Transmit Power Optimization of Cooperative NOMA-Aided Secure ISAC Systems With SWIPT

This paper proposes a cooperative non-orthogonal multiple access (C-NOMA) transmission scheme employing simultaneous wireless information and power transfer (SWIPT) for a secure integrated sensing and communication (ISAC) system for which channel state information (CSI) of the wiretap channels are imperfect. In particular, minimum transmit power is obtained under the constraints of data rates, eavesdropping rates and echo's signal to interference plus noise power ratio (SINR) by jointly optimizing the beamforming vectors, artificial noise (AN) covariance matrix, power splitting factor, and power allocations. To tackle this challenging non-convex problem, the S-Procedure and semi-definite relaxing (SDR) are first used to convert it in a more convenient form. The reformulated problem is then efficiently solved through a novel iterative block coordinate descending (BCD) based algorithm. Simulation results have shown that, as compared to the benchmark schemes the proposed scheme reduces the minimum transmit power effectively.