A hybrid PAPR reduction scheme for OFDM systems based on PTS and parabolic companding

Optical orthogonal frequency-division multiplexing (O-OFDM) systems have been severely limited in achieving a low peak-to-average power ratio (PAPR), as higher peaks can cause greater nonlinear distortion in optical transmitters. This work offers a hybrid PAPR-reduction method that combines generalized parabolic companding and partial transmit sequence (PTS) to minimize PAPR. The proposed scheme is evaluated using asymmetrically clipped optical OFDM (ACO-OFDM) and direct-current–biased optical OFDM (DCO-OFDM) with a fast Fourier transform (FFT) size of 1,024 and 16-QAM. The effect of the shaping parameter p is examined, and the optimum value p = 1.6 has been found to achieve an acceptable balance between PAPR reduction and bit error rate (BER) performance. The proposed generalized parabolic companding and PTS scheme, with a complementary cumulative distribution function (CCDF) level of 10 −3 , achieves PAPR reductions of 6.1 dB and 3.32 dB compared to conventional ACO-OFDM and DCO-OFDM schemes. Compared with PTS, it achieves additional reductions of 2.6 dB and 0.82 dB. BER performance on a VLC line-of-sight (LOS) channel with equal average transmitted optical power is also shown, illustrating the PAPR-BER trade-off.