Benets of tight coupled architectures for the integration of GNSS receiver and Vanet transceiver

Vehicular adhoc networks (VANETs) are one emerging type of networks that will enable a broad range of applications such as public safety, traffic management, traveler information support and entertain ment. Whether wireless access may be asynchronous or synchronous (respectively as in the upcoming IEEE 8021.11p standard or in some alternative emerging solutions), a synchronization among nodes is required. Moreover, the information on position is needed to let vehicular services work and to correctly forward the messages. As a result, timing and positioning are a strong prerequisite of VANETs. Also the diffusion of enhanced GNSS Navigators paves the way to the integration between GNSS receivers and VANET transceiv ers. This position paper presents an analysis on potential benefits coming from a tightcoupling between the two: the dissertation is meant to show to what extent Intelligent Transportation System (ITS) services could benefit from the proposed architectur

Determining the representative factors affecting warning message dissemination in VANETs

In this paper, we present a statistical analysis based on the 2k factorial methodology to determine the representative factors affecting traffic safety applications in Vehicular ad hoc networks (VANETs). Our purpose is to determine what are the key factors affecting Warning Message Dissemination (WMD) in order to concentrate on such parameters, thus reducing the amount of required simulation time when evaluating VANETs. Simulation results show that the key factors affecting warning messages delivery are: (i) the transmission range, (ii) the radio propagation model used, and (iii) the density of vehicles. Based on this statistical analysis, we evaluate a compound key factor: neighbor density. This factor combines the above-mentioned factors into a single entity, reducing the number of factors that must be taken into account for VANET researchers to evaluate the benefits of their proposals.This work was partially supported by the Ministerio de Educacion y Ciencia, Spain, under Grant TIN2008-06441-C02-01, and by the Fundacion Antonio Gargallo, under Grant 2009/B001.Martínez Domínguez, FJ.; Toh, CK.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2012). Determining the representative factors affecting warning message dissemination in VANETs. Wireless Personal Communications. 67(2):295-314. https://doi.org/10.1007/s11277-010-9989-4S295314672Eichler, S. (2007). Performance evaluation of the IEEE 802.11p WAVE communication standard. In Proceedings of the vehicular technology conference (VTC-2007 Fall), USA.Fall, K., & Varadhan, K. (2000). ns notes and documents. The VINT Project. UC Berkeley, LBL, USC/ISI, and Xerox PARC. Available at http://www.isi.edu/nsnam/ns/ns-documentation.html .Fasolo, E., Zanella, A., & Zorzi, M. (2006). An effective broadcast scheme for alert message propagation in vehicular ad hoc networks. In Proceedings of the IEEE International Conference on Communications, Istambul, Turkey.Korkmaz, G., Ekici, E., Ozguner, F., & Ozguner, U. (2004). Urban multi-hop broadcast protocols for inter-vehicle communication systems. In Proceedings of First ACM Workshop on Vehicular Ad Hoc Networks (VANET 2004).Martinez, F. J., Toh, C.-K., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2009). Realistic radio propagation models (RPMs) for VANET simulations. In IEEE wireless communications and networking conference (WCNC), Budapest, Hungary.Martinez, F. J., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2008). CityMob: A mobility model pattern generator for VANETs. In IEEE vehicular networks and applications workshop (Vehi-Mobi, held with ICC), Beijing, China.Martinez, F. J., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2009). A performance evaluation of warning message dissemination in 802.11p based VANETs. In IEEE local computer networks conference (LCN 2009), Zürich, Switzerland.Torrent-Moreno, M., Santi, P., & Hartenstein, H. (2005). Fair sharing of bandwidth in VANETs. In Proceedings of the 2nd ACM international workshop on vehicular ad hoc networks, Germany.Tseng Y.-C., Ni S.-Y., Chen Y.-S., Sheu J.-P. (2002) The broadcast storm problem in a mobile ad hoc network. Wireless Networks 8: 153–167Wisitpongphan N., Tonguz O., Parikh J., Mudalige P., Bai F., Sadekar V. (2007) Broadcast storm mitigation techniques in vehicular ad hoc networks. Wireless Communications IEEE 14(6): 84–94. doi: 10.1109/MWC.2007.4407231Yang, X., Liu, J., Zhao, F., & Vaidya, N. H. (2004). A vehicle-to-vehicle communication protocol for cooperative collision warning. In Proceedings of the first annual international conference on mobile and ubiquitous systems: Networking and services (MobiQuitous’04).Yoon, J., Liu, M., & Noble, B. (2003). Random waypoint considered harmful. Proceedings of IEEE INFOCOMM 2003, San Francisco, California, USA.Zang, Y., Stibor, L., Cheng, X., Reumerman, H.-J., Paruzel, A., & Barroso, A. (2007). Congestion control in wireless networks for vehicular safety applications. In Proceedings of the 8th European Wireless Conference, Paris, France

