Implicit Cooperative Positioning in Vehicular Networks

Absolute positioning of vehicles is based on Global Navigation Satellite Systems (GNSS) combined with on-board sensors and high-resolution maps. In Cooperative Intelligent Transportation Systems (C-ITS), the positioning performance can be augmented by means of vehicular networks that enable vehicles to share location-related information. This paper presents an Implicit Cooperative Positioning (ICP) algorithm that exploits the Vehicle-to-Vehicle (V2V) connectivity in an innovative manner, avoiding the use of explicit V2V measurements such as ranging. In the ICP approach, vehicles jointly localize non-cooperative physical features (such as people, traffic lights or inactive cars) in the surrounding areas, and use them as common noisy reference points to refine their location estimates. Information on sensed features are fused through V2V links by a consensus procedure, nested within a message passing algorithm, to enhance the vehicle localization accuracy. As positioning does not rely on explicit ranging information between vehicles, the proposed ICP method is amenable to implementation with off-the-shelf vehicular communication hardware. The localization algorithm is validated in different traffic scenarios, including a crossroad area with heterogeneous conditions in terms of feature density and V2V connectivity, as well as a real urban area by using Simulation of Urban MObility (SUMO) for traffic data generation. Performance results show that the proposed ICP method can significantly improve the vehicle location accuracy compared to the stand-alone GNSS, especially in harsh environments, such as in urban canyons, where the GNSS signal is highly degraded or denied.Comment: 15 pages, 10 figures, in review, 201

LEDs assisted navigation in connected cars

Dissertação de natureza científica para obtenção do grau de Mestre em Engenharia Eletrónica e TelecomunicaçõesAlternative wireless technologies are needed due to the increasing traffic demand and the shortage of RF band. VLC uses the visible light spectrum to encode and transmit information and is a complement to RF, providing additional bandwidth. Traffic lights are the main infrastructures to control access to roads and will soon be replaced by more efficient structures to improve traffic management. The goal of this dissertation is the characterization and test of communication links based on VLC technology for road management applications. Transmitters of the VLC link are tetrachromatic white LEDs used for illumination and data transmission. The characterization of the optical transmitter system is done through MATLAB simulations, using the Lambertian model. Receivers based on a-SiC:H/a-Si:H photodiodes with selective spectral sensitivity are used to. The studied scenario is a crossroad formed by five cells, with a LED at each corner providing a certain coverage and forming nine footprints. The OOK modulation was used, and the transmitted message follows a 64-bit frame structure. The coverage map and footprint map were obtained as outputs. A calibration curve was used in the encoding and decoding process. Two trajectories were tested: vehicle moving from West to East and from West to North. The encoded process was successful, proving that the simulation tool developed produces valid results. The decoding process was successful with the simulated results but not so much with the signals measured in the laboratory. The red LED/channel presented the least error followed by the green, since these are more distinguishable. The blue and violet LED/channel are less distinguishable and presented the most errors. Adjusting the calibration curve or implementing error detection mechanism are proposed as solutions. A GUI was developed to enable easy interaction between the user and the simulation tool.Devido ao aumento da procura de tráfego e diminuição da banda RF disponível são necessárias tecnologias sem fios alternativas. O VLC utiliza o espetro visível para codificar e transmitir informação, sendo um complemento ao RF fornecendo largura de banda adicional. Os semáforos são as principais infraestruturas de controlo de acesso às estradas e serão eventualmente substituídas por estruturas mais eficiente para melhorar a gestão do trânsito. O objetivo desta dissertação é a caracterização e teste da comunicação utilizando a tecnologia VLC em aplicações de gestão rodoviária. Os transmissores usados para iluminação e comunicação são LEDs tetra-cromáticos. A caracterização do transmissor ótico foi realizada em MATLAB usando o modelo Lambertiano. O recetor utilizado é um foto-detetor baseado em estruturas pin de a-SiC:H e a-Si:H que apresentam sensibilidade espectral seletiva. O cenário estudado é um cruzamento formado por cinco células, com um LED em cada canto, proporcionando uma cobertura específica e formando em conjunto nove footprints. Foi usada a modulação OOK e a mensagem enviada utiliza uma estrutura de 64 bits. Como resultados, foram obtidos mapas de cobertura e de footprints. A curva de calibração foi usada para o processo de codificação e descodificação. Foram testadas duas trajetórias: veículos provenientes de Oeste para Este e de Oeste para Norte. O processo de codificação foi bem-sucedido, mostrando que a ferramenta de simulação desenvolvida produz resultados válidos. O processo de descodificação foi bem-sucedido para os resultados simulados, mas apresenta erros para as medidas laboratoriais. O LED/canal vermelho apresentou menos erros, seguido do verde pois estes são mais distinguíveis. O azul e o violeta são menos distinguíveis, apresentando mais erros. As soluções propostas são ajustar a curva de calibração ou implementar de mecanismos de deteção de erros. Foi desenvolvida uma interface gráfica para facilitar a interação entre utilizador e ferramenta de simulação.info:eu-repo/semantics/publishedVersio

