This paper investigates the physical layer security issue in an unmanned aerial vehicle (UAV) aided cognitive radio network. Specially. a UAV operates as an aerial secondary transmitter to serve a ground secondary receiver (SR) by sharing the licensed wireless spectrum assigned to primary terrestrial communication networks. and in the meantime multiple eavesdroppers (Eves) try to wire... https://www.spidertattooz.com/Patchwork-Barn-Quilt-Pattern-by-Edyta-Sitar/