Localisation for TS-UNB IOT-transmission over LEO satellites without GNSS

In this paper, the position estimation for a low energy IoT transmitter on Earth is simulated using only the Doppler shifts of received signals at a Low Earth Orbit (LEO) satellite. For this purpose, no additional data to the anyway transmitted user data is required. This comes with the advantage that any extra transmission or reception can be avoided, both at the node and at the satellite. Additionally, no further processing at the user IoT node is required. Location calculation is performed entirely on the satellite. The originally terrestrial Low Power Wire Area Network (LPWAN) protocol "Telegram Splitting Ultra Narrowband" (TS-UNB) or "mioty®" is very suitable for this approach. Its characteristic of spreading a message in time enables the receiver to get a higher quantity and larger variety of radio frequency measurements. Regarding an optimal selection of two or three LEO satellites, the achievable accuracy can reach up to 100 m in an ideal setting. The accuracy heavily depends on the satellites position and trajectory relative to the transmitter's position. In a worst-case constellation, the position uncertainty might amount to several kilometres-or no position estimation is possible at all. Therefore, at least two satellite orbits perpendicular to each other are necessary in order to achieve an accuracy below 2 km within the considered localisation area.