At first glance, I'd say the resource consumption is actually going to be basically negligible. The Bluetooth and GPS radios would probably be on anyway, and th

At first glance, I'd say the resource consumption is actually going to be basically negligible. The Bluetooth and GPS radios would probably be on anyway, and the packets flow through the air anyway, so just making a note of the IDs you see, batching them, and sending that every hour or so, is not going to be very heavy.