IRS辅助下利用AN对抗窃听的双向通信安全传输方案

IRS-Aided Two-Way Secure Transmission with Artificial Noise against Eavesdropping

本文研究了IRS辅助的双向通信系统中利用人工噪声对抗窃听的安全传输方案。针对存在主动式窃听和用户间直接连接的一种通用系统模型,从双向通信的可达安全速率域出发,致力于提升该域中的最坏和保密率(SSR)。由于人工噪声对最坏SSR有影响,本文在合法用户处采用了人工噪声,通过对人工噪声的功率分配系数以及IRS相移的优化,实现最坏SSR的提高。采用交替优化方法求解相应的优化问题,其中优化功率分配系数的子问题以封闭形式给出最优解,而优化相移的子问题则通过半正定松弛和一种新颖的高斯随机化方法解决。仿真结果证实,该方案比传统方案具有更高的SSR,说明了在双向安全通信系统中采用AN的必要性。

This paper investigates the secure transmission in an IRS-aided two-way system.Differ⁃ent from existing works,a general model with active eavesdropping and direct links between users is considered,and we devote to improve the worst-case sum secrecy rate(SSR)provided by the achiev⁃able secrecy rate region since it characterizes the two-way wiretapping system better.Artificial noise is exploited at the legitimate users due to its impact on worst-case SSR and a secure communi⁃cation scheme is then developed which jointly designs the phase shifts at the IRS and the AN power at each legitimate user.The corresponding optimization problem is solved by alternating optimiza⁃tion where the power allocation coefficients are given in closed-form and the phase shift vector is obtained by using semidefinite relaxation along with a novel Gaussian randomization method.Simu⁃lation results verify that the proposed scheme provides higher SSR than traditional schemes,indicat⁃ing the necessity of AN in such systems.