Secure Transmission Method in Dual-Polarized Satellite Communication Based on Constellation Distortion

Polarization state modulation(PM) It is known that satellite communication signals are easy to eavesdrop and how to realize secure transmission is the key problem. This paper proposes a secure transmission scheme based on the polarized constellation rotation and the weighted fractional Fourier transform. Firstly, the pseudo-random sequence is used to process the phase of the two components of polarization signals to make them change randomly, and the constellation points will randomly rotate around the horizontal polarization axis in the Poincare sphere. Then two polarization signals are processed by WFRFT with different orders separately to further distort the polarization constellation. In this manner, the constellation points will be randomly distributed in, on and outside the sphere improve the transmission security. In addition, with the proposed, it is difficult for the eavesdropper to accurately recover the WFRFT parameters and when there are errors in the cracked WFRFT parameters, self-interferences occur in the recovered signals, which causes a decrease in the SNR of the signals received by the eavesdropper. In this way, it also obtains a positive secrecy capacity to ensure the transmission security. Finally, the performance of the proposed scheme is verified from three aspects: polarization constellation distortion, security capacity and the bit error rate performance.