Location Determinnation for Mobile Decives

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 yanchang’s
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

11. Wi-Fi Location

12. Wi-Fi Location
Google Street View
Maxrad
BMMG24005
SSID
MAC

13. Wi-Fi Location

14. Wi-Fi Location

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

16. Wi-Fi Location

17. 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/untrus
ted_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

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