Non-Orthogonal Multiple Access Techniques for Future Wireless Networks: Challenges, Applications and Emerging Directions

Non-orthogonal multiple access (NOMA) is a promising technology that can achieve higher spectral efficiency and accommodate a large number of users in wireless communication systems. In NOMA, multiple users are allowed to share the same time-frequency resource, but with different power levels and/or codebooks. This technology has attracted extensive attention from researchers and the academic community due to its potential to address the challenges of next-generation communication systems. In this paper, we provide a comprehensive review of the current state of research on NOMA, including its principles, advantages, and challenges, and provide a prospect for its future development.