Smart Roadside System for Driver Assistance and Safety Warnings: Framework and Applications

The use of newly emerging sensor technologies in traditional roadway systems can provide real-time traffic services to drivers through Telematics and Intelligent Transport Systems (ITSs). This paper introduces a smart roadside system that utilizes various sensors for driver assistance and traffic safety warnings. This paper shows two road application models for a smart roadside system and sensors: a red-light violation warning system for signalized intersections, and a speed advisory system for highways. Evaluation results for the two services are then shown using a micro-simulation method. In the given real-time applications for drivers, the framework and certain algorithms produce a very efficient solution with respect to the roadway type features and sensor type use

Information collection algorithm for vehicular ad-hoc networks (application domain: Urban Traffic Wireless Vehicular Ad-Hoc Networks (VANETs))

Vehicle to vehicle communication (V2VC) is one of the modern approaches for exchanging and generating traffic information with (yet to be realized) potential to improve road safety, driving comfort and traffic control. In this research, we present a novel algorithm which is based on V2V communication, uses in-vehicle sensor information and in collaboration with the other vehicles' sensor information can detect road conditions and determine the geographical area where this road condition exists – e.g. geographical area where there is traffic density, unusual traffic behaviour, a range of weather conditions (raining), etc. The algorithms' built-in automatic geographical restriction of the data collection, aggregation and dissemination mechanisms allows warning messages to be received by any car, not necessarily sharing the identified road condition, which may then be used to identify the optimum route taken by the vehicle e.g. avoid bottlenecks or dangerous areas including accidents or congestions on their current routes. This research covers the middle ground between MANET [1] and collaborative data generation based on knowledge granularity (aggregation). It investigates the possibility of designing, implementing and modelling of the functionality of an algorithm (as part of the design of an intelligent node in an Intelligent Transportation System - ITS) that ensures active participation in the formation, routing and general network support of MANETs and also helps in-car traffic information and real-time control generation and distribution. The work is natural extension of the efforts of several large EU projects like DRIVE [2], GST [3] and SAFESPOT [4]

Fastening the Initial Access in 5G NR Sidelink for 6G V2X Networks

The ever-increasing demand for intelligent, automated, and connected mobility solutions pushes for the development of an innovative sixth Generation (6G) of cellular networks. A radical transformation on the physical layer of vehicular communications is planned, with a paradigm shift towards beam-based millimeter Waves or sub-Terahertz communications, which require precise beam pointing for guaranteeing the communication link, especially in high mobility. A key design aspect is a fast and proactive Initial Access (IA) algorithm to select the optimal beam to be used. In this work, we investigate alternative IA techniques to fasten the current fifth-generation (5G) standard, targeting an efficient 6G design. First, we discuss cooperative position-based schemes that rely on the position information. Then, motivated by the intuition of a non-uniform distribution of the communication directions due to road topology constraints, we design two Probabilistic Codebook (PCB) techniques of prioritized beams. In the first one, the PCBs are built leveraging past collected traffic information, while in the second one, we use the Hough Transform over the digital map to extract dominant road directions. We also show that the information coming from the angular probability distribution allows designing non-uniform codebook quantization, reducing the degradation of the performances compared to uniform one. Numerical simulation on realistic scenarios shows that PCBs-based beam selection outperforms the 5G standard in terms of the number of IA trials, with a performance comparable to position-based methods, without requiring the signaling of sensitive information

An Intelligent V2I-Based Traffic Management System

International audienceVehicles equipped with intelligent systems designed to prevent accidents, such as collision warning systems (CWSs) or lane-keeping assistance (LKA), are now on the market. The next step in reducing road accidents is to coordinate such vehicles in advance not only to avoid collisions but to improve traffic flow as well. To this end, vehicle-to-infrastructure (V2I) communications are essential to properly manage traffic situations. This paper describes the AUTOPIA approach toward an intelligent traffic management system based on V2I communications. A fuzzy-based control algorithm that takes into account each vehicle's safe and comfortable distance and speed adjustment for collision avoidance and better traffic flow has been developed. The proposed solution was validated by an IEEE-802.11p-based communications study. The entire system showed good performance in testing in real- world scenarios, first by computer simulation and then with real vehicles

Vehicular networks and road safety: an application for emergency/danger situations management using the WAVE/802.11p standard

Car-to-car communication makes possible offering many services for vehicular environment, mainly to improve the safety. The decentralized kind of these networks requires new protocols to distribute information. The advantages that it offers depend on the penetration rate, that will be enough only after years since the introduction, due to the longevity of the current cars. The V2X communication requires On-Board Units (OBUs) in the vehicles, and Road-Side Units (RSUs) on the roads. The proposed application uses the peculiarities of the VANETs to advise danger or emergency situations with V2V and V2I message exchange. IEEE 802.11p is standard on which the communication is based, that provides the physical and the MAC layers. The WAVE protocol uses this standard, implementing other protocols defined by the family of standards IEEE P1609 in the upper layers. They define security services, resource management, multichannel operations and the message exchange protocol in WAVE. The performance of the application will be evaluated through many simulations executed in different scenarios, to provide general data independent from them