Low-complexity hybrid PAPR reduction technique for optical OFDM-based VLC systems

This paper investigates peak-to-average power ratio (PAPR) reduction and its impact on bit error rate (BER) and spectral characteristics in optical orthogonal frequency division multiplexing (Optical-OFDM) systems using different numbers of sub-carriers. Conventional optical-OFDM suffers from high PAPR, leading to severe nonlinear distortion, BER degradation, and increased out-of-band radiation. To address these issues, classical PAPR reduction techniques such as selective mapping (SLM), partial transmit sequence (PTS), and C-PTS-PSO are analyzed and compared with a proposed PTS-PSO scheme. Simulation results demonstrate that the proposed method consistently achieves the lowest PAPR across 64, 256, and 512 sub-carrier configurations, with PAPR reductions of up to 8–9 dB at a CCDF of 10 −3 compared to conventional optical-OFDM. The reduced PAPR significantly improves BER performance, where the proposed scheme achieves SNR gains of approximately 6–7 dB at a BER of 10 −3 for 64 and 256 sub-carriers relative to conventional methods. Furthermore, power spectral density (PSD) analysis confirms substantial suppression of out-of-band emissions, achieving more than 50 dB reduction compared to conventional Optical-OFDM. These results highlight that the proposed PTS-PSO method effectively mitigates nonlinear effects, enhances spectral efficiency, and improves overall system reliability.