For the former, the classic theory of signaldetectionandestimation methods can be used to solve the problem;
占用空闲频段的情况用经典信号检测与估计理论的方法即可以完成检测；
2
Traditional methods of signaldetectionandestimation were based on the assumption that the background noise is white.
传统的信号检测和估计方法一般是建立在背景噪声是白噪声这一假设基础之上。
3
First, the definition and properties of HOS are introduced. We especially notice that HOS is insensitive to Gaussian process. This is the theoretical basis of signaldetectionandestimation.