Performance Analysis of Layered OFDM-NOMA for Visible Light Communications

Benefit from the efficient resource utilization, nonorthogonal multiple access (NOMA) comes to be a promising multiple access solution for visible light communications (VLC). When it further combined with orthogonal frequency division multiplexing (OFDM), more ambitious system performance can be expected, constituting the OFDM-NOMA for VLC. Compared to the conventional OFDM in VLC, layered O-OFDM schemes, including layered asymmetrically clipped optical OFDM (LACO-OFDM) and adaptively biased layered optical OFDM (ABLO-OFDM), enjoy both higher spectral and power efficiency. However, the performance of the layered OFDM-NOMA is still unknown. Therefore, the performance of LACO-OFDM-NOMA and ABLO-OFDM-NOMA in terms of the data rate are analysed for the downlink VLC in this paper. It is found that the LACO-OFDM-NOMA scheme suffers from the performance degradation due to the strict constraint imposed by the successive interference cancellation (SIC) of LACO-OFDM. By contrast, thanks to the interference-free transmission, the ABLO-OFDM enabled NOMA scheme significantly outperforms the conventional OFDM and LACO-OFDM enabled NOMA schemes.