A New Vehicle Localization Scheme Based on Combined Optical Camera Communication and Photogrammetry

The demand for autonomous vehicles is increasing gradually owing to their enormous potential benefits. However, several challenges, such as vehicle localization, are involved in the development of autonomous vehicles. A simple and secure algorithm for vehicle positioning is proposed herein without massively modifying the existing transportation infrastructure. For vehicle localization, vehicles on the road are classified into two categories: host vehicles (HVs) are the ones used to estimate other vehicles' positions and forwarding vehicles (FVs) are the ones that move in front of the HVs. The FV transmits modulated data from the tail (or back) light, and the camera of the HV receives that signal using optical camera communication (OCC). In addition, the streetlight (SL) data are considered to ensure the position accuracy of the HV. Determining the HV position minimizes the relative position variation between the HV and FV. Using photogrammetry, the distance between FV or SL and the camera of the HV is calculated by measuring the occupied image area on the image sensor. Comparing the change in distance between HV and SLs with the change in distance between HV and FV, the positions of FVs are determined. The performance of the proposed technique is analyzed, and the results indicate a significant improvement in performance. The experimental distance measurement validated the feasibility of the proposed scheme

Etude et réalisation d'un système de communications par lumière visible (VLC/LiFi). Application au domaine automobile.

The scientific problematic of this PhD is centered on the usage of Visible LightCommunications (VLC) in automotive applications. By enabling wireless communication amongvehicles and also with the traffic infrastructure, the safety and efficiency of the transportation canbe substantially increased. Considering the numerous advantages of the VLC technologyencouraged the study of its appropriateness for the envisioned automotive applications, as analternative and/or a complement for the traditional radio frequency based communications.In order to conduct this research, a low-cost VLC system for automotive application wasdeveloped. The proposed system aims to ensure a highly robust communication between a LEDbasedVLC emitter and an on-vehicle VLC receiver. For the study of vehicle to vehicle (V2V)communication, the emitter was developed based on a vehicle backlight whereas for the study ofinfrastructure to vehicle (I2V) communication, the emitter was developed based on a traffic light.Considering the VLC receiver, a central problem in this area is the design of a suitable sensorable to enhance the conditioning of the signal and to avoid disturbances due to the environmentalconditions, issues that are addressed in the thesis. The performances of a cooperative drivingsystem integrating the two components were evaluated as well.The experimental validation of the VLC system was performed in various conditions andscenarios. The results confirmed the performances of the proposed system and demonstrated thatVLC can be a viable technology for the considered applications. Furthermore, the results areencouraging towards the continuations of the work in this domain.La problématique scientifique de cette thèse est centrée sur le développement decommunications par lumière visible (Visible Light Communications - VLC) dans lesapplications automobiles. En permettant la communication sans fil entre les véhicules, ou entreles véhicules et l’infrastructure routière, la sécurité et l'efficacité du transport peuvent êtreconsidérablement améliorées. Compte tenu des nombreux avantages de la technologie VLC,cette solution se présente comme une excellente alternative ou un complément pour lescommunications actuelles plutôt basées sur les technologies radio-fréquences traditionnelles.Pour réaliser ces travaux de recherche, un système VLC à faible coût pour applicationautomobile a été développé. Le système proposé vise à assurer une communication très robusteentre un émetteur VLC à base de LED et un récepteur VLC monté sur un véhicule. Pour l'étudedes communications véhicule à véhicule (V2V), l'émetteur a été développé sur la base d’un pharearrière rouge de voiture, tandis que pour l'étude des communications de l'infrastructure auvéhicule (I2V), l'émetteur a été développé sur la base d'un feu de circulation. Considérant lerécepteur VLC, le problème principal réside autour d’un capteur approprié, en mesured'améliorer le conditionnement du signal et de limiter les perturbations dues des conditionsenvironnementales. Ces différents points sont abordés dans la thèse, d’un point de vue simulationmais également réalisation du prototype.La validation expérimentale du système VLC a été réalisée dans différentes conditions etscénarii. Les résultats démontrent que la VLC peut être une technologie viable pour lesapplications envisagées

Sistemas de comunicação por luz visível aplicados para assistência ao tráfego automóvel

