  In this paper, the performance and system complexity of the candidate
multiple access (MA) techniques for the next generation of cellular systems,
namely, non-orthogonal multiple access (NOMA) (in this paper, we consider power
domain MA as NOMA) and sparse code multiple access (SCMA), are investigated. To
this end, for each MA technique, a resource allocation problem considering
heterogeneous cellular networks (HetNet) is formulated. We apply successive
convex approximation (SCA) method to each problem and obtain their solutions.
The simulation results show that SCMA-based system achieves better performance
than NOMA-based one at the cost of more complexity.
