Wireless vehicular communications for automatic incident detection and recovery

Incident detection is the process by which an incident is brought to the attention of traffic operators in order to design and activate a response plan. To minimize the detection time is crucial to mitigate the incident severity for victims as well to reduce the risk of secondary crashes. Automated incident information dissemination and traffic conditions is useful to alert in-route drivers to decide alternative routes on unexpected traffic congestion and may be also used for the incident recovery process, namely to optimize the response plan including the “nearest” rescue teams, thereby shortening their response times. Wireless vehicular communications, notably the emergent IEEE 802.11p protocol, is the enabling technology providing timely, dependable and secure properties that are essential for the devised target application. However, there are still some open issues with vehicular communications that require further research efforts. This paper presents an overview of the state of the art in wireless vehicular communications and describes the field operational tests proposed within the scope of the upcoming FP7 project ICSI - Intelligent Cooperative Sensing for Improved traffic efficiency

Controlo de acesso ao meio em comunicações veiculares de tempo-real

Despite several preventive measures, the number of roadway accidents is still very high, being considered even a problem of public health by some entities. This thesis has as global purpose of contributing to the reduction of that number of accidents, and consequent fatalities, by using safety-related applications that use communication among vehicles. In particular, the primary goal is guaranteeing that communication between users in vehicular environments is done with appropriate time bounds to transfer safety-critical information. In detail, it is studied how to manage the scheduling of message’s transmissions (medium access control - MAC), in order to define precisely who will communicate and when is the appropriate instant. The preferable situation where a communication infrastructure is present with full coverage (RSUs) is also studied, from which medium access control is defined precisely, and vehicles (OBUs) become aware of medium utilization. Also, sporadic situations (e.g., absence of RSUs) are studied in which the communication network is “ad hoc” and solely formed by the current vehicles. It is used the recently WAVE / IEEE 802.11p standard, specific for vehicular communications, and it is proposed a TDMA based solution, with appropriate coordination between RSUs in order to effectively disseminate a critical safety event. It is taken into account two different ways of choosing the instant for the initial broadcast, and both cases are compared. In case there is no infrastructure available, methods are derived to minimize communication medium access collisions, and to maximize the available bandwidth. The results reflect the total end-to-end delay, and show that adequate times are attained, and meet with the requisites for the type of applications being considered. Also, enhancements are obtained when using the alternate choice for the initial broadcast instant.Apesar de diversas medidas preventivas, o número de acidentes rodoviários continua a ser muito elevado, sendo mesmo considerado uma questão de saúde pública por algumas entidades. Esta tese tem como objetivo geral contribuir para a redução desse número de acidentes, e consequentes fatalidades, através da utilização de aplicações de segurança que envolvem comunicação entre veículos. Em particular, o objetivo principal é garantir que a comunicação entre utentes, em ambientes veiculares, seja efetuada com limites temporais apropriados à transferência de informações críticas. De forma mais detalhada, é estudada a gestão do escalonamento das transmissões (controlo de acesso ao meio – MAC) que irá definir quem vai comunicar e quando o pode fazer. São estudadas situações (desejadas) onde há uma infra-estrutura de comunicações com cobertura integral (RSUs), a partir da qual se faz a coordenação do acesso ao meio pelos veículos (OBUs), e situações (esporádicas, por ausência de RSU) em que a rede de comunicação é “ad hoc” e apenas constituída pelos veículos presentes. Utiliza-se a recente norma WAVE / IEEE 802.11p, específica para comunicações veiculares, e propõe-se uma solução baseada em TDMA, com coordenação apropriada entre RSUs para disseminação efetiva de um evento crítico de segurança. A escolha do instante para o broadcast inicial do evento de segurança também é tida em conta, e são comparados dois casos distintos. No caso da ausência de infraestrutura, derivam-se métodos para minimizar colisões no acesso ao meio de comunicação, e maximizar a largura de banda disponível. Os resultados refletem o atraso total end-to-end, mostrando tempos apropriados para os requisitos das aplicações em causa, e evidenciando melhorias aquando da escolha alternativa para o instante do broadcast inicial.Programa Doutoral em Engenharia Eletrotécnic

