Theme park launches new child-tracking system that relies on a combination of RFID and wireless LAN technologyParents worried about losing a kid at Legoland in Carlsbad, Calif., can stop by guest services for a "lost parents" sticker. If a sticker-wearing child gets lost in the park, someone helpful can call the parent's cell phone and report the child's location.That's one way to do it. Another way is what the amusement park's Denmark counterpart, Legoland Billund, is doing. Legoland Billund has taken lost-kid technology a giant step further. At its season opening day in March, the park launched a new child-tracking system that relies on a combination of radio frequency identification (RFID) and\u00a0wireless LAN\u00a0technology. Visiting parents with a cell phone and text-messaging capabilities can rent wireless-enabled wristbands for their kids, and then track the kids to within about 5 feet of their location if they become separated.Legoland's child-tracking system differs from traditional applications in that it combines\u00a0RFID\u00a0and 802.11 wireless technologies.The vendor's active RFID tags have an onboard power source - as opposed to passive tags, which need to be activated by a reader to transfer data - for sending out Wi-Fi compatible messages. At Legoland, Wi-Fi access points and location receivers scattered throughout the 2.5 million square-foot park are set to receive those messages. Working together, they pick up Wi-Fi messages from the tags and use triangulation to determine where a particular tag is located.One advantage of a 802.11-based location system is that it lets users locate not only RFID-tagged items but also other Wi-Fi devices, such as PDAs and laptops, says Andris Berzins, vice president of business development and marketing at Bluesoft. For example, if Legoland wanted to be able to let visitors with PDAs view interactive maps to find their location in the park, the Bluesoft infrastructure can communicate with those devices without requiring them to be tagged.Other applications for the system include tagging shopping carts in stores so retailers can track the path that shoppers take through their stores, identifying hot spots and dead spots based on traffic patterns. Bluesoft's existing tags are not intended for item-level tagging in stores, Berzins says; the vendor's active RFID tags start at $65 each.