Location Determination for Mobile Devices Wencong Yuan Apr

Keynotes Cell tower ip GPS Wi-Fi RSS Three-axis gyroscope

Cell Tower Triangulation Neighborhood or city level accuracy Two-step, crowd- sourcing approach: Estimate cellular tower location using crowd-sourcing data At serving time, depends on the content in the query, compute device location using : a :nearest tower b : neighbor towers and c : fingerprint

IP Geolocation City level accuracy For example

GPS or Assisted-GPS Location Best Available accuracy Power cost and unavailable indoors For example experiment in yanchangs grass ground

Wi-Fi Location Similar to cellular,however Wi-Fi radium is much much smaller 30m to 200m vs 500m to 2000m Most Wi-Fi AP are consumer grade, the RF is usually low quality and the radiation patterns among different vendors are usually poor

Wi-Fi Location Bad MAC address assignment : Ad-hoc, tethering mode, duplicated addresses Mobile APs

Wi-Fi Location Accuracy case study San Francisco

Wi-Fi Location

Google Street View Maxrad BMMG24005 SSID MAC

Wi-Fi Location

Google Location Database Geolocation API For example :

Wi-Fi Location

RSS Radio Signal Strength

Three-axis gyroscope & MEMS Accelerometer

Q & A More information:

Q & A sted_dlcp/ CN/events/facultysummit/2010/files/mobile_location.pdf sted_dlcp/ CN/events/facultysummit/2010/files/mobile_location.pdf g-user-location.html g-user-location.html

Q & A us/howto/wp7/web/location-and-my-privacy.aspx us/howto/wp7/web/location-and-my-privacy.aspx