First WiFi "RFID" tags appear - to track office equipment

by Guy Kewney | posted on 21 May 2004

Airespace does WiFi infrastructure in an unusual way; its background software not only handles the messages, but can locate each device, within three feet, as it moves around. And so they thought: what about tracking things that ought not to move?

Guy Kewney

The normal RFID tag is passive. It's undetectable unless you pass it within a couple of inches of a special reader. Airespace has invented a different one, using WiFi, which is active. Stick one on a fax machine or a data projector, and if it starts to walk out the building, alarms will ring.

Of course, the conventional idea would be to use something like ZigBee. Normally, WiFi would be absurd for the job; far too power-hungry, far too difficult to integrate into a LAN.

But the idea seems to be catching on. Zigbee seems to be the only technology not considered by Philips for its new garment-tracking system (though they say any wireless will work) either.

The new system was announced as a joint venture between Bluesoft and Airespace at the recent N+I conference and exhibition in Las Vegas. And you might expect Bluesoft to use Bluetooth, but no.

"The only real reason for going with WiFi rather than Bluetooth or ZigBee, is that it's there," said Marcel Dridje - general manager for EMEA - in an exclusive interview with "People were saying to us that they couldn't see why they should build a Bluetooth network when they already had a WiFi LAN in place, and when the Airespace infrastructure does location services so well."

The amazing thing about the product that Bluesoft and Airespace is working on in this "strategic alliance" is the power consumption.

Normally, WiFi is the most power-hungry of all short range wireless technologies. It's also a LAN, which means all the complications of setting up network addresses, IP authentication, and so on; and if a node drops out, normally the network forgets about it.

However, Airespace's software is set up to track unauthorised WiFi nodes and pinpoint them. So all these little match-box sized tags have to do is pop up every now and again and say "here I am" and they'll be logged as rogue devices. And all the software has to do is register their MAC addresses, and log where they are - and, of course, scream blue murder if they start moving away from where they ought to be.

The result is that they are anticipating two year and three year battery life figures from their tags. Normally, an active WiFi device would swallow all the power in a battery that size in a day.

Full details of the announcement are available as a press release on the Airespace web site.

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