# Spectrum Sharing Opportunities for 6G Terrestrial and Non-Terrestrial Networks +
## 3 Coexistence Analysis Results
### Separation Distances Between FS CS and FSS vs. FSS Earth Station Elevation Angle  
The evaluation of the separation distance between the FS CS and FSS Earth station has been performed considering the following technical characteristics of FSS transmitters (Table 1) and the FS CS receiver (Table 2): \begin{table}
\begin{tabular}{l c} \hline \hline  & **GSO FSS E-S Characteristics** \\ \hline Antenna pattern & Recommendation ITU-R S.465-6 \\ \hline Antenna gain & 52.91 dB \\ \hline Antenna height & 2 m; 10 m \\ \hline Antenna diameter & 1.8 m \\ \hline Antenna elevation & 10–50\({}^{\circ}\) \\ \hline Antenna azimuth & 0\({}^{\circ}\) (pointing versus FS) \\ \hline Channel bandwidth & 320 MHz \\ \hline Transmitted Power & 7.2 dBW \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters of FSS E-S system. \begin{table}
\begin{tabular}{l c} \hline \hline  & **FS WLL CS Characteristics** \\ \hline Antenna pattern & Recommendation ITU-R F.1336-5 \\ \hline Sector size & 15\({}^{\circ}\) \\ \hline Antenna gain & 27 dB \\ \hline Antenna height & 15 m \\ \hline Antenna elevation & 0\({}^{\circ}\); 2.5\({}^{\circ}\) \\ \hline Antenna azimuth & 0\({}^{\circ}\) (pointing versus FSS) \\ \hline Channel bandwidth & 28 MHz \\ \hline Receiver noise figure & 6.5 dB \\ \hline I/N max & \(-10\) dB [23] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulation parameters of FS WLL CS. Simulations were implemented assuming that the FSS transmitter and the FS receiver were aligned in the azimuthal plane, and therefore no azimuthal off-axis discrimination was applied in the calculations. Figure 3 shows the separation distance results as a function of the FSS elevation angles for different values of shielding factors (0-30 dB) and FS elevations of 0\({}^{\circ}\) and 2.5\({}^{\circ}\), assuming that the FSS antenna is installed in a suburban environment at 2 m (Figure 3a) and 10 m (Figure 3b). The range of nominal separation distance depends on the shielding factor, the FSS ES antenna height and the off-axis angle between the FS and FSS ES system. The maximum value of this range represents the case of a 0 dB shielding factor and FSS ES elevation angle of 10\({}^{\circ}\), whereas the minimum value represents the case of a 30 dB shielding factor and FSS ES elevation angle of 50\({}^{\circ}\). As can be seen from the figures above, when the FSS ES elevation angle increases, the nominal separation distance decreases significantly. Separation Distances Between FS P-MP CS/TS and FSS Earth Station vs. Different Azimuth Offset of the FS System  
The results presented in this section show the separation distances obtained between the victim system receiver FS and an FSS Earth station when the azimuth offset is applied on the FS sides, meaning that the FSS signal is not arriving at the main lobe of the FS antenna. The separation distances have been evaluated both between the FSS Earth station and the FS CS and between the FSS Earth station and the FS TS. The following technical characteristics of the FSS and FS systems have been considered:  
* FSS: an antenna diameter of 0.75 m, elevation angle of 10 degree, antenna height of 10 m, Pt = 51.28 W, antenna gain = 43.9 dBi and bandwidth = 80 MHz. * FS CS: an antenna height of 30 m, antenna gains of 15 dBi and 25 dBi, elevation angle of 0 degrees and bandwidth of 28 MHz. * FS TS: an antenna height of 30 m, antenna gain of 42 dBi, elevation angle of 0 degrees and bandwidth of 28 MHz. The following tables (Tables 3-5) show the separation distances in km when the FSS signal arrives at different azimuth offsets of the FS and FSS systems considering an FS TS receiver and an FS CS receiver with antenna gains of 15 dBi and 25 dBi, respectively.