{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T18:56:48Z","timestamp":1774292208641,"version":"3.50.1"},"reference-count":36,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2016,9,5]],"date-time":"2016-09-05T00:00:00Z","timestamp":1473033600000},"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":["61301132"],"award-info":[{"award-number":["61301132"]}],"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":["61300188"],"award-info":[{"award-number":["61300188"]}],"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":["61301131"],"award-info":[{"award-number":["61301131"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002858","name":"China Postdoctoral Science Foundation","doi-asserted-by":"publisher","award":["2014M561347"],"award-info":[{"award-number":["2014M561347"]}],"id":[{"id":"10.13039\/501100002858","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012226","name":"Fundamental Research Funds for the Central Universities","doi-asserted-by":"publisher","award":["3132016024"],"award-info":[{"award-number":["3132016024"]}],"id":[{"id":"10.13039\/501100012226","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012226","name":"Fundamental Research Funds for the Central Universities","doi-asserted-by":"publisher","award":["3132016311"],"award-info":[{"award-number":["3132016311"]}],"id":[{"id":"10.13039\/501100012226","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012226","name":"Fundamental Research Funds for the Central Universities","doi-asserted-by":"publisher","award":["3132016312"],"award-info":[{"award-number":["3132016312"]}],"id":[{"id":"10.13039\/501100012226","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To exploit the complementary strengths of WiFi positioning, pedestrian dead reckoning (PDR), and landmarks, we propose a novel fusion approach based on an extended Kalman filter (EKF). For WiFi positioning, unlike previous fusion approaches setting measurement noise parameters empirically, we deploy a kernel density estimation-based model to adaptively measure the related measurement noise statistics. Furthermore, a trusted area of WiFi positioning defined by fusion results of previous step and WiFi signal outlier detection are exploited to reduce computational cost and improve WiFi positioning accuracy. For PDR, we integrate a gyroscope, an accelerometer, and a magnetometer to determine the user heading based on another EKF model. To reduce accumulation error of PDR and enable continuous indoor positioning, not only the positioning results but also the heading estimations are recalibrated by indoor landmarks. Experimental results in a realistic indoor environment show that the proposed fusion approach achieves substantial positioning accuracy improvement than individual positioning approaches including PDR and WiFi positioning.<\/jats:p>","DOI":"10.3390\/s16091427","type":"journal-article","created":{"date-parts":[[2016,9,5]],"date-time":"2016-09-05T10:02:01Z","timestamp":1473069721000},"page":"1427","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":44,"title":["Continuous Indoor Positioning Fusing WiFi, Smartphone Sensors and Landmarks"],"prefix":"10.3390","volume":"16","author":[{"given":"Zhi-An","family":"Deng","sequence":"first","affiliation":[{"name":"School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guofeng","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5829-6121","authenticated-orcid":false,"given":"Danyang","family":"Qin","sequence":"additional","affiliation":[{"name":"School of Electronics Engineering, Heilongjiang University, Harbin 150080, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhenyu","family":"Na","sequence":"additional","affiliation":[{"name":"School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yang","family":"Cui","sequence":"additional","affiliation":[{"name":"School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juan","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,9,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Gre\u00dfmann, B., Klimek, H., and Turau, V. (2010, January 11\u201312). Towards Ubiquitous Indoor Location Based Services and Indoor Navigation. Proceedings of the 7th Workshop on Positioning Navigation and Communication (WPNC), Dresden, Germany.","DOI":"10.1109\/WPNC.2010.5653258"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"24791","DOI":"10.3390\/s151024791","article-title":"PRIMAL: Page Rank-Based Indoor Mapping and Localization Using Gene-Sequenced Unlabeled WLAN Received Signal Strength","volume":"15","author":"Zhou","year":"2015","journal-title":"Sensors"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1109\/MSP.2005.1458289","article-title":"Localization via Ultra-Wideband Radios: A Look at Positioning Aspects for Future Sensor Networks","volume":"22","author":"Gezici","year":"2005","journal-title":"IEEE Signal Proc. Mag."