Secure Authentication and Privacy-Preserving Techniques in Vehicular Ad-hoc NETworks (VANETs)

In the last decade, there has been growing interest in Vehicular Ad Hoc NETworks (VANETs). Today car manufacturers have already started to equip vehicles with sophisticated sensors that can provide many assistive features such as front collision avoidance, automatic lane tracking, partial autonomous driving, suggestive lane changing, and so on. Such technological advancements are enabling the adoption of VANETs not only to provide safer and more comfortable driving experience but also provide many other useful services to the driver as well as passengers of a vehicle. However, privacy, authentication and secure message dissemination are some of the main issues that need to be thoroughly addressed and solved for the widespread adoption/deployment of VANETs. Given the importance of these issues, researchers have spent a lot of effort in these areas over the last decade. We present an overview of the following issues that arise in VANETs: privacy, authentication, and secure message dissemination. Then we present a comprehensive review of various solutions proposed in the last 10 years which address these issues. Our survey sheds light on some open issues that need to be addressed in the future

An efficient cluster-based service model for vehicular ad-hoc networks on motorways

Vehicular Ad-Hoc Networks (VANET) can, but not limited to provide users with useful traffic and environmental information services to improve travelling efficiency and road safety. The communications systems used in VANET include vehicle-to-vehicle communications (V2V) and vehicle-to-infrastructure communications (V2I). The transmission delay and the energy consumption cost for maintaining good-quality communications vary depending on the transmission distance and transmission power, especially on motorways where vehicles are moving at higher speeds. In addition, in modern transportation systems, electric vehicles are becoming more and more popular, which require a more efficient battery management, this also call for an efficient way of vehicular transmission. In this project, a cluster-based two-way data service model to provide real-time data services for vehicles on motorways is designed. The design promotes efficient cooperation between V2V and V2I, or namely V2X, with the objective of improving both service and energy performance for vehicular networks with traffic in the same direction. Clustering is an effective way of applying V2X in VANET systems, where the cluster head will take the main responsibility of exchanging data with Road Side Units (RSU) and other cluster members. The model includes local service data collection, data aggregation, and service data downloading. We use SUMO and OMNET++ to simulate the traffic scenarios and the network communications. Two different models (V2X and V2I) are compared to evaluate the performance of the proposed model under different flow speeds. From the results, we conclude that the cluster-based service model outperforms the non-clustered model in terms of service successful ratio, network throughput and energy consumption

A Mini Review of Peer-to-Peer (P2P) for Vehicular Communication

In recent times, peer-to-peer (P2P) has evolved, where it leverages the capability to scale compared to server-based networks. Consequently, P2P has appeared to be the future distributed systems in emerging several applications. P2P is actually a disruptive technology for setting up applications that scale to numerous concurrent individuals. Thus, in a P2P distributed system, individuals become themselves as peers through contributing, sharing, and managing the resources in a network. In this paper, P2P for vehicular communication is explored. A comprehensive of the functioning concept of both P2P along with vehicular communication is examined. In addition, the advantages are furthermore conversed for a far better understanding on the implementation

Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks

This book presents collective works published in the recent Special Issue (SI) entitled "Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks”. These works expose the readership to the latest solutions and techniques for MANETs and VANETs. They cover interesting topics such as power-aware optimization solutions for MANETs, data dissemination in VANETs, adaptive multi-hop broadcast schemes for VANETs, multi-metric routing protocols for VANETs, and incentive mechanisms to encourage the distribution of information in VANETs. The book demonstrates pioneering work in these fields, investigates novel solutions and methods, and discusses future trends in these field