Design and analysis of a beacon-less routing protocol for large volume content dissemination in vehicular ad hoc networks

Largevolumecontentdisseminationispursuedbythegrowingnumberofhighquality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors’ best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well

Quality of service aware data dissemination in vehicular Ad Hoc networks

Des systèmes de transport intelligents (STI) seront éventuellement fournis dans un proche avenir pour la sécurité et le confort des personnes lors de leurs déplacements sur les routes. Les réseaux ad-hoc véhiculaires (VANETs) représentent l'élément clé des STI. Les VANETs sont formés par des véhicules qui communiquent entre eux et avec l'infrastructure. En effet, les véhicules pourront échanger des messages qui comprennent, par exemple, des informations sur la circulation routière, les situations d'urgence et les divertissements. En particulier, les messages d'urgence sont diffusés par des véhicules en cas d'urgence (p.ex. un accident de voiture); afin de permettre aux conducteurs de réagir à temps (p.ex., ralentir), les messages d'urgence doivent être diffusés de manière fiable dans un délai très court. Dans les VANETs, il existe plusieurs facteurs, tels que le canal à pertes, les terminaux cachés, les interférences et la bande passante limitée, qui compliquent énormément la satisfaction des exigences de fiabilité et de délai des messages d'urgence. Dans cette thèse, en guise de première contribution, nous proposons un schéma de diffusion efficace à plusieurs sauts, appelé Dynamic Partitioning Scheme (DPS), pour diffuser les messages d'urgence. DPS calcule les tailles de partitions dynamiques et le calendrier de transmission pour chaque partition; à l'intérieur de la zone arrière de l'expéditeur, les partitions sont calculées de sorte qu'en moyenne chaque partition contient au moins un seul véhicule; l'objectif est de s'assurer que seul un véhicule dans la partition la plus éloignée (de l'expéditeur) est utilisé pour diffuser le message, jusqu'au saut suivant; ceci donne lieu à un délai d'un saut plus court. DPS assure une diffusion rapide des messages d'urgence. En outre, un nouveau mécanisme d'établissement de liaison, qui utilise des tonalités occupées, est proposé pour résoudre le problème du problème de terminal caché. Dans les VANETs, la Multidiffusion, c'est-à-dire la transmission d'un message d'une source à un nombre limité de véhicules connus en tant que destinations, est très importante. Par rapport à la diffusion unique, avec Multidiffusion, la source peut simultanément prendre en charge plusieurs destinations, via une arborescence de multidiffusion, ce qui permet d'économiser de la bande passante et de réduire la congestion du réseau. Cependant, puisque les VANETs ont une topologie dynamique, le maintien de la connectivité de l'arbre de multidiffusion est un problème majeur. Comme deuxième contribution, nous proposons deux approches pour modéliser l'utilisation totale de bande passante d'une arborescence de multidiffusion: (i) la première approche considère le nombre de segments de route impliqués dans l'arbre de multidiffusion et (ii) la seconde approche considère le nombre d'intersections relais dans l'arbre de multidiffusion. Une heuristique est proposée pour chaque approche. Pour assurer la qualité de service de l'arbre de multidiffusion, des procédures efficaces sont proposées pour le suivi des destinations et la surveillance de la qualité de service des segments de route. Comme troisième contribution, nous étudions le problème de la congestion causée par le routage du trafic de données dans les VANETs. Nous proposons (1) une approche de routage basée sur l’infonuagique qui, contrairement aux approches existantes, prend en compte les chemins de routage existants qui relaient déjà les données dans les VANETs. Les nouvelles demandes de routage sont traitées de sorte qu'aucun segment de route ne soit surchargé par plusieurs chemins de routage croisés. Au lieu