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WLAN Finds Itself

Localized location systems are the latest application for the ever versatile 802.11b wireless LAN technology.

This week, at its developer's forum in San Jose, Calif., Intel Corp. (Nasdaq: INTC) has been talking about a WLAN-based research project it is working on that could help emergency services find people in buildings by locating their WiFi devices.

If that sounds a little bit like science fiction... well, there are companies such as Newbury Networks and Appear Networks that are delivering location systems and applications that use 802.11b.

So, how do you go about locating a person or device on a wireless LAN network? All the systems we've seen are server based and detect the strength of the signal between an access point and the radio onboard a device. Because wireless LAN has a range of about three hundred feet, these systems can calculate the distance between an access point and a user by checking how strong the signal is. The weaker the signal the farther from an access point a person is.

This is not as precise as the satellite-based general positioning system (GPS), so for its emergency services-oriented "Universal Location Framework," Intel is envisaging the use of triangulation among access points to boost the accuracy of the system. So, in a building with a multinode WLAN system, the signal strength coming from a device would be measured by several access points and the differing readings would be used to pinpoint the device.

Since GPS does not work well in buildings, Intel is envisaging the system as a complementary technology that could be used in WLAN-enabled phones. However, there aren't any mass-market phones with WLAN onboard yet. And when they do start arriving next year there will doubtless be problems with power consumption, as WLAN was not really designed to be used in small, battery-powered devices.

So, it could be a long time before Intel's WLAN-location technology system makes it to the market. "It will be several years before this becomes mainstream," agrees an Intel spokesperson.

But there are already WLAN-based location systems in use. Newbury Networks' Location Enabled Networks (LENs) system tends to be deployed for slightly more down-to-earth applications, so accuracy is not as crucial. The firm's LENs system builds a picture of the relative signal-strength-to-distance and can then place a user in a given zone.

For instance, some museums and galleries use the system to provide a sophisticated electronic tour of exhibitions. Patrons rent a WLAN-enabled handheld, which detects when a person is near a painting or other exhibits and gives them additional information about the specific objet d'art they're looking at.

Newbury says its system may also be used in the workplace to enable a high level of control over what a WLAN-enabled visitor can and can't use on the network or to allow employees roaming in a building to access resources like printers even if they're away from their cubicles.

— Dan Jones, Senior Editor, Unstrung
http://www.unstrung.com
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