Visible Light Communication Challenges in the Frame of Smart Cities

Visible Light Communication (VLC) is the family of telecommunication technologies that uses the visible range of the electromagnetic spectrum to send data. This technology mainly uses Light Emitting Diodes (LEDs) to simultaneously illuminate and send data. Furthermore, thanks to the adoption of LED lighting by cities and for car lights, VLC is about to bring a lot of interconnectivity possibilities among devices in the city, making this latter smarter. Even though outdoor VLC is still in the research phase, the main promising applications foreseen by this technology are urban Li-Fi (Light Fidelity), VLC-IoT (Internet of Things) and V2X (Vehicle to Vehicle or Vehicle to Infrastructure). VLC-IoT is envisioned as a streetlight communicating with the surrounding urban furniture or a streetlight sending location-based content to a visitor located under its light beam. V2X is intended to communicate with each other and/or with the street infrastructure. In this way, VLC could reply to the lack of connectivity in some places and relieve the RF spectrum. This work outlines and surveys the current state of Visible Light Communication in outdoor environments, its main challenges, the most promising outdoor applications and the still ongoing standardisation efforts in the context of Smart Cities.