Performance Analysis of Power Control in Urban UAV Networks With 3D Blockage Effects

Abstract

In urban UAV networks, UAVs deployment locations and air-to-ground (AtG) communication links will possibly conflict with densely located buildings, which exacerbate network irregularity and make interference management more complicated. This paper proposes interference coordination via power control under 3D blockage effects in urban environments, where buildings are distributed according to Boolean model with heights (<inline-formula><tex-math notation="LaTeX">$H_k$</tex-math></inline-formula>) followed Rayleigh distribution. Specifically, a dynamic UAV group (UAVG) is organized to serve each user for interference coordination, which consists several nearest <i>visible</i> UAVs with line-of-sight (LOS) connections considering buildings blockage effects, and the modified distribution from user to its nearest unblocked UAV is derived. Power control is executed in UAVG where adjacent interfering UAVs within the group will mute their transmission for interference mitigation, and optimal UAVG radius coefficient <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> is obtained, which reveals the trade-off between interference mitigation and resource utilization. Leveraging stochastic geometry, theoretical expressions of network metrics are derived with Nakagami-<inline-formula><tex-math notation="LaTeX">$m$</tex-math></inline-formula> fading assumption, including network coverage probability and network connectivity. Analytical results show that in urban city scenario, comparing with traditional terrestrial networks, coverage performance can achieve 4.1&#x00D7; gain by deploying UAVs with optimal height, and achieve additional 26<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> gain with respect to scenarios where power control is disabled.