This paper proposes the use of Visible Light Communication (VLC) in Vehicular Communication Systems for vehicle safety applications. A vehicle lighting system that combines the functions of illumination, signaling, communications, and positioning is presented. Using traffic signals, applies the connected vehicle concept to traditional intersections. 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.
|
