A systematic review of intelligent reflecting surface aided non-orthogonal multiple access beamforming-based free space optical communication systems

Abstract

The intelligent reflecting surfaces (IRSs) that support non-orthogonal multiple access (NOMA), and using beamforming techniques in free space optical (FSO), are systematically reviewed in this study. The IRS improves the spectral efficiency and connection by guiding channel users more efficiently through reconfigurable reflecting elements. This enhancement makes it easier to apply NOMA even when the original channels are not aligned. The study emphasizes how hardware limitations like phase shifters with poor precision affect performance. A thorough analysis of previous studies on IRS varieties, beamforming strategies, and multiple access strategies is given. Additionally, the research gaps and potential future paths are also detailed. Background information on IRS types is one of the key contributions. Another major contribution is highlighting the advantages of combining IRS with beamforming and multiple access strategies in FSO communication systems.