I am planning to create the indoor navigation system. It will provide the shortest path to user from source to destination.
Suppose I know all beacons location. Is that possible to calculate user facing direction by a set of beacons?
Sorry, this is not possible.
Off the shelf beacons are omnidirectional transmitters and mobile phones are omnidirectional receivers. There is no way to determine directionality of the signal.
The good news is that phones have two other ways of getting heading information -- the compass and a velocity vector. The compass is the general approach if you are standing still. If you are in motion, just calculate a vector between the last known location and the current location to get the heading.