I’m working on a small project where different Photon boards can communicate each other. I would like to create a network of 4 Photon boards that are able to talk and to identify how far the boards are among them. Imagine that I have board1 and board2. Board1 is close to board2, but if board2 moves away (some meters) from board1 a led blinks and if board2 gets back into the range, the led blinks twice. Is it possible doing so by using Wifi addresses? Or do I need to use external sensors?