{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T14:13:56Z","timestamp":1772806436360,"version":"3.50.1"},"reference-count":45,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2019,7,23]],"date-time":"2019-07-23T00:00:00Z","timestamp":1563840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61762079"],"award-info":[{"award-number":["61762079"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61662070"],"award-info":[{"award-number":["61662070"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Key Science and Technology Support Program of Gansu Province","award":["1604FKCA097"],"award-info":[{"award-number":["1604FKCA097"]}]},{"name":"Key Science and Technology Support Program of Gansu Province","award":["17YF1GA015"],"award-info":[{"award-number":["17YF1GA015"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Amid the ever-accelerated development of wireless communication technology, we have become increasingly demanding for location-based service; thus, passive indoor positioning has gained widespread attention. Channel State Information (CSI), as it can provide more detailed and fine-grained information, has been followed by researchers. Existing indoor positioning methods, however, are vulnerable to the environment and thus fail to fully reflect all the position features, due to limited accuracy of the fingerprint. As a solution, a CSI-based passive indoor positioning method was proposed, Wavelet Domain Denoising (WDD) was adopted to deal with the collected CSI amplitude, and the CSI phase information was unwound and transformed linearly in the offline phase. The post-processed amplitude and phase were taken as fingerprint data to build a fingerprint database, correlating with reference point position information. Results of experimental data analyzed under two different environments show that the present method boasts lower positioning error and higher stability than similar methods and can offer decimeter-level positioning accuracy.<\/jats:p>","DOI":"10.3390\/s19143233","type":"journal-article","created":{"date-parts":[[2019,7,23]],"date-time":"2019-07-23T10:44:51Z","timestamp":1563878691000},"page":"3233","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["A Device-Free Indoor Localization Method Using CSI with Wi-Fi Signals"],"prefix":"10.3390","volume":"19","author":[{"given":"Xiaochao","family":"Dang","sequence":"first","affiliation":[{"name":"College of Computer Science and Engineering, Northwest Normal University, Lanzhou 730070, China"},{"name":"Gansu Internet of Things Engineering Research Center, Lanzhou 730070, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7548-9988","authenticated-orcid":false,"given":"Xuhao","family":"Tang","sequence":"additional","affiliation":[{"name":"College of Computer Science and Engineering, Northwest Normal University, Lanzhou 730070, China"}]},{"given":"Zhanjun","family":"Hao","sequence":"additional","affiliation":[{"name":"College of Computer Science and Engineering, Northwest Normal University, Lanzhou 730070, China"},{"name":"Gansu Internet of Things Engineering Research Center, Lanzhou 730070, China"}]},{"given":"Yang","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Computer Science and Engineering, Northwest Normal University, Lanzhou 730070, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1109\/COMST.2015.2464084","article-title":"Wi-Fi Fingerprint-Based Indoor Positioning: Recent Advances and Comparisons","volume":"18","author":"He","year":"2016","journal-title":"IEEE Commun. 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