Vehicular Networks with Infrastructure: Modeling, Simulation and Testbed

This thesis focuses on Vehicular Networks with Infrastructure. In the examined scenarios, vehicular nodes (e.g., cars, buses) can communicate with infrastructure roadside units (RSUs) providing continuous or intermittent coverage of an urban road topology. Different aspects related to the design of new applications for Vehicular Networks are investigated through modeling, simulation and testing on real field. In particular, the thesis: i) provides a feasible multi-hop routing solution for maintaining connectivity among RSUs, forming the wireless mesh infrastructure, and moving vehicles; ii) explains how to combine the UHF and the traditional 5-GHz bands to design and implement a new high-capacity high-efficiency Content Downloading using disjoint control and service channels; iii) studies new RSUs deployment strategies for Content Dissemination and Downloading in urban and suburban scenarios with different vehicles mobility models and traffic densities; iv) defines an optimization problem to minimize the average travel delay perceived by the drivers, spreading different traffic flows over the surface roads in a urban scenario; v) exploits the concept of Nash equilibrium in the game-theory approach to efficiently guide electric vehicles drivers' towards the charging stations. Moreover, the thesis emphasizes the importance of using realistic mobility models, as well as reasonable signal propagation models for vehicular networks. Simplistic assumptions drive to trivial mathematical analysis and shorter simulations, but they frequently produce misleading results. Thus, testing the proposed solutions in the real field and collecting measurements is a good way to double-check the correctness of our studie

Performance Evaluation of Vehicular Ad Hoc Networks using simulation tools

Recent studies demonstrate that the routing protocol performances in vehicular networks can improve using dynamic information on the traffic conditions. WSNs (Wireless Sensor Networks) and VANETs (Vehicular Ad Hoc Networks) are exactly related with this statement and represent the trend of wireless networks research program in the last years. In this context, a new type of network has been developed: in fact, HSVN (Hybrid Sensor and Vehicular Network) let WSNs and VANETs cooperate through dynamic information data exchanges with the aim to improve road safety, and especially to warn the driver and the co-pilot of any event occurred in the road ahead, such as traffic jam, accidents or bad weather. The results will be immediate: less accidents means more saved lives, less traffic means a pollution decrease, and from the technological point of view, this communication protocol will open the door to attractive services, such as downloading of multimedia services or internet browsing, that means easier, safer and more comfortable trips. It is out of doubt that speaking about cars and road technology developments, the market and the interests about this field increase exponentially. Recent projects such as CVIS [1] and COMeSafety [2], focused on improving the road driving, and are the concrete demonstration that this entire context can get soon very close to reality. Owing to their peculiar characteristics, VANETs require the definition of specific networking techniques, whose feasibility and performance are usually tested by means of simulation. Starting from this point, this project will present a HSVN platform, and will also introduce and evaluate a communication protocol between VANETs and WSNs using the NCTUns 6.0 [3] simulator. We will particularly analyze the performances of 2 types of Scenarios developed during our project. Both of them are in an urban context, but we will extract different useful results analyzing the packet losses, the throughput and the end-to-end packet delay

