Secure spectrum-sharing networks with full-duplex multiple-antenna wireless-powered secondary system

Security and energy are two critical Issues for emerging wireless networks and thus we study wireless energy harvesting and physical-layer security for a spectrum-sharing network with a multi-antenna full-duplex secondary receiver in the presence of an eavesdropper. We adopt a time-switching strategy where in the first phase, secondary users are powered through wireless energy transfer from the primary source. In the second phase, the secondary transmitter and receiver use the harvested energy to transmit the information and jamming signal, respectively. We propose a beamforming scheme at the secondary receiver with the main purpose of minimizing the outage probability of the secondary data transmission and maximizing the achievable secrecy rate of the primary system. We derive analytical expression for the outage probability at the secondary receiver and the achievable secrecy rate of the primary network. Moreover, asymptotic closed-form outage probability is presented. Numerical simulations verify the performance of the proposed scheme and analytical results and allow us to investigate the impact of the key system parameters on the network performance.