Papr reduction through Gaussian pre-coding in DCO-OFDM systems

Abstract

Visible light communication (VLC) utilizes commercially available light-emitting diodes (LEDs) for short-distance wireless data transmission, aligning with lighting standards for indoor wireless access. The inherent challenge of achieving high data rates in VLC due to the limited spectral bandwidth of white LEDs has led to the adoption of orthogonal frequency division multiplexing (OFDM). However, conventional OFDM presents issues with peak-to-average power ratio (PAPR), pushing LEDs into a nonlinear zone, resulting in energy inefficiencies and signal distortion that degrades the bit error rate (BER). The study focuses on pre-coding within DC-biased optical OFDM (DCO-OFDM) using a Gaussian matrix (GM) for PAPR reduction. The proposed Gaussian pre-coding method demonstrates superior PAPR performance compared to conventional discrete cosine transform (DCT) pre-coding method, especially when integrated with μ-Law companding. Simulation results indicate that increasing the number of candidate GMs enhances PAPR performance, albeit with increased system complexity. The combination of DCT and Gauss pre-coding with μ-Law companding exhibits a 2 dB improvement in PAPR, though at the expense of BER performance.