Certificate status information distribution and validation in vehicular networks

Vehicular ad hoc networks (VANETs) are emerging as an functional technology for providing a wide range of applications to vehicles and passengers. Ensuring secure functioning is one of the prerequisites for deploying reliable VANETs. The basic solution envisioned to achieve these requirements is to use digital certificates linked to a user by a trusted third party. These certificates can then be used to sign information. Most of the existing solutions manage these certificates by means of a central Certification Authority (CA). According to IEEE 1609.2 standard, vehicular networks will rely on the public key infrastructure (PKI). In PKI, a CA issues an authentic digital certificate for each node in the network. Therefore, an efficient certificate management is crucial for the robust and reliable operation of any PKI. A critical part of any certificate-management scheme is the revocation of certificates. The distribution of certificate status information process, as well as the revocation process itself, is an open research problem for VANETs.In this thesis, firstly we analyze the revocation process itself and develop an accurate and rigorous model for certificate revocation. One of the key findings of our analysis is that the certificate revocation process is statistically self-similar. As none of the currently common formal models for revocation is able to capture the self-similar nature of real revocation data, we develop an ARFIMA model that recreates this pattern. We show that traditional mechanisms that aim to scale could benefit from this model to improve their updating strategies.Secondly, we analyze how to deploy a certificate status checking service for mobile networks and we propose a new criterion based on a risk metric to evaluate cached status data. With this metric, the PKI is able to code information about the revocation process in the standard certificate revocation lists. Thus, users can evaluate a risk function in order to estimate whether a certificate has been revoked while there is no connection to a status checking server. Moreover, we also propose a systematic methodology to build a fuzzy system that assists users in the decision making process related to certificate status checking.Thirdly, we propose two novel mechanisms for distributing and validating certificate status information (CSI) in VANET. This first mechanism is a collaborative certificate status checking mechanism based on the use based on an extended-CRL. The main advantage of this extended-CRL is that the road-side units and repository vehicles can build an efficient structure based on an authenticated hash tree to respond to status checking requests inside the VANET, saving time and bandwidth. The second mechanism aims to optimize the trade- off between the bandwidth necessary to download the CSI and the freshness of the CSI. This mechanism is based on the use of a hybrid delta-CRL scheme and Merkle hash trees, so that the risk of operating with unknown revoked certificates remains below a threshold during the validity interval of the base-CRL, and CAs have the ability to manage this risk by setting the size of the delta-CRLs. Finally, we also analyze the impact of the revocation service in the certificate prices. We model the behavior of the oligopoly of risk-averse certificate providers that issue digital certificates to clients facing iden- tical independent risks. We found the equilibrium in the Bertrand game. In this equilibrium, we proof that certificate providers that offer better revocation information are able to impose higher prices to their certificates without sacrificing market share in favor of the other oligarchs.Las redes vehiculares ad hoc (VANETs) se están convirtiendo en una tecnología funcional para proporcionar una amplia gama de aplicaciones para vehículos y pasajeros. Garantizar un funcionamiento seguro es uno de los requisitos para el despliegue de las VANETs. Sin seguridad, los usuarios podrían ser potencialmente vulnerables a la mala conducta de los servicios prestados por la VANET. La solución básica prevista para lograr estos requisitos es el uso de certificados digitales gestionados a través de una autoridad de certificación (CA). De acuerdo con la norma IEEE 1609.2, las redes vehiculares dependerán de la infraestructura de clave pública (PKI). Sin embargo, el proceso de distribución del estado de los certificados, así como el propio proceso de revocación, es un problema abierto para VANETs.En esta tesis, en primer lugar se analiza el proceso de revocación y se desarrolla un modelo preciso y riguroso que modela este proceso conluyendo que el proceso de revocación de certificados es estadísticamente auto-similar. Como ninguno de los modelos formales actuales para la revocación es capaz de capturar la naturaleza auto-similar de los datos de revocación, desarrollamos un modelo ARFIMA que recrea este patrón. Mostramos que ignorar la auto-similitud del proceso de revocación lleva a estrategias de emisión de datos de revocación ineficientes. El modelo propuesto permite generar trazas de revocación sintéticas con las cuales los esquemas de revocación actuales pueden ser mejorados mediante la definición de políticas de emisión de datos de revocación más precisas. En segundo lugar, se analiza la forma de implementar un mecanismo de emisión de datos de estado de los certificados para redes móviles y se propone un nuevo criterio basado en una medida del riesgo para evaluar los datos de revocación almacenados en la caché. Con esta medida, la PKI es capaz de codificar la información sobre el proceso de revocación en las listas de revocación. Así, los usuarios pueden estimar en función del riesgo si un certificado se ha revocado mientras no hay conexión a un servidor de control de estado. Por otra parte, también se propone una metodología sistemática para construir un sistema difuso que ayuda a los usuarios en el proceso de toma de decisiones relacionado con la comprobación de estado de certificados.En tercer lugar, se proponen dos nuevos mecanismos para la distribución y validación de datos de estado de certificados en VANETs. El primer mecanismo está basado en el uso en una extensión de las listas estandares de revocación. La principal ventaja de esta extensión es que las unidades al borde de la carretera y los vehículos repositorio pueden construir una estructura eficiente sobre la base de un árbol de hash autenticado para responder a las peticiones de estado de certificados. El segundo mecanismo tiene como objetivo optimizar el equilibrio entre el ancho de banda necesario para descargar los datos de revocación y la frescura de los mismos. Este mecanismo se basa en el uso de un esquema híbrido de árboles de Merkle y delta-CRLs, de modo que el riesgo de operar con certificados revocados desconocidos permanece por debajo de un umbral durante el intervalo de validez de la CRL base, y la CA tiene la capacidad de gestionar este riesgo mediante el ajuste del tamaño de las delta-CRL. Para cada uno de estos mecanismos, llevamos a cabo el análisis de la seguridad y la evaluación del desempeño para demostrar la seguridad y eficiencia de las acciones que se emprenden