Efficient medium access control protocol for vehicular ad-hoc networks

Intelligent transportation systems (ITS) have enjoyed a tremendous growth in the last decade and the advancement in communication technologies has played a big role behind the success of ITS. Inter-vehicle communication (IVC) is a critical requirement for ITS and due to the nature of communication, vehicular ad-hoc network technology (VANET) is the most suitable communication technology for inter-vehicle communications. In Practice, however, VANET poses some extreme challenges including dropping out of connections as the moving vehicle moves out of the coverage range, joining of new nodes moving at high speeds, dynamic change in topology and connectivity, time variability of signal strength, throughput and time delay. One of the most challenging issues facing vehicular networks lies in the design of efficient resource management schemes, due to the mobile nature of nodes, delay constraints for safety applications and interference. The main application of VANET in ITS lies in the exchange of safety messages between nodes. Moreover, as the wireless access in vehicular environment (WAVE) moves closer to reality, management of these networks is of increasing concern for ITS designers and other stakeholder groups. As such, management of resources plays a significant role in VANET and ITS. For resource management in VANET, a medium access control protocol is used, which makes sure that limited resources are distributed efficiently. In this thesis, an efficient Multichannel Cognitive MAC (MCM) is developed, which assesses the quality of channel prior to transmission. MCM employs dynamic channel allocation and negotiation algorithms to achieve a significant improvement in channel utilisation, system reliability, and delay constraints while simultaneously addressing Quality of Service. Moreover, modified access priority parameters and safety message acknowledgments will be used to improve the reliability of safety messages. The proposed protocols are implemented using network simulation tools. Extensive experiments demonstrated a faster and more efficient reception of safety messages compared to existing VANET technologies. Finally, improvements in delay and packet delivery ratios are presented

Comunicações veiculares híbridas

Vehicle Communications is a promising research field, with a great potential for the development of new applications capable of improving road safety, traffic efficiency, as well as passenger comfort and infotainment. Vehicle communication technologies can be short-range, such as ETSI ITS-G5 or the 5G PC5 sidelink channel, or long-range, using the cellular network (LTE or 5G). However, none of the technologies alone can support the expected variety of applications for a large number of vehicles, nor all the temporal and spatial requirements of connected and autonomous vehicles. Thus, it is proposed the collaborative or hybrid use of short-range communications, with lower latency, and of long-range technologies, potentially with higher latency, but integrating aggregated data of wider geographic scope. In this context, this work presents a hybrid vehicle communications model, capable of providing connectivity through two Radio Access Technologies (RAT), namely, ETSI ITS-G5 and LTE, to increase the probability of message delivery and, consequently, achieving a more robust, efficient and secure vehicle communication system. The implementation of short-range communication channels is done using Raw Packet Sockets, while the cellular connection is established using the Advanced Messaging Queuing Protocol (AMQP) protocol. The main contribution of this dissertation focuses on the design, implementation and evaluation of a Hybrid Routing Sublayer, capable of isolating messages that are formed/decoded from transmission/reception processes. This layer is, therefore, capable of managing traffic coming/destined to the application layer of intelligent transport systems (ITS), adapting and passing ITS messages between the highest layers of the protocol stack and the available radio access technologies. The Hybrid Routing Sublayer also reduces the financial costs due to the use of cellular communications and increases the efficiency of the use of the available electromagnetic spectrum, by introducing a cellular link controller using a Beacon Detector, which takes informed decisions related to the need to connect to a cellular network, according to different scenarios. The experimental results prove that hybrid vehicular communications meet the requirements of cooperative intelligent transport systems, by taking advantage of the benefits of both communication technologies. When evaluated independently, the ITS-G5 technology has obvious advantages in terms of latency over the LTE technology, while the LTE technology performs better than ITS-G5, in terms of throughput and reliability.As Comunicações Veiculares são um campo de pesquisa promissor, com um grande potencial de desenvolvimento de novas aplicações capazes de melhorar a segurança nas estradas, a eficiência do tráfego, bem com o conforto e entretenimento dos passageiros. As tecnologias de comunicação veícular podem ser de curto alcance, como por exemplo ETSI ITS-G5 ou o canal PC5 do 5G, ou de longo alcance, recorrendo à rede celular (LTE ou 5G). No entanto, nenhuma das tecnologias por si só, consegue suportar a variedade expectável de aplicações para um número de veículos elevado nem tampouco todos os requisitos temporais e espaciais dos veículos conectados e autónomos. Assim, é proposto o uso colaborativo ou híbrido de comunicações de curto alcance, com latências menores, e de tecnologias de longo alcance, potencialmente com maiores latências, mas integrando dados agregados de maior abrangência geográfica. Neste contexto, este trabalho apresenta um modelo de comunicações veiculares híbrido, capaz de fornecer conectividade por meio de duas Tecnologias de Acesso por Rádio (RAT), a saber, ETSI ITS-G5 e LTE, para aumentar a probabilidade de entrega de mensagens e, consequentemente, alcançar um sistema de comunicação veicular mais robusto, eficiente e seguro. A implementação de canais de comunicação de curto alcance é feita usando Raw Packet Sockets, enquanto que a ligação celular é estabelecida usando o protocolo Advanced Messaging Queuing Protocol (AMQP). A contribuição principal desta dissertação foca-se no projeto, implementação e avaliação de uma sub camada hibrída de encaminhamento, capaz de isolar mensagens que se formam/descodificam a partir de processos de transmissão/receção. Esta camadada é, portanto, capaz de gerir o tráfego proveniente/destinado à camada de aplicação de sistemas inteligentes de transportes (ITS) adaptando e passando mensagens ITS entre as camadas mais altas da pilha protocolar e as tecnologias de acesso rádio disponíveis. A sub camada hibrída de encaminhamento também potencia uma redução dos custos financeiros devidos ao uso de comunicações celulares e aumenta a eficiência do uso do espectro electromagnético disponível, ao introduzir um múdulo controlador da ligação celular, utilizando um Beacon Detector, que toma decisões informadas relacionadas com a necessidade de uma conexão a uma rede celular, de acordo com diferentes cenários. Os resultados experimentais comprovam que as comunicações veículares híbridas cumprem os requisitos dos sistemas cooperativos de transporte inteligentes, ao tirarem partido das vantagens de ambas tecnologias de comunicação. Quando avaliadas de forma independente, constata-se que que a tecnologia ITS-G5 tem vantagens evidentes em termos de latência sobre a tecnologia LTE, enquanto que a tecnologia LTE tem melhor desempenho que a LTE, ai nível de débito e fiabilidade.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Motorway Vehicular Networks with Renewable Energy Powered Access Points

