We're doing sensor-fusion trying to use as much data as possible coming from different sources, so besides RSSI from beacons there's also accelerometer, magneto

We're doing sensor-fusion trying to use as much data as possible coming from different sources, so besides RSSI from beacons there's also accelerometer, magnetometer, etc. Lots of non-trivial maths to combine that into a robust model, but results are getting more and more incredible. :)