Impact of Imperfect SIC in NOMA Enabled Heterogeneous Cellular Network

To accommodate a large number of users requiring higher data rates and improved outage performance, a heterogeneous cellular network (HCN) uses a multi-tier architecture made up of a macro-base station (MBS) and pico-base station (PBS). Due to its superior spectrum efficiency, non-orthogonal multiple access (NOMA) has been identified as a suitable multiple-access strategy for the upcoming sixth-generation wireless networks. Successive interference cancellation (SIC) is an essential technique in NOMA that enables multiple users to share the same resource while maintaining high performance and fairness. Thus, it is essential to understand the performance guarantees of actual NOMA-enabled HCN systems (HCN-NOMA) using a multi-tier design under both ideal and imperfect SIC using a stochastic geometry. In multi-tier HCN, the outage probability and system throughput of orthogonal multiple access (OMA) and NOMA under perfect and imperfect SIC are evaluated and compared in this paper. It has been found that using NOMA rather than OMA results in performance gains of up to 40% at 25 dB SNR in HCN. Performance increases of up to 30% against OMA at 25 dB SNR can be observed, despite imperfections in the SIC at NOMA.