Where am I - positioning for mobile applications

I am currently working on Location Based Services (LBS) and have spent some time trying to get decent positioning for my mobile phone application. Since GPS tends to fail indoors (where most users are most of the time) and is really too slow, some other ways of positioning are needed. There is plenty of research on GSM and UMTS positioning concepts - a good overview are the slides of Shu Wang et al. - but the question remains: Which LoCation Services (LCS) are available for application developers right now?

Until the mobile network operators make available network-based positioning techniques, only mobile-based and mobile-assisted positioning methods are available. Proximity sensing is a common technology for locating mobile devices. Mobile phones can use radio beacons like GSM cells and WLANs. Cellids and BSSIDs are unique identifiers which can be mapped to spatial positions.

The market for LBS is huge with new players showing up daily. Several companies provide commercial LCS to support this development, e.g. Navizon, or Skyhook Wireless, who are also the location service behind Apple’s iPhone, loki.com and the Firefox project Geode. Both use central databases, mapping cellids and WLAN BSSIDs, and proprietary client software on the mobile device. Especially Skyhook Wireless seems to provide great coverage and accuracy, but developers need to license and integrate their black-box software.

Yahoo’s take on LBS is called Fire Eagle and is centered on Yahoo’s users. Software using the API can update or query the location of a single user, but this is not of much help if you want to develop applications for a more general audience.

If you don’t need street-level accuracy and want to stay in control of your client software on the mobile device, cellid-based positioning with a web service is a good choice. Opencellid.org provides an open database for mapping cellids and a well documented API, a good introduction and tutorial can be found on mobiforge.

Placelab.org is an older research project, based on Jeffrey Hightower’s Location Stack, and sponsored by intel, which offers GPL software and various ways of interoperability. Their open beacon database is continued on wigle.net.

Another web service for mapping cell ids is the (hidden) Google API, which is used by the Google Maps “My location” feature. The accuracy is sufficient for neighbourhood level and integration into own applications is straight-forward. Code examples can be found here and here.

Some clever people have also found out how to use the skyhook API without their software, you can find some code here.