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The Perfect Hand-Off

In an ideal world, a cell phone or PDA would seamlessly switch from, say, GPS to Wi-Fi when its user walked indoors, providing continuously updated location information. In the real world, though, the pieces still don’t quite fit together. “We have a whole tool chest of location technologies, but what there isn’t is a unified go-anywhere approach,” says Smarr of the California Institute for Telecommunications.

Generally, the problem isn’t technological: Wi-Fi and cellular radios, for example, can be integrated into a single device. Symbol Technologies, a Holtsville, NY, mobile-computing company, has developed a handheld for UPS that can access both types of networks. The difficulty lies in setting up service plans and contracts that will allow users to get location-based services as they move from outside to indoors. Cellular and Wi-Fi integrator Transat Technologies, in Southlake, TX, and Gemplus, a leading smart-card company based in Luxembourg, have begun to tackle the problem with special software embedded in smart cards. As carriers start to offer both Wi-Fi and cellular services, mobile users will be able to plug these cards into their cell phones and get access to both types of networks-and, presumably, all the location-based services they make possible.

In the shorter term, however, an even bigger problem looms: what if callers want to access location-based services using multiple cellular networks, say, AT&T Wireless and Sprint PCS, as opposed to a single carrier’s combined Wi-Fi/cellular network? Software standards that will allow callers to use location-based services across the two main U.S. cellular technologies (which are known by the acronyms CDMA and TDMA) were expected to be ratified by this fall, according to Paul Hebert, a senior product manager at Redwood City, CA-based Openwave Systems, which sells location-based applications to carriers. Similar roaming standards for GSM, the world’s other major wireless standard, could be approved next year, he says. The lingering question, though, is whether carriers will share their services with other companies’ customers. “For location services, it is the business issues that need to be resolved,” not technological ones, says Hebert.

On the assumption those business issues can be resolved, Intel is pushing to enable even greater interoperability across technologies. While the proposed standards would allow callers to use location-based services offered by different cellular networks, Intel’s idea is to let them switch just as effortlessly between cellular, Wi-Fi, and ultrawideband networks. Intel’s “location stack” system will also be able to compensate for the imprecisions of the various technologies to yield more exact position information, says Gaetano Borriello, director of Intel Research Seattle. “The reason we are pushing the stack model is to keep [location finding] independent of a specific technology,” says Borriello. “We want to provide the infrastructure that will allow others to experiment and find those killer apps.”

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