RSSI to identify zones indoor specifcally bluetooth hc05
Because BT uses frequencies in the 2.4 GHz region, you will find that the RSSI is subject to attenuation by the human body and other objects in the field. Reflections can also produce odd results. Adding more beacons can help to mitigate these effects.

It may work to some degree but you will find it to be less than reliable.

Edit:
As you work on your RSSI algorithm, don't forget that signal strength is inversely related to the distance squared. So if you double your distance, the signal strength will be 1/4 of what it was. 

Also check to make certain you know the units/scale by which RSSI is reported by your devices. It sometimes is linear and in other cases it is logarithmic. It would be best to do some range testing to develop your own calibration for RSSI for the particular device.