Motivated by the topic of promoting traffic safety applications and information systems, this work aims to bring a study on VLC outdoor application scenarios. The developed topic is part of intelligent transportation systems (ITS) that aim at the delivery of traffic safety and information amongst other safety functions. VLC technology in traffic communication applications gains interest due to some advantages it presents. The use of LEDs in traffic signaling infrastructures and vehicle headlights started to be a growing standard. With the combination of illuminating proprieties and communication in the same device, VLC becomes a very attractive technology for the implementation of outdoor communication systems for traffic information and control. Outdoor VLC channels present variable ambient conditions, with the presence of different optical sources. One major problem in this communication channel is the presence of shot-noise, generated by optical background radiance from different light sources. This dissertation presents two different communication scenarios for traffic information systems, the first being directed at the infrastructure to car (I2C) link and the second one for car to car (C2C) communication. In order to simulate the communication link performance with variable ambient channel conditions, several models for optical propagation, emitter, receiver and noise sources were implemented in MATLAB. Models for different optical sources were also implemented, with field measurements on the illuminance incident on a photo detector and their impact on the noise generated. In the simulation’s performance of the VLC link, several baseband modulation schemes were considered, aiming at the assessment of link performance, based on the traditional digital modulation performance metrics.Motivado em promover o tópico de segurança rodoviária e sistemas de informação, este trabalho providência um estudo dedicado a sistemas de comunicação por luz visível (VLC) para aplicação em cenários de exterior. O tópico desenvolvido faz parte de sistemas de transporte inteligentes (ITS) cujo propósito é a disseminação de sistemas de segurança no tráfego e transferência de informação, para aplicações de segurança. A tecnologia VLC aplicada a sistemas de comunicação de tráfego rodoviário suscita elevado interesse devido a vantagens que esta apresenta. O uso de LED’s em semáforos e faróis de carros começa a ser bastante comum. Com a combinação de diferentes valências, como iluminação e transferência de dados no mesmo dispositivo, a tecnologia VLC torna-se muito atrativa para a implementação em sistema de comunicação exterior dedicados a sistemas de informação e controlo de tráfego. O canal de comunicação VLC exterior apresenta condições variáveis, devido ao fato de existirem condições ambientais diferentes. Um grave problema neste tipo de canal de comunicação é a presença de ruido Shot, que é normalmente gerado devido á radiância causada por diferentes fontes de luz de fundo. Nesta dissertação estão presentes dois tipos de cenários para sistemas de informação de tráfego, em que o primeiro dedica-se á comunicação semáforo-carro (I2C) e o segundo cenário para a comunicação entre carros (C2C). Para simular o desempenho do canal de comunicação com diferentes condições ambientais, foram implementados em MATLAB modelos para a propagação ótica, descrição do emissor, recetor e fontes de ruido. Também foram incluídos modelos para diferentes fontes óticas de radiação, com medições de campo da iluminância incidente num foto recetor e modulado o impacto na geração de ruido. Nas simulações de desempenho da comunicação por luz visível, foram considerados diferentes esquemas de modulação da informação com o intuito de avaliar o desempenho da ligação, a qual foi feita recorrendo a métricas clássicas de desempenho de modulações digitais.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

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

A study of visible light communication channels for high speed roadways

A visible light communication channel study is conducted for high speed roadways under clear night sky conditions in which street light poles transmit to receivers on top of moving vehicles. A detailed analysis of the communication channel is undertaken. Exact and approximate analytical DC channel responses are obtained and analyzed, and the channel capacity and RMS time delay spreads are derived. Numerical studies verify that visible light communications are feasible for high speed roadways

Achieving reliable and enhanced communication in vehicular ad hoc networks (VANETs)

A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirement for the degree of Doctor of PhilosophyWith the envisioned age of Internet of Things (IoTs), different aspects of Intelligent Transportation System (ITS) will be linked so as to advance road transportation safety, ease congestion of road traffic, lessen air pollution, improve passenger transportation comfort and significantly reduce road accidents. In vehicular networks, regular exchange of current position, direction, speed, etc., enable mobile vehicle to foresee an imminent vehicle accident and notify the driver early enough in order to take appropriate action(s) or the vehicle on its own may take adequate preventive measures to avert the looming accident. Actualizing this concept requires use of shared media access protocol that is capable of guaranteeing reliable and timely broadcast of safety messages. This dissertation investigates the use of Network Coding (NC) techniques to enrich the content of each transmission and ensure improved high reliability of the broadcasted safety messages with less number of retransmissions. A Code Aided Retransmission-based Error Recovery (CARER) protocol is proposed. In order to avoid broadcast storm problem, a rebroadcasting vehicle selection metric η, is developed, which is used to select a vehicle that will rebroadcast the received encoded message. Although the proposed CARER protocol demonstrates an impressive performance, the level of incurred overhead is fairly high due to the use of complex rebroadcasting vehicle selection metric. To resolve this issue, a Random Network Coding (RNC) and vehicle clustering based vehicular communication scheme with low algorithmic complexity, named Reliable and Enhanced Cooperative Cross-layer MAC (RECMAC) scheme, is proposed. The use of this clustering technique enables RECMAC to subdivide the vehicular network into small manageable, coordinated clusters which further improve transmission reliability and minimise negative impact of network overhead. Similarly, a Cluster Head (CH) selection metric ℱ(\u1d457) is designed, which is used to determine and select the most suitably qualified candidate to become the CH of a particular cluster. Finally, in order to investigate the impact of available radio spectral resource, an in-depth study of the required amount of spectrum sufficient to support high transmission reliability and minimum latency requirements of critical road safety messages in vehicular networks was carried out. The performance of the proposed schemes was clearly shown with detailed theoretical analysis and was further validated with simulation experiments

Vision Science and Technology at NASA: Results of a Workshop

A broad review is given of vision science and technology within NASA. The subject is defined and its applications in both NASA and the nation at large are noted. A survey of current NASA efforts is given, noting strengths and weaknesses of the NASA program

Visible Light Communication (VLC)

Visible light communication (VLC) using light-emitting diodes (LEDs) or laser diodes (LDs) has been envisioned as one of the key enabling technologies for 6G and Internet of Things (IoT) systems, owing to its appealing advantages, including abundant and unregulated spectrum resources, no electromagnetic interference (EMI) radiation and high security. However, despite its many advantages, VLC faces several technical challenges, such as the limited bandwidth and severe nonlinearity of opto-electronic devices, link blockage and user mobility. Therefore, significant efforts are needed from the global VLC community to develop VLC technology further. This Special Issue, “Visible Light Communication (VLC)”, provides an opportunity for global researchers to share their new ideas and cutting-edge techniques to address the above-mentioned challenges. The 16 papers published in this Special Issue represent the fascinating progress of VLC in various contexts, including general indoor and underwater scenarios, and the emerging application of machine learning/artificial intelligence (ML/AI) techniques in VLC

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression