Abstract:

A sensing assisted robust secure beamforming （BF） algorithm is proposed to address the physical layer security issue of the satellite terrestrial integrated networks. The satellite uses multicast technology to serve multiple Earth stations, while there are also airborne eavesdropper （AE） attempting to wiretap the satellite privacy signals. The ground base station employs the integrated sensing and communication technology to serve multiple users while sensing and interfering with AE to assist satellite networks in achieving secure transmission. Specifically, under the condition that only the imperfect channel state information of all users and AE is available, a transmit power minimization problem is formulated, constrained by the quality-of-service requirements of all users, the perceived signal quality requirements, and the maximum intercept probability. To solve the nonconvex problem, the maximum Rayleigh quotient theorem is first used to obtain the receive BF weight vectors of the ground base station. Then, by jointly using Bernstein inequality and Cauchy Schwarz inequality, the complex nonconvex constraints are transformed into convex ones. Then, based on the rank minimization iterative method, the weight vector of the transmission BF is solved. Simulation results verify that the proposed scheme can minimize the total transmit power of the system while guaranteeing the requirements of secure communication. By enhancing the synergy of integrated communication, sensing, and security designs, the system ultimately ensured secure communication within the space-ground integrated network, thereby demonstrating the superiority of sensing-assisted secure communication.

Key words: satellite terrestrial integrated network, integrated sensing and communication, robust beamforming （BF）, physical layer security