Identifying the key factors affecting warning message dissemination in VANET real urban scenarios

[EN] In recent years, new architectures and technologies have been proposed for Vehicular Ad Hoc networks (VANETs). Due to the cost and complexity of deploying such networks, most of these proposals rely on simulation. However, we find that most of the experiments made to validate these proposals tend to overlook the most important and representative factors. Moreover, the scenarios simulated tend to be very simplistic (highways or Manhattan-based layouts), which could seriously affect the validity of the obtained results. In this paper, we present a statistical analysis based on the 2 k factorial methodology to determine the most representative factors affecting traffic safety applications under real roadmaps. Our purpose is to determine which are the key factors affecting Warning Message Dissemination in order to concentrate research tests on such parameters, thus avoiding unnecessary simulations and reducing the amount of simulation time required. Simulation results show that the key factors affecting warning messages delivery are the density of vehicles and the roadmap used. Based on this statistical analysis, we consider that VANET researchers must evaluate the benefits of their proposals using different vehicle densities and city scenarios, to obtain a broad perspective on the effectiveness of their solution. Finally, since city maps can be quite heterogeneous, we propose a roadmap profile classification to further reduce the number of cities evaluatedThis work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01, and by the Diputacion General de Aragon, under Grant "subvenciones destinadas a la formacion y contratacion de personal investigador".Fogue, M.; Garrido, P.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2013). Identifying the key factors affecting warning message dissemination in VANET real urban scenarios. Sensors. 13(4):5220-5250. https://doi.org/10.3390/s130405220S52205250134Galaviz-Mosqueda, G., Aquino-Santos, R., Villarreal-Reyes, S., Rivera-Rodríguez, R., Villaseñor-González, L., & Edwards, A. (2012). Reliable Freestanding Position-Based Routing in Highway Scenarios. Sensors, 12(11), 14262-14291. doi:10.3390/s121114262Gramaglia, M., Bernardos, C., & Calderon, M. (2013). Virtual Induction Loops Based on Cooperative Vehicular Communications. Sensors, 13(2), 1467-1476. doi:10.3390/s130201467Rahim, A., Khan, Z. S., Muhaya, F. T. B., Sher, M., & Kim, T.-H. (2010). Sensor Based Framework for Secure Multimedia Communication in VANET. Sensors, 10(11), 10146-10154. doi:10.3390/s101110146Martinez, F. J., Fogue, M., Toh, C. K., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2012). Computer Simulations of VANETs Using Realistic City Topologies. Wireless Personal Communications, 69(2), 639-663. doi:10.1007/s11277-012-0594-6Cenerario, N., Delot, T., & Ilarri, S. (2011). A Content-Based Dissemination Protocol for VANETs: Exploiting the Encounter Probability. IEEE Transactions on Intelligent Transportation Systems, 12(3), 771-782. doi:10.1109/tits.2011.2158821Sahoo, J., Wu, E. H.-K., Sahu, P. K., & Gerla, M. (2011). Binary-Partition-Assisted MAC-Layer Broadcast for Emergency Message Dissemination in VANETs. IEEE Transactions on Intelligent Transportation Systems, 12(3), 757-770. doi:10.1109/tits.2011.2159003Liu, C., & Chigan, C. (2012). RPB-MD: Providing robust message dissemination for vehicular ad hoc networks. Ad Hoc Networks, 10(3), 497-511. doi:10.1016/j.adhoc.2011.09.003Perkins, D. D., & Hughes, H. (2002). Investigating the performance of TCP in mobile ad hoc networks. Computer Communications, 25(11-12), 1132-1139. doi:10.1016/s0140-3664(02)00024-5Fogue, M., Garrido, P., Martinez, F. J., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2012). Evaluating the impact of a novel message dissemination scheme for vehicular networks using real maps. Transportation Research Part C: Emerging Technologies, 25, 61-80. doi:10.1016/j.trc.2012.04.017Sanguesa, J., Fogue, M., Garrido, P., Martinez, F., Cano, J.-C., Calafate, C., & Manzoni, P. (2013). An Infrastructureless Approach to Estimate Vehicular Density in Urban Environments. Sensors, 13(2), 2399-2418. doi:10.3390/s130202399Tseng, Y.-C., Ni, S.-Y., Chen, Y.-S., & Sheu, J.-P. (2002). Wireless Networks, 8(2/3), 153-167. doi:10.1023/a:1013763825347Wisitpongphan, N., Tonguz, O. K., Parikh, J. S., Mudalige, P., Bai, F., & Sadekar, V. (2007). Broadcast storm mitigation techniques in vehicular ad hoc networks. IEEE Wireless Communications, 14(6), 84-94. doi:10.1109/mwc.2007.4407231Alasmary, W., & Zhuang, W. (2012). Mobility impact in IEEE 802.11p infrastructureless vehicular networks. Ad Hoc Networks, 10(2), 222-230. doi:10.1016/j.adhoc.2010.06.006Harri, J., Filali, F., & Bonnet, C. (2009). Mobility models for vehicular ad hoc networks: a survey and taxonomy. IEEE Communications Surveys & Tutorials, 11(4), 19-41. doi:10.1109/surv.2009.090403Simulation of Urban MObility (SUMO)http://sumo.sourceforge.nethttp://www.openstreetmap.orghttp://www.census.gov/geo/www/tigerKrauss, S., Wagner, P., & Gawron, C. (1997). Metastable states in a microscopic model of traffic flow. Physical Review E, 55(5), 5597-5602. doi:10.1103/physreve.55.5597Wagner, P. (2006). How human drivers control their vehicle. The European Physical Journal B, 52(3), 427-431. doi:10.1140/epjb/e2006-00300-1ns Notes and Documentshttp://www.isi.edu/nsnam/ns/ns-documentation.htm

