GPS Gets More Assists

Although A-GPS is one of the most reliable location technologies, it needs an assist in challenging environments
Wireless Week
February 1st, 2009

For years, GPS has played a role in helping solve one of the industry's stickiest problems: fixing the location of phones for E911. But as location-based services (LBS) increasingly go commercial, engineers are looking for ways to improve the performance of GPS indoors.

Assisted GPS (A-GPS) incorporates a fall-back solution in the chipsets, so if a phone can't connect with a satellite, it will use information from the cellular network to calculate a position. It offers some of the best indoor capabilities compared to stand-alone GPS. It can help pinpoint whether someone is in a building, but it probably won't know that person is on the 10th floor or the 18th, explained Leslie Presutti, director of product management at A-GPS technology provider Qualcomm CDMA Technologies.

ENHANCING A-GPS 
As developers bring more applications indoors, they need something more reliable than A-GPS. A common expectation in the LBS community is applications will benefit if A-GPS, once considered a hybrid of its own, is accompanied by another hybrid. Qualcomm itself has enlisted a solution through its partnersip with Skyhook Wireless, distributor of Wi-Fi positioning technology. Qualcomm has a license to incorporate Skyhook's technology into its gpsOne positioning platforms, so phones can tap Wi-Fi in challenging indoor environments. "We're already looking to complement A-GPS with other ancillary technologies out there," Presutti said. Qualcomm is interested in looking at other technologies as well, she said.

Feuerstein: Polaris' solution works best where A-GPS doesn't.

Polaris Wireless is another vendor with a hybrid solution. The company's solution, which taps handset "signature" technology, works most efficiently in areas where GPS doesn't perform well, explained Marty Feuerstein, chief technology officer. Polaris' Advanced Hybrid Solution is designed to work with A-GPS systems to provide the highest possible accuracy across environments, especially dense urban corridors and indoors. It uses various techniques, including measurements of neighboring cell signal strengths, time delay and other network parameters.

At SiRF Technology, engineers are readying for the day when location will permeate everything. That's why they developed, first for the auto industry, a way to make vehicles location-aware - even in tunnels and concrete parking garages. SiRF's first big stage is with the Ford Sync.

SiRF addressed the problem by combining GPS with sensors in vehicles. One big negative to using dedicated sensors is the costs go up, said Lars Boeryd, director of marketing for the automotive segment at SiRF. But by using sensors that are already in the car for other purposes, SiRF keeps the costs in check.

SiRF would like to apply the same concept to mobile devices. "We haven't solved all the problems as yet," said Kanwar Chadha, founder and vice president of marketing. But SiRF has proven the concept in the automotive platform, so eventually, "we can make the mobile platform location-aware everywhere."

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