The goal of this work is to consider the potential of using renewable energy only to power roadside units (RSUs), which not only reduces CO2 footprint but also reduces the infrastructure needed in motorway vehicular communication. The thesis begins with collation and analysis of wind and motorway traffic data for the purpose of determining the energy demand of vehicular networks as well as the energy supply obtainable from wind. This is followed by the study of a standalone RSU powered by wind energy. Small size standalone wind energy systems which have benefits of low cost, easy and large scale deployments are implemented for the low power RSUs. The concept of wind energy based rate adaptation is introduced and implemented in the RSU through which RSU can vary transmission power according to the availability of wind energy. This reduces the outage and improves the overall service quality. Traditionally rate adaptation was employed to cater for wireless channel unavailability. A queuing model for the RSU is developed and verified through simulation to evaluate the performance in terms of delay, packet loss and utilisation. Channel fading is considered and the performance of the RSU is re-evaluated in terms of the same quality of service parameters, viz. delay, packet loss and utilisation to investigate the impact of fading in the network. Next, the reliability of the RSU is redefined in the context of unavailability of sufficient wind power. The transient nature of wind energy causes the RSUs to either transmit at full data rate or not transmit at all depending on the availability of sufficient energy. Thus, a failure occurs when the wind power is less than the load. Therefore, a framework has been developed for redefining a number of reliability parameters in the context of wind powered RSUs. A detailed wind data analysis was carried out based upon the hourly wind speed obtained from the UK air information resource (AIR) database for a period of five years, to determine the energy model of the deployed micro-turbine. An energy storage device (a small battery) is connected to the micro-wind turbine for improved service quality

Simulation and Improvement of the Handover process in IEEE 802.11p based VANETs (Vehicle Ad-hoc NETworks)

Projecte final de carrera fet en col.laboració amb College of Electronics and Information Engineering. Tongji UniversityThis research focuses on the study of the handover process and the di erent simulation environments available in order to generate valid results for the optimization of seamless handover in VANET networks. Handover parameter analysis has been performed and implemented in a application developed in order to batch simulate the process of modifying the selected variables and statistically analyzing the results in order to allow further research on the topic to achieve valid results for VANET handover simulations in a very convenient manner

