Outage Performance Analysis of Terahertz Band Drone-to-Ground Communications

Recent studies have shown the potential of employing the Terahertz (THz) band for 6G non-terrestrial communications including drones. This paper assesses the outage performance of the THz band Drone-to-Ground (D2G) vertical communications up to 100 m altitude at four practically feasible THz transmission windows (TWs):.. 1 = 0.140 THz; [0.110-0.170] THz, f(2) = 0.300 THz; [0.275-0325] THz, f(3) = 0.850 THz; [0.790-0.910] THz, and f(4) = 0.935 THz; [0.930-03940] THz. We consider vertical D2G communication, where realistic THz-based absorption gains of the four THz TWs at the drone altitudes are obtained via the International Telecommunications Union (ITU) model using the Standard Weather Profile. Additionally, multipath (MP) fading and beam misalignment (BM) fading are incorporated into the overall channel gain for assessing the outage performance. Numerical results reveal that under severe BM fading and Rayleigh fading, THz band D2G communication employing 60 dBi total antenna gains at f(1), f(2), f(3), and f(4) can be reliably established up to the drone altitudes: 76.9 m, 59.2 m, 34.4 m, and 43.2 m, and up to 85.1 m, 60.3 m, 36.9 m, 45.5 m under the severe BM fading and the presence of a strong Line-of-Sight component, truly showcasing the achievable altitude and range limits for the THz band D2G communications among 6G non-terrestrial cognitive networks.