基于循环前缀频域自相关的OFDM信号频谱感知

针对无线通信频谱资源有限并且利用率非常低的问题，研究了认知无线电系统中基于信号典型特征的频谱感知策略，并进行动态频谱检测。提出了一种基于循环前缀频域自相关的频谱感知算法，利用正交频分复用（Orthogonal Frequency Division Multiplexing，OFDM）信号的循环前缀具有循环平稳特性，在信号频域进行自相关运算，设定判决门限，完成对信号频谱的检测，同时具备较好的抑制平稳噪声和干扰的能力。在低信噪比或者噪声不确定度大的应用场景下，能够获得比能量检测方法更优、更稳定的频谱感知效果，增强了噪声鲁棒性。在算法中采用双门限检测，进一步减弱了噪声不确定度对检测性能的影响，提高了频谱感知性能。

OFDM signal spectrum sensing based on cyclic prefix frequency domain autocorrelation

For the problem of limited wireless communication spectrum resources and low utilization rate,this paper studies the spectrum sensing strategy based on typical characteristics of signals in cognitive radio systems for dynamic spectrum detection.A spectrum sensing algorithm based on cyclic prefix frequency domain autocorrelation is proposed.Based on the cyclic stationary of the cyclic prefix of the orthogonal frequency division multiplexing(OFDM) signal,this method performs autocorrelation operation in the frequency domain,sets the decision threshold and completes the detection of the signal spectrum.At the same time,the method has a good ability to suppress stationary noise and interference.In application scenarios of low signal-to-noise ratio or high noise uncertainty,it can obtain better and more stable results of spectrum perception than the energy detection method,and enhance the noise robustness.Double-threshold detection is also presented to reduce the impact of uncertain noise on detection performance and further improve the performance of spectrum sensing.