Among the many applications in the IoT field, geolocation tracking is one of the most sought-after trends today.
LoRa geolocation allows you to determine the coordinates of a device operating in the LoRaWAN network without using a GPS receiver.
LoRaWAN end device can be discovered if data is received by three or more base stations. The location determination process using the TDoA method is based on triangulation/trilateration. Several BSs simultaneously receive the same packet, record the time and send the data to the network server. Time synchronization on gateways is ensured with nanosecond accuracy. By measuring the signal time delay at each base station, the difference in signal arrival time between stations can be determined. Using known base station coordinates and time differences, triangulation can be used to calculate the location of an object.

Some of the main advantages of implementing the solution are the following:
• the technology provides communication over long distances between end devices and BS, which makes it possible to track objects over a large area;
• the network can be deployed according to customer needs to provide continuous coverage both indoors and outdoors;
• LoRa geolocation is supported by any existing LoRaWAN end devices, which eliminates additional costs for their modification;
• low power consumption of devices and low cost, exactly what the market now requires;
• To determine the location of an object, a high data rate is not required, so the low transmission rate of LoRa becomes an advantage, ensuring long battery life.

Our colleagues, the company AirBit, used this method to determine the location of end devices.
The work was carried out in an open area: Lake Yakhrobolskoye in the Nekrasovsky district of the Yaroslavl region. Three test samples of the Vega BS-2.2 Base Station were deployed with support for the geolocation function at the vertices of a triangle with a side of 2-2.2 km.


The search devices Vega LM-1, Vega LM-211, network tester TS-12, which moved in a boat across the lake at different speeds, were used as terminal devices.
Every 10 seconds the coordinates of the boats location were recorded by a mobile phone. Data transmission from LoRaWAN devices was carried out every 5 minutes with confirmation. The packets arrived at the AirBit LoRaWAN Network Server.


The data obtained were analyzed using the Shapiro-Wilk test and standard methods of mathematical statistics.

Results:
• It was found that the accuracy of determining the position of an object using the triangulation method falls within the stated interval, which was published by chip manufacturer Semtech when announcing the new SX1303 LoRa Core chip
• Geolocation accuracy can be 75–150 m, depending on related factors.