Joint Robust Secure Beamforming Designs for ISAC-Enabled LEO Satellite Systems

The security of low-earth orbit (LEO) satellite communication systems faces challenges due to the high-speed movement characteristic. In this paper, we study the secure transmission for an ISAC-enabled LEO satellite system by considering the sensing function to enhance security. With the assistance of the sensing capability, more precise angle information of potential targets/eavesdroppers (Eve) can be estimated, thereby strengthening the system's performance. However, it is impossible to avoid the errors. To tackle this problem, we consider the channel uncertainty model and maximize the sum secrecy rate by jointly designing the secure transmit beamforming and radar receive filters. Furthermore, the non-convex problem is transformed into a series of convex optimization sub-problems, and the required optimization parameters are obtained through iterative calculation. Simulation results verify the advantages of the proposed scheme in achieving secure transmission of the LEO satellite system.