Bluetooth LE RSSI for proximity detection iOS

Question

I\'ll start with the question.

Is the BTLE RSSI a good way to indicate two devices proximity to each other or not? does it only work with small devices like fobs et

Answer 1

I've spent the last week dealing strictly with RSSI, trying to use Wifi and Bluetooth LE sensors for location triangulation and for distance conversion.

Unfortunately, what I have found is that RSSI is just too finicky and unreliable to consistently use to determine distance. In theory, the RSSI and distance behave according to the inverse square law (double the distance, and the RSSI will go down a fixed number of decibels), but in practice the RSSI is affected by uncontrollable factors such as weather (dry weather allows RF fields to travel better) and obstacles (any metal objects or humans in the path from one sensor to another will cause attenuation, and any metal objects closely positioned by one of the sensors will cause gain in the signal strength).

There are ways to try to compensate for this. This paper is one of the best papers I read on how to get accurate results, but the bottom line is that is an unreliable method unless you just want a general idea of where the device is.