Cell-Free Massive MIMO-NOMA Systems with Imperfect SIC and Non-Reciprocal Channels

In this letter, we investigate the impact of non-reciprocities in cell-free massive MIMO with non-orthogonal multiple access (NOMA). To this end, closed-form expressions for the users’ spectral efficiency (SE) are derived assuming pilot contamination, imperfect successive interference cancellation (SIC), and non-reciprocal channels. Based on the attained expressions, illustrative numerical examples are plotted for a scenario with 100 APs covering an area of 1 km with 20 users. Our results show that under mismatches and imperfect SIC, NOMA still outperforms OMA, providing a good SE gain, especially for 40 % worst likely users, increasing the user fairness.