IPS (Indoor positioning systems) is basically a network of devices, such as smartphones, WiFi and Bluetooth antennas, digital cameras, clocks that are used to locate people or objects. But apart from already deployed devices, IPS can also include strategically placed Bluetooth-based beacons – hardware transmitters that broadcast their identifier to nearby portable electronic devices so they can get the beacon location throughout a defined space.
The most reasonable case of using IPS is applying it in places where GPS and other satellite technologies lack precision or fail entirely. Those might be multistory buildings, airports, alleys, parking garages, and underground locations. However, Bluetooth can have trouble receiving and transmitting signals in places like these as well. Common causes for interference are: shielding materials and constructions (e.g. concrete walls), devices operating in the same frequency range (WiFi routers and smartphones - 2.4 GHz spectrum) and even human bodies!
To date, Bluetooth 5.1 demonstrates the most accurate results for determining the position of a device. It provides new direction-finding features supporting Angle of Arrival (AoA) and Angle of Departure (AoD) methods. AoA is designed for RTLS (Real-Time Locating Service) solutions and basically applicable for static items, such as point of interest (PoI) information services. But the AoD method is exactly what we need in terms of defining locations of frequently moving Bluetooth devices and their owners – people escaping a burning building.
Now let's bring all this information together. The goal is to identify the location of a rescuee (his Bluetooth device) in a certain space. To complete this task we will need two components: 3-4 beacons installed perimeter-wise and a mobile application downloaded on the rescuee's smartphone. With the help of the AoD method, the smartphone receives signals transmitted by the beacons and calculates its precise location in the space. Once the device learns where it is, the app is ready to send the location to the backend part, which processes the data and generates the safest escape route.