Outage Analysis of Multiple IRS-aided Cooperative NOMA System

The traditional cooperative non-orthogonal multiple access (CNOMA) technique improves the outage and data rate performance for cell-edge users, albeit at the expense of near users. Due to the ability to control the propagation environment, introducing intelligent reflective surfaces (IRS) into a multi-user network can reduce costs, signal processing complexity, and energy consumption. In this work, a comprehensive downlink framework for a blind-IRS-supported CNOMA system is established to enhance outage performance for both cell-edge and near users. The closed-form analytical expressions for the outage probability of the near and cell-edge users within this proposed system are derived. Furthermore, these analytical expressions are validated through Monte-Carlo simulations. The cell-edge user of our proposed model outperforms traditional NOMA and IRS-assisted NOMA variants. To achieve a target outage probability of $10^{-3}$, our proposed system requires $\sim 4$ dB lower signal-to-noise ratio (SNR) compared to other IRS-assisted NOMA variants.