Design of Physical Layer Secure Transmission in RF Energy Harvesting Cognitive Radio Network

This paper considers a multiple-input multiple-output (MIMO) cognitive radio network (CRN) with multiple primary user nodes, multiple secondary user nodes, and an eavesdropping node. The primary user network includes a primary user transmitting node (PUT) and multiple primary user receiving nodes (PURs), all of which are equipped with one antenna. The secondary user network includes a secondary user transmitting node (SUT) and multiple secondary user receiving nodes (SURs), all of which are equipped with multiple antennas. The eavesdropping node (Eve) is equipped with multiple antennas. The energy of PUT is sufficient, while the energy of SUT is limited. SUT communicates with SURs by harvesting the radio frequency (RF) energy emitted by PUT. Based on the dual selection of SUT antennas and SURs, the optimal selection (OS) scheme and the suboptimal selection (SS) scheme are proposed. The closed-form expressions of the secrecy outage probability (SOP) of two schemes are derived. Finally, the derivation is verified by simulation and the simulation results show that the security performance of OS scheme is better than SS scheme. In addition, the influence of different parameters on SOP is also analyzed.