WhereNet Debuts Bimodal 2.4 GHz Active RFID Tag

May 21, 2007—WhereNet has introduced a new 2.4 GHz active tag, the WhereTag IV, which supports two communications protocols: the IEEE 802.11 Wi-Fi and ISO 24730 real-time locating system (RTLS) standards. The bimodal tag is designed to allow companies to more easily track assets throughout their organizations.

Support for the 802.11 protocol can make it possible for firms to leverage Wi-Fi networks, which use access points that are generally less expensive than those knitting active RTLS systems together. Companies can decide where in their operations it makes the most sense to use the tag's ISO 24730 mode, and where the tag's Wi-Fi mode is the better choice. The ISO 24730 mode can provide location accuracy of 5 to 10 feet, using single access points able to cover more than 300 feet indoors and 3,000 feet outdoors. The Wi-Fi-based tags typically provide less accurate location tracking, though some vendors, such as Ekahau, claim their Wi-Fi-based asset-tracking system has an average accuracy of up to 1 meter (approximately 3.5 feet) when combining three or more overlapping access points. ISO 24730 is a new standard, ratified by the International Standards Organization in March (see ISO Ratifies 2.4 GHz RTLS Standard).

"After putting in our [ISO 24730-based RTLS] system, some of the companies have recognized it'd be nice to have visibility across the entire organization," says Tim Harrington, VP of product strategy at WhereNet (which was acquired by Zebra Technologies in January—see Zebra Buys WhereNet). But those companies don't want to put in the more expensive access points in office areas. Instead, Harrington says, they'd rather use Wi-Fi.

The bimodal tag lets them support both, without having to put two tags on items to be tracked. The WhereTag IV can also provide visibility across the supply chain. For example, explains Harrington, an ISO 24730 RTLS system can track goods tagged with the new tags as they come into ports and are processed through yards and distribution systems. A traditional 802.11 access point could then track the tagged goods as they are delivered at a dock door in the back of a store.

Available in August for $55 apiece, the new tag employs WhereNet's time difference of arrival (TDOA) technology to locate asset tags in ISO 24730 mode, and the Cisco Wireless Location Appliance to locate tags in IEEE 802.11 mode. The tags currently work only with Cisco's access points, Harrington says.

According to Harrington, WhereNet has been working on the bimodal tag for about two years. The company's partner, G2 Microsystems, is manufacturing the multi-mode chip. "They were developing an 802.11 chip," he says, "and we met them and discussed that a multimode chip would be of interest to our customers."

The WhereTag IV can be preprogrammed to support either ISO 24730 or 802.11 alone, or both simultaneously (for use in a mixed environment). When programmed to use both protocols, the tag can automatically alternate between the two, sending out signals, or beacons, in both modes. Whichever nearby access point (either ISO 24730 or 802.11) is capable of hearing the beacon is the one that will ultimately receive the signal.