UAV Interference to Existing Satellite Services in C-band

Cellular connected UAVs can operate in beyond visual line of sight scenarios. However, inter-cell interference has been shown to be the main limiting factor at high altitudes, so that many companies and researchers try to use less congested parts of the radio spectrum. One of the pioneer bands identified in Europe for the early deployment of 5G systems is the 3400-3800 MHz (C-band), which is still relatively free. However, this band is already used in Europe (and elsewhere) for Fixed Satellite Service (FSS). Coexistence with broadband mobile services should be investigated to properly identify operational conditions in real environments. Very Small Aperture Terminals (VSATs) represent an important class of FSS terminals worldwide. Unlike the large Earth stations, they use smaller antennas. VSATs do not require licensing (i.e. their locations are unknown). Moreover, they typically have modest ability for mitigating interference due to the relatively cheap consumer-grade equipment being used. Coexistence of cellular connected UAVs and FSS is not investigated in literature. In this article, we provide useful information to regulatory bodies for defining appropriate rules for coexistence between FSS and UAVs connected to cellular networks. Using a realistic 3D simulator model of a city combined with the state of the art channel models, this study confirms that UAVs create significant interference to FSS. We estimated on- and off-axis separation distances as well as the permissible interference levels allowing functioning of FSS. We defined the minimum separation distances and angles for different interference types (long- and short- term interference).