Transmitter-Side Clipping-Overlap Suppression for Single-FFT Demodulation in LACO-OFDM VLC

Abstract

Layered asymmetrically clipped optical OFDM (LACO-OFDM) improves spectral efficiency in IM/DD visible light communication but usually requires receiver-side SIC to remove lower-to-upper clipping overlap. This paper proposes a transmitter-side deterministic overlap-suppression scheme for single-FFT LACO-OFDM reception. The transmitter computes lower-layer clipping spectra, projects the predictable overlap onto upper-layer subcarriers, and pre-subtracts the gain-compensated components before clipping. The receiver only performs Cyclic prefix (CP) removal, one FFT, gain compensation, and QAM demapping. For a three-layer N = 256 system, simulations show an 11.84-dB reduction in deterministic overlap-error power and lower upper-layer BER floors compared with conventional direct demodulation. Conventional SIC remains the Additive White Gaussian Noise (AWGN) BER benchmark, whereas the proposed scheme reduces receiver complexity and improves robustness under the considered amplitude-clipping channel.