Wi-Fi positioning system

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Not to be confused with Wi-Fi Protected Setup.

Wi-Fi-based positioning system (WPS) or WiPS/WFPS is used where GPS is inadequate due to various causes including multipath and signal blockage indoors. Such systems include indoor positioning systems. Wi-Fi positioning takes advantage of the rapid growth in the early 21st century of wireless access points in urban areas.

The localization technique used for positioning with wireless access points is based on measuring the intensity of the received signal (received signal strength in English RSS) and the method of "fingerprinting".[1][2] Typical parameters useful to geolocate the Wi-Fi hotspot or wireless access point include the SSID and the MAC address of the access point. The accuracy depends on the number of positions that have been entered into the database. The Wi-Fi hotspot database gets filled by correlating mobile device GPS location data with Wi-Fi hotspot MAC addresses.[3] The possible signal fluctuations that may occur can increase errors and inaccuracies in the path of the user. To minimize fluctuations in the received signal, there are certain techniques that can be applied to filter the noise.

In the case of low precision, some techniques have been proposed to merge the Wi-Fi traces with other data sources such as cell ids.[4]

Privacy concerns[edit]

Citing the specific privacy concerns arising out of WPS, Google suggested a unified approach for opting-out a particular access point from taking part in determining location using WPS.[5] Appending "_nomap" to a wireless access point's SSID excludes it from Google's WPS database. Google hopes that other WPS providers and data collectors, like Apple and Microsoft, follow that recommendation so that it becomes an accepted standard.[6] Mozilla honors _nomap as a method of opting-out of its location service.[7]

Public Wi-Fi location databases[edit]

A number of public Wi-Fi location databases are available:

Name Unique Wi-Fi networks Observations Free database download Active project Search by SSID Search by BSSID Data License Opt-out Comment
Mozilla Location Service [8] 49,070,000[9] 1,985,840,000[9] no yes no no Not publicly released _nomap[7] Also Cell ID database.
Openbmap.org [10] 654,416 yes [11] yes no yes [12] Open Database License 1.0 [13] Also Cell ID database.
Openwlanmap.org [14] 17,356,901 yes [15] yes no yes [16] GNU Free Documentation License [17] request [16]
WiGLE [18] 166,445,718 [19] 2,147,483,647 [19] no yes yes [20] yes [20] Proprietary request Also Cell ID database.


See also[edit]

References[edit]

  1. ^ P. Bahl and V. N. Padmanabhan, “RADAR: an in-building RF-based user location and tracking system,” in Proceedings of 19th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM ’00), vol. 2, pp. 775–784, Tel Aviv.Israel, March 2000.
  2. ^ Y. Chen and H. Kobayashi, “Signal strength based indoor geolocation,” in Proceedings of the IEEE International Conference on Communications (ICC ’02), vol. 1, pp. 436–439, New York, NY, USA, April–May 2002.
  3. ^ How Does a Wi-Fi Positioning System Work?
  4. ^ Danalet, Antonin; Farooq, Bilal; Bierlaire, Michel. "A Bayesian approach to detect pedestrian destination-sequences from WiFi signatures". Transportation Research Part C: Emerging Technologies 44: 146–170. doi:10.1016/j.trc.2014.03.015. 
  5. ^ http://www.infosecurity-magazine.com/blog/2011/11/20/googles-approach-of-a-nomap-wifi-zone/460.aspx.
  6. ^ Google Help - Location-based services - How do I opt out? Obtained 2012-05-30
  7. ^ a b "MLS-Opt-Out". Retrieved 2 September 2014. 
  8. ^ "Mozilla Location Service". Retrieved 2014-12-19. 
  9. ^ a b "Stats Mozilla Location Service". Retrieved 2014-12-19. 
  10. ^ "openBmap". Retrieved 2014-12-19. 
  11. ^ "Openbmap Database Download". Retrieved 2014-12-19. 
  12. ^ "Wifi Access Point finder". Retrieved 2014-12-19. 
  13. ^ "Openbmap license".  Text "url-http://openbmap.org/openBmap-wifi-odbl-10.txt " ignored (help);
  14. ^ "OpenWLANMap". Retrieved 2014-12-19. 
  15. ^ "OpenWLANMap Database Download". Retrieved 2014-12-19. 
  16. ^ a b "Find WLAN network". Retrieved 2014-12-19. 
  17. ^ "OpenWLANMap license". Retrieved 2014-12-19. 
  18. ^ "WiGLE". Retrieved 2014-12-19. 
  19. ^ a b "Stats WiGLE". Retrieved 2014-12-19. 
  20. ^ a b "WiGLE Wireless Network Map". Retrieved 2014-12-19. 
General
  • Anthony LaMarca, Yatin Chawathe, Sunny Consolvo, Jeffrey Hightower, Ian Smith, James Scott, Tim Sohn, James Howard, Jeff Hughes, Fred Potter, Jason Tabert, Pauline Powledge, Gaetano Borriello, Bill Schilit: Place Lab: Device Positioning Using Radio Beacons in the Wild. In Pervasive (2005)