Measurement-based Spectrum Database for Non-Terrestrial Networks

Recently, non-terrestrial networks (NTNs) such as satellites have been attracting attention and are expected to provide communication services to areas where mobile networks are not sufficiently provided. For NTN, depending on the time and location of the observation, the radio wave may be blocked by buildings, vegetation, etc., around the observer at land, and also not being able to track changes in positional relationships with structures over time by using existing radio propagation models, making it difficult to predict the radio environment. So, in this paper, to improve the predictability of the radio environment of NTN, we propose a method for constructing the measurement-based spectrum database for NTN and a method for statistical processing of observation data in the database. In the proposed method, based on the celestial coordinate system, NTNs (i.e., satellites) transmission area is divided into meshes and the mesh can be created using elevation and azimuth angle parameters for each receiving mesh to perform statistical processing of the observation data sets. Creating meshes with nearly identical radio propagation characteristics at the transmission area of NTN can be expected to reduce the amount of statistical processing data. And also for meshes at the zenith and near the zenith on the celestial sphere, it causes decreasing the amount of the observation data by small mesh size is expected to degrade the prediction accuracy of radio environment, the integration of the meshes can be expected to suppress the degradation of prediction accuracy of radio environment. As a result of this study, it was found that the proposed method can be expected to specify a transmitting mesh with nearly identical radio propagation characteristics by using a finer division angle of the sky when creating meshes in the sky.