Visible Light Communication Using Receivers of Camera Image Sensor and Solar Cell

TLDR

Using a camera image sensor as a VLC receiver is difficult because its data rate is limited by frame rate and uneven light exposure. The paper proposes and demonstrates an electronic label and sensor system that uses VLC, specifically demodulating rolling‑shutter patterns with a second‑order polynomial extinction‑ratio enhancement and adaptive thresholding. The system transmits VLC via a white‑light LED lamp, receives the downlink with a solar cell, captures the uplink with a surveillance camera image sensor exploiting the rolling‑shutter effect, and demodulates the signal using SOP ER enhancement and iterative quick adaptive thresholding. The extinction‑ratio enhancement markedly reduces ER fluctuation and improves BER by up to two orders of magnitude, indicating the system’s suitability for IoT sensing networks.

Abstract

We propose an electronic label and sensor system using visible light communication (VLC). The downlink signal is transmitted by a white-light light-emitting diode (LED) lamp that can provide lighting, VLC, and energy harvesting for mobile devices. The downlink is received by a solar cell. The uplink can be captured by a surveillance camera image sensor. However, using the camera image sensor as a VLC receiver (Rx) is challenging since the data rate is limited by the frame rate and due to uneven light exposure. The rolling shutter effect of the image sensor can be used to increase the data rate. In this paper, we propose and demonstrate how to demodulate the obtained rolling shutter pattern using a second-order polynomial (SOP) extinction ratio (ER) enhancement scheme, together with iterative and modified quick adaptive thresholding schemes. The ER enhancement scheme can significantly reduce the large ER fluctuation. Experimental results show that by using the proposed SOP ER enhancement scheme, the bit error rate (BER) improvement can be up to two orders of magnitude. We also believe that the proposed electronic label and sensor system may be applicable to Internet-of-Things sensing networks for connecting a number of mobile devices.