## 3 System Model
### Dataset  
In the data set, one satellite serves three cells as a beam. The data set consists of two parts. The location information data set of the UE and the satellite serving three cells are cell-centered latitude and longitude data at intervals of 0.001 s according to the movement of the satellite. To collect the two data sets, a simulator using the STK 11.3 engine between the satellite and the UE was created. The STK engine is composed of a C#-based net framework. The objects used in the simulator are satellites and several UEs. About 60,000 UEs were randomly distributed around three cells. If there is a UE within the coverage among the three cells serviced by the satellite, the UE and the satellite are connected through a service link and the corresponding data is collected.  
After creating two data sets, the distance between the center of each cell and the UE from the satellite presented in Section 3.3.1 in this paper and the altitude angle between the UE from the center of the satellite presented in Section 3.3.2 were created. The diameter of the cell is 250 km, cell number 0 in the middle is the cell that the UE is receiving service from, and the cells on the left and right are candidates for the target cell. In conclusion, a simulation data set was used in which one moving satellite serves three cells. Figure 8 shows a satellite supporting three cells.  
Figure 7: Flow chart of system model.  
There are location data sets centered on target cells and serving cells according to satellite motion per 0.001 ms, and data sets containing UE location information. The characteristics of each data set are shown in Tables 11 and 12.  
Dataset Distribution Analysis  
The overall distribution of the range of features used to train the model was analyzed and visualized. Figure 9 shows the change in the distribution of the altitude angle and the distance between cell centers of a satellite at the location of one UE during 600 s of simulation.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Feature** & **Description** \\ \hline Time (UTGC) & The time at which the cell center of the satellite was measured \\ Latitude (deg) & Latitude of cell center \\ Longitude (deg) & Longitude of cell center \\ Altitude (km) & Altitude of the satellite \\ Latitude Rate (deg/s) & Cell center latitude change rate \\ Longitude Rate (deg/s) & Cell center longitudinal change rate \\ Altitude Rate (km/s) & Satellite altitude change rate \\ \hline \hline \end{tabular}
\end{table}
Table 11: Feature description of cell-centric dataset.  
Figure 8: Moving satellite simulation supporting three cells.  
As the UE moves away from the satellite, the distance between each cell increases, and it can be confirmed that most of the distance between the satellite and the UE is long. In addition, if the altitude angle between the satellite and the UE is large, it means that the satellite and the UE are adjacent, and it can be confirmed that most of them are similarly far away. Figure 10 confirmed the distribution of the min and max values of the distance between the centers of each cell and the elevation angle in the 3000 UE data.  
Figure 10: Min, Max distribution of 3000 UEs.  
Figure 9: Changes in feature distribution during simulation.  
Most of the distribution of the distance between the UE and the cell center and the elevation angle formed a constant distribution.