A children's theme park in Denmark is using a combination of wireless technologies to track very important assets: kids gone astray. Not only does the service use RFID and Wi-Fi, the interface to it is through the parents' mobile phones.

Legoland, in Billund, runs a 2.5-million square-foot 802.11
(Wi-Fi) network. It recently began offering a service called "Kidspotter," which entails renting a wristband with a Wi-Fi-enhanced radio frequency identification (RFID) tag on it for a child's arm. Parents also get a map of the site.

If they lose sight of their child, parents can send a text (SMS) message to the Kidspotter system, which will automatically send a return message stating the name of the park area and the coordinates of their child's location. Parents can locate their child on the map provided.

The Wi-Fi/RFID technology is being supplied by Bluesoft, and the scheme is sponsored by the Tryg insurance company.

The application is representative of synergies emerging between wireless technologies. Wi-Fi, as you know, has been honed primarily for locally mobile communications. Meanwhile, RFID has garnered attention for real-time asset tracking - whether those assets are animal, vegetable or mineral.

These two technologies shall meet, at least occasionally, when organisations decide it doesn't make sense to run separate wireless infrastructures to support both capabilities.

High-frequency RFID systems operate in the 850 MHz to 950 MHz and 2.4 GHz to 2.5 GHz ranges, overlapping somewhat with 802.11b and g, which run at 2.4 GHz.

Bluesoft's wireless LAN real-time location tracking system can pinpoint the whereabouts of both traditional 802.11 devices (computing devices and handsets with 802.11 interfaces) and other types of assets (medical equipment affixed with 802.11-enabled RFID tags, for example) using a single Wi-Fi network infrastructure.

For location tracking, Bluesoft uses technology called time difference of arrival (TDOA). Three or more receivers in Wi-Fi access points document the arrival times of a radio signal. Then triangulation software uses the measurements to determine an asset's location.

Bluesoft also resells Cisco Aironet 1200 access points with TDOA bundled into them and aims these at organisations wishing to merge location tracking with their WLAN infrastructures.

The Legoland application makes use of Bluesoft's AeroScout T2 Wi-Fi tag, a new version of the AeroScout tag, to be announced this week. The T2 tag size is 1.5 by 2.5 inches, and it can be mounted on wristbands, on flat assets and on badge clips, says Andris Berzins, Bluesoft vice president of marketing and business development.

The Bluesoft software/hardware location tracking system

  • A location "receiver" that resembles an access point, but handles the TDOA function.
  • RFID tags with a Wi-Fi radio inside.
  • Server software, where location information is stored.

RFID tags don't associate or authenticate with the network, so they represent no security threat and very low overhead on the existing 802.11b or g network, says Berzins.

Look for partnerships between Bluesoft and other WLAN systems vendors in the coming months.