QPSK Modulation for AC-Power-Signal-Biased Visible Light Communication System

Abstract

With the integration of light emitting diode (LED), visible light communication (VLC) can provide wireless communication link using the lightning system. Due to the consideration of power efficiency, AC-LED has the design of reducing energy waste with alternating current from the power outlet. In this work, we propose an AC-power-signal-biased system that provides communication on both DC-LED and AC-LED. The bias circuit is designed to combine AC-power signal and the message signal with QPSK format. This driving scheme needs no AC-to-DC converters and it is suitable for driving AC LED. Synchronization is completed to avoid threshold effect of LED.