I'd like to uniquely identify all wireless devices (phones, tablets, etc) within range. I don't care how far the devices are nor do I need to send them anything. I just want to be able to say: phone ABC was in this zone between 9:00 - 9:30, and 17:00 - 18:00.
I was thinking of sniffing Wifi packets but it seems that some phones avoid sending Probe Request packets, furthermore it's difficult to get Wifi cards into Monitor Mode. I've been unable to find any information on EDGE/3G detection.
I'm trying to do something similar to http://louwrentius.com/blog/2011/04/determining-smartphone-market-share-using-wireless-sniffing/.
The approach must "uniquely identify" the device. Meaning I want to be able to differentiate between the same device entering the zone multiple times versus new devices entering.
The approach must collect "anonymous" data, meaning I don't want to record any information that would allow someone to figure out the owner's identity.
What's the best way to detect the presence of mobile devices?