Simultaneous Visible Light Communication and Ranging Using High-Speed Stereo Cameras Based on Bicubic Interpolation Considering Multi-Level Pulse-Width Modulation

Visible light communication (VLC) and visible light rang-ing are applicable techniques for intelligent transportation systems (ITS). They use every unique light-emitting diode (LED) on roads for data trans-mission and range estimation. The simultaneous VLC and ranging can be applied to improve the performance of both. It is necessary to achieve rapid data rate and high-accuracy ranging when transmitting VLC data and esti-mating the range simultaneously. We use the signal modulation method of pulse-width modulation (PWM) to increase the data rate. However, when using PWM for VLC data transmission, images of the LED transmitters are captured at different luminance levels and are easily saturated, and LED saturation leads to inaccurate range estimation. In this paper, we establish a novel simultaneous visible light communication and ranging system for ITS using PWM. Here, we analyze the LED saturation problems and ap-ply bicubic interpolation to solve the LED saturation problem and thus, im-prove the communication and ranging performance. Simultaneous commu-nication and ranging are enabled using a stereo camera. Communication is realized using maximal-ratio combining (MRC) while ranging is achieved using phase-only correlation (POC) and sinc function approximation. Fur-thermore, we measured the performance of our proposed system using a field trial experiment. The results show that error-free performance can be achieved up to a communication distance of 55 m and the range estimation errors are below 0.5 m within 60 m.