Ergodic Performance of the MIMO-NOMA Cooperative Relay System with Imperfect SIC Over κ-μ Fading Channels

The non-orthogonal multiple access (NOMA) technique has been envisaged as an emerging radio access technology for next-generation systems. Cooperative relaying strategy is a powerful tool to deal with channel impairments such as path loss and shadowing. This article presents the expressions of ergodic capacity (EC) for a relay-based MIMO-NOMA system in the presence of imperfect successive interference cancellation (SIC). This mathematical investigation is performed over κ−μ fading channels. Available users are grouped into clusters, and a beamforming weight vector is applied among the clusters to alleviate the effects of inter-cluster interference. Simulation results are presented to validate the derived results, and it furnishes few useful insights into the EC of a relay-based MIMO-NOMA system. It also corroborates that the EC of MIMO-NOMA outperforms the MIMO-OMA (Orthogonal multiple access) system. Furthermore, the influence of imperfect SIC and the number of multipath components on the sum EC have been studied.