Selectively Biased Optical Orthogonal Frequency Division Multiplexing for Visible Light Communication Systems

Traditional direct-current biased optical orthogonal frequency division multiplexing (DCO-OFDM) achieves unipolar signaling by adding a direct current (DC) bias and performing clipping. To suppress signal nonlinearity distortion caused by clipping, the DC bias needs to be set at a higher level, which results in low power efficiency of the DCO-OFDM. A scheme named Selectively Biased Optical OFDM (SBO-OFDM) was proposed in this letter. SBO-OFDM multiplies the OFDM signals with random phase sequences, selects the signal that requires the least amount of bias for transmission, and dynamically adds the bias based on signal variations to improve power efficiency. The experimental results demonstrate that the proposed SBO-OFDM exhibits a significant decrease in requirement of the normalized optical bit energy to noise power ratio $[E_{b(opt)}/N_{o}]$ compared to DCO-OFDM, ACO-OFDM, and PAM-DMT at a BER of 10⁻³. The results indicate that SBO-OFDM outperforms traditional optical OFDM (O-OFDM) in terms of power efficiency and have better BER performance than traditional DCO-OFDM.