Peak-to-average power ratio and illumination-to-communication efficiency considerations in visible light OFDM systems

Visible light communication (VLC) systems can provide illumination and communication simultaneously via light emitting diodes (LEDs). Orthogonal frequency division multiplexing (OFDM) waveforms transmitted in a VLC system will have high peak-to-average power ratios (PAPRs). Since the transmitting LED is dynamic-range limited, peaks of the OFDM waveform can be clipped causing signal degradation. This same phenomenon also occurs in RF communication system, although in RF systems it is straightforward to quantify the performance in terms of RF power conversion efficiency. Results on quantifying VLC performance are scarce. Specifically, because VLC differs from RF communication in system constraint, baseband signal format, and nonlinearity characteristic of the transmitter, it is not obvious how PAPR is related to illumination-to-communication conversion efficiency in VLC. In this paper, we will attempt to quantify the illumination-to-communication conversion efficiency and clarify how PAPR is related to efficiency in VLC systems. We also present a method to improve the efficiency of VLC OFDM systems.