Inter-user interference (IUI) engineering is utilized to degrade eavesdropping and enhance the physical layer security (PLS). In this letter, we propose a secure transmission strategy via IUI engineering for an intelligent reflecting surface (IRS)-assisted non-orthogonal multiple access (NOMA) system without eavesdroppers channel state information (CSI). We aim to reduce the signal-to-interference-plus-noise ratio (SINR) of the passive eavesdropper to deteriorate eavesdropping by maximizing the transmit power of weaker users and modifying the successive interference cancelation (SIC) order. Moreover, two cases of combating eavesdropping via IUI engineering are considered according to different channel gain of secure users. The formulated problem is non-convex due to the highly coupled beamformers and reflection coefficients, we employ an alternating optimization (AO) framework to solve it. The results validate the advantages of introducing IUI engineering in the IRS-assisted NOMA system and the effectiveness of this optimization algorithm.

中文翻译：

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通过 IUI 工程实现 IRS 辅助 NOMA 系统的安全传输


利用用户间干扰（IUI）工程来降低窃听并增强物理层安全（PLS）。在这封信中，我们提出了一种通过 IUI 工程的安全传输策略，用于智能反射表面 (IRS) 辅助的非正交多址 (NOMA) 系统，而无需窃听者信道状态信息 (CSI)。我们的目标是通过最大化较弱用户的发射功率和修改连续干扰消除（SIC）阶数来降低被动窃听者的信号与干扰加噪声比（SINR），从而恶化窃听。此外，根据安全用户信道增益的不同，考虑了两种通过IUI工程对抗窃听的情况。由于高度耦合的波束形成器和反射系数，公式化的问题是非凸的，我们采用交替优化（AO）框架来解决它。结果验证了在IRS辅助NOMA系统中引入IUI工程的优势以及该优化算法的有效性。