We are doing a research on using Estimote beacons for indoor mapping and we need to have accurate distance to the Estomote Beacons from the mobile devices. Our major issue is if the actual distance to the beacons is 1.5m , we are getting rapidly changing values to the distance and it can changing to 3.5metters , 10 netters, 6metters.
We need a solid solution to keep actual distance values to the devices if the devices are not moving. Currently if we positioned device in a static location its rapidly changing distance values.
Really sorry for the late reply, the question went under our radar. Please keep in mind that iBeacon, as a standard, was not designed to give exact distance calculations. It's more about providing apps and devices with location context. To get more stable results you can try adjusting the advertising interval, but keep in mind it will also affect battery life.
Additionaly, you can also develop your own noise reduction algorithms, to counter the effects of multipath wave propagation, absorption, and interferemce. Keep in mind though that it's a big overhead to take care of. We did a lot of work on that with our Indoor Location SDK (http://estimote.com/indoor/) - feel free to check it out :)
Also, I highly recommend you read our post about physics and beacons: http://blog.estimote.com/post/106913675010/how-do-beacons-work-the-physics-of-beacon-tech. It can shed some light on how beacons work and how to approach proximity estimations and achieve best performance.