d'acheminer les données en utilisant des chemins de routage sur un nombre limité de segments de route, notre approche équilibre la charge des données en utilisant des chemins de routage sur l'ensemble des tronçons routiers urbains, dans le but d'empêcher, dans la mesure du possible, les congestions locales dans les VANETs; et (2) une approche basée sur le réseau défini par logiciel (SDN) pour surveiller la connectivité VANET en temps réel et les délais de transmission sur chaque segment de route. Les données de surveillance sont utilisées en entrée de l'approche de routage.Intelligent Transportation Systems (ITS) will be eventually provided in the near future for both safety and comfort of people during their travel on the roads. Vehicular ad-hoc Networks (VANETs), represent the key component of ITS. VANETs consist of vehicles that communicate with each other and with the infrastructure. Indeed, vehicles will be able to exchange messages that include, for example, information about road traffic, emergency situations, and entertainment. Particularly, emergency messages are broadcasted by vehicles in case of an emergency (e.g., car accident); in order to allow drivers to react in time (e.g., slow down), emergency messages must be reliably disseminated with very short delay. In VANETs, there are several factors, such as lossy channel, hidden terminals, interferences and scarce bandwidth, which make satisfying reliability and delay requirements of emergency messages very challenging. In this thesis, as the first contribution, we propose a reliable time-efficient and multi-hop broadcasting scheme, called Dynamic Partitioning Scheme (DPS), to disseminate emergency messages. DPS computes dynamic partition sizes and the transmission schedule for each partition; inside the back area of the sender, the partitions are computed such that in average each partition contains at least a single vehicle; the objective is to ensure that only a vehicle in the farthest partition (from the sender) is used to disseminate the message, to next hop, resulting in shorter one hop delay. DPS ensures fast dissemination of emergency messages. Moreover, a new handshaking mechanism, that uses busy tones, is proposed to solve the problem of hidden terminal problem. In VANETs, Multicasting, i.e. delivering a message from a source to a limited known number of vehicles as destinations, is very important. Compared to Unicasting, with Multicasting, the source can simultaneously support multiple destinations, via a multicast tree, saving bandwidth and reducing overall communication congestion. However, since VANETs have a dynamic topology, maintaining the connectivity of the multicast tree is a major issue. As the second contribution, we propose two approaches to model total bandwidth usage of a multicast tree: (i) the first approach considers the number of road segments involved in the multicast tree and (ii) the second approach considers the number of relaying intersections involved in the multicast tree. A heuristic is proposed for each approach. To ensure QoS of the multicasting tree, efficient procedures are proposed for tracking destinations and monitoring QoS of road segments. As the third contribution, we study the problem of network congestion in routing data traffic in VANETs. We propose (1) a Cloud-based routing approach that, in opposition to existing approaches, takes into account existing routing paths which are already relaying data in VANETs. New routing requests are processed such that no road segment gets overloaded by multiple crossing routing paths. Instead of routing over a limited set of road segments, our approach balances the load of communication paths over the whole urban road segments, with the objective to prevent, whenever possible, local congestions in VANETs; and (2) a Software Defined Networking (SDN) based approach to monitor real-time VANETs connectivity and transmission delays on each road segment. The monitoring data is used as input to the routing approach

