In this letter, the Meta distributions (MDs) of the secrecy rate in downlink non-orthogonal multiple access (NOMA) systems with randomly located eavesdroppers are investigated. Due to the complexity of calculation, the MDs for NOMA users are approximated by Beta approximation and the analytical expressions for the first two moments of conditional secrecy connection probability of NOMA users are derived, while perfect/imperfect successive interference cancellations on the near user are considered. Finally, the accuracy of the result is verified by Monte Carlo simulations. The results show that the MD can capture the statistics of the secrecy rate in a given secrecy connection probability.

中文翻译：

---

下行NOMA系统保密率元分布

在这封信中，研究了具有随机定位窃听者的下行链路非正交多址 (NOMA) 系统中保密速率的元分布 (MD)。由于计算的复杂性，NOMA用户的MDs采用Beta近似，推导出NOMA用户条件保密连接概率前两个矩的解析表达式，同时考虑近端用户的完美/不完美连续干扰消除. 最后，通过蒙特卡罗模拟验证了结果的准确性。结果表明，MD可以捕获给定保密连接概率下保密率的统计数据。