Research On The Non-stationary Signal Based On Cyclic Stationary Feature

The wireless communication network has become an indispensable part of modern life. While the wireless communication channel is naturally open, the wireless communication signals can be intercepted, eavesdropped, and deciphered. Therefore, how to guarantee the security of transmitted informationhas become a very important aspect in the evolution of the wireless communication network.The safety and reliability of wireless communication system based on the perspective of physical layer security technologies have attracted much and more attention. From the point of physical layer signal waveform design, if we can construct a non-stationary wireless communication signal,with time-varying mean and autocorrelation values, we can reduce or even eliminate the cyclostationarity of the signal. It means the more measurements,the more uncertainty on the signal feature.The anti-interception performance of the signal could be improved because we can no longer obtain enough statistical characteristics of the signal through long-term observation. Based on the traditional spread spectrum technology, this thesis constructedthe non-stationary wireless communication signal in the random processing of the constant communication parameters.Based on Short-time Fourier transform and Cyclic spectrum correlation analysis method, the main work of this thesis is to compare the signal features and the anti-interception performance of the traditional frequency hopping spread spectrum signal with the non-stationary communication signal. The main work of this thesis can be divided into the following sections.(1) Introduce the Short-time Fourier transform and the Cyclic spectrum correlation analysis method. Based on the structure of the traditional frequency hopping spread spectrum signal, we constructed the non-stationary wireless communication signal in the random processing of the constant communication parameters.(2) Based on thetime-frequency ridge algorithm, we analyzed and compared the traditional frequency hopping spread spectrum signal and non-stationary wireless communication signals as well as improved the algorithm. The simulation results showed that the change of non-stationary communication signal is more complex and more difficult to detect on the time-frequency map.(3)In the study of the detection principle of the cyclostationarity and the choice of the cyclic statistics, we analyzed and compared the traditional frequency hopping spread spectrum signal and the non-stationary communication signal based on the cyclic spectrum analysis. Simulation results showed that the non-stationary communication signal is lower than the traditional frequency hopping spread spectrum signal in the cyclostationarity. Its circular frequency spectrum line is more subtle on the cyclic spectrum So that it has a better anti-interception performance.