Coverage Characterization of STAR-RIS Networks: NOMA and OMA

The novel concept of simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is investigated, where incident signals can be transmitted reflected to users located at different sides the surface. In particular, fundamental coverage range STAR-RIS aided two-user communication networks studied. A sum maximization problem formulated for both non-orthogonal multiple access (NOMA) orthogonal (OMA), resource allocation point transmission reflection coefficients are jointly optimized satisfy requirements users. For NOMA, we transform non-convex decoding order constraint into a linear resulting convex, which optimally solved. OMA, first show that optimization given time/frequency convex. Then, employ one dimensional search-based algorithm obtain optimal solution. Numerical results reveal significantly extended by compared with conventional RISs.