Improving bit error rate in optical wireless OFDM systems through hybrid companding and precoding strategies

Visible light communication (VLC) is a promising wireless high-data-rate transmission technology that uses visible light. Optical Orthogonal Frequency Division Multiplexing (OOFDM)-based systems, especially asymmetrically clipped optical OFDM (ACO-OFDM), face challenges such as high peak-to-average power ratio (PAPR), which causes signal distortion, power inefficiency, and degraded bit error rate (BER) performance. Previous methods like clipping, tone reservation, and standard companding tried to minimize PAPR, but at the expense of increased complexity or BER loss. To mitigate these shortcomings, in this paper, a hybrid scheme is proposed that combines nonlinear companding techniques (NCT) with other precoding schemes—discrete cosine transform (DCT), discrete Hartley transform (DHT), Walsh–Hadamard transform (WHT), and Vandermonde-like matrix (VLM). Simulation results indicate that the presented approach substantially reduces PAPR by up to 6.73 dB while maintaining or even improving BER performance. The proposed approach is an effective solution to high-performance ACO-OFDM-based VLC systems.