Title: Secrecy of Opportunistic User Scheduling in RIS-Aided Systems: A Comparison with NOMA Scheduling Show Chinese title

Title: RIS辅助系统中机会用户调度的保密性：与NOMA调度的比较

Abstract: In this paper, we propose an opportunistic user scheduling scheme in a multi-user reconfigurable intelligent surface (RIS) aided wireless system to improve secrecy. We derive the secrecy outage probability (SOP) and its asymptotic expression in approximate closed form. The asymptotic analysis shows that the SOP does not depend on the transmitter-to-RIS distance and saturates to a fixed value depending on the ratio of the path loss of the RIS-to-destination and RIS-to-eavesdropper links and the number of users at high signal-to-noise ratio. It is shown that increasing the number of RIS elements leads to an exponential decrease in the SOP. We also compare our scheme with that of a non-orthogonal multiple access (NOMA) scheduling scheme, which chooses a pair of users to schedule in each time slot. The comparison shows that the SOP of all of the NOMA users is compromised, and that our proposed scheduling scheme has better performance. Show Chinese abstract

Abstract: 本文提出了一种机会用户调度方案，用于多用户可重构智能表面（RIS）辅助无线系统以提高保密性能。我们推导了安全中断概率（SOP）及其近似封闭形式的渐近表达式。 渐近分析表明，SOP 不依赖于发送机到 RIS 的距离，并且在高信噪比时饱和为一个固定值，该值取决于 RIS 到目的地和 RIS 到窃听者链路的路径损耗比以及用户的数量。 结果表明，增加 RIS 元素的数量会导致 SOP 指数级下降。 我们还将我们的方案与非正交多址接入（NOMA）调度方案进行了比较，后者在每个时隙内选择一对用户进行调度。 比较结果显示，所有 NOMA 用户的安全中断概率均受到影响，而我们提出的调度方案具有更好的性能。