I want to produce a small, low-cost, identifiable (wirelessly) device, battery operated, really low current consumption, has a readable range <=100ft, sort of like an emergency beacon, that can be identified by a WiFi / Bluetooth equipped cellphone.
I started out looking at WiFi because it's such a ubiquitous technology, low-cost, small, well understood . . . . however, it appears that, whilst a 802.11 device such as the Nordic Semiconductor nRF24LU1 is just the form-factor I imagine, and the additional ancilliaries like power, xtal, etc... would add very little to cost of footprint (button battery included) getting the thing to broadcast a unique identifier on a regular basis is beyond my understanding right now.