Protection Zone Requirement of FSS for the Coexistence of 5G-FSS in the C-Band (Case Study of Indonesia)

In Indonesia, the issue of 5G service and FSS coexistence in C-Band of $3.4-3.6 \mathrm{GHz}$ is still unclear. The protection for incumbent service, FSS in C-Band, still needs to be established to ensure the future service continuity of satellites could coexist with 5G service. Many simulations and field tests in the world, including Indonesia, have been conducted and showed that the use of a Bandpass filter (BPF) and the replacement of a Low Noise Block-Downconverter (LNB) to be operated in Standard C-Band is still insufficient to protect the ground station of satellite away from 5G signal interference. This paper proposes an additional solution for FSS protection zones in accordance with the protection criteria analysis, which refers to the set of ITU Radio Regulations and Recommendations as required, considering the effect of BPF rejection for each case of interference that happens in the actual field. The output of this paper is the visualization plot of the protection zone for the FSS Earth station in a particular area in Indonesia and to provide the relation of BPF rejection with the area of the protection zone. Using the BPF rejection data of 45 dB and also the insertion loss influenced by BPF of 1 dB, the result of this paper shows when the 5G transmit power of 50 W, 100 W, and 200 W, the Earth station needs a safe perimeter distance away of 38.32 - ${4 9. 5} \mathrm{km}, 54.19$ - 70 km, and 76.64 - 99 km, respectively, from 5G BTS. The maximum distance is estimated at the BRIsat Earth station azimuth of 83°. The protection zone of Earth station could be reduced by improving the BPF rejection. However, the trade-off between the BPF parameters should be examined strictly.