location determination for mobile devices wencong yuan apr 27 2012 [email protected]
TRANSCRIPT
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 ： http://ip.taobao.com
http://ip.taobao.com
GPS or Assisted-GPS Location
Best Available accuracy
Power cost and unavailable indoors
For example ： experiment in yanchang’s 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
Wi-Fi Location
Wi-Fi Location
Google Street View
Maxrad BMMG24005
SSID MAC
Wi-Fi Location
Wi-Fi Location
Wi-Fi Location
Google Location Database
Geolocation API
For example : http://www.ip2location.com/html5geolocationapi.aspx
Wi-Fi Location
Wi-Fi Location
RSS
Radio Signal Strength
Three-axis gyroscope & MEMS Accelerometer
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
Q & A http://static.googleusercontent.com/
external_content/untrusted_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/obtaining-user-location.html
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