Illumination distribution and signal transmission for indoor visible light communication with different light-emitting diode arrays and pre-equality circuits

摘要

The purpose of this study was to seek the optimal design for light-emitting diode (LED) arrays and pre-equality circuits in indoor visible lighting illumination combined with communication. The optical and com-municational properties of illumination distribution and signal transmission were investigated. These illumination distributions of array sources were derivate and simulated and actually can be used in free-space communication. Simulated results show the total flux size was rectangle > radial > circlearray, and real measurements also showed the total flux was rectangle > radial > circlearray. The simulated and measured results have a similarity of over 98% by normalized cross correlation. In addition, when the distance of the installed lamp from the wall was 1 m, the rectangular array had the best illumination uniformity of 77.24%, and the size of uniformity was the rectangle > radial ≈ circle array. Finally, the gain and constant-current pre-equality circuits were used in free-space communication with a carrier frequency from 1 KHz to 1 MHz at a distance of 1.8 m. Both the received signal intensity and divergence angle were rectangle > radial > circle array. The constant-current pre-equality circuit could add the divergence angle from ±18.6 deg to ±36.68 deg in the rectangle array at a carrier frequency of 1 MHz.