Intelligent transportation : a hybrid FSO/VLC-assisted relay system

Various intelligent transportation systems are proposed in different forms of wireless communication technologies. Recently, the importance of visible light communication and free-space optics has been demonstrated in accomplishing vehicle-to-vehicle and infrastructure-to-vehicle communication systems, due to power efficiency, free licenses, and safety for human health. In this paper, a new hybrid relay system supported by free-space optics/visible light communication with two scenarios is proposed. The first one is that the data are transferred from the source to the relay through a free-space optics communication link and are then directed to the destination through a visible light communication link. The second scenario is that the data are transmitted from the source to the destination passing through two different relays to ensure larger coverage. A 10‾⁶ bit error rate is achieved at a distance of 900 m for the first scenario with a remarkable signal-to-noise ratio of ~25.5 dB, while the largest distance that can be covered by the second scenario is 1200 m with a signalto- noise ratio of ~30 dB.