Construction of a real vehicular delay-tolerant network testbed

Vehicular Delay-Tolerant Networks (VDTNs) appear as innovative network architecture, able to outline communication challenges caused by issues like variable delays, disruption and intermittent connectivity once that it utilizes the store-carry-and-forward method to allow that in-transit messages (called bundles) can be delivered to the destination by hopping over the mobile vehicles even that an end-to-end path does not exist. Since messages are stored persistently in a buffer and forward to the next hop, a new communication infrastructure is created allowing low-cost asynchronous opportunistic communication under the most critical situations like variable delays and bandwidth constraints. VDTN introduces a layered architecture, acting as an overlay network over the link layer, aggregating incoming IP packets in data bundles (large IP packets), using out-of-band signaling, based on the separation of the control plane and planes. This dissertation presents and evaluates the performance of a real VDTN testbed, demonstrating the real applicability of this new vehicular communication approach. It includes an embedded VDTN testbed created to evaluate safety systems in a real-world scenario. It was used cars with laptops to realize terminal and relay nodes. A real testbed is very important because some complex issues presented in vehicular communication systems can be treated with more realism in real-world environments than in a laboratory environment. The experiments were performed on the internal streets of Brazilian Fiat Automobile manufacturing plant. Performance measurements and analysis were also conduct to verify the efficiency of the system. The results obtained show that safety applications and services can be executed with the actual proposal VDTN architecture in several environments, although notable interference as fading and characteristics of the radio channel, require the use of more modern, appropriate and robust technologies. Thus, the real deployment of VDTNs confirms that VDTNs can be seen as a very promising technology for vehicular communications.Fundação para a Ciência e a Tecnologia (FCT

Design and Evaluation of a Traffic Safety System based on Vehicular Networks for the Next Generation of Intelligent Vehicles

La integración de las tecnologías de las telecomunicaciones en el sector del automóvil permitirá a los vehículos intercambiar información mediante Redes Vehiculares, ofreciendo numerosas posibilidades. Esta tesis se centra en la mejora de la seguridad vial y la reducción de la siniestralidad mediante Sistemas Inteligentes de Transporte (ITS). El primer paso consiste en obtener una difusión eficiente de los mensajes de advertencia sobre situaciones potencialmente peligrosas. Hemos desarrollado un marco para simular el intercambio de mensajes entre vehículos, utilizado para proponer esquemas eficientes de difusión. También demostramos que la disposición de las calles tiene gran influencia sobre la eficiencia del proceso. Nuestros algoritmos de difusión son parte de una arquitectura más amplia (e-NOTIFY) capaz de detectar accidentes de tráfico e informar a los servicios de emergencia. El desarrollo y evaluación de un prototipo demostró la viabilidad del sistema y cómo podría ayudar a reducir el número de víctimas en carretera

