all aspects of V2X Communication scenarios, different simulators have to be combined and an interaction among them at runtime of the simulation has to be enabled. Hence, we have developed the V2X Simulation Runtime Infrastructure (VSimRTI) which couples discrete eventbased simulators, e.g. for communication network, traffic, and V2X application simulation. The flexibility of VSimRTI allows us to vary the composition of integrated simulators depending on the specific requirements of a scenario.

Proceedings ArticleDOI
28 Jun 2010
TL;DR: It is shown, through simulation results, that the proposed solution not only allows vehicles to detect road congestion ahead of time, but also contributes to reducing the congestion level on the roads by allowing vehicles to avoid congestion points.
Abstract: Thanks to the advances in wireless technologies, mobile vehicular networks are likely to become the most relevant form of mobile ad hoc networks (MANET). Vehicular communication which facilitates the exchange of information between vehicles is the prerequisite not only for extending the access to the Internet while on the road, but also to cater for special applications such as of road traffic and travel management. However despite the increasing number of studies on vehicular routing protocols, the support for applications other than the access to the internet remains limited. In this paper we propose a novel vehicular communication system for road congestion detection and avoidance by disseminating and exploiting road information. The system is an integrated solution for sharing congestion information using a simple geocast protocol and dynamic Dijkstra algorithm for planning and computing least congested travel itineraries. In this paper, we show, through simulation results, that the proposed solution not only allows vehicles to detect road congestion ahead of time, but also contributes to reducing the congestion level on the roads by allowing vehicles to avoid congestion points.

Journal ArticleDOI
TL;DR: The dangerous-vehicle-detection protocol (DVDP) is proposed to detect drivers who violate the permitted speed limit, and results revealed that DVDP's detection probability is greater than 80% when vehicle density is above 40 vehicles/min.
Abstract: Recently, considerable research has been focused on applying ad hoc wireless networking technology to on-the-move vehicles. In this paper, we focus on distributed detection of dangerous vehicles on roads and highways. We propose the dangerous-vehicle-detection protocol (DVDP) to detect drivers who violate the permitted speed limit. In DVDP, each vehicle collects surrounding vehicles' identifications (IDs) and propagates warning information (including its position, speed, time, and collected IDs). This information is then forwarded hop-by-hop using ad hoc communications. A vehicle that receives this information will start to observe its surrounding vehicles. If surrounding vehicles are identified in the received warning information, it will estimate the speed of such vehicles. If the estimated speed exceeds the permitted speed, such vehicles are then marked as ?suspected vehicles,? and the updated warning information is further propagated. By repeating this process, the suspected vehicle (where other vehicles observe the speed violation) will ultimately be marked as a ?dangerous vehicle.? This judgment is then further propagated to warn others and to inform the traffic police. We evaluated the performance of DVDP using a simulator that performs both macroscopic and microscopic traffic simulation, taking into account realistic lane and speed models, mobility, position, and location errors. Simulation results revealed that DVDP's detection probability is greater than 80% when vehicle density is above 40 vehicles/min. When vehicle density is low, deployment of relay points can help to further improve detection probability. In addition, by utilizing vehicles in opposite lanes, detection probability can be further improved.

Proceedings ArticleDOI
01 Dec 2010
TL;DR: A fuzzy logic based multi-hop broadcast protocol for information dissemination in high-density vehicular ad hoc networks that exhibits low message overheads by means of using only a subset of neighbor nodes to relay messages.
Abstract: Vehicular ad hoc networks have been attracting the interest of both academic and industrial communities on account of their potential role in Intelligent Transportation Systems (ITS). In vehicular ad hoc networks, vehicles are usually located quite densely within the range of radio transmission. In this paper, we propose a fuzzy logic based multi-hop broadcast protocol for information dissemination in high-density vehicular ad hoc networks. The proposed protocol exhibits low message overheads by means of using only a subset of neighbor nodes to relay messages. In the relay node selection, the proposed protocol jointly considers multiple metrics of inter-vehicle distance, node mobility and signal strength by employing the fuzzy logic. We use computer simulations to evaluate the performance of the proposed protocol.

Proceedings ArticleDOI
21 Jun 2010
TL;DR: This work discusses physical parameters of traffic flow and networking parameters for both free-flow and congested traffic and provides an analytical framework for the computation of relevant networking parameters.
Abstract: In vehicular ad-hoc networks, physical parameters of traffic flow (traffic density and velocities), directly relate to networking parameters (node degree and duration of communication). While existing research on these relations has mainly focused on simulative work or on the free-flow regime of traffic, we discuss these relations for both free-flow and congested traffic and provide an analytical framework for the computation of relevant networking parameters. We also discuss some results and analyze their impact on vehicular communications.

Proceedings ArticleDOI
01 Dec 2010
TL;DR: The results show that the methods developed in this research scale very well for increasing vehicle density, and take advantage of the multi-channel operations in IEEE 1609.
Abstract: In this paper, the primary objective is to discuss the details of scalable methods for distributing certificate revocation lists and other large files using vehicle-to-vehicle and vehicle-to-infrastructure communications while taking advantage of the multi-channel operations in IEEE 1609.4. We also discuss the results from a simulation study using the ns-3 network simulator to closely replicate the WAVE environment discussed in the IEEE 802.11p and 1609 draft standards. Realistic vehicle traces were used in the simulation study. The results show that the methods developed in this research scale very well for increasing vehicle densities.

