DFT-Spread Combined with Clipping Method to Reduce the PAPR in VLC-OFDM System

Orthogonal frequency division multiplexing (OFDM) is an attractive technique to realize high date rate in light emitting diodes (LEDs)-based visible light communication (VLC). However, high peak-to-average power ratio (PAPR) of OFDM makes VLC-OFDM very sensitive to nonlinearity of LEDs. In this paper, discrete Fourier transform-spread (DFT-Spread) combined with clipping method is proposed to reduce the PAPR of OFDM signal in VLC system. Combining simulation with experiment, a comparison is made among the performance of conventional OFDM, DFT-Spread-OFDM, and clipped DFT-Spread-OFDM with different clipping ratios (CRs) in a single LED-based VLC system. The experimental results show that, at the optimum signal peak-to-peak (PTP) value, clipped DFT-S-OFDM scheme with CR at 8 dB can achieve the lowest bit-error-rate (BER) of 2.87e-4. It demonstrates that the proposed clipped DFT-Spread-OFDM method can effectively improve the system performance compared with conventional OFDM and DFT-Spread-OFDM method.