Visible Light Communication System Using Low-speed Image Sensor and Two-dimensional Optical Scanner

Visible light communication (VLC) is an optical wireless communication scheme that has potential uses in indoor navigation and in cooperation among vehicles. To receive data efficiently using commercial devices (e.g., smartphones), we proposed a VLC system using a low-speed image sensor and a one-dimensional optical scanner (polygon mirror and MEMS mirror) at a receiver (Rx). In this system, when a rapidly blinking light is incident to the Rx, the light is converted to a dotted and dashed line by an optical scanner, enabling the Rx to receive multiple bits modulated at a high frequency within one frame. However, a scanned signal overlaps with a scanned noise on the image-sensor under the condition that the signal and noise sources exist in the same scanning direction. In this paper, we address this signal-to-noise interference problem by using a two-dimensional optical scanner (galvo mirror). In our improved VLC system, the Tx emits a rapidly blinking light to the Rx. The Rx measures the positional relationship between the signal and noise sources prior to the communication. Then the Rx scans the incoming light using a galvo mirror, whose scanning direction is established to minimize the signal-to-noise interference. The performance of our improved system was evaluated in experiments. The experimental results suggested that the improved system could reduce interference between signal and noise while providing superior communication quality.