Clipping-Free Multilayer Optical OFDM for IM/DD-Based Communication Systems

Abstract

A low-complexity and high-performance clipping-free multilayer optical orthogonal frequency division multiplexing scheme is proposed for optical wireless communication (OWC). At the transmitter, the symbols of multi-layer quadrature amplitude modulation (QAM) are first arranged according to a specific rule in the frequency domain to generate a bipolar time-domain signal using a single inverse fast Fourier transform (IFFT). Then the bipolar signal is superimposed with an adaptive periodic DC bias to meet the real and positive requirements in intensity modulation / direct detection (IM/DD) systems. At the receiver, a zero-value regression (Re0) -based demodulation is proposed to optimize the bit error rate (BER). As the signal generation and demodulation are realized by single IFFT and fast Fourier transform (FFT) respectively, the proposed scheme has nearly the same system complexity as the single-layer modulations and similar spectral efficiency with those advanced multilayer modulations. In addition, the proposed periodic DC improves the power efficiency and avoids the interlayer interference. Numerical simulation results show that, compared with LACO-OFDM [34] with 3 layers, the proposed scheme can attain a PAPR gain of 2.4 dB and BER gain of 1.4 dB and 3 dB for the linear and nonlinear channel, respectively.