Improved scheme of asymmetrically clipped optical-orthogonal frequency division multiplexing (ACO-OFDM) for wireless IM/DD optical systems

Visible light communication (VLC) systems that employ optical orthogonal frequency division multiplexing (O-OFDM) face a critical challenge in the form of a high peak-to-average power ratio (PAPR), which limits transmission efficiency and system reliability. This study proposes and evaluates a set of hybrid techniques aimed at mitigating PAPR while simultaneously enhancing bit error rate (BER) performance. The approach integrates nonlinear companding transformations with various precoding methods, specifically tailored for asymmetrically clipped optical OFDM (ACO-OFDM), a promising scheme for VLC due to its unipolar signal structure and resilience to nonlinear distortions. In addition, a dedicated noise cancellation (N.C.) model is introduced to further improve BER performance by suppressing channel and clipping noise. Simulation results demonstrate significant improvements, with PAPR reductions reaching up to 6.329 dB, 7.123 dB, and 7.549 dB, and corresponding Eb/N0 differences of -0.727 dB, 1.435 dB, and 1.799 dB with respect to conventional ACO-OFDM. These outcomes highlight the efficacy of the proposed hybrid methods and their practical suitability for real-world VLC systems, offering a balanced trade-off between power efficiency and signal fidelity.