On the use of visible light communication in cooperative vehicular communication systems

The paper proposes the use of Visible Light Communication (VLC) in Vehicular Communication Systems for vehicle safety applications. A smart vehicle lighting system that combines the functions of illumination, signaling, communications, and positioning is presented. The system aims to ensure the communication between a LED based VLC emitter and an on-vehicle VLC receiver. A traffic scenario is stablished. Vehicle-to-vehicle (V2V) and Infrastructure-to-Vehicle (I2V) communications are analyzed. For the V2V communication study, the emitter was developed based on the vehicle head lights, whereas for the study of I2V communication system, the emitter was built based on streetlights. The VLC receiver is used to extract the data from the modulated light beam coming from the white RGB-LEDs emitters. The VLC receiver is based on amorphous SiC technology and enhances the conditioning of the signal enabling to decode the transmitted information. The [p(SiC:H)/i(SiC:H)/n(SiC:H)/p(SiC:H)/i(Si:H)/n(Si:H)] tandem photodetectors are located at the roof-top of the vehicle, for I2V communications, and at the tails for V2V reception. Clusters of emitters, in a square topology, are used in the I2V 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.