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Nowadays, with the explosive growth of the capabilities in handheld no devices, various components are embedded into smartphones, such as GPS, WLAN (a.k.a. Wi-Fi), Bluetooth, accelerometers, magnetometers, cameras, etc. Because of their locating capabilities, which are quickly becoming one of the standard features in mobile devices, more and more people are getting used to the location-enabled life. Employing Global Navigation Satellites Systems (GNSS), the applications in the ��smart�� devices can greatly enrich the end users’ outdoor activities. However, given the nature of GNSS design, they are clearly not well-suited for applications in urban canyons and indoor environments.
Satellite-based positioning technologies continue to struggle indoors, due to well known issues, such as the weak signal or non-line-of-sight (NLOS) conditions between the mobile user and satellites.To address positioning and navigation in GNSS-degraded or denied areas, various technologies are broadly researched [1]. Most research topics focus on the high-sensitivity GNSS [2], optical navigation systems [3,4], ultrasound solutions [5], WLAN [6], Bluetooth [7,8], Zig Bee [9], Ultra Wide Band [10], cellular networks [2], RFID [11], magnetic localization [12], inertial Anacetrapib measurement units [13,14], signals of opportunity [15], biosensor [16,17], and also hybrid solutions [18�C21].Benefiting from the existing infrastructure, RF-based technologies, such as WLAN, Bluetooth, cellular network, and RFID, are definitely one of highest potential alternatives.
RADAR [6] was one of the first WLAN-based positioning systems to compute the mobile device’s location based on radio signal strength (RSS) from many access points (APs). Rucaparib side effects Skyhook wireless is a system that depends on information about the AP’s coordinates in a database in order to predict location [22]. Ekahau [23] provides an easy and cost-effective solution for locating people, assets, inventory and other objects using Wi-Fi. The Active Badge [24] system uses ceiling-mounted infrared sensor detectors to detect signals from a mobile active badge. Place Lab [25] has even more ambitious goals as seeking to create a comprehensive location database that uses fixed-commodity Wi-Fi, GSM and Bluetooth devices as global beacons.Meanwhile, human physical activity recognition using MEMS sensors has been extensively applied for health monitoring, emergency services, athletic training, navigation, etc. [26,27]. Since motion sensors such as accelerometers, gyroscopes and magnetometers are integrated into a smartphone, they bring the opportunity to assist navigation with knowledge about the motion of a pedestrian [28,29].