## 4 System Perspective Compatibility Analysis
### Interference Assessment during the Take-Off and Landing Phases of an Aircraft  
In Section 4.2, it can be determined from the analysis that in the interference study of 5G systems on RDSS systems, the interference impact of the 5G terminal on the RDSS system is not significant, so this section focuses on the study of the interference of 5G base station, and the comprehensive consideration of the aggregate interference of the 5G base station on the ground at the airport is analyzed to determine the impact of interference on the airborne RDSS receivers during the takeoff and landing of the aircraft. In this paper, different routes are selected for comparison, and the data are obtained from the real trajectory files downloaded from the official FlightAware ([[https://www.flightaware.com/live/23](https://www.flightaware.com/live/23)]([https://www.flightaware.com/live/23](https://www.flightaware.com/live/23)) July 2021). In order to make the data accurate and reliable, the interpolation process is carried out to obtain the position information of the airplane per second. The Flight path of Berlin to Washington UAL235 (EDDB-KIAD), New York to Los Angeles DAL482 (KJFK-KLAX), and Tianjin to Chengdu CSC8861 (ZBTJ-ZUTF) are selected to be analyzed, and the changes of the aggregate interference in the takeoff phase under the simulation of different propagation environments are shown in Figure 12.  
The simulation results show that the aggregate interference of the airborne RDSS receiver by the 5G signal from the ground is related to the 5G signal propagation environment and the flight altitude and horizontal projection distance. When the aircraft takes off, as the flight altitude increases, the projection distance of the aircraft to the ground increases from the horizontal distance of the center point of the aggregate interference, and the aggregate interference suffered by the RDSS receiver decreases continuously. The relationship between the airplane altitude and the 5G base station is shown in Figure 13. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Frequency** \\ **Isolation** \\ **(MHz)** \\ \end{tabular} } & \multirow{2}{*}{**ACLR (dB)**} & \multirow{2}{*}{\begin{tabular}{c} **5G Base** \\ **Station** \\ **Transmit** \\ **(dBm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **5G Base** \\ **Station** \\ **Antenna** \\ **Gain (dBi)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **BeiDou** \\ **Terminal** \\ **Antenna** \\ **Gain (dBi)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Interference** \\ **Received** \\ **by BeiDou** \\ **Terminals** \\ **(dBm)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Allowable** \\ **Maximum** \\ **Parth Loss** \\ **(dB)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Required** \\ **Distance** \\ **Isolation** \\ **(km)** \\ \end{tabular} } \\ \hline
16 & 27.70 & 21 & 0 & 0 & \(-\)6.70 & \(-\)127 & 120.30 & 0.1000 \\ \hline
17 & 28.79 & 21 & 0 & 0 & \(-\)7.79 & \(-\)127 & 119.21 & 0.0870 \\ \hline
18 & 30.31 & 21 & 0 & 0 & \(-\)9.31 & \(-\)127 & 117.69 & 0.0724 \\ \hline
19 & 32.67 & 21 & 0 & 0 & \(-\)11.67 & \(-\)127 & 115.33 & 0.0562 \\ \hline
20 & 38.22 & 21 & 0 & 0 & \(-\)17.22 & \(-\)127 & 109.78 & 0.0295 \\ \hline
21 & 38.74 & 21 & 0 & 0 & \(-\)17.74 & \(-\)127 & 109.26 & 0.0275 \\ \hline
22 & 39.34 & 21 & 0 & 0 & \(-\)18.34 & \(-\)127 & 108.66 & 0.0257 \\ \hline
23 & 40.04 & 21 & 0 & 0 & \(-\)19.04 & \(-\)127 & 107.96 & 0.0239 \\ \hline
24 & 40.86 & 21 & 0 & 0 & \(-\)19.86 & \(-\)127 & 107.14 & 0.0218 \\ \hline
25 & 41.88 & 21 & 0 & 0 & \(-\)20.88 & \(-\)127 & 106.12 & 0.0194 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._In particular, the total aggregate interference value in the RMa NLOS scenario is slightly smaller than in the free space propagation due to the consideration of building shading equal to the factor.