Automatic mapping coordinate system center with UWB Beacons

I have a 4 UWB beacons kit and I would like to find the center of the coordinate system (i.e. 0,0).
How can I do that? Is there a convention that a specific beacon is the center?

Always one of the beacons should have the (0,0) coordinates, but it’s chosen pretty much randomly.
You can always check the coordinates of beacons in Estimote Cloud:

And if you would like to change the location, so some other beacon is in the center, you can do that manually (

The EILLocation has the polygon property which contains the (0,0) too. Using this property I can find out the physical setup of the location.