{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T22:29:49Z","timestamp":1773354589597,"version":"3.50.1"},"reference-count":26,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2016,9,22]],"date-time":"2016-09-22T00:00:00Z","timestamp":1474502400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"Natural Science Foundation of China","doi-asserted-by":"publisher","award":["71031007"],"award-info":[{"award-number":["71031007"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"Natural Science Foundation of China","doi-asserted-by":"publisher","award":["71373282"],"award-info":[{"award-number":["71373282"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the era of mobile internet, Location Based Services (LBS) have developed dramatically. Seamless Indoor and Outdoor Navigation and Localization (SNAL) has attracted a lot of attention. No single positioning technology was capable of meeting the various positioning requirements in different environments. Selecting different positioning techniques for different environments is an alternative method. Detecting the users\u2019 current environment is crucial for this technique. In this paper, we proposed to detect the indoor\/outdoor environment automatically without high energy consumption. The basic idea was simple: we applied a machine learning algorithm to classify the neighboring Global System for Mobile (GSM) communication cellular base station\u2019s signal strength in different environments, and identified the users\u2019 current context by signal pattern recognition. We tested the algorithm in four different environments. The results showed that the proposed algorithm was capable of identifying open outdoors, semi-outdoors, light indoors and deep indoors environments with 100% accuracy using the signal strength of four nearby GSM stations. The required hardware and signal are widely available in our daily lives, implying its high compatibility and availability.<\/jats:p>","DOI":"10.3390\/s16101563","type":"journal-article","created":{"date-parts":[[2016,9,22]],"date-time":"2016-09-22T09:59:55Z","timestamp":1474538395000},"page":"1563","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":63,"title":["Indoor-Outdoor Detection Using a Smart Phone Sensor"],"prefix":"10.3390","volume":"16","author":[{"given":"Weiping","family":"Wang","sequence":"first","affiliation":[{"name":"College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China"}]},{"given":"Qiang","family":"Chang","sequence":"additional","affiliation":[{"name":"College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China"}]},{"given":"Qun","family":"Li","sequence":"additional","affiliation":[{"name":"College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China"}]},{"given":"Zesen","family":"Shi","sequence":"additional","affiliation":[{"name":"College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China"}]},{"given":"Wei","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China"}]}],"member":"1968","published-online":{"date-parts":[[2016,9,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1017\/S0373463311000087","article-title":"Shadow matching: A new GNSS positioning technique for urban canyons","volume":"64","author":"Groves","year":"2011","journal-title":"J. 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