GPS Isn't The Only Tool For Location

While GPS does provide the best accuracy, drawbacks include not working well around tall buildings or indoors. These urban canyons or dark zones reflect the GPS signal or make it inaccessible.

Other methods include network-based or handset-based triangulation. The first is more practical. Three or more of the nearest cell towers measure the handset's signal power and calculate a position based on the location and orientation of antennas. Handset-based triangulation requires a handset to scan its surroundings and discover three or more towers. Unless the database is stored locally, this information is sent via cellular or Wi-Fi link to a server that does the calculation and returns a coordinate.

Google's My Location feature, a handset-based approach announced late last year for mobile Google Maps, attempts to use cellular triangulation in lieu of GPS or as a complement to get an approximate location on a map. Services from the likes of Navizon give approximate location using Wi-Fi hotspots, comparing the Wi-Fi networks a person is near against a catalog of known hotspots.

The movement for getting a fix on mobile users was fueled by the FCC's 1996 Enhanced 911 initiative, requiring that cell phone carriers provide emergency responders with the location of mobile users making 911 calls.

Carriers balked about the technical requirements and costs, but they're now largely compliant. Today, third-party companies would like to use that data to provide location-based services, but carriers are reluctant because of sticky privacy concerns and a natural desire to reserve the data for their own service offerings. To address privacy, some carriers provide anonymized data, but there's still no standard path for companies to get location data, even for employees using company devices.

Photo by Steve Gates