Recently a number of communications schemes have been proposed for Vehicular Ad hoc Networks (VANETs). One of these, the Universal Geocast Scheme (UGS) proposed by Hossein Pishro-Nik and Mohammad Nekoui, provides for a diverse variety of VANET-specific characteristics such as time-varying topology, protocol variation based on road congestion, and support for non line-of-sight communication. In this research, the UGS protocol is extended to consider inter-vehicle multi-hop connections in intersections with surrounding obstructions along with single-hop communications in an open road scenario. Since UGS is a probabilistic, repetition-based scheme, it supports the capacity-delay tradeoffs crucial for periodic safety message exchange. The approach is shown to support both vehicle-to-vehicle and vehicle-to-infrastructure communication. This research accurately evaluates this scheme using network (NS-2) and mobility (SUMO) simulators, verifying two crucial elements of successful VANETs, received packet ratio and message delay. A contemporary wireless radio propagation model is used to augment accuracy. Results show a 6% improvement in received packet ratio in intersection simulations combined with a decrease in average packet delay versus a previous, well-known inter-vehicle communication protocol.

L'objectif de cette thèse CIFRE est de contribuer à la communication véhiculaire autonome et au développement de la mobilité urbaine. Les travaux sont basés sur les limitations et défis de la communication par radio pour les applications de sécurité et envisagent de déployer le système d'éclairage des véhicules en tant que solution de communication de soutien pour le platooning d'IVC-activées par VC Véhicules autonomes. L'objectif principale de cette recherche doctorale consiste à intégrer le système VLC dans l'architecture existante de C-ITS en développant un prototype VLC, ainsi que des algorithmes de transfert suffisants permettant VLC, RF et des solutions basées sur la perception afin d'assurer les exigences de sécurité maximales et l'échange continu d'informations entre les véhicules. La faisabilité et l'efficacité de la mise en oeuvre du système et des algorithmes de transfert ont fait l'objet de recherches approfondies sur six chapitres, destinés à faciliter une progression logique des matériaux et permettre un accès relativement facile. En plus de l'amélioration de la capacité routière en utilisant les systèmes de conduite autonome à la base de convoi. Les simulations réalisées ainsi que les résultats expérimentaux ont montré que l'intégration de VLC avec les solutions existantes RF a un avantage certain dans la qualité du canal de communication et les exigences de sécurité d'un système de platooning quand un algorithme approprié est utilisé. / This thesis effort contributes to the autonomous vehicular communication and urban mobility improvements. The work addresses the main radio-based V2V communication limitations and challenges for ITS hard-safety applications and intends to deploy the vehicular lighting system as a supportive communication solution for platooning of IVC-enabled autonomous vehicles. The ultimate objectives of this Ph.D research are to integrate the VLC system within the existing C-ITS architecture by developing a VLC prototype, together with sufficient, hand-over algorithms enabling VLC, RF, and perception-based solutions in order to ensure the maximum safety requirements and the continuous information exchange between vehicles. The feasibility and efficiency of the VLC-RF system implementation and hand-over algorithms were subjects to deep investigations over six self-contained chapters meant to facilitate a logical progression of materials and to enable a relatively easy access. In addition to the improvement in road capacity by utilizing the convoy-based autonomous driving systems. The carried out simulations followed-up by experimental results proved that the integration of VLC with the existed RF solutions lead to a definite benefit in the communication channel quality and safety requirements of a platooning system when a proper hand-over algorithm is utilized.

