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- Cooperative vehicular systems: crossroad management through visible lightPublication . Vieira, Manuel Augusto; Vieira, Manuela; Louro, Paula; Vieira, PedroInformation and communication technologies enable optoelectronic cooperative vehicular systems with bi-directional communication, where vehicles communicate with other vehicles, road infrastructures, traffic lights, and vulnerable road users. We use the concept of request/response for the management of a trajectory in a two-way-two-way traffic lights controlled crossroad, using visible-light communication (VLC). The connected vehicles receive information from the network (Infrastructure to Vehicle, I2V), interact with each other (Vehicle to Vehicle, V2V) and with the infrastructure (Vehicle to Infrastructure, V2I), using a request distance and pose estimation concept. In parallel, an intersection manager (IM) coordinates the crossroad and interacts with the vehicles (I2V) using the response distance and the pose estimation concepts. The communication is performed through VLC using the street lamps and the traffic signaling, to broadcast the information. Data are encoded, modulated, and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used, providing a different data channel for each chip. As receivers and decoders, SiC wavelength division multiplexer (WDM) devices, with light filtering properties, are considered. A simulated vehicle-to-everything (V2X) traffic scenario is presented, and a generic model of cooperative transmission is established. The primary objective is to control the arrival of vehicles to the intersection and schedule them to cross over at time instants that minimize delays. A phasing traffic flow is developed as a proof of concept (PoC). The simulated/experimental results confirm the cooperative VLC architecture. Results show that the communication between connected cars is optimized using a request/response concept and that pose analysis is an important issue to control driver’s behavior in a crossroad. The block diagram conveys that the vehicle’s behavior (successive poses) is influenced by the maneuver permission, by the I2V messages and also by the intersection redesigned layout and presence of other vehicles. An increase in the traffic throughput with least dependency on infrastructure is achieved.
- Indoor positioning and intuitive advertising using visible light communicationPublication . Vieira, Manuela; Vieira, Manuel; Louro, Paula; Fantoni, Alessandro; Vieira, PedroThis paper researches the applicability of an intuitive advertising system for large indoor environments using Visible Light Communication (VLC). This VLC based positioning system includes the use of the visible light signal to light the space and to transmit the information for travelers’ positioning and of advertising campaigns in the surroundings. White RGB-LEDs, whose original function is providing illumination, are used as transmitters due to the ability of each individual chip to switch quickly enough to transfer data. This functionality is used for communication where the multiplexed data can be encoded in the emitting light. The light signals emitted by the LEDs positioned in the area of the advertising campaign are interpreted directly by the customers’ receivers. A SiC optical sensor with light filtering and demultiplexing properties receives the modulated signals containing the ID and the geographical position of the LED and other information, demultiplexes and decodes the data and locates the mobile device in the environment. Different layouts are analysed: square and hexagonal meshes are tested, and a 2D localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. For both, the transmitted information, indoor position and motion direction of the customer are determined. The results showed that the LED-aided VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction as a function of time and to interact with information received.
- Cooperative vehicular visible light communication in smarter split intersectionsPublication . Vieira, Manuel Augusto; Vieira, Manuela; Louro, Paula; Vieira, PedroThis paper addresses the issues related to the Visible Light Communication (VLC) usage in vehicular communication applications. We propose a Visible Light Communication system based on Vehicle-to-Vehicle, Vehicle-to-Infrastructure and Infrastructure-to-Vehicle communications able to safely manage vehicles crossing through an intersection leveraging Edge of Things facilities. By using the streetlamps, street lights and traffic signaling to broadcast information, the connected vehicles interact with one another and with the infrastructure. By using joint transmission, mobile optical receivers collect data at high frame rates, calculate their location for positioning and, concomitantly, read the transmitted data from each transmitter. In parallel with this, an intersection manager coordinates traffic flow and interacts with the vehicles via Driver Agents embedded in them. A communication scenario is stablished and a “mesh/cellular” hybrid network configuration proposed. Data is encoded, modulated and converted into light signals emitted by the transmitters. As receivers and decoders, optical sensors with light filtering properties, are used. Bidirectional communication between the infrastructure and the vehicles is tested. To command the passage of vehicles crossing the intersection safely queue/request/response mechanisms and temporal/space relative pose concepts are used. Results show that the short range mesh network ensures a secure communication from street lamp controllers to the edge computer through the neighbor traffic light controller with active cellular connection and enables peer-to-peer communication, to exchange information between V-VLC ready connected cars. The innovative treatments for the congested intersections are related with the introduction of the split intersection. In the split intersection a congested two-way-two-way traffic light controlled intersection was transformed into two lighter intersections which facilitate a smoother flow with less driver delay by reducing the number of vehicle signal phases. Based on the results, the V-VLC system provides direct monitoring of critical points including queue formation and dissipation, relative speed thresholds and inter-vehicle spacing, increasing safety.
