I'm trying to figure out if there is a protocol for wireless phone to phone communication (so not WIFI) where an application can determine that another phone with the same application is in the same room (or a couple meters) and transfer data between the applications.
Bluetooth would work but I want the application to pre-establish the handshake instead of requiring the Bluetooth handshake.
NFC would be perfect if the range was more than 10cm.
Is there anything else out there that might work?