Les réseaux véhiculaires font l’objet de recherches actives aussi bien dans le domaine des réseaux que dans celui des transports. Le potentiel des réseaux véhiculaires à fournir des services comme l’information sur le trafic en temps réel ou sur les accidents font de cette technologie un domaine de recherche très important. Ces réseaux peuvent comporter des communications véhicule-à-véhicule (V2V), véhicule-à-infrastructure (V2I), ou une combinaison des deux. La norme IEEE 1609.4 est la spécification multicanal pour l’IEEE802.11p/WAVE des réseaux véhiculaires (VANETs). Elle utilise sept canaux, l'un étant un canal de contrôle (CCH) qui est écouté par les équipements de façon périodique, et les six autres canaux sont utilisés comme canaux de service (SCH). Elle définit également une division du temps en alternance entre les intervalles CCH et les intervalles SCH. L’objet de cette thèse de doctorat est d’évaluer les performances des réseaux VANETs dans le cas des communications véhiculaires sans infrastructure, et au niveau des couches inférieures du standard 802.11p. Dans la première partie, nous proposons une approche MAC d’allocation multicanal opportuniste dans un contexte sans infrastructure. Cette approche est conforme à la norme IEEE1609.4 -2010 de l'architecture WAVE pour un fonctionnement multicanal, et elle est conçue pour des applications de services de données (non urgentes), tout en assurant la transmission des messages de sécurité routière et des paquets de contrôle. Pour maintenir la qualité de service des deux types de messages (urgents et non-urgents) en exploitant la capacité du canal, deux solutions sont proposées. Dans la deuxième partie, lorsque le véhicule sélectionne son canal et contrôle son alternance temporelle entre CCH et SCH, il commence à transmettre ses paquets, en particulier sur le canal CCH, lesquels ont une durée de péremption. Nous présentons une approche visant à minimiser les collisions des émetteurs tout en évitant la contention de début d’intervalle, en particulier dans un contexte de densité élevée de véhicules. Même si les mécanismes proposés ci-dessus diminuent le taux de collision, il n’est pas possible de les supprimer complètement. Dans la troisième partie, nous traitons le problème des collisions entre les paquets diffusés sur le CCH, en particulier quand la charge des messages transmis dépasse la capacité du canal. Pour cela, nous proposons un nouveau mécanisme de codage réseau analogique adapté à la modulation QPSK pour les messages diffusés sur le CCH. Dans cette approche des symboles connus sont envoyés avant d'envoyer les paquets pour estimer les paramètres du canal et une solution explicite est utilisée pour inverser le système de la superposition de deux paquets / Vehicular networks are the subject of active research in the field of networks as well as transport. The potential for vehicular networks to provide services such as traffic information in real time or accident makes this technology a very important research domain. These networks may support vehicle-to-vehicle communications (V2V), vehicle-to-infrastructure (V2I), or a combination of both. The IEEE 1609.4 is the specification of multichannel operations for IEEE802 .11p/WAVE vehicular networks (VANETs). It uses seven channels; one being a control channel (CCH) which is listened periodically by the vehicles and the other six channels are used as service channels (SCH). It also defines a time division between alternating CCH and SCH intervals. The purpose of this thesis is to evaluate the performance of VANETs in the case of vehicular communications without infrastructure, and at the lower layers of IEEE 802.11p standard. In the first part, we propose an opportunistic multichannel MAC allocation in an environment without infrastructure. This approach is consistent with the standard IEEE1609.4 -2010/WAVE for a multi-channel operation, and it is designed for data services applications (non-urgent), while ensuring the transmission of road safety messages and control packets. To maintain the quality of service of the two types of messages (urgent and non-urgent) by exploiting the channel capacity, two solutions are proposed. In the second part, when the vehicle selects its channel and controls its temporal alternation between CCH and SCH, it starts transmitting its packets, particularly on the CCH, which have an expiration time. We present an approach to minimize collisions between transmitters while avoiding contention at the beginning of CCH interval, especially in a context of high vehicular density. Although the mechanisms proposed above reduce the collision rate, it is not possible to completely remove these collisions. In the third part, we address the problem of collisions between broadcast packets on the CCH, especially when the load of transmitted messages exceeds the channel capacity. For this purpose, we propose a new analog network coding mechanism adapted to QPSK modulation for broadcast messages on the CCH. In this approach, known symbols are sent before sending the packets to estimate the channel parameters and an explicit solution is used to reverse the system of the superposition of two packets

Vehicular ad-hoc networks (VANETs) are used for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. The IEEE 802.11p/WAVE (Wireless Access in Vehicular Environment) and with WAVE Short Messaging Protocol (WSMP) has been proposed as the standard protocol for designing applications for VANETs. This communication protocol must be thoroughly tested before reliable and efficient applications can be built using its protocols. In this paper, we perform on-road experiments in a variety of scenarios to evaluate the performance of the standard. We use commercial VANET devices with 802.11p/WAVE compliant chipsets for both BSM (basic safety messages) as well as video streaming applications using WSMP as a communication protocol. We show that while the standard performs well for BSM application in lightly loaded conditions, the performance becomes inferior when traffic and other performance metric increases. Furthermore, we also show that the standard is not suitable for video streaming due to the bursty nature of traffic and the bandwidth throttling, which is a major shortcoming for V2X applications.

