Reconstructed Hybrid Optical OFDM-NOMA for Multiuser VLC Systems

• Published in: Photonics Vol. 9; no. 11; p. 857
• Main Authors: Li, Baolong, Shi, Jianfeng, Feng, Simeng
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2022
• Subjects: Bias; Connectivity; Efficiency; Errors; Light emitting diodes; non-orthogonal multiple access (NOMA); Nonorthogonal multiple access; Optical communication; optical orthogonal frequency division multiplexing (O-OFDM); Orthogonal Frequency Division Multiplexing; Power efficiency; Propagation; Signal processing; Transmitters; visible light communication (VLC); Wireless communications
• ISSN: 2304-6732; 2304-6732
• DOI: 10.3390/photonics9110857

Non-orthogonal multiple access (NOMA) is deemed to be a prospective multiple access technology of the next generation. However, in visible light communication (VLC), when advanced hybrid optical orthogonal frequency division multiplexing (O-OFDM), such as hybrid asymmetrically clipped O-OFDM (HACO-OFDM), is combined with NOMA, error propagation is induced, which degrades the system performance. Therefore, a novel reconstructed hybrid O-OFDM-NOMA (RHO-OFDM-NOMA) scheme is conceived in this paper. In order to eliminate the error propagation, the users in RHO-OFDM-NOMA opt for the ACO-OFDM or clipping-free O-OFDM signals according to their channel qualities, which are subsequently superimposed on pulse-amplitude-modulated discrete multitone (PAM-DMT) to yield the spectrum-efficient hybrid O-OFDM signal. Furthermore, a reconstruction process is designed to ensure the non-negativity. Compared with HACO-OFDM, the proposed RHO-OFDM can retain the error propagation in NOMA-VLC, whilst maintaining the superiorities of high spectral and power efficiency. It is demonstrated by simulation results that RHO-OFDM-NOMA can support a notably higher data rate than the NOMA schemes using conventional O-OFDM.