中文说明：利用多天线，发送有用信号和人工噪声，人工噪声位于合法接收者信道的零空间，因此噪声对合法接收者无影响，对窃听者，增加了背景噪声，降低检测性能，防止窃听
English Description：
Using multiple antennas, send useful signals and manual noise and artificial noise in the null space of the legitimate receiver channel, so noise does not affect legitimate recipients, an eavesdropper, adds background noise, reducing performance, preventing eavesdropping