3,196 research outputs found
Safety Information Dissemination in Vehicular Networks using Facilities Layer Mechanisms
International audienceVehicle ad-hoc networks are considered as an essential building block of future intelligent transportation systems. One of the major roles of vehicular communication is the dissemination of information on the road in order to increase the awareness of the drivers and improve road safety. The facilities layer is a recently standardized component in the vehicular communication architecture, with an important role to play in the process of information dissemination. In this paper, we propose facilities layer-based mechanisms for information propagation and we show they outperform classical network layer solutions. We also demonstrate that previous studies that do not consider the cohabitation of different types of safety messages on the vehicular control channel highly under-estimate the dissemination delay, which can lead to unrealistic assumptions in the design of safety applications
Survey on decentralized congestion control methods for vehicular communication
Vehicular communications have grown in interest over the years and are nowadays recognized as a pillar for the Intelligent Transportation Systems (ITSs) in order to ensure an efficient management of the road traffic and to achieve a reduction in the number of traffic accidents. To support the safety applications, both the ETSI ITS-G5 and IEEE 1609 standard families require each vehicle to deliver periodic awareness messages throughout the neighborhood. As the vehicles density grows, the scenario dynamics may require a high message exchange that can easily lead to a radio channel congestion issue and then to a degradation on safety critical services. ETSI has defined a Decentralized Congestion Control (DCC) mechanism to mitigate the channel congestion acting on the transmission parameters (i.e., message rate, transmit power and data-rate) with performances that vary according to the specific algorithm. In this paper, a review of the DCC standardization activities is proposed as well as an analysis of the existing methods and algorithms for the congestion mitigation. Also, some applied machine learning techniques for DCC are addressed
Reverse back-off mechanism for safety vehicular ad hoc networks
International audienceVehicular ad hoc networks can play an important role in enhancing transportation efficiency and improving road safety. Therefore, direct vehicle-to-vehicle communications are considered as one of the main building blocks of a future Intelligent Transportation System. The success and availability of IEEE 802.11 radios made this technology the most probable choice for the medium access control layer in vehicular networks. However, IEEE 802.11 was originally designed in a wireless local area network context and it is not optimised for a dynamic, ad hoc vehicular scenario. In this paper, we investigate the compatibility of the IEEE 802.11 medium access control protocol with the requirements of safety vehicular applications. As the protocols in this family are well-known for their scalability problems, we are especially interested in high density scenarios, quite frequent on today’s roads. Using an analytical framework, we study the performance of the back-off mechanism and the role of the contention window on the control channel of a vehicular network. Based on these findings, we propose a reverse back-off mechanism, specifically designed with road safety applications in mind. Extensive simulations are carried out to prove the efficiency of the proposed enhancement scheme and to better understand the characteristics of vehicular communications
Improving quality of service through road side back-bone network in VANET
The vehicular ad hoc Networks (VANETs) are expected to support a large spectrum of traffic alert, dynamic route planning, file sharing, safety and infotainment applications to improve traffic management. User satisfaction plus in time delivery of real-time messages is the most significant quality evaluation criterion for vehicular applications. High mobility and rapidly changing topologies always lead to intermittent quality of services, higher delay and packet dropping issues in network. To improve the quality of services for multi-hop and dynamic environment, different types of solutions have been proposed. The article introduces multi-protocol label switching based on roadside backbone network to provide widespread, scalable, high-speed, robust quality of services and improve network efficiency. The simulation results showed that proposed model improves data transmission and routing performance in terms of data delivery, throughput, end-to-end delay and achieve adequate utilization of resources
Experimental evaluation of CAM and DENM messaging services in vehicular communications
The Cooperative Awareness Basic Service and Decentralized Environmental Notification Basic Service have been standardized by the European Telecommunications Standards Institute (ETSI) to support vehicular safety and traffic efficiency applications needing continuous status information about surrounding vehicles and asynchronous notification of events, respectively. These standard specifications detail not only the packet formats for both the Cooperative Awareness Message (CAM) and Decentralized Environmental Notification Message (DENM), but also the general message dissemination rules. These basic services, also known as facilities, have been developed as part of a set of standards in which both ISO and ETSI describe the Reference Communication Architecture for future Intelligent Transportation Systems (ITS). By using a communications stack that instantiates this reference architecture, this paper puts in practice the usage of both facilities in a real vehicular scenario. This research work details implementation decisions and evaluates the performance of CAM and DENM facilities through a experimental testbed deployed in a semi-urban environment that uses IEEE 802.11p (ETSI G5-compliant), which is a WiFi-like communication technology conceived for vehicular communications. On the one hand, this validation considers the development of two ITS applications using CAM and DENM functionalities for tracking vehicles and disseminating traffic incidences. In this case, CAM and DENM have demonstrated to be able to offer all the necessary functionality for the study case. On the other hand, both facilities have been also validated in a extensive testing campaign in order to analyze the influence in CAM and DENM performance of aspects such as vehicle speed, signal quality or message dissemination rules. In these tests, the line of sight, equipment installation point and hardware capabilities, have been found as key variables in the network performance, while the vehicle speed has implied a slight impact.This work has been sponsored by the European Seventh Framework Program, through the ITSSv6 (contract 270519), FOTsis (contract 270447) and GEN6 (contract 297239) projects, and the Ministry of Science and Innovation, through the Walkie-Talkie project (TIN2011-27543-C03)