Cette thèse analyse la possibilité d'utiliser des communications sans fil inter-véhiculaires pour améliorer la sécurité routière. Les performances du nouveau réseau ainsi créé (réseau ad-hoc véhiculaire) sont étudiées analytiquement et par des simulations dans un environnement réaliste. La thèse se concentre surtout sur des scénarios avec une forte densité de véhicules. Dans ce cas, l'accès au support devient un problème essentiel, en principal pour les applications de sécurité routière qui nécessitent une qualité de service élevée pour fonctionner dans un tel contexte. Ce travail montre que la version actuelle du standard IEEE 802.11, proposé comme méthode d'accès dans les réseaux véhiculaires, ne peut pas résoudre ce problème de passage à l'échelle pour supporter correctement les applications de sécurité routière. Plusieurs améliorations possibles sont analysées, liées à l'utilisation optimale de certains paramètres du protocole comme la taille de la fenêtre de contention ou bien le seuil de détection de la porteuse. Des nouveaux mécanismes adaptatifs visant ces paramètres sont proposés et les améliorations ainsi obtenues sont non-négligeables. Finalement, une nouvelle méthode d'accès est définie, en tenant compte des caractéristiques des applications de sécurité routière. Toujours basée sur des techniques CSMA, cette technique donne des résultats largement supérieurs à la version standard actuelle. / The equipment of vehicles with wireless communication devices in order to improve road safety is a major component of a future intelligent transportation system. The success and availability of IEEE 802.11-based products make this technology the main competitor for the Medium Access Control (MAC) layer used in vehicle-to-vehicle communication. The IEEE 802.11p amendment has been specially designed in this special context of wireless access in vehicular environments. However, as all the other approaches based on Carrier Sense Multiple Access (CSMA), this protocol presents scalability problems, which leads to poor performance in high density scenarios, quite frequent in the case of a vehicular ad hoc network (VANET). This thesis studies the congestion control problem in the context of safety vehicular communications, with a special focus on the back-off mechanism and the carrier sense function. First of all, a number of important characteristics presented by the safety messages are discovered and understood by the means of an analytical framework. Second, the lessons learned from the analytical study are put into practice with the design of two adaptive mechanisms (one for the contention window and the other one for the carrier sense threshold) that take into account the local vehicular density. These mechanisms remain simple, but highly efficient, while also being straightforward to integrate in IEEE 802.11 devices. Finally, by taking into account the most important properties of a safety VANET, a new CSMA-based MAC protocol is proposed. This new access method, named Safety Range CSMA (SR-CSMA), relies on the idea that collisions can not be avoided in a high density network. However, by increasing the number of simultaneous transmissions between geographically distant nodes, SR-CSMA manages to better protect the immediate neighborhood, the most important area for safety applications.

In this research oriented master’s thesis we have proposed a future vision of ITS (Intelligent Transport Systems) by utilizing the novel concept of HWA (Heterogeneous Wireless Access). Our proposal is backed by the investigation of the results of experiments conducted at CERES (Centre for Research on Embedded Systems), Halmstad University, Sweden to evaluate the quality of communication for V2V and V2I by using the IEEE 802.11p standard. We have also identified the expected scenarios with need of any other communication technology in replacement of IEEE 802.11p for V2V and V2I communication. We have also investigated the relevant research projects, experiments and their results on the basis of predefined constraints. In the investigated research projects the concept of HWA has been correlated with our proposal of HWA for ITS. We have identified that for smooth integration of any communication technology with IEEE 802.11p, an efficient and smart vertical handover protocol or method will be required. We have presented a blue print of a custom designed vertical handover technique which can be implemented for future ITS with further enhancements and experimental evaluations. We have also evaluated the worst case scenarios to assess the suitability of the HWA for the ITS. We proposed few solutions based on the evaluation of communication scenarios for the integration of IEEE 802.11p with other wireless communication technologies. Finally we have provided some conclusions and suggested future researches which must be conducted to realize the dream of ITS with support of HWA.

