Cooperative spectrum sensing method used for cognitive radio system

The invention discloses a cooperative spectrum sensing method used for a cognitive radio system, which comprises the steps that 10), a cognitive network is established, and various sensing nodes report SNRs (signal to noise ratios) of authorized user signals received by the sensing nodes to a fusion center every other a time period; 20), the fusion center compares the SNRs, and takes the sensing node with the maximum SNR as a first sensing node, and the first sensing node transmits a spectrum sensing result to the fusion center; 30), if the spectrum sensing result is that an authorized user works in an authorized frequency band, the spectrum sensing result is a final judgment result, or else Step 40) is executed; 40), the fusion center informs other K sensing nodes with greater SNRs to perform spectrum sensing through a public channel; and 50), the fusion center analyzes the spectrum sensing result, and gives a judgment result. The method has higher detection probability, and requires few expenses of extra time, bandwidth, energy consumption and the like.