Polarization encoded visible light communication at 550 m in full daylight

Outdoor visible light communications offer significant promise for applications including vehicular communication and intelligent transportation systems. While outdoor optical communication systems must contend with significantly higher amounts of background noise than indoor visible light communication systems, simply increasing transmit power is not practical. Existing light sources used for communication must adhere to their original illumination specifications. Polarization encoding provides a robust way to increase the received signal-to-noise ratio, allowing improved throughput at longer ranges with the same transmitted luminance. In this paper, we present a system that uses polarization to encode data and demonstrate that it achieves throughput at distances up to 550 m with a very low (26 cd) transmitted power. Within the constraints of a low-cost commodity sensor with a limited sampling rate, polarization encoding allowed the signal to remain flicker-free operating at a data rate of 15 bits per second, consistent with many automotive and Internet of Things applications. Experimental results demonstrated throughput over a distance 37.5% greater than that achieved by the previous state of the art outdoor optical camera communication system while using 97% less transmitted luminous intensity. Analysis of polarization effects in the atmosphere and experimentation with a low-cost, low-power polarized transmitter validate the potential for effective long-range outdoor polarized visible light communication.