RFID vs WiFi-ID -- What's the Difference?

One of the most fascinating things about following the field of RFID as I do, is seeing new and innovative uses for the technology develop before my eyes. Nearly every day -- certainly every week -- something different or barely-heard-of-before is being reported. Granted, many of these uses are experimental or evolving, but that just makes them all the more interesting to me.

WiFi-ID falls into the category of an evolving -- and experimental -- area.

InformationWeek has an article describing WiFi-ID:

"Wireless networks and Radio Frequency Identification (RFID) have always been closely linked: One of Wi-Fi's first applications was transferring data from portable RFID readers. But the popularity of RFID has led some to envision whole networks of readers embedded throughout a building's infrastructure. Start-up Reva Systems has announced what it calls a Tag Acquisition Network (TAN), an array of RFID readers that work with passive, batteryless tags. Meanwhile, established networking vendors led by Cisco Systems are promoting Wi-Fi itself as a way to enable RFID-like applications.

Reva hasn't announced any products yet, but the basic TAN architecture it's promoting is identical to a switched Wi-Fi network: A central appliance controls and mitigates interference between many radios, which are analogous to access points. The difference is that whereas an access point can communicate with a client hundreds of feet away, passive RFID tag readers have a reliable range of only a few inches, so ubiquitous coverage is impossible. Even with the millions of radios needed to cover an entire room, the physical infrastructure holding them in place would prevent human occupation.

Instead, Reva is targeting smaller, more restricted areas. Its technology is currently being trialed by shops and warehouses, which embed readers into shelves and tags into the items sitting on them. When a customer picks up an item from a shelf, the system sends an XML message to the store's inventory database and can notify a staff member if the item is replaced incorrectly."