Secrecy Outage Performance Analysis of Energy Harvesting Enabled Two-tier UAV Assisted Cognitive Communication

In this paper, we investigate the secrecy outage probability (SOP) for a multi-tier unmanned aerial vehicular (UAV) assisted cognitive communication network. Specifically, the low-altitude rotary-wing (LARW) UAV relays harvest radio frequency (RF) energy from the transmission of a high-altitude fixed-wing (HAFW) UAV and forward the information to a ground destination under a decode-and-forward protocol while a ground eavesdropper tries to capture the relay signal. The multi-tier UAV system transmits in an underlay fashion over a licensed spectrum of a primary user. We study the exact statistics of SOP assuming that the number of UAV relays follows a Poisson point process (PPP). The simulation results are presented to illustrate and verify the analytical results.