基于物理层信息加密的卫星隐蔽通信研究

为了增强卫星通信信号的隐蔽性和安全性，提出一种基于物理层信息加密的加权分数傅里叶变换（WFRFT）调制方式。结合WFRFT的低概率截获特性以及无线信道状态信息（CSI）的动态唯一性，在WFRFT系统中构造一个具有加密性质的酉矩阵，克服了传统WFRFT方法的不足，增加了信号处理的多样性。加密酉矩阵的生成利用了卫星通信系统的物理层信道特征，合法通信双方通过约定方式将合法信道的CSI转化为相位旋转因子，并以此为密钥完成对传输信号的加密和解调。仿真结果表明，经酉矩阵加密后的卫星信号在保持原WFRFT信号统计特性的基础上具有更复杂的星座分布，窃听者的误码率始终保持在0.5左右，有效保证了信息的安全传输。

Research on Satellite Covert Communication Based on the Information Encryption of Physical Layer

In order to enhance the concealment and security of satellite communications,a weighted fractional Fourier transform (WFRFT) modulation scheme based on the information encryption of physical layer was proposed.The low probability interception features of WFRFT and the dynamic uniqueness of channel state information (CSI) were collaborated to guarantee the secrecy of wireless communications.In the proposed WFRFT system,a unitary matrix with the encryption properties was constructed,which overcomes the shortcoming of traditional WFRFT method and increases the diversity of signal processing.In addition,the physical properties of wireless channels were taken into account and the CSI matrix was converted into a phase rotation factor as a final key.Then,the encryption and demodulation between legitimate users were completed by certain means with this key.Simulation results showed that the encrypted satellite signal has more complex constellation distribution while maintaining the statistical characteristics of WFRFT signal,besides,the bit error rate for eavesdropper keeps 0.5,which could effectively guarantee the secure transmission.