Signal Processing based Iterative Channel Estimation Techniques for Noma-OFDM Systems

Interference has recently been a significant barrier to effectively implementing the 5G wireless network that supports various end-user applications.Many communication standards, as well as protocols, have been created and put to use throughout this time.It has been determined from the available literature that Non-Orthogonal Multiple Access (NOMA) can address the majority of the problems with the current solutions.In this study, we give an overview of the basics of NOMA, the current 5G enabling technologies that support NOMA, the classification of multiple access systems, and channel estimation approaches in NOMA.Future generation networks have been acknowledged to benefit from the NOMA method.To achieve greater spectral efficiency (SE), the orthogonal frequency division multiplexing (OFDM) technique could be combined with the NOMA system.We comprehensively compare the existing NOMA papers based on channel estimation, the algorithm used, the wireless system, the coding technique, and the modulation scheme.We also go into considerable detail about the primary distinctions between 5G Orthogonal Multiple Access (OMA) and NOMA.Several unresolved issues and research difficulties with NOMA-based systems are also examined.