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Wi-Fi-based positioning system (WPS) or WiPS/WFPS is used where GPS and GLONASS are inadequate due to various causes including multipath and signal blockage indoors. Such systems include indoor positioning systems. Wi-Fi positioning takes advantage of the rapid growth in the early 21st century of wireless access points in urban areas. The most common and widespread localization technique used for positioning with wireless access points is based on measuring the intensity of the received signal (''received signal strength indication'' or RSSI) and the method of "fingerprinting".〔P. Bahl and V. N. Padmanabhan, “RADAR: an in-building RF-based user location and tracking system,” in Proceedings of 19th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM ’00), vol. 2, pp. 775–784, Tel Aviv.Israel, March 2000.〕〔Y. Chen and H. Kobayashi, “Signal strength based indoor geolocation,” in Proceedings of the IEEE International Conference on Communications (ICC ’02), vol. 1, pp. 436–439, New York, NY, USA, April–May 2002.〕 Typical parameters useful to geolocate the Wi-Fi hotspot or wireless access point include the SSID and the MAC address of the access point. The accuracy depends on the number of positions that have been entered into the database. The Wi-Fi hotspot database gets filled by correlating mobile device GPS location data with Wi-Fi hotspot MAC addresses.〔(How Does a Wi-Fi Positioning System Work? )〕 The possible signal fluctuations that may occur can increase errors and inaccuracies in the path of the user. To minimize fluctuations in the received signal, there are certain techniques that can be applied to filter the noise. In the case of low precision, some techniques have been proposed to merge the Wi-Fi traces with other data sources such as geographical information and time constraints (i.e., time geography). == Motivation & applications == Accurate indoor localization is becoming more important for Wi-Fi based devices due to the increased use of augmented reality, social networking, health care monitoring, personal tracking, inventory control and other indoor location-aware applications.〔J. Xiong and K. Jamieson, “Arraytrack: A fine-grained indoor location system,” NSDI ’13.〕 The popularity and low price of Wi-Fi network interface cards is an attractive incentive to use it as the basis for a localization system and significant research has been done in this area in the past 15 years.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wi-Fi positioning system」の詳細全文を読む スポンサード リンク
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