<p>The number of vehicles has increased significantly in recent years, which causeshigh density in traffic and further problems like accidents and road congestions.A solution regarding to this problem is vehicle-to-vehicle communication, wherevehicles are able to communicate with their neighboring vehicles even in the absenceof a central base station, to provide safer and more efficient roads and toincrease passenger safety.The goal of this thesis is to investigate basic physical layer parameters of ainter-vehicle communication system, like emission power, spectral emission, errorvector magnitude, guard interval, ramp-up/down time, and third order interceptpoint. I also studied the intelligent transportation system’s channel layout inEurope, how the interference of other systems are working in co-channel and adjacentchannels, and some proposals to use the allocated frequency bands. On theother hand, the fundamentals of OFDM transmission and definitions of OFDMkey parameters in IEEE 802.11p are investigated.The focus of this work is on the measurement of transmitter frontend parametersof a new testbed designed and fabricated in order to be used at inter-vehiclecommunication based on IEEE 802.11p.</p> / Road safety applications, Vehicle-to-Vehicle communication

The number of vehicles has increased significantly in recent years, which causeshigh density in traffic and further problems like accidents and road congestions.A solution regarding to this problem is vehicle-to-vehicle communication, wherevehicles are able to communicate with their neighboring vehicles even in the absenceof a central base station, to provide safer and more efficient roads and toincrease passenger safety.The goal of this thesis is to investigate basic physical layer parameters of ainter-vehicle communication system, like emission power, spectral emission, errorvector magnitude, guard interval, ramp-up/down time, and third order interceptpoint. I also studied the intelligent transportation system’s channel layout inEurope, how the interference of other systems are working in co-channel and adjacentchannels, and some proposals to use the allocated frequency bands. On theother hand, the fundamentals of OFDM transmission and definitions of OFDMkey parameters in IEEE 802.11p are investigated.The focus of this work is on the measurement of transmitter frontend parametersof a new testbed designed and fabricated in order to be used at inter-vehiclecommunication based on IEEE 802.11p. / Road safety applications, Vehicle-to-Vehicle communication

The C2X Communication is of high interest to the automotive industry. Ongoing research on this topic mainly bases on the simulation of Vehicular Ad Hoc Networks. In order to estimate the necessary level of simulation details their impact on the results needs to be examined. This thesis focuses on different channel models as the freespace, shadowing, and Ricean model, along with varying parameters. For these simulations the network simulator ns-2 is extended to provide IEEE 802.11p compliance. However, the WAVE mode is not considered since it is still under development and not finally approved. Besides a more sophisticated packet error model than the existing implementation, as well as a link adaptation algorithm, is added. In this thesis several simulations examine specific details of wireless communication systems such as fairness of multiple access, interferences, throughput, and variability. Furthermore, the simulation points out some unexpected phenomena as starving nodes and saturation effects in multi hop networks. Those led to the conclusion that the IEEE 802.11 draft amendment does not solve known problems of the original IEEE 802.11 standard.

