On Secrecy Analysis of Underlay Cognitive UAV-Aided NOMA Systems With TAS/MRC

This article investigates the secrecy performance for an unmanned aerial vehicle (UAV)-aided nonorthogonal multiple access (NOMA) network in the context of an underlay cognitive radio. Specifically, a multiantenna secondary source (S) transmits a mixed signal incorporated with NOMA to two multiantenna secondary destinations (Dᵢ) via a UAV-enabled decode-and-forward relay in the presence of an eavesdropper (E). In addition, both a transmit antenna selection scheme atSand a maximal ratio combining protocol atDᵢandEare taken into account. Considering all the links undergo Nakagami-mfading with path loss, we analyze the secrecy performance in terms of secrecy outage probability for both users. Moreover, we also use Monte-Carlo simulations to verify the accuracy of those derived expressions.