Abstract:

Idle spectrum sensing is the key that cognitive radio can be implemented. Energy detection is frequently applied as a idle spectrum sensing technology for easy principle and easy implement. However, the detection performance may have abrupt change in the bad external communication environment (SNR:Signal to Noise Ratio is low). Firstly this paper analyzed the performances of energy detection under different SNRs, and then denoised the signal before spectrum sensing improving the performances of detection under low SNR. The improved energy detection algorithm is applied to cooperate spectrum sensing to ensure certain reliability of each CR(cognitive radio) node detection performance. So that the detection performances of cooperate sensing are improved. The result of simulation indicates that comparing to traditional cooperate sensing algorithm, the ROC（Receive Operating Characteristic） curve has a marked improvement when cooperate the detection results after the process of wavelet denoise from each node.

Key words: cognitive radio, idle spectrum sensing, energy detection, wavelet denoise, cooperate idle spectrum sensing