- Redesign of the trajectory within a complex intersection for visible light communication ready connected carsPublication . Vieira, Manuel Augusto; Vieira, Manuela; Louro, Paula; Vieira, PedroTo serve the changing needs of road traffic control, the road space and road structure surrounding an intersection have evolved into complex forms. The redesign of the trajectories, though complex, can be accomplished by the application of methods for navigation, guidance, and combination of expert knowledge of road traffic control of vehicles, using a concept of request/response in a two-way-to-way traffic light-controlled crossroad. The communication between the infrastructures and the vehicles (I2V), between vehicles (V2V), and from the vehicles to the infrastructures (V2I) is performed through visible light communication (VLC) using the street lamps and the traffic signaling to broadcast the information. Vehicle headlamps and taillights are used to transmit data to other vehicles or infrastructures allowing digital safety and data privacy. Data are encoded, modulated, and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. As receivers and decoders, silicon/carbon wavelength division multiplexer devices, with light filtering properties, are used. The primary objective is to control the arrival of vehicles to an intersection and schedule them to cross at times that minimize delays. A further objective is to allocate delays between left-turns and forward movements, moderating the speed and slot between vehicles traveling in these directions, maintaining a safe distance from one to another. Pedestrians and bicycles are incorporated. A I2V2V2I traffic scenario is established. A phasing traffic flow is developed as a proof of concept. The experimental results confirm the cooperative VLC architecture showing that communication between connected cars is optimized.
- Indoor wayfinding using visible light communicationPublication . Vieira, Manuela; Vieira, Manuel Augusto; Louro, Paula; Fantoni, Alessandro; Vieira, PedroOptical wireless communication has been widely studied during the last years in short-range applications. This paper investigates the applicability of an intuitive wayfinding system in complex buildings using Visible Light Communication (VLC). Typical scenarios include finding places, like a particular shop or office, guiding users across different floors, through elevators and stairs. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by SiC photodetector with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission become a single cell, in which the optical access point (AP) is located in the ceiling and the mobile users are scattered within the overlap discs of each cells underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the users positioned underneath. The effect of the location of the Aps is evaluated and a model for the different cellular networks is analyzed. Orthogonal topologies are tested, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented and the 3D best route to navigate through venue calculated. Buddy wayfinding services are also implemented. The results showed that the system make possible to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received and to optimize the route towards a static or dynamic destination.
- Wayfinding services in crowded buildings through visible lightPublication . Vieira, Manuela; Vieira, Manuel; Louro, Paula; Fantoni, Alessandro; Vieira, PedroThis paper investigates the applicability of an intuitive risk of transmission wayfinding system in public spaces, virtual races, indoor large environments and complex buildings using Visible Light Communication (VLC). Typical scenarios include: finding places, like a particular shop or office, guiding users across different floors, and through elevators and stairs. The system is able to inform the users, in real time, not only of the best route to the desired destination, through a route without clusters of users, but also of crowded places. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used providing a different data channel for each chip. At the receiver side, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by a SiC optical sensor with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission becomes a single cell, in which the optical Access Point (AP) is located in the ceiling and the mobile users are scattered across the overlap discs of each cell, underneath. The light signals emitted by the LEDs are interpreted directly by the receivers of the positioned users. Bidirectional communication is tested. The effect of the location of the Aps is evaluated and a 3D model for the cellular network is analyzed. In order to convert the floorplan to a 3D geometry, a tandem of layers in a orthogonal topology is used, and a 3D localization design, demonstrated by a prototype implementation, is presented. Uplink transmission is implemented, and the 3D best route to navigate through venue is calculated. Buddy wayfinding services are also considered. The results showed that the dynamic VLC navigation system enables to determine the position of a mobile target inside the network, to infer the travel direction along the time, to interact with received information and to optimize the route towards a static or dynamic destination.
- Footprint model in a navigation system based on visible light communicationPublication . Louro, Paula; Vieira, Manuela; Vieira, Manuel; Lima, Mirtes de; Rodrigues, João; Vieira, PedroIndoor navigation is hardly managed by the usual Global Positioning System (GPS) due to the strong attenuation of signals inside the buildings. Alternative based on RF optical, magnetic or acoustic signals can be used. Among the optical technologies, Visible Light Communication (VLC) provides good position accuracy. The proposed system uses commercial RGB white LEDs for the generation of the light, which is simultaneously coded and modulated to transmit information. The receiver includes a multilayered photodetector based on a-SiC:H operating in the visible spectrum. The positioning system includes multiple, identical navigation cells. Inside each cell, the optical pattern defined by the VLC transmitters establishes specific spatial regions assigned each to different optical excitations, which configures the footprint of the navigation cell. Demodulation and decoding procedures of the photocurrent signal measured by the photodetector are used to identify the input optical excitations and enable position recognition inside the cell. The footprint model is characterized using geometrical and optical assumptions, namely the Lambertian model for the LEDs and the evaluation of the channel gain of the VLC link. An algorithm to decode the information is established and the positioning accuracy is discussed. The experimental results confirmed that the proposed VLC architecture is suitable for the intended application.
