How to calculate Distance from RSSI?

Gateways
1

Hi,
I’m trying to calculate Distance from the RSSI of LoRa.
So i need the formula to convert RSSI to Distance.
However, I couldn’t find it. Maybe I use the wrong keyword?
Does anyone have the formula to do this? :pray:

Thanks!! :smile:

2

This is not really possible, physically.

In given circumstance you might be able to make a crude guess. You’d do better if you had multiple gateways and could compare their RSSI (for example a mobile phone network with many microcells, just knowing which base station is closest can narrow things down). But the scheme will always be quite crude.

A little experience will show that even for nodes not moving, RSSI will vary from packet to packet.

Real location services use radio time-of-flight, for example GPS. There is some limited support for this in the latest generations of LoRaWAN gear but it is quite complex, requires multiple gateways with this feature, and the results achieved will be of limited precision - it is not a GPS alternative.

3

Thanks for answer.
I know that RSSI is unstable.
I want to do this because I want to do Trilateration later. Just like you said. (roughly positioning)
I think I will try RSSI and TDOA together to improve accuarcy.
But I am in urgent need of a solution that is available, even if it is rough.
I would be very grateful if you have a solution.:smiley:

4

I want to do the same thing, multilateration with LoRa RSSI, and i wanted to know if the result are ok, and how did you do it.