IP Mobility Support in Multi-hop Vehicular Communications Networks

The combination of infrastructure-to-vehicle and vehicle-to-vehicle communications, namely the multi-hop Vehicular Communications Network (VCN) , appears as a promising solution for the ubiquitous access to IP services in vehicular environments. In this thesis, we address the challenges of multi-hop VCN, and investigate the seamless provision of IP services over such network. Three different schemes are proposed and analyzed. First, we study the limitations of current standards for the provision of IP services, such as 802.11p/WAVE, and propose a framework that enables multi-hop communications and a robust IP mobility mechanism over WAVE. An accurate analytical model is developed to evaluate the throughput performance, and to determine the feasibility of the deployment of IP-based services in 802.11p/WAVE networks. Next, the IP mobility support is extended to asymmetric multi-hop VCN. The proposed IP mobility and routing mechanisms react to the asymmetric links, and also employ geographic location and road traffic information to enable predictive handovers. Moreover, since multi-hop communications suffer from security threats, it ensures that all mobility signalling is authenticated among the participant vehicles. Last, we extend our study to a heterogeneous multi-hop VCN, and propose a hybrid scheme that allows for the on-going IP sessions to be transferred along the heterogeneous communications system. The proposed global IP mobility scheme focuses on urban vehicular scenarios, and enables seamless communications for in-vehicle networks, commuters, and pedestrians. The overall performance of IP applications over multi-hop VCN are improved substantially by the proposed schemes. This is demonstrated by means of analytical evaluations, as well as extensive simulations that are carried out in realistic highway and urban vehicular scenarios. More importantly, we believe that our dissertation provides useful analytical tools, for evaluating the throughput and delay performance of IP applications in multi-hop vehicular environments. In addition, we provide a set of practical and efficient solutions for the seamless support of IP tra c along the heterogeneous and multi-hop vehicular network, which will help on achieving ubiquitous drive-thru Internet, and infotainment traffic access in both urban and highway scenarios

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

A simulation approach for increased safety in advanced C-ITS scenarios

Com os recentes desenvolvimentos em diferentes áreas de conhecimento, como redes de comunicação sem fio e sensores, bem como a evolução recente em vários tópicos na área da Computação, os Sistemas Inteligentes e Cooperativos de Transporte (CITSs) tornaram-se um tema muito importante, e espera-se que comecem a ser cada vez mais implementados num futuro próximo. Nesta tese, é feita uma análise sobre estes sistemas e diferentes possiveis cenários focando no cenário de Platooning, assim como sobre comunicações Veículo-a-Tudo (V2X) com foco no ETSI ITS-G5, o standard europeu mais amplamente aceite na indústria automóvel para este tipo de comunicações. O desenvolvimento de duas ferramentas de co-simulação para análise de cenários C-ITS usando comunicações veículo para veículo (V2V), foi feito no contexto desta tese. COPADRIVe é uma ferramenta de co-simulação que junta um simulador de rede e um simulador robótico. A outra ferramenta de co-simulação, é uma ferramenta hardware-in-the-loop que úne um simulador robótico com comunicações feitas através de hardware real, On-Board units (OBUs). Ambas as ferramentas foram desenvolvidas e usadas como forma de análise e teste de situações de Platooning e componentes de software para implementação neste tipo de cenários. Este desenvolvimento teve origem na necessidade de existência deste tipo de ferramentas para suporte dos desenvolvimentos feitos no contexto dos Projetos europeus de I&D SafeCOP e ENABLE-S3, onde o CISTER participava ativamente.With the developments in different areas like Wireless Communication Networks and sensors, as well as, the recent evolution on various topics on Computing, Cooperative Intelligent Transportation Systems(C-ITSs) became a hot topic for research, and are expected to be increasingly deployed in the future. From the different possible scenarios, in this thesis, we focus in analyzing Cooperative Platooning and particularly, in enabling a set of simulation tools capable of encompassing the supporting Vehicle-to-Everything(V2X) communications guaranteed by the ETSI ITS-G5, the most widely accepted European standard on the automotive industry for these kind of communications. Therefore this thesis presents the development of two co-simulation tools for analysis of C-ITS scenarios using Vehicle-to-Vehicle(V2V) communications. First, COPADRIVe is a co-simulation tool joining together a network simulator and a robotic simulator. The other co-simulation tool, uses a a hardware-in-theloop approach one bridging a robotic simulator with real communications via OnBoard-Units (OBUs). Both tools were developed and used as the means to test and analyze Platooning scenarios and software components relevant in such applications, importantly. These tools’ were developed in line with the R&D European Projects SafeCOP and ENABLE-S3, where CISTER was and active participant

