Exploring Performance and Complexity of Selected NOMA Candidates in 5G New Radio

In this paper, we provide an overview on the Non-Orthogonal Multiple Access (NOMA) technique in the light of the recent 5th Generation (5G) New Radio (NR) standardization. Especially, four representative NOMA solutions are selected out of more than fifteen candidate solutions. The schemes are representing four key principles of user signature separation, based on spreading, interleaving, scrambling and sparse coding. They are Non-Orthogonal Coded Access (NOCA), Resource Spread Multiple Access (RSMA), Interleave Division Multiple Access (IDMA) and Sparse Code Multiple Access (SCMA). Basically, the performance evaluation is carried out in link level simulations, by possibly exploiting the similar parameters for these NOMA solutions to reach a fair comparison. Numerical results reveal that an absolutely dominant NOMA scheme does not exist, in sense of performance, complexity, use cases and scenarios. Thus, the NOMA selection procedure should allow the coexistence of multiple NOMA candidate solutions, which is a cooperative approach rather than a competitive one.