Google Service Uses Cell Towers to Locate Users

Google launched a location service for mobile users on Wednesday that doesn't rely on GPS.

Google Maps with My Location, currently in beta, locates users who don't have GPS-enabled phones based on their location to nearby cell towers. The result isn't as accurate as GPS (Global Positioning System) but works for people who lack the positioning technology in their phones.

"It helps users speed up search by showing the general neighborhood they're in," said Steve Lee, product manager at Google for the service. Without the location service, users must type in their address or neighborhood in order to find nearby businesses using Google Maps.

Google Maps with My Location will use GPS data to locate the user if the phone has the capability. But even for users of GPS-enabled phones, the cell location service might be useful, Lee said. That's because the cell tower feature works better indoors than GPS, it doesn't drain the phone battery as quickly and can bring up a result quicker, he said.

The service could be useful to a person who might be traveling in an unfamiliar city and looking for restaurants or other businesses. A user pulls up Google Maps and hits the zero key on the phone. A blue dot will appear on the map in the user's location. If the service used GPS in the phone, the blue dot will be solid. If the service used cell towers to determine the location, the blue dot will have a halo around it, indicating that the location isn't precise. The user can then search for nearby businesses.

Google says the cell tower technique will locate the user within about 1000 meters. It doesn't use triangulation, which calculates a user location based on the user's distance to three nearby towers. Instead, it essentially shows the range of the tower that the user's phone is connecting to.

But the accuracy should improve as more people use the service, Lee said. That's because Google is keeping a database of location queries, minus any personal information like individual phone numbers or names. That will allow Google to learn more precise information about the range of each tower, so that it can deliver a more accurate location area to users. The coverage area of cell towers can vary from about a quarter of a mile to several miles based on whether the tower is in an urban or rural area.

For now, Google Maps with My Location doesn't feature any advertising, but it could in the future. "This product makes a lot of sense for advertising," Lee said.

In order to use the service, phone owners must download a free application from Google. The application will work on BlackBerry, Windows Mobile and Symbian phones as well as many phones that support Java. A few notable exceptions include the Samsung Blackjack, Moto Q and Palm Treo 700W, which don't support the APIs (application programming interfaces) Google requires to find cell towers, Lee said.