Ergodic Sum Rate Analysis of STAR-RIS-Aided NOMA Network with Imperfect SIC

Abstract

In this work, we consider the use of a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) to assist the communication between the access point (AP) and two users, served in opposite planes of STAR-RIS, along with the existence of direct links. Considering the non-orthogonal multiple access (NOMA) based transmission by AP, we derive the expressions for ergodic rates of both the users assuming Nakagami- m fading channels with the possibility of imperfect successive interference cancellation (SIC) at the near user. We also perform the high SNR analysis of ergodic rates to get a better insight. The superiority of the proposed system is shown through numerical results in contrast to a STAR-RIS assisted orthogonal multiple access (OMA) transmission and a conventional NOMA scheme without RIS. The impact of various other system parameters like number of STAR-RIS elements and fraction of imperfect SIC is demonstrated on the system performance. © 2023 IEEE.