A Study on MIMO Gain of UAV-to-Ground Channel in Urban Environments

Unnamed aerial vehicle (UAV)-to-ground communication is continuing to play a significant role in next-generation wireless technologies. Adopting Multiple-input multiple-output (MIMO) arrays for wireless services provided by UAV offers higher data rates and enhanced spectral efficiency. Since UAVs usually hover higher than typical cellular towers, the UAV-to-ground MIMO channel requires detailed investigation in the urban environments in terms of fading and spatial correlation. In this paper, we study the behaviour of MIMO capacity gain in urban environments using a parameterized city model, such that the radio modelling can be performed using ray-tracing simulations. The presented framework investigates how the MIMO capacity gain is estimated and modeled based on the channel’s impulse response. The presented insights demonstrate the impact of both (i) the spacing of antenna elements and (ii) the elevation angle on the MIMO gain. It also shows the impact of the underlying urban environment on the channel capacity compared to the free space case.