Secrecy Performance Analysis for OTFS Modulation Based Downlink LEO Satellite Communication

Satellite communication (Sat-Com) has developed rapidly in recent years and its security issue is of paramount importance. In this paper, we investigate the security performance of a downlink low earth orbit (LEO) satellite communication system in which cooperative unmanned aerial vehicle (UAV) is used to send jamming signals to the eavesdropper. In particular, the downlink transmission is based on the orthogonal time frequency space (OTFS) scheme to counteract the severe Doppler effect caused by the high mobility of the LEO satellite. Furthermore, we employ two different beamforming schemes on the UAV side, the Zero Forcing (ZF) and the Minimum Mean Square Error (MMSE) precoding algorithm, with the aim of improving the secure transmission performance of the downlink transmission system. Finally, a comprehensive performance analysis is provided.