Le cadre général de cette thèse porte sur les communications véhicule à véhicule (V2V). L'objectif principal de ce type de communication est d'améliorer la sécurité routière et d'optimiser la fluidité du trafic. Les performances de systèmes de communication embarqués dépendent principalement de la configuration des antennes, du type de récepteurs utilisés (modem) et du canal de propagation. Le sujet de la thèse se concentre précisément sur l'élaboration d'un outil de simulation robuste et fiable pour optimiser les choix technologiques d'antennes et leurs implantations à bord. Il permettra de limiter ainsi le recours aux prototypes et aux essais de roulage. Dans un premier temps, nous avons proposé une méthode de type géométrique-stochastique pour modéliser des canaux de propagation d'un système de communication V2V. Cette méthode permet de définir des scénarios dynamiques et sa flexibilité nous offre l'opportunité de paramétrer les caractéristiques d'un canal de propagation. Nous montrons pour l'essentiel de quelle manière l'agencement et le nombre de diffuseurs de forme simple peuvent contribuer à influencer les statistiques de l'étalement des retards, la distribution des angles d'arrivée et les spectres Doppler. Dans la deuxième partie de ces travaux, nous nous focalisons sur la problématique d'intégration d'antenne. Il a été constaté qu'il est particulièrement utile de simplifier la maquette numérique du véhicule complet lors d'une simulation électromagnétique de l'antenne intégrée à bord de ce véhicule. De plus, dans cette section, nous avons étudié la limite de la validité de substitution d'une antenne intégrée à bord par son seul diagramme de rayonnement dans les modèles de canaux de propagation. A partir de cette étude, nous en avons déduit, que les interactions électromagnétiques avec les éléments se situant dans le champ-proche n'étaient plus valides. Ainsi, une stratégie de correction a été trouvée en considérant l'élément en champ proche dans la simulation initiale de l'antenne intégrée sur le véhicule. L'évaluation des performances d'antennes, en termes de taux d'erreurs paquet, après l'implémentation de la couche physique du standard 802. 11 p, est au cœur de la troisième partie de cette thèse. Des résultats de simulation, pour chaque configuration d'antenne, ont été donnés pour plusieurs combinaisons de paramètres de couche PHY tels que le débit et la longueur de paquet. La dernière partie de ce manuscrit traite de la présentation d'une campagne de mesure qui a été réalisée principalement dans un environnement de type rural. Les essais de roulage avaient pour but de démontrer la capacité des méthodes de simulation à faire un choix approprié d'installation d'antenne. Nous avons constaté que les tendances attendues des performances de communication en termes de PER sont globalement prévisibles à partir de notre modèle bien que nous ayons obtenu des résultats surprenants dans certains cas. Ce qui nécessitera une enquête plus approfondie. / The general framework of this Ph.D. thesis deals with Vehicle to Vehicle (V2V) communications. This communication is principally dedicated to reinforce security through exchange of information between vehicles in case of unexpected events. The development of V2V solutions requires the understanding and merging of a number of techniques from several communication technology areas. Indeed, the performance of these systems are related to three main blocks: the implementation of the modems, the antenna configuration and the fast varying electromagnetic environment surrounding the transmitter and the receiver. The purpose of this PhD thesis is precisely to elaborate a design strategy to investigate all the different blocks constituting the communication chain. The ultimate goal is to optimize antenna selection and location on board the vehicle. In the first place, we proposed a geometry-based stochastic channel modelling approach to develop virtual dynamic scenarios. It was shown that the most common propagation environments such as rural, highway or urban-like propagation channels are reached through adjustment or numbers and location of simple metallic plates. Using this method, we are able to emulate the characteristics, such as the delay spread, angles of arrival distribution and the Doppler spectrum, of these typical driving scenarios. Moreover, we dealt with antenna integration problems in the second part of this work. A study on the simplification of numerical models of vehicles was carried out. Furthermore in this section, we investigated the limit of validity of representing the integrated antenna on board vehicle solely by its radiation pattern. We deduced from this study that the interactions with the elements present in the near-field is no longer valid. Thus, a strategy to alleviate the degree of error was found upon consideration of the near-field scatter in the a-priori simulation of the antenna integrated on the vehicle. In the third part of this thesis, we evaluated the performance of different antenna configurations in terms of packet error rate after the embodiment of the PHY layer of the LEEE 802.11p standard. Simulation results, for each antenna configurations, was given for several combinations of PHY layer parameters such as data rate and packet length. The last part of this manuscript is dedicated to the presentation of a measurement campaign that was carried out in a rural driving environment. Results obtained from these functional tests were confronted with simulation results to demonstrate the strength of the latter. We found that the expected trends in communication performance in terms of PER are globally predictable from our model though we obtained surprising results in some cases, needing further investigation.