基于方向极化调制的安全可靠传输技术研究

Research on secure and reliable transmission based on directional polarization modulation

由于极化调制和方向调制单一调制方式的安全性不够,在信息传输过程中,容易被窃听者窃听。将方向调制和极化调制相结合,利用方向调制中天线阵列的方向性和在理想方向信道的零空间上加上干扰激励,可以使窃听者接收的信息产生畸变,将极化调制(PM)代替方向调制的PSK后,可以进一步增大窃听者接收信息的误码率。仿真实验证明,利用本方法,在非期望方向上,每一个信息符号产生的畸变更剧烈,各点的最小欧氏距离更小,误码率更大,因此可以提高信息传输的安全性。

Based on the analysis of electromagnetic wave polarization characteristics,the polarization modulation（ PM） scheme is proposed and the PM transceiver is designed in the satellite communication in this paper. The symbol error rate of the polarization modulation is deduced and verified by the Monte Carlo simulation in the AWGN channel. It is proven that the polarization modulation does not require accurate carrier synchronization and transmit signals are immune to nonlinearity of the high power amplifier. Comparing with the DPSK non-coherent demodulation,PM scheme is more suitable in no carrier recovery systems,such as high frequency narrow-band or high dynamic satellite communication. Because the security of polarization modulation and directional modulation is not enough,in the process of information transmission,eavesdroppers can easily eavesdrop. In this paper,the directional modulation and polarization modulation are combined. By utilizeing the directivity of antenna array in directional modulation and the interference excitation in the null space of ideal direction channel,the information received by the eavesdropper can be distorted. Instead of the PSK of directional modulation,polarization modulation（ PM） can further increase the bit error rate（ BER） of eavesdroppers. The simulation results show that the distortion of each information symbol is more severe,the minimum Euclidean distance of each point is smaller,and the bit error rate is larger,so the security of information transmission can be improved by the method.