Satellite

Energy consumption

Transmitter

Algorithm

Engineering

Efficient energy use

Aerospace engineering

Cognitive radio

Telecommunications

Computer science

Mathematical optimization

Beamforming

Computer network

Mathematics

Geometry

Transmission (telecommunications)

Transmitter power output

Channel (broadcasting)

Wireless

Base station

Convex optimization

Optimization problem

Regular polygon

Secure transmission

Electrical engineering

IEEE Wireless Communications Letters

Rate-splitting multiple access (RSMA) has recently received considerable attention due to its high efficiency in both spectral utilization and energy consumption. Inspired by this emerging technique, this letter presents a secure beamforming (BF) scheme for RSMA-based cognitive satellite terrestrial networks in the presence of multiple eavesdroppers. Assuming that the system operates in the millimeter wave band and only imperfect wiretap channel state information is available at the satellite and terrestrial base station, our objective is to maximize the secrecy-energy efficiency of the earth station (ES) while meeting the constraints on the ES secrecy rate, the cellular users' rate requirements, and transmit power budgets of the satellite and base station. As the formulated optimization problem is mathematically intractable, by applying successive convex approximation and Taylor expansion methods, we propose a robust BF scheme to convert the nonconvex objective and constraints into convex ones, which can be iteratively solved. The effectiveness and superiority of the proposed scheme are confirmed through simulation results.

Secure and Energy Efficient Transmission for RSMA-Based Cognitive Satellite-Terrestrial Networks