Enhanced design of visible light communication sensor for automotive applications: Experimental demonstration of a 130 meters link

Communication-based vehicle safety technology represents one of the most promising solutions to enhance the safety and the efficiency of the transportation system. For this purpose, visible light communications (VLC) have great potential of development due to low-cost, widespread distribution, and unregulated radiation spectrum. Nevertheless, existing VLC systems are not able to fully comply with the requirements imposed by vehicle safety applications. One of the main aspects that need further enhancement is the communication distance. Within this context, this paper presents the preliminary experimental results of a novel VLC system achieving a 130 m traffic light to vehicle communication distance. The key elements for obtaining this result are the use of a phototransistor based VLC sensor for better sensitivity, a logarithmic transimpedance amplifier circuit to reduce the strong influence of parasitic light and the possibility of photoelement saturation, a Schmitt trigger with adaptive thresholds to enhance noise mitigation under variable signal-to-noise ratios, and advanced techniques for signal processing. To the best of our knowledge, this is the longest communication distance reported for automotive VLC link.