High dynamic-range dimming control for CFMO-OFDM-based VLC systems utilizing a grouped direct current scheme

Since visible light communication (VLC) uses light-emitting diode (LED) as transmitters, it has dual functions of illumination and communication. To meet flexible lighting and energy-saving needs, we propose a novel, to the best of our knowledge, dimming control scheme for spectrally efficient clipping-free multilayer optical orthogonal frequency division multiplexing (CFMO-OFDM)-based VLC systems. In order to achieve high dynamic-range dimming control for LEDs, the time-domain CFMO-OFDM signals are first grouped based on frequency-domain subcarrier distribution. Then, the periodic grouped direct current (DC) signal can be flexibly chosen and added to the above CFMO-OFDM signals. Simulation results demonstrate that, compared with classical asymmetrical hybrid optical OFDM (AHO-OFDM) and DC bias-based dimming methods, the proposed scheme offers higher dimming range, better flexibility, and lower implementation complexity, as well as superior bit error rate (BER) performance.