Performance analysis of NOMA under practical constraints and noise variability

Abstract

The rapid growth of wireless connectivity, expected to intensify with the advent of next-generation wireless technologies, brings a substantial increase in the number of connected users. Given the physical limitations of bandwidth expansion, there is a critical need for communication strategies that efficiently accommodate this expanding user base within finite spectral resources. Traditionally, Orthogonal Multiple Access (OMA) techniques have addressed bandwidth limitations by assigning distinct resources to each user. However, as user density increases, the rigid orthogonality of OMA becomes a constraint, particularly for emerging wireless systems. In contrast, Non-Orthogonal Multiple Access (NOMA) offers a more flexible solution by enabling multiple users to share the same time-frequency resources. Through the use of superposition coding and power domain separation, NOMA improves spectral efficiency and supports massive connectivity. User signals are differentiated via power levels and decoded using successive interference cancellation (SIC), making it a promising candidate for 5G and beyond.