说明：  感测（检测信号）是一个根本性的问题，在认知 收音机。本文提出一种新的方法，基于接收信号的协方差矩阵的特征值。
(Sensing (signal detection) is a fundamental problem in cognitive radio. In this paper, a new method is proposed based on the eigenvalues of the covariance matrix of the received signal.)