Energy-efficient optimisation for secrecy wireless information and power transfer in massive MIMO relaying systems

In this study, the problem of energy-efficient power allocation (EEPA) for secrecy wireless information and power transfer in a massive multiple-input multiple-output relay aided secure communication system is well addressed. The relay forwards the signal sent from a source to a legitimate destination with the harvested energy based on a decode-and-forward relaying protocol, while a passive eavesdropper intends to intercept the message. The authors first derive a closed-form expression for the secrecy energy efficiency of the considered system under practical conditions, i.e. no instantaneous eavesdropper channel state information (CSI) and only imperfect legitimate CSI. Then, they propose an EEPA scheme for maximising the secrecy energy efficiency. Finally, simulation results validate the effectiveness of the proposed scheme.