Proceedings ArticleDOI
01 Dec 2010
TL;DR: A platform for realistic and computationally efficient online vehicular networks simulation that permits decentralized traffic management applications simulation as nodes mobility is modifiable at runtime thanks to the integration of two state-of-the-art network and traffic simulators.
Abstract: This paper introduces a platform for realistic and computationally efficient online vehicular networks simulation. It permits decentralized traffic management applications simulation as nodes mobility is modifiable at runtime thanks to the integration of two state-of-the-art network and traffic simulators. The platform embeds a tool that generates vehicular traces based on traffic counting data and ensures performance through a geographical decomposition of the network. Evidence of its performance is given on a Luxembougian traffic management scenario, using real road network and traffic data.

Proceedings ArticleDOI
21 Jul 2010
TL;DR: This paper analyzes how messages are forwarded by vehicles communicating via a hybrid protocol exploiting both short-range V2V communication schemes and Vehicle-to-Infrastructure (V2I) concepts and describes the bounds of information propagation.
Abstract: This paper addresses a hybrid approach on message propagation in vehicular networks. Short-range Vehicle-to-Vehicle (V2V) communications cannot always guarantee connectivity to the network cloud, especially when traffic density is very low. By utilizing existing wireless network infrastructure it is possible to greatly enhance the capabilities of short range V2V technologies. Such existing and future communications infrastructure includes UMTS, HSDPA, Wi-Fi, and WiMax. For this multi-network environment we analyze how messages are forwarded by vehicles communicating via a hybrid protocol exploiting both short-range V2V communication schemes and Vehicle-to-Infrastructure (V2I) concepts. The protocol switching from V2V to V2I, and vice versa, occurs through a decision algorithm that considers observed network state. We characterize the bounds of information propagation and compare performance with traditional message propagation based on opportunistic networking. Simulation results show the effectiveness of the proposed hybrid vehicular communication protocol.

Posted Content
TL;DR: This paper explores the dynamics of VANETs in urban environments and investigates the impact of these findings in the design ofVANET routing protocols by exploiting the knowledge of VIANET graphs analysis.
Abstract: Vehicular Ad hoc NETworks (VANETs) have emerged as a platform to support intelligent inter-vehicle communication and improve traffic safety and performance The road-constrained, high mobility of vehicles, their unbounded power source, and the emergence of roadside wireless infrastructures make VANETs a challenging research topic A key to the development of protocols for inter-vehicle communication and services lies in the knowledge of the topological characteristics of the VANET communication graph This paper explores the dynamics of VANETs in urban environments and investigates the impact of these findings in the design of VANET routing protocols Using both real and realistic mobility traces, we study the networking shape of VANETs under different transmission and market penetration ranges Given that a number of RSUs have to be deployed for disseminating information to vehicles in an urban area, we also study their impact on vehicular connectivity Through extensive simulations we investigate the performance of VANET routing protocols by exploiting the knowledge of VANET graphs analysis

Proceedings ArticleDOI
09 Jan 2010
TL;DR: This paper evaluates the performance of multi-hop broadcast communication using the ns-2 simulator with vehicles following a shockwave mobility pattern in fully-connected traffic streams and proposes mechanism to improve broadcast reliability using dynamic transmission range that leverages the understanding of fundamental traffic flow relationships.
Abstract: A primary goal of intelligent transportation systems (ITS) is to improve road safety The ability for vehicles to communicate is a promising way to alleviate traffic accidents by reducing the response time associated with human reaction to nearby drivers In addition the limitations of standard driving can be overcome by providing drivers with instantaneous information about complications up ahead Shockwaves, induced by vehicle speed differentials, are a typical mobility pattern that occurs with the formation and propagation of vehicle queues These induce sudden braking and increase the occurrence of traffic incidents In this paper, we investigate safety applications in highways with shockwave mobility and different lane configurations in vehicular ad hoc networks (VANET) We evaluate the performance of multi-hop broadcast communication using the ns-2 simulator with vehicles following a shockwave mobility pattern in fully-connected traffic streams We propose mechanism to improve broadcast reliability using dynamic transmission range that leverages our understanding of fundamental traffic flow relationships

Proceedings ArticleDOI
29 Nov 2010
TL;DR: Using analytical models, the results show that the mechanism defined in the standard can satisfy the needed latency requirements, but cannot satisfy the required reliability for safety message delivery.
Abstract: Vehicular ad-hoc networks (VANETs) will enable a wide variety of future inter-vehicle and vehicle-to-roadside applications. These services will span a large range of functionality, such as those supporting vehicular safety, to those used for best-effort roadside advertising. To support this wide range, the IEEE 802.11p standard defines seven communication channels, consisting of a single control channel for safety applications, and six service channels which can be used for other purposes. To allow a single radio interface to support both types of applications, the standard defines a channel coordination mechanism that allows the vehicular radio to alternately access the control and service channels. When this happens it is very important that safety messages are transmitted with high reliability and low latency. Using analytical models, this paper provides a performance evaluation of vehicular safety message delivery. Our results show that the mechanism defined in the standard can satisfy the needed latency requirements, but cannot satisfy the required reliability for safety message delivery.