Separate Dimming Controlling and Data Transmission for an Indoor Visible Light Communication System

Simultaneous dimming controlling and data transmission are usually required in a white LED based indoor visible light communication system. However, the diming controlling of LED normally interferes the data transmission due to the modulation nonlinearity of LED. In order to solve this problem, a scheme by separating the LEDs for the functions of dimming control and data transmission respectively is proposed in this paper. In the scheme, the LEDs used for dimming control function are driven by a dc amplified circuit, and the LEDs for data transmission are driven by a digital modulation circuit respectively. In this way, the modulation distortion to the data signal caused by the modulation nonlinearity can be avoided even if the dimming is at high level de driven current. The proof-of-concept experiment of a 2.5Mbit/s visible light communication system demonstrates that the dimming controlling and data transmission can be realized simultaneously in a simple way, and the data transmission is not affected by the dimming controlling function. Compared to previous methods, the scheme in this paper is simpler and cost effective, and makes sense when high rate data is transmitted in a visible light communication system.