In addition to cell phone GPS tracking and GSM tracking techniques, you can also track down a handset’s location using WiFi hotspots (or called WiFi access points).
The Boston-based company Skyhook Wireless is the first to use the WiFi hotspots to determine the location of a portable device without GPS; the accuracy is around some 20 to 30 meters. Skyhook Wireless has a database of more than 100 million WiFi access points surveyed by drivers and covers 70 percent of population centers in the United States and Canada, which enables it to provide locating service for Motorola Android cell phones.
In addition to Skyhook Wireless, Google has been doing the same thing. Google’s Street View car is equipped with commercially available Maxrad BMMG24005 omnidirectional radio antenna which receives publicly broadcast WiFi radio signals passively within range of the vehicle when travels at normal speed. The data collected includes the header data, SSID, MAC addresses and the GPS coordinates of the vehicle.
The signals are then processed onboard in the vehicle, and then the data is transferred to Google’s location servers for further processing. Google use this data to provide location based service within Google products.
Here is how Google LBS service works:
- The user’s device sends a request to the Google location server with a list of MAC addresses which are currently visible to the device;
- The location server compares the MAC addresses seen by the user’s device with its list of known MAC addresses, and identifies associated geocoded locations (such as latitude and longitude etc);
- The location server then uses the geocoded locations associated with visible MAC address to triangulate the approximate location of the user;
- This approximate location is geocoded and sent back to the user’s device.