Comparison of peak power reduction techniques in optical OFDM systems based on FFT and FHT

In this paper, we present different peak-to-average power ratio (PAPR) reduction techniques, for optical orthogonal frequency division multiplexing (O-OFDM) systems based on both the fast Fourier transform (FFT) and the fast Hartley transform (FHT). We analyze the performance of selective mapping (SLM), interleaving and partial transmit sequence (PTS) techniques for transmitting real-valued OFDM signals. In O-OFDM systems based on FFT, a direct implementation of PTS and interleaving techniques destroy the Hermitian symmetry. In FHT-based O-OFDM, all the proposed techniques are implemented and compared, showing that PTS provides the highest PAPR reduction. Furthermore, we demonstrate that the proposed solutions considerably improve the bit error rate (BER), by reducing the clipping noise in intensity-modulated direct-detection O-OFDM systems.