For the test transmission, the institute said that it employed portable, ground-based transmitters equipped with small, omnidirectional C-band antennas. Fraunhofer IIS developed this particular transmission method specifically for Internet of Things applications that use satellites (Satellite IoT).
The particular challenges associated with using GEO satellites for IoT applications include the vast distance between the transmitters and the satellites (about 36,000 km) and the fact that satellites in orbit tend to use the same frequencies. As a result, antennas on the ground must be relatively large, with high amplification and suitable directional capabilities, so as to minimise interference to neighbouring satellites and systems.
The transmission concept used for the technology demonstration makes it possible to establish a direct connection from IoT sensor nodes to a GEO satellite using portable transmission terminals equipped with a small, omnidirectional C-band antenna developed at Fraunhofer IIS. The waveform has been optimised for low data rates and it has been successful in data transmissions even at extremely low transmit power.
Transmit power has been reduced enough for the waveform to be transmitted below the threshold mandated for C-band communications. This makes omnidirectional antennas a viable option, since they require no alignment and will still not interfere with other satellite systems. The solution’s real advantage is that it can be operated using small, cost-effective transmitter and receiver terminals that offer long battery life.
IoT connectivity via satellite is the most practicable solution in situations where small amounts of data have to be transmitted and no mobile communications or terrestrial IoT network infrastructure is available. The demonstration using GPS data from individual sensors showed that in the future, Satellite IoT can also be used for blue force tracking. Other potential applications include temperature and humidity monitoring in agriculture, and condition monitoring for oil and gas infrastructure for maintenance purposes and to detect leaks early on.
Future developments should make it possible to add the transmission of IoT data to regular satellite operations without having to increase satellite capacity. This means that global IoT applications could make use of existing satellite infrastructure.