1. Location Determination for Mobile Devices Wencong Yuan Apr 27 2012 yuanwencong@gmail.com

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

3. 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

4. IP Geolocation City level accuracy For example http://ip.taobao.com

5. http://ip.taobao.com

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

7. 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

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

9. Wi-Fi Location Accuracy case study San Francisco

10. Wi-Fi Location

12. Google Street View Maxrad BMMG24005 SSID MAC

13. Wi-Fi Location

15. Google Location Database Geolocation API For example : http://www.ip2location.com/html5geolocationapi.aspx

16. Wi-Fi Location

18. RSS Radio Signal Strength

19. Three-axis gyroscope & MEMS Accelerometer

20. Q & A More information: http://www.ip2location.com/html5geolocationapi.aspx http://www.cnbeta.com/articles/110000.htm http://www.xieyidian.com/3240 http://ucdchina.com/snap/9797 http://en.wikipedia.org/wiki/W3C_Geolocation_API

21. Q & A http://static.googleusercontent.com/external_content/untru sted_dlcp/www.google.com/zh-CN/us/intl/zh- CN/events/facultysummit/2010/files/mobile_location.pdf http://static.googleusercontent.com/external_content/untru sted_dlcp/www.google.com/zh-CN/us/intl/zh- CN/events/facultysummit/2010/files/mobile_location.pdf https://developers.google.com/maps/documentation/places/ http://www.zhihu.com/question/19809431 http://developer.android.com/guide/topics/location/obtainin g-user-location.html http://developer.android.com/guide/topics/location/obtainin g-user-location.html

22. Q & A http://www.microsoft.com/windowsphone/en- us/howto/wp7/web/location-and-my-privacy.aspx http://www.microsoft.com/windowsphone/en- us/howto/wp7/web/location-and-my-privacy.aspx http://support.apple.com/kb/HT4995?viewlocale=en_US