A framework for IP and non-IP multicast services for vehicular networks
International audienceEnabling drivers to be connected to the Internet and/or Vehicular Ad-hoc networks, is one of the main challenges of the future networking. This enables drivers to benefit from the existing Internet services as well as emerging ITS applications based on IP or non-IP communications (e.g geonetworking). Many of ITS applications such as fleet management require multicast data delivery. Existing works on this subject tackle mainly the problems of IP multicasting inside the Internet or geocasting in VANETs. This paper presents a new framework that enables Internet-based multicast services on top of VANETs. We introduce a self-configuring multicast addressing scheme based on the geographic locations of the vehicles coupled with a simplified approach that locally manages the group membership to allow packet delivery from the Internet. Moreover, we propose an approach that selects the appropriate network-layer protocol for either geocasting or IP multicasting depending on the vehicles' context and the application requirements. Finally, we present the integration of the designed framework to the ITS reference architecture
Infraestrutura de beira de estrada para apoio a sistemas cooperativos e inteligentes de transportes
The growing need of mobility along with the evolution of the automotive industry
and the massification of the personal vehicle amplifies some of the road-related
problems such as safety and traffic congestion. To mitigate such issues, the evolution
towards cooperative communicating technologies and autonomous systems
is considered a solution to overcome the human physical limitations and the limited
perception horizon of on-board sensors. Short-range vehicular communications
such as Vehicle-to-Vehicle or Vehicle-to-Infrastructure (ETSI ITS-G5) in conjunction
with long-range cellular communications (LTE,5G) and standardized messages,
emerge as viable solutions to amplify the benefits that standalone technologies can
bring to the road environment, by covering a wide array of applications and use
cases. In compliance with the standardization work from European Telecommunications
Standards Institute (ETSI), this dissertation describes the implementation of
the collective perception service in a real road infrastructure to assist the maneuvers
of autonomous vehicles and provide information to a central road operator. This
work is focused on building standardized collective perception messages (CPM)
by retrieving information from traffic classification radars (installed in the PASMO
project) for local dissemination using ETSI ITS-G5 radio technology and creating
a redundant communication channel between the road infrastructure and a central
traffic control centre, located at the Instituto de Telecomunicações - Aveiro, taking
advantage of cellular, point-to-point radio links and optical fiber communications.
The output of the messages are shown to the user by a mobile application. The
service is further improved by building an algorithm for optimizing the message
dissemination to improve channel efficiency in more demanding scenarios. The results
of the experimental tests showed that the time delay between the production
event of the collective perception message and the reception by other ITS stations
is within the boundaries defined by ETSI standards. Moreover, the algorithm for
message dissemination also shows to increase radio channel efficiency by limiting
the number of objects disseminated by CPM messages. The collective perception
service developed and the road infrastructure are therefore, a valuable asset to
provide useful information for improving road safety and fostering the deployment
of intelligent cooperative transportation systems.A crescente necessidade de mobilidade em paralelo com a evolução da indústria automóvel
e com a massificação do uso de meios de transportes pessoais, têm vindo
a amplificar alguns problemas dos transportes rodoviários, tais como a segurança
e o congestionamento do tráfego. Para mitigar estas questões, a evolução das
tecnologias de comunicação cooperativas e dos sistemas autónomos é vista como
uma potencial solução para ultrapassar limitações dos condutores e do horizonte
de perceção dos sensores veículares. Comunicações de curto alcance, tais como
Veículo-a-Veículo ou Veículo-a-Infrastrutura (ETSI ITS-G5), em conjunto com comunicações
móveis de longo alcance (LTE,5G) e mensagens padrão, emergem como
soluções viáveis para amplificar todos os beneficios que tecnologias independentes
podem trazer para o ambiente rodoviário, cobrindo um grande leque de aplicações
e casos de uso da estrada. Em conformidade com o trabalho de padronização
da European Telecommunications Standards Institute, esta dissertação descreve
a implementação do serviço de perceção coletiva, numa infrastrutura rodoviária
real, para suporte a manobras de veículos autónomos e para fornecer informações
aos operadores de estradas. Este trabalho foca-se na construção de mensagens
de perceção coletiva a partir de informação gerada por radares de classificação de
tráfego (instalados no âmbito do projeto PASMO) para disseminação local usando
a tecnologia rádio ETSI ITS-G5 e criando um canal de comunicação redundante
entre a infraestrutura rodóviaria e um centro de controlo de tráfego localizado no
Instituto de Telecomunicações - Aveiro, usando para isso: redes móveis, ligações
rádio ponto a ponto e fibra ótica. O conteúdo destas messagens é mostrado ao
utilizador através de uma aplicação móvel. O serviço é ainda melhorado, tendo-se
para tal desenvolvido um algoritmo de otimização de disseminação das mensagens,
tendo em vista melhorar a eficiência do canal de transmissão em cenários mais exigentes.
Os resultados dos testes experimentais efetuados revelaram que o tempo
de atraso entre o evento de produção de uma mensagem de perceção coletiva e a
receção por outra estação ITS, usando comunicações ITS-G5, se encontra dentro
dos limites definidos pelos padrões da ETSI. Além disso, o algoritmo para disseminação
de mensagens também mostrou aumentar a eficiência do canal de rádio,
limitando o número de objetos disseminados pelas mesmas. Assim, o serviço de
perceção coletiva desenvolvido poderá ser uma ferramenta valiosa, contribuindo
para o aumento da segurança rodóviaria e para a disseminação da utilização dos
sistemas cooperativos de transporte inteligente.Mestrado em Engenharia Eletrónica e Telecomunicaçõe
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