  Based on the geometry and ray tracing (RT) theory, a millimeter wave (mmWave)
channel model and parameter computation method for unmanned aerial vehicle
(UAV) assisted air-to-ground (A2G) communications are proposed in this paper.
In order to speed up the parameter calculation, a reconstruction process of
scene database on the original digital map is developed. Moreover, the effects
of reconstruction accuracy on the channel parameter and characteristic are
analyzed by extensive simulations at 28 GHz under the campus scene. The
simulation and analysis results show that the simplified database can save up
to 50% time consumption. However, the difference of statistical properties is
slight in the campus scenario.