Dissimilarity metric based on local neighboring information and genetic programming for data dissemination in vehicular ad hoc networks (VANETs)

This paper presents a novel dissimilarity metric based on local neighboring information and a genetic programming approach for efficient data dissemination in Vehicular Ad Hoc Networks (VANETs). The primary aim of the dissimilarity metric is to replace the Euclidean distance in probabilistic data dissemination schemes, which use the relative Euclidean distance among vehicles to determine the retransmission probability. The novel dissimilarity metric is obtained by applying a metaheuristic genetic programming approach, which provides a formula that maximizes the Pearson Correlation Coefficient between the novel dissimilarity metric and the Euclidean metric in several representative VANET scenarios. Findings show that the obtained dissimilarity metric correlates with the Euclidean distance up to 8.9% better than classical dissimilarity metrics. Moreover, the obtained dissimilarity metric is evaluated when used in well-known data dissemination schemes, such as p-persistence, polynomial and irresponsible algorithm. The obtained dissimilarity metric achieves significant improvements in terms of reachability in comparison with the classical dissimilarity metrics and the Euclidean metric-based schemes in the studied VANET urban scenarios

Designing Smart Adaptive Flooding in MANET using Evolutionary Algorithm

International audienceThis paper deals with broadcasting warning / emergency messages in mobile ad hoc networks. Traditional broadcasting schemes tend to focus on usually high and homogeneous neighborhood densities environments. This paper presents a broadcasting protocol that locally and dynamically adapts its strategy to the neighborhood densities. The behavior of the protocol is tuned using various internal parameters. Multiple combinations of those parameters have been pre-computed as optimal solutions for a range of neighborhood densities, and the most relevant one is dynamically chosen depending on the locally perceived environment. The combinations were determined by coupling an evolutionary algorithm and a network simulator, using a statistically realistic radio-propagation model (Shadowing Pattern). This approach is compared with other probabilistic methods while broadcasting an emergency message in vehicular ad hoc networks with variable and heterogeneous vehicle densities. In such a context, it is expected from the network to enable each node to receive the warning message. The results show that our protocol covers the whole network, whereas other methods only have a probability of 0.57 to 0.9 to cover the entire network

A Comprehensive Approach to WSN-Based ITS Applications: A Survey

In order to perform sensing tasks, most current Intelligent Transportation Systems (ITS) rely on expensive sensors, which offer only limited functionality. A more recent trend consists of using Wireless Sensor Networks (WSN) for such purpose, which reduces the required investment and enables the development of new collaborative and intelligent applications that further contribute to improve both driving safety and traffic efficiency. This paper surveys the application of WSNs to such ITS scenarios, tackling the main issues that may arise when developing these systems. The paper is divided into sections which address different matters including vehicle detection and classification as well as the selection of appropriate communication protocols, network architecture, topology and some important design parameters. In addition, in line with the multiplicity of different technologies that take part in ITS, it does not consider WSNs just as stand-alone systems, but also as key components of heterogeneous systems cooperating along with other technologies employed in vehicular scenarios

Seamless Connectivity Techniques in Vehicular Ad-hoc Networks

In this chapter we describe the traditional techniques used for seamless connectivity in heterogeneous wireless network environments, and in particular adopt them in VANETs, where V2V and V2I represent the main communication protocols. Section 2 deals with the basic features of Vertical Handover (VHO) in the general context of a hybrid wireless network environment, and it discusses how decision metrics can affect handover performance (i.e. number of handover occurrences, and throughput). Instead, Section 3 briefly introduces two proposed techniques achieving seamless connectivity in VANETs. The first technique is a vertical handover mechanism applied to V2I-only communication environments; it is presented in Section 4 via an analytical model, and main simulated results are shown. The second approach is described in Section 5. It addresses a hybrid vehicular communication protocol (i.e. called as Vehicle-to-X) performing handover between V2V and V2I communications, and vice versa.