Research on performance optimization of NOMA-VLC based on LWT

NOMA-VLC system based on FFT-OFDM has low reliability and poor user fairness. Therefore, this paper proposes to establish a NOMA-VLC system based on LWT-OFDM by using Lifting Wavelet Transform (LWT) as a carrier modulation method. Firstly, the user channel characteristics of NOMA-VLC system are derived, and the causes of poor reliability and user fairness are analyzed; On this basis, the LWT-OFDM signal decomposition and reconstruction formula is derived; Finally, multi-user correct demodulation is achieved at the receiving end by serial interference detection technology. The experimental results of the indoor space of $4m \times 4m \times 3m$ show that: The transmission efficiency of the proposed system is improved compared with that of FFT-OFDM system; When the average BER is $10^{-4}$, the reliability of the proposed method is improved by at least 7dB and the user fairness is improved by at least 1.4dB compared with the NOMA-VLC system based on FFT-OFDM; The communication system using sym4 wavelet base has better reliability and fairness among users; With the improvement of front-end modulation order, the performance of this method in reliability and fairness is more significant. The proposed method provides a guarantee for indoor visible light communication in multi-user scenarios.