Performance Analysis of Downlink IRS-Assisted NOMA Systems with Cooperative Full-Duplex Relaying

Intelligent reflecting surface (IRS) technology is emerging as a pivotal solution for enhancing coverage and performance in sixth-generation wireless networks. In this study, we explore a downlink IRS-assisted non-orthogonal multiple access (NOMA) scheme that incorporates cooperative full-duplex relaying (CFR-NOMA) to improve coverage for cell-edge users. Specifically, both the IRS and user-relaying are employed to help the base station send signals to the cell-edge user over Nakagami-m fading channels. To assess the reliability of the considered IRS-assisted CFR-NOMA scheme, we first derive a closed-form expression for its outage probability. Subsequently, we conduct an asymptotic analysis on the outage probability, and it reveals an error floor for the cell-edge user at a sufficiently high BS transmit power. Our findings indicate that increasing the number of IRS reflecting elements can significantly reduce the outage probability and enhance the network coverage. Simulation results validate our analysis and reveal the superiority of our considered scheme over the conventional orthogonal multiple access (OMA) schemes for cell-edge users.