Mecanismos de suporte para MAC 802.11p determinística

Mestrado em Engenharia Eletrónica e TelecomunicaçõesTransportation systems play an extremely important role in modern society. A huge research e ort has been devoted to this eld in the past few years making them safer cleaner and more e cient, originating the so-called Intelligent Transportation Systems (ITS). While some of the enabling technologies are entering their mature phase, there are still many open problems that must be solved before such systems can be e ectively leveraged. Specifically, the medium access is regarded as being one of the most challenging issues to solve in order to provide dependable wireless communications in vehicular networks [BUSB09]. The standard protocols have been shown to fail in addressing this issue and some possible solutions are being proposed, but despite the di culty of correctly modelling the channel dynamics, most work on MAC protocols for real-time vehicular communications has been performed under simulated environments, using simplistic assumptions that do not necessarily hold in a read environment. The implementation of a deterministic MAC scheme is hampered by the fact that commercial devices do not allow modi cations to the standard MAC mechanism, and the development of a device from scratch to implement one Medium Access Control (MAC) scheme is an extremely laborious endeavour. However, over the last few years, the IT2S platform for vehicular communication has been developed and is now in a stage that allows implementation and testing of new solutions for the vehicular communications environment. It is a exible platform that allows modi cation to be made in any layer of the communication stack and therefore suited to be adapted for the implementation of new MAC schemes. This work presents an overview of MAC mechanisms capable of providing deterministic real-time access and assesses the features a communications device must include in order to allow the implementation of these mechanisms. It then proposes an implementation of such as device based on the existing IT2S plaform. A exible solution was obtained that allows all the studied MAC schemes to be implemented purely in software, with no modi cations required to the hardware mechanisms, lowering the needed amount of skills required to perform a working implementation of a novel MAC scheme. The performance of the solution was also found to be appropriate for the required uses. It is now possible to create test beds for new MAC schemes and perform more concrete and accurate analysis of their performance.Os meios de transporte têm um papel preponderante na sociedade moderna. Muito esforço de investigação tem sido dedicada e este campo nos últimos anos, com vista a tornar estes meios mais limpos, seguros e eficientes, originado os chamados Sistemas de Transporte Inteligentes (ITS). Enquanto algumas das tecnologias base estão já prontas a ser utilizadas, ainda existem problemas a ser resolvidos antes de se poder utilizar todo o potencial destes sistemas. Um problema específico, o acesso ao meio, é atualmente considerado um dos mais desa antes em termos de investigação e que detém ainda uma quantidade interessante de problemas a ser resolvidos para que se possa depender de comunicações sem fios em ambientes veiculares. Estudos provaram que os protocolos standard nãoo resolvem este problema e têm sido propostas soluções, Mas apesar da dificuldade de modelar corretamente a dinâmica do canal, a maior parte das análises tem sido realizada em ambientes de simulação, com assunçõess simplistas que não correspondem necessariamente ao ambiente real. A implementação de um mecanismo de acesso ao meio determinístico é dificultada pelo facto de que os dispositivos comerciais não permitem modificações aos mecanismos standard e o desenvolvimento de um dispositivo de raiz que implemente o mecanismo proposto ser extremamente trabalhoso. No entanto,ao longo dos últimos anos tem sido desenvolvida a plataforma de comunicações veiculares IT2S, que atingiu agora uma fase que permite a sua utilização para implementar e testar novas soluções para ambientes veiculares. Trata-se de uma plataforma flexível que permite a realização de modificações em qualquer camada da pilha protocolar, portanto passível de ser adaptada para a implementação de novos mecanismos de acesso ao meio. Este trabalho apresenta uma perspetiva alargada dos mecanismos de acesso ao meio determinísticos propostos na literatura e estuda quais as características necessárias que um dispositivo de comunicação precisa fornecer para os poder implementar. Segue-se então uma proposta de implementação de um tal dispositivo, baseada na plataforma IT2S. Foi possível obter uma solução flexível o suficiente para implementar todos os mecanismos estudados recorrendo apenas a software, sem necessidade de alterações ao hardware, baixando a fasquia da dificuldade na criação de uma implementação prática de um mecanismo de acesso ao meio. A solução foi testada e a desempenho considerada adequada para as possíveis utilizações. É agora possível criar bancadas de teste para novos mecanismos de acesso ao meio e executar análises mais concretas e precisas da sua desempenho