Experimental outdoor visible light data communication system using differential decision threshold with optical and color filters

Abstract

An experimental outdoor optical wireless data communication system with a differential decision threshold (DDT) using filtering techniques in the presence of sunlight or artificial light is presented. In the proposed system, an optical filter is employed for reducing ambient light noise and sunlight, and a red color filter is also applied for detecting a specific wavelength only at the receiver with DDT. Unlike previously reported methods, such as spread spectrum techniques, combining methods, and preamble methods, the proposed method is very practical and efficient in that it uses filters on the top of the photodiode to occlude obliquely incident unwanted light under the realistic assumption that the light noise does not come directly into the photodiode. The proposed outdoor visible light communication can thus facilitate a practical free space outdoor optical wireless data transmission system.