Abstract: We analyzed the performance of spectrum sensing with energy detector in cognitive radio network. The resups of simulation indicate that fading decreases the detection performance of an individual cognitive radio user, and hard combination cooperative spectrum sensing can improve the cognitive radio system's detection probability, but the cognitive radio system's false alarm probability increases as the number of cooperative users increasing. Especially,when control channels are not reliable, low bound of false alarm probability will appear and result in decrease of spectrum utilization.

Key words: Cognitive radio, Spectrum hole, Spectrum sensing