中文摘要：

针对现有的窃密算法计算复杂度高,抗噪性能差的问题,提出了一种基于主轴投影的窃密算法.首先证明了当窃听天线数大于或等于发送天线数时,空域加扰信号存在主轴方向.然后利用Fisher线性判别准则,求解出加扰信号的主轴方向,沿该方向的投影能够在保留信息成分的同时抑制人工噪声,从而实现信息获取.理论分析与仿真结果表明,与现有的MUSIC-like窃密算法相比,主轴投影法的计算复杂度低5～8个数量级,抗噪声性提升6dB ～10dB.

英文摘要：

The existing eavesdropping method has high complexity and poor anti-noise performance, which makes it unpractical. It is proved that the receiving scrambling signals have principal direction when the eavesdropper has equal or more antennas than the transmitter. The principal direction can be evaluated by the Fisher linear discriminant criterion. The artificial noise can be cancelled by pro- jecting the receiving signals along the principal direction, while the information components are still maintained, which can be used to decode messages. Simulations show that the Principal Projection algorithm has the benefits of lower complexity and better anti-noise performance compared with existing MUSIC-like algorithms.