Secure energy efficiency maximization for joint ITS and IRS assisted satellite downlink communications

Satellite communications (SatCom) have been viewed as a promising technique to achieve ubiquitous global coverage in next-generation wireless systems. This article investigates the secure energy efficient downlink transmission for SatCom where an intelligent transmissive surface-aided transmitter is deployed at the satellite to perform energy efficient beamforming and an intelligent reflecting surface as well as a cooperative jammer are deployed on the ground to enhance the secure performance. The aim is to maximize the secure energy efficiency by jointly designing ITS beamforming, IRS phase shift, jammer precoding vector, and transmit power allocation. To develop a low-complexity solution,first, an approximated concave lower bound of the non-concave objective function is derived by utilizing Dinkelbach's method and a novel successive convex approximation technique. Then the reformulated problem is decoupled using alternating optimization algorithm and the subproblems are solved by adopting Riemannian manifold optimization, element-wise block coordinate descent, Lagrange dual method and Karush–Kuhn–Tucker conditions. At last, simulation results demonstrate the effectiveness of the proposed scheme.