Adaptive Mechanisms to Improve Message Dissemination in Vehicular Networks

En el pasado, se han dedicado muchos recursos en construir mejores carreteras y autovías. Con el paso del tiempo, los objetivos fueron cambiando hacia las mejoras de los vehículos, consiguiendo cada vez vehículos más rápidos y con mayor autonomía. Más tarde, con la introducción de la electrónica en el mercado del automóvil, los vehículos fueron equipados con sensores, equipos de comunicaciones, y otros avances tecnológicos que han permitido la aparición de coches más eficientes, seguros y confortables. Las aplicaciones que nos permite el uso de las Redes Vehiculares (VNs) en términos de seguridad y eficiencia son múltiples, lo que justifica la cantidad y recursos de investigación que se están dedicando en los últimos años. En el desarrollo de esta Tesis, los esfuerzos se han centrado en el área de las Vehicular Ad-hoc Networks, una subclase de las Redes Vehiculares que se centra en las comunicaciones entre los vehículos, sin necesidad de que existan elementos de infraestructura. Con la intención de mejorar el proceso de diseminación de mensajes de alerta, imprescindibles para las aplicaciones relacionadas con la seguridad, se ha propuesto un esquema de difusión adaptativo, capaz de seleccionar automáticamente el mecanismo de difusión óptimo en función de la complejidad del mapa y de la densidad actual de vehículos. El principal objetivo es maximizar la efectividad en la difusión de mensajes, reduciendo al máximo el número de mensajes necesarios, evitando o mitigando las tormentas de difusión. Las propuestas actuales en el área de las VANETs, se centran principalmente en analizar escenarios con densidades típicas o promedio. Sin embargo, y debido a las características de este tipo de redes, a menudo se dan situaciones con densidades extremas (altas y bajas). Teniendo en cuenta los problemas que pueden ocasionar en el proceso de diseminación de los mensajes de emergencia, se han propuesto dos nuevos esquemas de difusión para bajas densidades: el \emph{Junction Store and Forward} (JSF) y el \emph{Neighbor Store and Forward} (NSF). Además, para situaciones de alta densidad de vehículos, se ha diseñado el \emph{Nearest Junction Located} (NJL), un esquema de diseminación que reduce notablemente el número de mensajes enviados, sin por ello perder prestaciones. Finalmente, hemos realizado una clasificacion de los esquemas de difusión para VANETs más importantes, analizando las características utilizadas en su diseño. Además hemos realizado una comparación de todos ellos, utilizando el mismo entorno de simulación y los mismos escenarios, permitiendo conocer cuál es el mejor esquema de diseminación a usar en cada momento

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

Efficient channel allocation and medium access organization algorithms for vehicular networking

Due to the limited bandwidth available for Vehicular Ad-hoc Networks (VANETs), organizing the wireless channel access to efficiently use the bandwidth is one of the main challenges in VANET. In this dissertation, we focus on channel allocation and media access organization for Vehicle-to-Roadside Units (V2R) and Vehicle-to-Vehicle (V2V) communications. An efficient channel allocation algorithm for Roadside Unit (RSU) access is proposed. The goal of the algorithm is to increase system throughput by admitting more tasks (vehicles) and at the same time reduce the risk of the admitted tasks. The algorithm admits the new requests only when their requirements can be fulfilled and all in-session tasks\u27 requirements are also guaranteed. The algorithm calculates the expected task finish time for the tasks, but allocates a virtual transmission plan for the tasks as they progress toward the edges of the RSU range. For V2V mode, we propose an efficient medium access organization method based on VANETs\u27 clustering schemes. In order to make this method efficient in rapid topology change environment like VANET, it\u27s important to make the network topology less dynamic by forming local strongly connected clustering structure, which leads to a stable network topology on the global scale. We propose an efficient cluster formation algorithm that takes vehicles\u27 mobility into account for cluster formation. The results of the proposed methods show that the wireless channel utilization and the network stability are significantly improved compared to the existing methods

Detecting Non-Line of Sight to Prevent Accidents in Vehicular Ad hoc Networks

There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Performance of management solutions and cooperation approaches for vehicular delay-tolerant networks

