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 km2 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.

中文翻译：

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具有不完美 SIC 和非互易信道的无小区大规模 MIMO-NOMA 系统


在这封信中，我们研究了非互易性对非正交多址接入 (NOMA) 的无小区大规模 MIMO 的影响。为此，在假设导频污染、不完美的连续干扰消除（SIC）和非互易信道的情况下，导出了用户频谱效率（SE）的封闭式表达式。基于所获得的表达式，针对具有 100 个 AP 覆盖 1 km2 区域、20 个用户的场景绘制了说明性数值示例。我们的结果表明，在不匹配和不完善的 SIC 下，NOMA 仍然优于 OMA，提供了良好的 SE 增益，特别是对于 40% 最差可能的用户，提高了用户公平性。