  Radio dynamic zones (RDZs) are geographical areas within which dedicated
spectrum resources are monitored and controlled to enable the development and
testing of new spectrum technologies. Real-time spectrum awareness within an
RDZ is critical for preventing interference with nearby incumbent users of the
spectrum. In this paper, we consider a 3D RDZ scenario and propose to use
unmanned aerial vehicles (UAVs) equipped with spectrum sensors to create and
maintain a 3D radio map of received signal power from different sources within
the RDZ. In particular, we introduce a 3D Kriging interpolation technique that
uses realistic 3D correlation models of the signal power extracted from
extensive measurements carried out at the NSF AERPAW platform. Using C-Band
signal measurements by a UAV at altitudes between 30 m-110 m, we first develop
realistic propagation models on air-to-ground path loss, shadowing, spatial
correlation, and semi-variogram, while taking into account the knowledge of
antenna radiation patterns and ground reflection. Subsequently, we generate a
3D radio map of a signal source within the RDZ using the Kriging interpolation
and evaluate its sensitivity to the number of measurements used and their
spatial distribution. Our results show that the proposed 3D Kriging
interpolation technique provides significantly better radio maps when compared
with an approach that assumes perfect knowledge of path loss.
