Is iPhone Proximity detection possible with Bluetooth?

Would it be possible to fill a building with 20 - 30 bluetooth devices that act as proximity detectors and write an app that can calculate location in the building based on distance from the current detected sensors.

I've looked at the GameKit API, but I don't see anything about calculating distance from devices.

Can someone point me in the direction of an Apple API, or a 3rd party API that can be used for this k开发者_运维百科ind of application.

We don't get the low level BlueTooth or WiFi control that would be required to do this. So unless you jailbreak you can't.

Low level Bluetooth can provide RSSI and Trasmit power level at the maximum for any kind of proximity indications.

As I understand it is extremely difficult to calculate the distance from these reliably.

Location services is surprisingly good at estimating location even in a residential area with only secured wireless APs detectable. But how you would add your APs into that DB, I don't know.