Physical layer analysis of optical MIMO NOMA waveform for 64-QAM in visible light communications

Abstract This paper discusses three optical non-orthogonal multiple access (NOMA) techniques – multiple-input multiple-output (MIMO), rate-splitting (RS), and auxiliary signal superposition (ASSP) – as efficient physical-layer security solutions to protect transmitted data. With these sophisticated NOMA methods, higher-layer encryption approaches can be avoided while improving security. This paper offers an in-depth analysis of the current survey papers on MIMO NOMA, RS NOMA, and ASSP NOMA, providing comparative analysis of their methodologies, merits, and demerits. The research discovers the major gaps in the current methods, specifically their capability to combat eavesdropping attacks, maximize spectral efficiency, and provide robustness across different channel conditions. To overcome these limitations, this paper suggests a new framework that combines MIMO, RS, and ASSP into an integrated security-enhanced NOMA system. By integrating these methods, the suggested approach improves secrecy capacity, decreases signal interception threats, and enhances system robustness in optical wireless communications. The combined application of these strategies results in remarkable performance gains, such as improved interference management, improved user fairness, and efficient power allocation. The results of this work prove the potential of this hybrid NOMA system as a more efficient and secure solution for future optical communication networks.