Outage probability modelling of multi-user downlink IRS-NOMA network over α-κ-µ and α-κ-µ shadowed faded channels

The next generation wireless networks demand innovative approaches to deliver reliable and high-capacity communication service to the users. However, achieving consistent performance remains challenging, especially in complex indoor environments where signal degradation occurs due to obstacles, multi-path propagation and structural attenuation. To overcome these challenges, this work explores the intelligent reflecting surfaces (IRS) with non-orthogonal multiple access (NOMA), two emerging technologies that enhance signal propagation and spectral efficiency. This work presents a comprehensive outage probability analysis of a multi-user downlink IRS-NOMA system operating under the generalized fading environments: (i) α-κ-µ fading model and (ii) α-κ-µ shadowed fading model. The proposed work provide a flexible framework under diverse propagation conditions, including line-of-sight conditions, multi-path clustering, nonlinearity effects and shadowing effects. The analysis incorporates practical impairments such as imperfect channel state information (CSI) and residual errors in successive interference cancellation (SIC). To provide deeper insight, the derived outage expressions are specialized to several classical and composite fading models, including Nakagami- m , Rician, Rayleigh, κ-µ , η-µ , α-µ , and α-η-µ models. The impact of impairments and channel parameters on outage behaviour is thoroughly investigated through analytical derivations and validated via extensive Monte Carlo simulations.