The invention discloses a method for estimating the
signal-to-
noise ratio of time-frequency overlapped signals in
cognitive radio. The method includes the following steps that: a normalized higher-order cumulant equation is constructed according to the normalized higher-order cumulant of received signals; all component
signal modulation type combinations are traversed, the power of component signals is calculated through the normalized higher-order cumulant equation, and whether the modulation type combinations are correct is judged; and correct component
signal modulation type combinations and power are obtained, the
noise power of the time-frequency overlapped signals is calculated, so that the signal-to-
noise ratio of the time-frequency overlapped signals in the
underlay cognitive radio can be estimated. According to method, the
normalized mean square error of the
estimation of the signal-to-noise ratio is smaller than 0.2 under a high spectrum overlap rate when a signal-to-noise ratio is 0dB. The method has excellent performance in the
estimation of the signal-to-noise ratio of the time-frequency overlapped signals in the
underlay cognitive radio. With the method of the invention adopted, the measurement of interference temperature can be facilitated, primary users and secondary users can coexist under the interference temperature, and therefore, spectrum efficiency can be improved.