Where Can I Find an RFID Solution That Uses Cell Towers or Satellites?

I would like to use Wi-Fi. Is this possible—and, if so, can you suggest vendors?

—Name withheld

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Well, it depends on what you mean by "uses cell towers or satellites." If you mean that the tag communicates only with cell towers or satellites, then this would not be an RFID solution. There are, however, hybrid active RFID tags that communicate with RFID readers when in range of such readers, and with cell towers or satellites when not in range of RFID readers.

In 2007, Santa Clara, Calif.-based WhereNet (now part of Zebra Technologies) introduced GPS capabilities to version 4.0 of its Marine Terminal Solution, a hardware and software package for tracking cargo containers within a marine-terminal environment. I'm not sure if Zebra is still selling this solution or the hybrid tag, however.

That same year, Identec Solutions, based in Lustenau, Austria, added GPS to its I-Q RFID tags. The addition of GPS technology, the companies predicted, would enable end users to track high-value assets even if the RFID technology they'd installed was unable to provide visibility at the level of granularity they required (see WhereNet, Identec Solutions Offer GPS Tracking).

In 2009, Savi Technology and Numerex introduced a hybrid tag that could intelligently determine whether to communicate via an active RFID network or satellite communications (see Hybrid Tag Includes Active RFID, GPS, Satellite and Sensors). And AeroScout introduced a Unified Asset Visibility (UAV) solution combining GPS and Wi-Fi tags (see Air Force Base Deploys Wi-Fi/GPS RFID System Across 2,500 Acres).

Wi-Fi-based active RFID systems are fairly common. AeroScout and Ekahau are the leading providers, though Aeroscout was aquired by Stanley Black & Decker, which decided to focus on health-care solutions.

Radianse is another company that offers Wi-Fi-based RFID systems. And San Jose wireless systems company Redpine Signals has developed what it says is the first dual-band real-time location system (RTLS) tag that can transmit at the 2.4 GHz or 5 GHz ISM bands over a Wi-Fi network. The tag receives a transmission from an exciter, known as a WM0 configurator, and then transmits its own identifier, along with that of the configurator, to the nearest Wi-Fi node. The company's dual-band WM1-50 tag can transmit not only at 2.4 GHz, but also at 5 GHz, complying with the IEEE 802.11a Wi-Fi standard. Redpine Signals also offers the WiseMote WM1-20 tag, which transmits only at 2.4 GHz. Both tags are commercially available now (see Redpine Signals Intros Dual-Frequency Wi-Fi RFID Tag).

In addition, there are 802.11 tags that you can buy off the Internet from suppliers of unknown repute in Asia. I would caution you to test any tags you purchase with the same Wi-Fi system with which you plan to deploy them. There are issues with how tags initiate handshakes with Wi-Fi networks.

—Mark Roberti, Founder and Editor, RFID Journal