Physical Layer Security for NOMA Systems: Requirements, Issues, and Recommendations

Non-orthogonal multiple access (NOMA) has been viewed as a potential candidate for the upcoming generation of wireless communication systems. Comparing to traditional orthogonal (OMA), multiplexing users in same time-frequency resource block can increase number served and improve efficiency systems terms spectral efficiency. Nevertheless, from security view-point, when are utilizing resource, there may be concerns regarding keeping information confidential. In this context, physical layer (PLS) introduced supplement protection conventional encryption techniques by making use random nature transmission media ensuring secrecy. The recent years have seen significant interests PLS being applied NOMA networks. Numerous scenarios investigated assess systems, including active passive eavesdroppers present, well these combined with relay reconfigurable intelligent surfaces (RIS). Additionally, ambient backscatter (AmB)-NOMA other issues that lately drawn lot attention. paper, thorough analysis PLS-assisted research state-of-the-art is presented. regard, we begin outlining foundations PLS, respectively. Following that, discuss performances four categories depending on type eavesdropper, existence relay, RIS, AmB different conditions. Finally, explanation most given.