Passive cooperative spectrum sensing method in multi-user cognitive radio network

The invention relates to a passive cooperative spectrum sensing method in multi-user cognitive radio network. According to the method, on the basis of spectrum detection based on energy, the cognitive communication mode of sensing first and communication later is converted into the mode of communication first and sensing service compensation later, the following problems in the communication process of cognitive radio are optimized: (1) the spectrum sensing time before communication of secondary user is eliminated, the spectrum sensing work is carried out after the communication is ended, the overall delay between 'requiring communication' and 'being capable of communication' is shortened, and the efficiency of spectrum detection is greatly improved; (2) the shortening of the overall delay is capable of further reducing the amount of master users appearing in the sensing time delay, and the interference with the master users is reduced; (3) only the secondary users in communication are required to carry out spectrum sensing and the secondary users in the whole network are not required to carry out sensing so that the network energy consumption is reduced; and (4) who senses who communicates accords with equity principle, no communication is avoided but the collision to the cognitive radio by sensing users is required.