Date Added: Mar 2012
GPS is the premier method of localization and way-finding in outdoor environments. Indoor environments prevent GPS from functioning properly or at all. RF-based solutions have been proposed using varieties of radio triangulation and spectral fingerprinting. Such technically attractive methods have not seen widespread adoption in places where the demand is greatest: supermarkets, shopping malls, airports, etc. This may be due to the obstacles of funding, installing, or accessing sufficient wireless infrastructure for triangulation, as well as the scalability challenge in site-by-site fingerprinting.