Intelligent reflective surface (IRS) technology is emerging as a promising performance enhancement technique for next-generation wireless networks. Hence, we investigate the physical layer security of the downlink in IRS-aided non-orthogonal multiple access networks in the presence of an eavesdropper, where an IRS is deployed for enhancing the quality by assisting the cell-edge user to communicate with the base station. To characterize the network's performance, the expected value of the new channel statistics is derived for the reflected links in the case of Nakagami- m fading. Furthermore, the performance of the proposed network is evaluated both in terms of the secrecy outage probability (SOP) and the average secrecy capacity (ASC). The closed-form expressions of the SOP and the ASC are derived. We also study the impact of various network parameters on the overall performance of the network considered. To obtain further insights, the secrecy diversity orders and the high signal-to-noise-ratio (SNR) slopes are obtained. We finally show that: 1) the expectation of the channel gain in the reflected links is determined both by the number of IRS elements and by the Nakagami- m fading parameters; 2) If the Nakagami- m parameter is no less than 2, the SOP of both User 1 and User 2 becomes unity, when the number of IRS elements tends to infinity; 3) The secrecy diversity orders are affected both by the number of IRS elements and by the Nakagami- m fading parameters, whereas the high-SNR slopes are not affected by these parameters. Our Monte-Carlo simulations perfectly demonstrate the analytical results.

中文翻译：

---

智能反射表面辅助NOMA网络的物理层安全


智能反射表面（IRS）技术正在成为下一代无线网络的一种有前景的性能增强技术。因此，我们研究了在存在窃听者的情况下IRS辅助的非正交多址网络中下行链路的物理层安全性，其中部署IRS以通过协助小区边缘用户与基站通信来提高质量。为了表征网络的性能，在 Nakagami-m 衰落的情况下，针对反射链路导出新信道统计数据的期望值。此外，所提出的网络的性能根据保密中断概率（SOP）和平均保密容量（ASC）进行评估。推导了SOP和ASC的封闭式表达式。我们还研究了各种网络参数对所考虑网络整体性能的影响。为了获得进一步的见解，获得了保密分集阶数和高信噪比 (SNR) 斜率。我们最终证明： 1）反射链路中信道增益的期望由 IRS 元素的数量和 Nakagami-m 衰落参数决定； 2）如果Nakagami-m参数不小于2，当IRS元素的数量趋于无穷大时，用户1和用户2的SOP都变为1； 3）保密分集阶数受IRS元件数量和Nakagamim衰落参数的影响，而高SNR斜率不受这些参数的影响。我们的蒙特卡罗模拟完美地展示了分析结果。