Secrecy Analysis for Orthogonal Time Frequency Space Scheme based uplink LEO Satellite Communication

Recently, satellite communication (Sat-Com) has developed rapidly, and its security is critical. In this letter, we investigate the security performance for an uplink low earth orbit (LEO) Sat-Com system, where the cooperative UAV is employed to send jamming signals against the reconnaissance satellite. In particular, the uplink transmission is based on the orthogonal time frequency space (OTFS) technique, in order to combat the severe Doppler effect caused by the high mobility of the LEO satellite. As a pioneer work, we derive the closed-form expression for the security outage probability (SOP) at the legitimate receiver, where a novel moment matching approach is used for finding a summed probability distribution function (PDF) of the shadowed-Rician (SR) distributed terms. Furthermore, we analyze the SOP advantage achieved by the OTFS scheme over the traditional orthogonal frequency division multiplexing (OFDM) scheme. Simulation results validate the theoretical results for SOP performance of the uplink LEO Sat-Com, and show the effectiveness of employing UAV jammer in terms of enhancing secrecy transmission.