Abstract: In cognitive radio, fast and effective spectrum sensing method is a key technology. The conventional energy detection algorithm can’t resist the influence of low SNR, and high-order cyclic spectrum detection algorithm is of high complexity. This paper combines the two algorithms, and presents a double threshold three level joint spectrum sensing algorithm. This algorithm can effectively improve the detection performance and decrease the algorithm complexity. It simulates the traditional energy detection algorithm and analyzes the influence factors of this system. It also makes a theoretical analysis of high-order cyclic spectrum detection, and makes a detailed analysis of the performance of three level joint spectrum sensing algorithm. It reaches a conclusion that three level joint sensing algorithm not only promotes the detection performance of cognitive users, but also just has a small increase in computation complexity. So, it is an effective and fast spectrum sensing algorithm.

Key words: spectrum sensing, energy detection, cyclic spectrum detection, joint sensing

摘要： 认知无线电中，快速有效的频谱感知是一项关键技术。传统的能量检测算法不能抵抗低信噪比的影响，高阶循环谱检测又有着较高的算法复杂度。将二者进行结合，提出一种双门限三级联合频谱感知算法，有效提高了系统的检测性能并降低了算法复杂度。对传统的能量检测算法进行了仿真，并对检测概率的影响因素进行了分析和仿真；对高阶循环谱检测算法进行了理论分析，并对三级联合感知算法的性能进行了详细分析。最终得出结论，三级联合感知算法不但大大提高了认知用户的检测性能，而且并没有增加过多的运算量，因此是一种高效、快速的频谱感知算法。

关键词: 频谱感知, 能量检测, 循环谱检测, 联合感知