Potential risks of WiFi-based indoor positioning and progress on improving localization functionality

Much effort has been expended to develop and improve indoor positioning. Many wireless sensor technologies have been used for indoor positioning systems; however WiFi has been the most widely employed sensor system as an alternative to Global Positioning System (GPS). Many commercial indoor positioning services such as those developed for and available on Apple and Android systems are hardly satisfying users' demand, primarily because of their inaccurate positioning. The Saskatchewan Enhanced Positioning System (SaskEPS) has been developed to provide reliable indoor positioning as a complement to GPS. SaskEPS successfully produces very reliable 2.5-Dimensional positioning (X-Y and floor) information at randomly selected fixed locations across an extensive indoor environment at the University of Saskatchewan. SaskEPS produces GPS-like positioning accuracy (sub 10 metre error) during testing; however there are several additional limitations that reduce the ability of non-GPS systems to provide accurate and reliable positioning indoors as compared to GPS. SaskEPS and other trilateration-based WiFi-based Positioning Systems can improve their positioning abilities with techniques commonly used in GPS-based positioning systems; therefore, SaskEPS has integrated a map-matching technique (Post-positioning correction) with its trilateration-based algorithm (Pre-positioning determination). In this paper we explore some limitations for WiFi-based indoor positioning with an explicit examination of SaskEPS in a complex multi-building environment. As well, some add-on localization functionalities are tested for reducing positioning errors and increasing reliability of SaskEPS.