Seamless Positioning and Navigation System Based on GNSS, WIFI and PDR for Mobile Devices

As the rapid development of mobile Internet, many location-based services (LBS) have emerged for commercial cooperation, entertainment, security, and so forth. All of these require accurate and real time positioning of mobile devices with seamless indoor-outdoor transition in high dense urban regions. While satisfactory outdoor location services are achieved based on the global navigation satellite system (GNSS) technology, a really ubiquitous location system for both indoor and outdoor scenarios is not yet available. To cope with this challenge, we propose a hybrid location system, which makes the best of WIFI reference signal strength index (RSSI) fingerprinting technique for indoor positioning, traditional GNSS for the outdoor positioning, and pedestrian dead reckoning (PDR) technology for supplement. An environment-adaptive positioning handover module is proposed to perform positioning technology switching as environment changes. Moreover, a novel algorithm based on continuous hidden Markov model (CHMM) is proposed for the navigation in the indoor regions. Extensive tests for the seamless system proposed have been performed with satisfactory results and effectiveness.