Multi-points Trilateration to be used with beacon data on Android

Question

I've been struggling for a while with this, I'm currently using Estimote Beacon on Android and I'm collecting their RSSI and TxPower to calculate their range. Once I got this data and I know their position (latitude, longitude, altitude), I need to calculate my rough position for an Indoor Location purpose.

All the solution provided only are either for three single points or doesn't work. There must be an existing Java Solution somewhere since it's a common problem.

---

Now I know that this was asked before but no answer really helped me in my case. Here is a resume of some of them:

- Solution using three points only:

Trilateration Method Android Java

Multi-point trilateration algorithm in Java

Trilateration Method Android Java

- Solution I've tried but gets me a wrong result

Trilateration Java Algorithm

Another side question If I might ask, What unit of measure should I use for the distance when I'm calculating this? I though it would be the same result whatever distance unit I was using but It turned out the result vary a lot depending if I plug meter or kilometer...

Hialeah

When using the trilateration java algorithm, did you convert your position in (lat, long, alt) into Cartesian coordinates (x, y, z) as required by the library? github.com/lemmingapex/trilateration/issues/1 See en.wikipedia.org/wiki/ECEF for more information. – Bloodsucker

The unit of distance and coordinates must be same. I use meters because it is the measurement distance returned by iBeacon devices. – Corinnecorinth