Google Gears enhances geolocation with WiFi positioning

Google has hopped on the WiFi positioning bandwagon by adding support for an undisclosed database of WiFi network locations to its Gears Geolocation API. Google said on its Code Blog that the service for laptops "securely locate[s] users to within 200m accuracy" and Google's Mobile Blog said the improvement is immediately available for BlackBerry users who download an updated Google Maps for Mobile application. It will soon be rolled out to other platforms, including the Google-backed Android.

Google Gears is a plugin or add-on for several browsers, and one built into Google's Chrome beta, that allows web applications to continue running when offline. The Geolocation API adds several calls related to position. Previously, Google focused on mobile devices, using the cellular base station information that phones must collect to maintain seamless voice service in order to triangulate on a location using a database Google had assembled. (The API is under consideration at the W3C as an informal proposal, but it's already been picked up by The Mozilla Foundation, too.)

I've been pinpointed

In any browser, Gears prompts a web surfer about whether he or she wants to reveal the computer or device's current location to a web site the first time that site requests it. Google says the API doesn't record user location, and company asserts it isn't storing location information tied to an IP address or other identifying information.

A Google spokesperson explained via e-mail that WiFi data was drawn from "multiple data sources," not licensed, but declined to identify the sources. Skyhook Wireless confirmed to Ars that its own WiFi Positioning System (WPS) wasn't what Google relies on. Skyhook's system is used by the iPhone's Location Service (including in the Maps software powered by Google Maps), and was just incorporated into Symbian 9.5 for developers.

Though the Skyhook system differs from Google's approach, a look at Skyhook provides some general insight into how Google may provide geolocation to non-GPS devices.

Skyhook

Skyhook uses two methods to gather data. Company employees drive the streets of medium-to-large cities around the world in vehicles that have extra-sensitive GPS and WiFi receivers. The vehicles' system automatically captures the openly broadcast details from WiFi access points. The company also collects snapshots of WiFi signals that its direct and indirect customers transmit in order to obtain a fix.

Those snapshots are used to expand and correct Skyhook's wardriving database. The firm has proprietary algorithms that turn the snapshot into a latitude and longitude with some knowledge of the degree of error. (Skyhook and Google both say that they don't tie personally identifiable information with the data points they gather for positioning results.)

The iPhone combines Skyhook's WiFi scan, Google's knowledge of cellular towers (which is also part of the Geolocation API), and, on the iPhone 3G, a GPS receiver to provide a location. On the iPhone 3G, the WiFi and cellular triangulation allow an almost immediate rough response before the GPS receiver can get a more exact fix.

The Mozilla Foundation introduced its own positioning technology, Geode, two weeks ago. Geode can be downloaded as an add-on for Firefox 3.0 and will be included in 3.1. Geode uses Skyhook's WiFi data in the current add-on, but the full release will allow a choice of positioning provider, such as a GPS receiver or a Web services firm.

With more focus on location, users may need to make a concerted effort to rebuff attempts to find them when they choose to be left alone. The iPhone has a switch that allows Location Services to be turned off globally for users to avoid being asked whether their locations should be provided; that might soon be an important requirement for browser implementation, too.