A PAPR reduction scheme combining superimposed O-OFDM and μ-law mapping for VLC-OFDM systems

Due to the high peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals, the inherent nonlinearity of light emitting diodes (LEDs) is a challenge for optical OFDM (O-OFDM) schemes in visible light communication (VLC) systems. In order to reduce PAPR to mitigate the effects of the nonlinearity of LEDs, and avoid the asymmetric clipping interference in the conventional hybrid O-OFDM schemes, a novel superimposed O-OFDM scheme is proposed in this paper, which reduce the PAPR by combining the mu-law mapping and the superposition modulation. Moreover, at the transmitter, the hybrid O-OFDM components are superimposed in an interference-free way, the receiver does not require the operation of interference cancellation, and the symbols of each branch can be demodulated independently. Simulation results verify that the proposed scheme can significantly reduce the PAPR. At the same time, the comprehensive performance of the proposed scheme outperforms other competing schemes under the constraints of the nonlinearity and limited dynamic range of LEDs.