## 6 Discussion and Conclusions  
The research performed simulations for different orbital position transponders, for each transponder DVB-S2 waveforms with different modulation and coding schemes were taken into account. It was observed that the results depend a lot on the latitudes of 5G base station deployments rather than on the number of base station interferers, the higher latitude led to higher interference due to the lower elevation angles. At the same time, even for low elevation angles, the amount of aggregate interference generated by 5G base stations deployed within victim satellite footprints does not cause harmful interference and the link performance of satellite bent pipe communication transponders does not experience any adverse effect. The analysis was made for two protection criteria. The first one was the signal-to-noise degradation rate which is a general criterion for different satellite systems which shows the reduction of spectral efficiency, according to Recommendation ITU-R S.2131, the tolerable signal-to-noise degradation is 1 dB which corresponds to the 10% of spectral efficiency reduction As may be noted in Figure 13, the signal-to-noise degradation of the satellite with orbital position 90E (presented in Figure 9) is between 0.005 and 0.015 dB, for the satellite with orbital position 140E (presented in Figure 8) it is between 0.04 and 0.055 dB and for the satellite with orbital position 183E (presented in Figure 7) it is between 0.055 and 0.09 dB. Given that the tolerable degradation threshold is 1 dB, it may be seen that the margins are very high and is far less than the tolerable link threshold margin for all three satellite victim receivers ranging between 9.995 dB and 9.91 dB. The second protection criterion is a more detailed one that takes into account the DVB-S2 standard that satellite systems use within 6/4 GHz transponders and takes into account BER levels for different MODCOD schemes of QPSK and 8 PSK that are used to correct errors and recover information. In different communication systems, there are different requirements for BER levels, however overall it may be summarized that a BER level of \(10^{-9}\) or lower is considered as excellent, the BER levels between \(10^{-9}\) and \(10^{-6}\) as very good, the BER levels between \(10^{-6}\) and \(10^{-3}\) as good and BER levels between \(10^{-3}\) and \(10^{-2}\) as acceptable. The BER level of \(10^{-1}\) is considered as bad and higher than \(10^{0}\) as unacceptable. When analyzing link level performance based on the DVB-S2 parameters, it was shown that for the different MODCODs the overall ranges of the BER levels of all three victim receiver satellites for the QPSK modulation did not exceed \(10^{-6}\), and for the 8 PSK modulation, did not exceed \(10^{-3}\). For the satellite with orbital position 90E, it can be seen in Figure 17 that for QPSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 10.4 dB and 11.4 dB which approximately corresponds to BER level \(10^{-7}\) whereas for 8 PSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 9.75 dB and 10.42 dB which approximately corresponds to BER level \(10^{-3}\). For the satellite with orbital position 90E, it can be seen in Figure 16 that for  
Figure 18: Constellation diagrams of satellite demodulators (**a**) QPSK modulation; (**b**) 8 PSK modulation. QPSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 12.2 dB and 13.15 dB which approximately corresponds to BER level \(10^{-9}\) whereas for 8 PSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 11.5 dB and 12.18 dB which approximately corresponds to BER level \(10^{-4}\). For the satellite with orbital position 90E, it can be seen in Figure 15 that for QPSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 11.45 dB and 12.4 dB which approximately corresponds to BER level \(10^{-8}\) whereas for 8 PSK modulation \(\rm E_{b}/N_{o}+I_{o}\) levels are between 10.75 dB and 11.45 dB which approximately corresponds to BER level \(10^{-3}\).