Envelope Level Crossing Rate and Average Fade Duration of Low-Altitude UAV-to-UAV Channels

The envelope level crossing rate (LCR) and average fade duration (AFD) of low-altitude unmanned aerial vehicle (UAV) air-to-air Rician fading channels are obtained from an arbitrary-elevation two-sphere geometry-based stochastic model. The key parameters in those second-order statistics, i.e., the spectral moments of the temporal correlation, are derived into closed-form expressions, which are verified by the close agreement with numerical solutions. Based on the expressions, the impacts of some model parameters on the LCR and AFD are studied, which may serve the system design for UAV-to-UAV communications.