Bell Labs Geolocation Technology Pinpoints Wireless 911 Calls Within 15 Feet

The Bell Labs geolocation technology offers marked improvements over currently deployed systems for locating wireless 911 emergency calls. Moreover, it provides network operators the double benefit of meeting a 2001 federal mandate while opening opportunities for new service revenues. For example, pinpointing a customer's location could yield such services as detailed driving directions and local traffic information, especially when combined with improved data services expected two years from now.

"We intend to pursue standardization of this geolocation technology so that it can be widely and inexpensively deployed," said John Freidenfelds, director of wireless technology applications at Lucent's Wireless Networks Group.

The Bell Labs technology works with all of today's global digital networks and also will be compatible with next-generation (3G) broadband wireless networks, which will provide a broad assortment of location-based services, as well as high-speed, Internet-based multimedia services.

The driving force for the Bell Labs research has been a U.S. Federal Communications Commission mandate stating that by October 2001, all wireless 911 calls must be pinpointed within 410 feet. Currently, wireless 911 calls can be pinpointed within only a three- to six-square mile service area on average.

The Bell Labs geolocation technology would provide more precise location information to police, which is especially helpful when callers are unfamiliar with their whereabouts, and also would allow 911 calls to be routed more quickly to the appropriate rescue squad.

The Bell Labs approach involves both the wireless handset and network infrastructure. Global positioning system (GPS) units are placed throughout a wireless network. As the units keep track of GPS satellites orbiting the Earth, they pass along key satellite information – including estimated time of the signal's arrival – to nearby wireless handsets, which are equipped with scaled-down GPS units. Then, based on time differences between when the network's GPS units and the handsets receive signals from the satellites, it's possible to precisely pinpoint the handset's location.

"With the information boost that the network gives the handset, our approach is 100 times more sensitive than the handset approach for wireless geolocation that involves putting an entire conventional GPS unit into each handset," said Bell Labs researcher Giovanni Vannucci. Besides providing very poor performance indoors, those handsets are costly, bulky and are a drain on portable batteries.

Another common wireless geolocation technology is solely network-based, but that approach requires expensive base-station equipment, is imprecise, and does not perform well in hilly areas.

The Bell Labs researchers also have enhanced their geolocation approach by developing a method to estimate handset location, which shortens the handset's initial search for a satellite signal. A software program, based on the wireless signals that a handset receives from several base station antennas, helps to estimate a handset's location.

Other researchers working on the Bell Labs geolocation technology include Bob Richton, T.C. Chiang, Richard Leung, Ren Da, and others in Whippany and Naperville, Ill.

Lucent Technologies, headquartered in Murray Hill, N.J., designs, builds and delivers a wide range of public and private networks, communications systems and software, data networking systems, business telephone systems and microelectronics components. Bell Laboratories is the research and development arm for the company. For more information on Lucent Technologies, visit the company's web site at http://www.lucent.com or the Bell Labs web site at http://www.bell-labs.com.