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A generic model of cooperative transmissions for vehicular communications services is established, which share the common features among diverse vehicular communications scenarios. Three specific vehicular communications are analyzed. One is for Infrastructure-to-Vehicle (I2V) communications from the street lamps, located on roadside, to the vehicles; the other is for in line Vehicle-to-Vehicle (V2V) communications and the last for Vehicle-to-Infrastructure (V2I) communications from cars to the traffic lights, at the crossroad. For the V2V and V2I communication study, the emitter was developed based on the vehicle headlights, whereas for the study of I2V communication system, the emitter was built based on streetlights, whose primary purpose is to provide illumination, and are also used for data communication if modulated at fast rates. The VLC receivers extract the data from the modulated light beam coming from the LEDs emitters. The receivers consist in a double SiC pi’npin photodetector, with light filtering characteristics, located at the rooftop of the vehicle, for I2V communications; at the traffic lights, for V2I; and at the tails, for V2V reception. Clusters of emitters, in a square topology, are used in the I2V transmission. The encoded message contains ID code of each emitter concomitantly with a traffic message that is received, decoded and resent to another vehicle (V2V) or to traffic light, in the crossroad. An algorithm to decode the information at the receivers is established. A phasing traffic flow is presented as a proof of concept. The experimental results, confirmed that the proposed cooperative VLC architecture is suitable for the intended applications.
Different indoor layouts, using as position technique a four-code assignment for the LEDs, are proposed. Square and hexagon mesh are tested, and a 2D localization design, demonstrated by a prototype implementation, is presented. The key differences between both topologies are discussed. The location and motion information is calculated by position mapping and estimating the location areas along the time. In both topologies, the transmitted data information, indoor position and motion direction of the mobile device are determined.
The results showed that the LED-aided VLC navigation system make possible not only to determine the position of a mobile target inside the unit cell but also in the network and concomitantly to infer the travel direction along the time.
The system topology for positioning is a self-positioning system in which the measuring unit is mobile. This unit receives the signals of several transmitters in known locations, and has the capability to compute its location based on the measured signals. LED bulbs work as transmitters, sending information together with different IDs related to their physical locations. A triangular topology for the unit cell is analysed. A 2D localization design, demonstrated by a prototype implementation is presented. Fine-grained indoor localization is tested. The received signal is used in coded multiplexing techniques for supporting communications and navigation concomitantly on the same channel. The position is estimated through the visible multilateration metodh using several non-collinear transmitters. The location and motion information is found by mapping position and estimates the location areas.
Data analysis showed that by using a pinpin double photodiode based on a a-SiC:H heterostucture as receiver, and RBGLEDs as transmitters it is possible not only to determine the mobile target’s position but also to infer the motion direction over time, along with the received information in each position.
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