Natural computing for vehicular networks

La presente tesis aborda el diseño inteligente de soluciones para el despliegue de redes vehiculares ad-hoc (vehicular ad hoc networks, VANETs). Estas son redes de comunicación inalámbrica formada principalmente por vehículos y elementos de infraestructura vial. Las VANETs ofrecen la oportunidad para desarrollar aplicaciones revolucionarias en el ámbito de la seguridad y eficiencia vial. Al ser un dominio tan novedoso, existe una serie de cuestiones abiertas, como el diseño de la infraestructura de estaciones base necesaria y el encaminamiento (routing) y difusión (broadcasting) de paquetes de datos, que todavía no han podido resolverse empleando estrategias clásicas. Es por tanto necesario crear y estudiar nuevas técnicas que permitan de forma eficiente, eficaz, robusta y flexible resolver dichos problemas. Este trabajo de tesis doctoral propone el uso de computación inspirada en la naturaleza o Computación Natural (CN) para tratar algunos de los problemas más importantes en el ámbito de las VANETs, porque representan una serie de algoritmos versátiles, flexibles y eficientes para resolver problemas complejos. Además de resolver los problemas VANET en los que nos enfocamos, se han realizado avances en el uso de estas técnicas para que traten estos problemas de forma más eficiente y eficaz. Por último, se han llevado a cabo pruebas reales de concepto empleando vehículos y dispositivos de comunicación reales en la ciudad de Málaga (España). La tesis se ha estructurado en cuatro grandes fases. En la primera fase, se han estudiado los principales fundamentos en los que se basa esta tesis. Para ello se hizo un estudio exhaustivo sobre las tecnologías que emplean las redes vehiculares, para así, identificar sus principales debilidades. A su vez, se ha profundizado en el análisis de la CN como herramienta eficiente para resolver problemas de optimización complejos, y de cómo utilizarla en la resolución de los problemas en VANETs. En la segunda fase, se han abordado cuatro problemas de optimización en redes vehiculares: la transferencia de archivos, el encaminamiento (routing) de paquetes, la difusión (broadcasting) de mensajes y el diseño de la infraestructura de estaciones base necesaria para desplegar redes vehiculares. Para la resolución de dichos problemas se han propuesto diferentes algoritmos CN que se clasifican en algoritmos evolutivos (evolutionary algorithms, EAs), métodos de inteligencia de enjambre (swarm intelligence, SI) y enfriamiento simulado (simulated annealing, SA). Los resultados obtenidos han proporcionado protocolos de han mejorado de forma significativa las comunicaciones en VANETs. En la tercera y última fase, se han realizado experimentos empleando vehículos reales circulando por las carreteras de Málaga y que se comunicaban entre sí. El principal objetivo de estas pruebas ha sido el validar las mejoras que presentan los protocolos que se han optimizado empleando CN. Los resultados obtenidos de las fases segunda y tercera confirman la hipótesis de trabajo, que la CN es una herramienta eficiente para tratar el diseño inteligente en redes vehiculares

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