location determinnation for mobile decives

Location Determination for

Mobile DevicesWencong Yuan Apr 27 2012

yuanwencong@gmail.com

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