Secrecy Outage Performance for SIMO Underlay Cognitive Radio Systems With Generalized Selection Combining Over Nakagami-$m$ Channels

This paper considers a single-input-multiple-output underlay cognitive wiretap system over Nakagami-m channels with generalized selection combining, where confidential messages transmitted from a single-antenna transmitter to a multiple-antenna legitimate receiver are overheard by a multiple-antenna eavesdropper. Passive eavesdropping scenario is considered in this work, while the channel state information of the eavesdropping channel is not available at the secondary transmitter. We derived the closed-form expression for the exact secrecy outage probability. Simulations are conducted to validate the accuracy of our proposed analytical models.