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

The COST IRACON Geometry-based Stochastic Channel Model for Vehicle-to-Vehicle Communication in Intersections

Vehicle-to-vehicle (V2V) wireless communications can improve traffic safety at road intersections and enable congestion avoidance. However, detailed knowledge about the wireless propagation channel is needed for the development and realistic assessment of V2V communication systems. We present a novel geometry-based stochastic MIMO channel model with support for frequencies in the band of 5.2-6.2 GHz. The model is based on extensive high-resolution measurements at different road intersections in the city of Berlin, Germany. We extend existing models, by including the effects of various obstructions, higher order interactions, and by introducing an angular gain function for the scatterers. Scatterer locations have been identified and mapped to measured multi-path trajectories using a measurement-based ray tracing method and a subsequent RANSAC algorithm. The developed model is parameterized, and using the measured propagation paths that have been mapped to scatterer locations, model parameters are estimated. The time variant power fading of individual multi-path components is found to be best modeled by a Gamma process with an exponential autocorrelation. The path coherence distance is estimated to be in the range of 0-2 m. The model is also validated against measurement data, showing that the developed model accurately captures the behavior of the measured channel gain, Doppler spread, and delay spread. This is also the case for intersections that have not been used when estimating model parameters.Comment: Submitted to IEEE Transactions on Vehicular Technolog

Comparison of Radio Frequency and Visible Light Propagation Channels for Vehicular Communications

Recent research has shown that both radio and visible light waves can be used to enable communications in highly dynamic vehicular environments. However, the roles of these two technologies and how they interact with each other in future vehicular communication systems remain unclear. Understanding the propagation characteristics is an essential step in investigating the benefits and shortcomings of each technology. To this end, we discuss salient properties of radio and visible light propagation channels, including radiation pattern, path loss modeling, noise and interference, and channel time variation. Comparison of these properties provides an important insight that the two communication channels can complement each other’s capabilities in terms of coverage and reliability, thus better satisfying the diverse requirements of future cooperative intelligent transportation systems

A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

In recent years, there has been a dramatic increase in the use of unmanned aerial vehicles (UAVs), particularly for small UAVs, due to their affordable prices, ease of availability, and ease of operability. Existing and future applications of UAVs include remote surveillance and monitoring, relief operations, package delivery, and communication backhaul infrastructure. Additionally, UAVs are envisioned as an important component of 5G wireless technology and beyond. The unique application scenarios for UAVs necessitate accurate air-to-ground (AG) propagation channel models for designing and evaluating UAV communication links for control/non-payload as well as payload data transmissions. These AG propagation models have not been investigated in detail when compared to terrestrial propagation models. In this paper, a comprehensive survey is provided on available AG channel measurement campaigns, large and small scale fading channel models, their limitations, and future research directions for UAV communication scenarios

Impact of Dynamic Traffic on Vehicle-to-Vehicle Visible Light Communication Systems

In this article we studies the impact of dynamic vehicular traffic density on the signal-to-noise-ratio and the associated bit-error-rate (BER) performance of vehicle-to-vehicle visible light communication (V2V-VLC) systems. The article uses traffic data from the M42 and M6 motorways in the U.K. to investigate the probability of coexistence of other vehicles in the adjacent lanes, which induce interference and act as potential reflectors. The results show that the probability of coexistence of other vehicles in the adjacent lanes is lane-independent and it increases during the rush hours to 90%, while it decays to less than 10% during the off-peak and early morning hours. The intervehicular distance and the BER performance vary widely between different lanes and different periods of the day. The results also show that the BER performance of V2V-VLC system with non-line-of-sight (NLOS) component and with LOS component are comparable at rush hours. However, high BER values are predicted during the off-peak hours for NLOS components of the channel

Impact of Vehicle Headlights Radiation Pattern on Dynamic Vehicular VLC Channel

This article develops a statistical large-scale fading (path loss) model of a dynamic vehicular visible light communication (VVLC) system. The proposed model combines the impact of inter-vehicle spacing and the radiation intensity distribution as a function of the irradiance angle which changes with the traffic conditions. Three models (Lambertian, Gaussian, and empirical) are utilized to examine the impact of vehicles headlights radiation pattern on the statistical path loss of VVLC system. The analytical model of channel path loss is validated by Monte Carlo simulation with the headlight model simulated with a raytracing software. The path loss values of the Gaussian model differ by 2 dB compared to the Lambertian model, irrespective of the traffic conditions while it differs by 24.6 dB during late night and 8.15 dB during rush hours compared to the empirical model of a Toyota Altis headlight. This variation shows that the radiation intensity distribution should be modelled for each vehicle's headlights from each manufacturer to ensure accurate VVLC channel model. The proposed Gaussian model provides a close approximation to describe such radiation pattern and can easily be adapted to model for different manufacturers' headlights

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