Local Positioning system using ARM
This is very unlikely to work well.

The RSSI measured by a Bluetooth receiver will be affected by distance, but it will also be affected significantly by other factors, such as:


Random noise and atmospheric conditions.
Interference from 2.4 GHz devices in the vicinity.
Non-uniform antenna radiation patterns.
Physical objects between the transmitting and receiving antennas.


Even if these factors are (somehow!) mitigated, the precision of RSSI readings will not be very high -- the RSSI reading is mainly intended as an indicator of signal quality for users, after all. Even BLE devices can only make a very rough estimate of distance; the Bluetooth proximity profile is only intended to detect whether a device is nearby or not.