LED nonlinearity mitigation and BER optimization for ACO-OFDM-Based VLC systems utilizing non-linear companding and noise mitigation techniques

Visible Light Communication (VLC) systems utilizing Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM) face significant challenges, including high peak-to-average power ratio (PAPR) and the adverse effects of clipping and channel noise. This paper addresses these issues by proposing two noise cancellation techniques to enhance bit error rate (BER) performance, specifically by alleviating clipping and channel noise. Additionally, it introduces root, logarithmic, and hyperbolic tangent companding methodologies as nonlinear companding techniques designed to reduce high PAPR in ACO-OFDM-based VLC systems. The proposed noise cancellation techniques improve the energy per bit to noise power spectral density ratio Eb/N0 by 1.6 to 3 dB while maintaining the target BER, outperforming conventional ACO-OFDM across various modulation schemes. Simulations of the proposed nonlinear companding methods demonstrate significant PAPR reductions of 4.647 dB and 5.309 dB, with corresponding Eb/N0 enhancements of 0.261 dB and 0.1 dB, respectively. These methods achieve a BER and PAPR performance that surpasses conventional ACO-OFDM. Furthermore, integrating the proposed companding techniques with noise cancellation further enhances system performance, achieving PAPR reductions of 4.06 dB and 6.259 dB, with Eb/N0 improvements of 1.808 dB and 0.015 dB, respectively. The findings highlight the effectiveness of logarithmic and hyperbolic tangent companding methods in achieving substantial PAPR reductions while maintaining acceptable BER performance. This research provides valuable insights into combining nonlinear companding techniques with noise mitigation strategies, establishing a robust framework for optimizing ACO-OFDM systems. Comparative analyses validate the proposed methods, confirming their superiority over existing PAPR reduction techniques.