A wide range of daily-life applications supported by vehicular networks attracted the interest, not only from the research community, but also from governments and the automotive industry. For example, they can be used to enable services that assist drivers on the roads (e.g., road safety, traffic monitoring), to spread commercial and entertainment contents (e.g., publicity), or to enable communications on remote or rural regions where it is not possible to have a common network infrastructure. Nonetheless, the unique properties of vehicular networks raise several challenges that greatly impact the deployment of these networks. Most of the challenges faced by vehicular networks arise from the highly dynamic network topology, which leads to short and sporadic contact opportunities, disruption, variable node density, and intermittent connectivity. This situation makes data dissemination an interesting research topic within the vehicular networking area, which is addressed by this study. The work described along this thesis is motivated by the need to propose new solutions to deal with data dissemination problems in vehicular networking focusing on vehicular delay-tolerant networks (VDTNs). To guarantee the success of data dissemination in vehicular networks scenarios it is important to ensure that network nodes cooperate with each other. However, it is not possible to ensure a fully cooperative scenario. This situation makes vehicular networks suitable to the presence of selfish and misbehavior nodes, which may result in a significant decrease of the overall network performance. Thus, cooperative nodes may suffer from the overwhelming load of services from other nodes, which comprises their performance. Trying to solve some of these problems, this thesis presents several proposals and studies on the impact of cooperation, monitoring, and management strategies on the network performance of the VDTN architecture. The main goal of these proposals is to enhance the network performance. In particular, cooperation and management approaches are exploited to improve and optimize the use of network resources. It is demonstrated the performance gains attainable in a VDTN through both types of approaches, not only in terms of bundle delivery probability, but also in terms of wasted resources. The results and achievements observed on this research work are intended to contribute to the advance of the state-of-the-art on methods and strategies for overcome the challenges that arise from the unique characteristics and conceptual design of vehicular networks.O vasto número de aplicações e cenários suportados pelas redes veiculares faz com que estas atraiam o interesse não só da comunidade científica, mas também dos governos e da indústria automóvel. A título de exemplo, estas podem ser usadas para a implementação de serviços e aplicações que podem ajudar os condutores dos veículos a tomar decisões nas estradas, para a disseminação de conteúdos publicitários, ou ainda, para permitir que existam comunicações em zonas rurais ou remotas onde não é possível ter uma infraestrutura de rede convencional. Contudo, as propriedades únicas das redes veiculares fazem com que seja necessário ultrapassar um conjunto de desafios que têm grande impacto na sua aplicabilidade. A maioria dos desafios que as redes veiculares enfrentam advêm da grande mobilidade dos veículos e da topologia de rede que está em constante mutação. Esta situação faz com que este tipo de rede seja suscetível de disrupção, que as oportunidades de contacto sejam escassas e de curta duração, e que a ligação seja intermitente. Fruto destas adversidades, a disseminação dos dados torna-se um tópico de investigação bastante promissor na área das redes veiculares e por esta mesma razão é abordada neste trabalho de investigação. O trabalho descrito nesta tese é motivado pela necessidade de propor novas abordagens para lidar com os problemas inerentes à disseminação dos dados em ambientes veiculares. Para garantir o sucesso da disseminação dos dados em ambientes veiculares é importante que este tipo de redes garanta a cooperação entre os nós da rede. Contudo, neste tipo de ambientes não é possível garantir um cenário totalmente cooperativo. Este cenário faz com que as redes veiculares sejam suscetíveis à presença de nós não cooperativos que comprometem seriamente o desempenho global da rede. Por outro lado, os nós cooperativos podem ver o seu desempenho comprometido por causa da sobrecarga de serviços que poderão suportar. Para tentar resolver alguns destes problemas, esta tese apresenta várias propostas e estudos sobre o impacto de estratégias de cooperação, monitorização e gestão de rede no desempenho das redes veiculares com ligações intermitentes (Vehicular Delay-Tolerant Networks - VDTNs). O objetivo das propostas apresentadas nesta tese é melhorar o desempenho global da rede. Em particular, as estratégias de cooperação e gestão de rede são exploradas para melhorar e optimizar o uso dos recursos da rede. Ficou demonstrado que o uso deste tipo de estratégias e metodologias contribui para um aumento significativo do desempenho da rede, não só em termos de agregados de pacotes (“bundles”) entregues, mas também na diminuição do volume de recursos desperdiçados. Os resultados observados neste trabalho procuram contribuir para o avanço do estado da arte em métodos e estratégias que visam ultrapassar alguns dos desafios que advêm das propriedades e desenho conceptual das redes veiculares

Road-based routing in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) can provide scalable and cost-effective solutions for applications such as traffic safety, dynamic route planning, and context-aware advertisement using short-range wireless communication. To function properly, these applications require efficient routing protocols. However, existing mobile ad hoc network routing and forwarding approaches have limited performance in VANETs. This dissertation shows that routing protocols which account for VANET-specific characteristics in their designs, such as high density and constrained mobility, can provide good performance for a large spectrum of applications. This work proposes a novel class of routing protocols as well as three forwarding optimizations for VANETs. The Road-Based using Vehicular Traffic (RBVT) routing is a novel class of routing protocols for VANETs. RBVT protocols leverage real-time vehicular traffic information to create stable road-based paths consisting of successions of road intersections that have, with high probability, network connectivity among them. Evaluations of RBVT protocols working in conjunction with geographical forwarding show delivery rate increases as much as 40% and delay decreases as much as 85% when compared with existing protocols. Three optimizations are proposed to increase forwarding performance. First, one- hop geographical forwarding is improved using a distributed receiver-based election of next hops, which leads to as much as 3 times higher delivery rates in highly congested networks. Second, theoretical analysis and simulation results demonstrate that the delay in highly congested networks can be reduced by half by switching from traditional FIFO with Taildrop queuing to LIFO with Frontdrop queuing. Third, nodes can determine suitable times to transmit data across RBVT paths or proactively replace routes before they break using analytical models that accurately predict the expected road-based path durations in VANETs