A Review on NOMA scheme for emerging 6G wireless networks: State of the Art, Key Schemes, Future scope and Security Issues
DOI:
https://doi.org/10.3103/S0735272725010017Abstract
Non-orthogonal multiple access (NOMA) lets numerous users share time and frequency resources at varying power levels, unlike orthogonal multiple access (OMA). NOMA enables multiple transmissions in the same resource block, increases system capacity and spectral efficiency (SE), and adaptively allocates power for user fairness. The sixth-generation (6G) network encompasses remarkable technical breakthroughs such as high SE, high flexibility, low transmission latency, massive connectivity, better cell-edge throughput, and user fairness. NOMA has achieved extensive acclaim as a promising technology for the next generation of wireless networks. NOMA distinguishes itself from conventional OMA solutions by its capacity to accommodate a greater number of users compared to orthogonal resource slots. NOMA approaches enable the simultaneous usage of numerous users in a single resource block by combining users in either the power or code domain. The objective of this study is to provide a comprehensive review of the potential NOMA systems. Firstly, the authors examine the current advancements and available research on NOMA systems. This research also investigates the actual implementation of NOMA and important performance metrics. This study also provides a summary of the latest breakthroughs and uses of NOMA. Furthermore, the authors discuss how NOMA can effectively integrate with various advanced wireless technologies like massive multiple-input multiple-output (M-MIMO), visible light communications (VLC), cognitive and cooperative communications, intelligent reflecting surface (IRS), unmanned aerial vehicles (UAV), heterogeneous networks (HetNets), backscatter communication, mobile edge computing (MEC), deep learning (DL), and others. This research conducts a comprehensive investigation of the relationships between NOMA and the previously stated technologies. Finally, the authors will tackle numerous unresolved challenges and security concerns for NOMA, along with pertinent opportunities and potential areas for future research.