说明：  由于实际信道中的多径和阴影效应，单个认知用户频谱感知的性能受到影响，因此需要靠不同用户间的协同频谱感知来对抗多径和阴影效应。本设计要求在文中采用一种协作机制，即两用户进行协作频谱感知，提高主用户的检测率，减少检测时间，并且得到捷变增益。要求给出仿真结果。
(As the actual channel of the multi-path and shadow effect, a single user of spectrum sensing of cognitive performance are affected, it needs to depend on collaboration between different users of spectrum sensing to combat multipath and shadow effects. The design requirements in the text using a cooperation mechanism, namely, two user collaborative spectrum sensing, to improve the detection rate of the primary users, reducing detection time, and get agility gain. Required to give simulation results.)