  A reconfigurable intelligent surface (RIS) enhanced non-orthogonal multiple
access assisted backscatter communication (RIS-NOMABC) system is considered. A
joint optimization problem over power reflection coefficients and phase shifts
is formulated. To solve this non-convex problem, a low complexity algorithm is
proposed by invoking the alternative optimization, successive convex
approximation and manifold optimization algorithms. Numerical results
corroborate that the proposed
  RIS-NOMABC system outperforms the conventional non-orthogonal multiple access
assisted backscatter communication (NOMABC) system without RIS, and demonstrate
the feasibility and effectiveness of the proposed algorithm.