- Cooperative vehicular communication systems based on visible light communicationPublication . Vieira, Manuel; Vieira, Manuela; Louro, Paula; Vieira, PedroThe use of visible light communication (VLC) in vehicular communication systems for vehicle safety applications is proposed. The system aims to ensure the communication between a LED-based VLC emitter and an on-vehicle VLC receiver. A traffic scenario is established. Vehicle-to-vehicle (V2V) and infrastructure-to-vehicle (12V) communications are analyzed. For the V2V communication study, the emitter was developed based on the vehicle headlights, whereas for the study of 12V communication system, the emitter was built based on streetlights. The VLC receiver is based on amorphous SiC technology and enhances the conditioning of the signal enabling to decode the transmitted information. Receivers are located at the rooftop of the vehicle, for 12V communications, and at the tails for V2V reception. Clusters of emitters, in a square topology, are used in the 12V transmission. The information and the ID code of each emitter in the network are sent simultaneously by modulating the individual chips of the trichromatic white LED. Free space is the transmission medium. An on-off code is used to transmit data. An algorithm to decode the information at the receivers is set. The proposed system was tested. The experimental results confirmed that the proposed cooperative VLC architecture is suitable for the intended applications.
- Trajectory redesign within a complex intersection for VLC ready connected carsPublication . Vieira, Manuel Augusto; Vieira, Manuela; Louro, Paula; Vieira, PedroIn order to serve the changing needs of road traffic control, the road space and road structure surrounding an intersection have evolved into complex forms. Using a new concept of request/response in a two-way-to-way traffic light controlled crossroad, the redesign of the trajectories can be accomplished by the application of methods for navigation, guidance and combination of expert knowledge of vehicle road traffic control. In this work, the communication between the Infrastructures and the Vehicles (I2V), between vehicles (V2V) and from the Vehicles to the Infrastructures (V2I) is performed through Visible Light Communication (VLC), using the street lamps and the traffic signaling to broadcast the information. Vehicle headlamps are used to transmit data to other vehicles or infrastructures, allowing digital safety and data privacy. Data is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used, providing a different data channel for each chip. As receivers and decoders, SiC Wavelength Division Multiplexer (WDM) devices, with light filtering properties, are considered. The primary objective is to control the arrival of vehicles to an intersection and schedule them to cross at times that minimize traffic delay. A further objective is to allocate delays between left-turns and forward movements, moderating the speed and slot between vehicles travelling in these directions, maintaining a safe distance from one to another. Pedestrians and bicycles are also incorporated. An I2V2V2I traffic scenario is proposed, and bidirectional communication between the infrastructure and the vehicles is tested, using the VLC request/response concept. A phasing traffic flow is developed as a proof of concept. The experimental results confirm the cooperative VLC architecture, showing that communication between connected cars and infrastructures can be optimized using the mentioned request/response concept. A significant increase in traffic throughput with the least dependency on infrastructure is achieved.
- Geolocation and communication in unfamiliar indoor environments through visible lightPublication . Vieira, Manuela; Vieira, Manuel; Louro, Paula; Fantoni, Alessandro; Vieira, PedroTo support people’s wayfinding activities in unfamiliar indoor environments, a method able to generate ceiling landmark route instructions using Visible Light Communication (VLC) is proposed. The system is composed of several transmitters (ceiling luminaries) which send the map information and path messages required to wayfinding. Mobile optical receivers, using joint transmission, extracts theirs location to perform positioning and, concomitantly, the transmitted data from each transmitter. Bidirectional communication between the emitters and the receivers is available in strategic optical access point. Typical scenarios are simulated and include finding places and guiding users across different floors. Data from the sender is encoded, modulated and converted into light signals emitted by the transmitters. Tetra-chromatic white sources are used, providing a different data channel for each chip. At the receiver, the modulated light signal, containing the ID and the 3D geographical position of the transmitter and wayfinding information, is received by SiC photodetectors with light filtering and demultiplexing properties. Since lighting and wireless data communication is combined, each luminaire for downlink transmission become a single cell, in which the optical access point (AP) is located. The coded light signals are interpreted directly by the receivers of the users positioned underneath. The effect of the location of the APs is evaluated and a model for the different cellular networks is analyzed. Orthogonal and hexagonal topologies are tested, and a 3D localization design, demonstrated by a prototype is presented. Uplink transmission is implemented and the 3D best route to navigate through venue calculated. The results show that the system make possible to determine the position of a mobile target inside the network, to infer the travel direction along the time and to interact with information received and optimize the route towards a static or dynamic destination.