Internet access in Indonesia is still limited in many areas, especially in remote islands and during air travel. SATRIA-1 is a geostationary satellite that helps provide internet across the country using Ka-band frequencies. In the future, the ViaSat-3 APAC satellite will also serve the Asia-Pacific region and may use nearby orbital positions and the same frequency band. This creates a risk of signal disruption, especially from Aeronautical Earth Stations in Motion (A-ESIM) on airplanes, which can accidentally occur due to tracking delays and antenna pointing errors.
Since ViaSat-3 APAC has not yet been launched and its orbital position is not fixed, this study analyzes potential interference based on hypothetical placements from 148°E to 152°E. Four interference scenarios were examined, involving A-ESIM, VSAT, and large ground stations such as the Gateway Cikarang (for SATRIA-1) and Gateway Hokkaido (for ViaSat-3). Signal quality was evaluated using Carrier-to-Noise (C/N), Carrier-to-Interference (C/I), and Carrier-to-Noise-plus-Interference (C/N+I), while system performance was tested using different modulation schemes such as QPSK, 8-PSK, and 16-APSK. Also analyzes capacity and CDF (Cumulative Distribution Function).
The results confirm that interference between Viasat-3 APAC and SATRIA-1 in the Ka-band uplink depends on orbital position. At 148°E, Case 1 (VSAT interfered by Hokkaido Gateway and A-ESIM) shows the lowest C/(N+I) of 18.54 dB and capacity of 123.60 Mbps, indicating high interference. In contrast, Case 4 (Cikarang Gateway interfered by A-ESIM) shows 63.84 dB and 5301.91 Mbps, with minimal impact. At 152°E, conditions improve: Case 1 reaches 33.26 dB and 221.01 Mbps, while Case 4 reaches 64.32 dB and 5341.67 Mbps. Therefore, 152°E is recommended for coordination. Regulation should support this using TASFRI and ITU-R standards.
Keywords: A-ESIM, Viasat-3 APAC, Satria-1, Interference