Evaluation of GEO Satellite NB-IoT Performance in Urban Mobility Scenarios

Non-terrestrial networks (NTNs) represent a promising solution for extending IoT connectivity beyond terrestrial infrastructure. This paper presents a measurement campaign that evaluates the performance of NB-IoT (Narrowband Internet of Things) communication over a Skylo GEO (geostationary Earth orbit) satellite link, in partnership with Deutsche Telekom. The experiment was carried out in Split, Croatia, using a Murata Type 1SC module, an NTN-capable device certified for the operation of GEO NB-IoT. Measurements were obtained under realistic mobility conditions in two scenarios: with the antenna placed inside a vehicle (indoor) and mounted externally on the roof (outdoor). Signal quality parameters including RSRP (Reference Signal Received Power), RSSI (Received Signal Strength Indicator), SINR (Signal-to-Interference-plus-Noise Ratio), and pathloss were recorded and georeferenced using GPS(Global Positioning System). A comparative analysis demonstrates that the external antenna configuration yields a significant improvement in signal strength and link quality. The correlation analysis confirms strong relationships between RSRP and SINR, supporting the link budget assumptions in GEO NTN environments. These findings validate the viability of commercial NB-IoT deployments over satellite links and highlight the importance of antenna placement in mobile NTN applications.