现有的保密自由度衡量多用户高斯干扰信道系统安全性能时在低信噪比域受限。针对该问题,定义安全度的概念,即期望用户与窃听用户信干噪比的比率,安全度越大,安全性越强;该定义能够全面衡量不同信噪比时系统性能;在此基础上提出一种多用户干扰信道下基于空域干扰对齐的安全度最大化算法:首先设计发送预编码矩阵,保证期望用户处干扰对齐,窃听用户处信号对齐;然后以最大化安全度为目标优化设计期望用户的干扰抑制矩阵。仿真结果表明:当信噪比为15d B时,文章方法比参考的人工噪声算法所能获得的安全度提高了10个单位。
Secure degrees of freedom (SDoF) cannot measure performance of multi-user security based on Gauss interference channel in the low SNR domain. To solve this problem, the concept of degree of security(DoS)is defined in this paper: the greater the DoS, the higher the security. By this definition, the overall system performance with different signal-to-noise ratios could be meas- ured. A physical layer security algorithm based on space interference alignment for maximum DoS is proposed. First, precoding matrix is designed to align the interference signal at the desired users, and to align the signal of all users at the undesired users; second, in order to achieve maximum DoS, the interference inhibition matrix is designed for the desired users. The simulation results show that when the SNR is 15dB, the proposed method can obtain 10 more units than the referenced arti- ficial noise method.