Robustness of NOMA in HetNets: Impact of Hardware Impairments and Imperfect CSI

To meet the ever-growing demands of sixth-generation (6G) wireless networks, this letter investigates the integration of non-orthogonal multiple access (NOMA) in multi-tier heterogeneous cellular networks (HCNs) comprising macro-base stations (MBS) and pico-base stations (PBS). By leveraging NOMA, we aim to enhance spectral efficiency and maximize data rates, making it a promising candidate for the next-generation wireless systems. Utilizing stochastic geometry, we conduct a comprehensive performance analysis under practical conditions, accounting for transceiver hardware impairments (HIs) and imperfect channel state information (i-CSI). Key performance metrics—including outage probability, system throughput, and energy efficiency—are evaluated and compared against OMA under both ideal and non-ideal scenarios. The results reveal that NOMA maintains a significant performance advantage over OMA, even in the presence of HIs and i-CSI, demonstrating its resilience and practicality for real-world multi-tier HCN deployments.