Steven J. Crowley, P.E.

Google patent application: Estimating wireless device location using measured data rates

Location-based services are reaching beyond navigation and E911. Social networking, advertising, and other emerging applications are driving research and development into better technologies in support of these services, starting with the location estimation process itself.

Today, there are several ways to determine the location of a wireless device in a network. As a rough estimate, the device knows the identification of the base station or access point with which it is associated. That’s a start, but a base station can cover a wide area. To refine that, devices can use GPS. Networks of cellular base stations can measure differences in the timing or signal strength of an uplink signal, and use the results to estimate location. MAC addresses of Wi-Fi access points can be sniffed and mapped by roving monitors. Sometimes, two or more of these techniques are used in concert.
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