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"596","DOI":"10.3390\/s16050596","article-title":"Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons","volume":"16","author":"Zhuang","year":"2016","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"701","DOI":"10.1023\/B:WINE.0000044029.06344.dd","article-title":"LANDMARC: Indoor Location Sensing Using Active RFID","volume":"10","author":"Ni","year":"2004","journal-title":"Wirel. Netw."},{"key":"ref_6","unstructured":"Zhao, Y., Dong, L., Wang, J., Hu, B., and Fu, Y. (2008, January 26\u201329). Implementing Indoor Positioning System via ZigBee Devices. Proceedings of the 42nd Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, USA."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"523","DOI":"10.3390\/mi6040523","article-title":"Extended Kalman Filter for Real Time Indoor Localization by Fusing WiFi and Smartphone Inertial Sensors","volume":"6","author":"Deng","year":"2015","journal-title":"Micromachines"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1292","DOI":"10.3390\/s150101292","article-title":"Received Signal Strength Recovery in Green WLAN Indoor Positioning System Using Singular Value Thresholding","volume":"15","author":"Ma","year":"2015","journal-title":"Sensors"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"738","DOI":"10.1016\/j.comcom.2011.12.011","article-title":"Indoor Positioning via Nonlinear Discriminative Feature Extraction in Wireless Local Area Network","volume":"35","author":"Deng","year":"2012","journal-title":"Comput. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2287","DOI":"10.1109\/JSAC.2015.2430514","article-title":"Robust Indoor Positioning With Lifelong Learning","volume":"33","author":"Xiao","year":"2015","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"22864","DOI":"10.3390\/s141222864","article-title":"Magnetic, Acceleration Fields and Gyroscope Quaternion (MAGYQ)-Based Attitude Estimation with Smartphone Sensors for Indoor Pedestrian Navigation","volume":"14","author":"Renaudin","year":"2014","journal-title":"Sensors"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"715","DOI":"10.3390\/s150100715","article-title":"Fusion of WiFi, Smartphone Sensors and Landmarks Using the Kalman Filter for Indoor Localization","volume":"15","author":"Chen","year":"2015","journal-title":"Sensors"},{"key":"ref_13","first-page":"1","article-title":"SemanticSLAM: Using Environment Landmarks for Unsupervised Indoor Localization","volume":"1","author":"Abdelnasser","year":"2015","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Wang, H., Lenz, H., Szabo, A., Bamberger, J., and Hanebeck, U.D. (2007, January 22). WLAN-Based Pedestrian Tracking Using Particle Filters and Low-Cost MEMS Sensors. Proceedings of the 2007 4th Workshop on Positioning, Navigation and Communication (WPNC\u201907), Hannover, Germany.","DOI":"10.1109\/WPNC.2007.353604"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Rai, A., Chintalapudi, K.K., Padmanabhan, V.N., and Sen, R. (2012, January 22\u201326). Zee: Zero-Effort Crowdsourcing for Indoor Localization. Proceedings of the 18th Annual International Conference on Mobile Computing and Networking, Istanbul, Turkey.","DOI":"10.1145\/2348543.2348580"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2957","DOI":"10.3390\/s100402957","article-title":"Development of an Indoor Location Based Service Test Bed and Geographic Information System with a Wireless Sensor Network","volume":"10","author":"Jan","year":"2010","journal-title":"Sensors"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"8","DOI":"10.3390\/ijgi5020008","article-title":"Integrated WiFi\/PDR\/Smartphone Using an Adaptive System Noise Extended Kalman Filter Algorithm for Indoor Localization","volume":"5","author":"Li","year":"2016","journal-title":"ISPRS Int. J. Geo-Inf."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"8031","DOI":"10.3390\/e17127859","article-title":"An Information-Based Approach to Precision Analysis of Indoor WLAN Localization Using Location Fingerprint","volume":"17","author":"Zhou","year":"2015","journal-title":"Entropy"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Evennou, F., and Marx, F. (2006). Advanced Integration of WiFi and Inertial Navigation Systems for Indoor Mobile Positioning. EURASIP J. Appl. Signal Proc.","DOI":"10.1155\/ASP\/2006\/86706"},{"key":"ref_20","first-page":"52","article-title":"Energy Efficient Access Point Selection and Signal Projection for Accurate Indoor Positioning","volume":"9","author":"Deng","year":"2012","journal-title":"China Commun."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Scott, D.W. (1992). Multivariate Density Estimation, Wiley.","DOI":"10.1002\/9780470316849"},{"key":"ref_22","unstructured":"Silverman, B.W. (1986). Density Estimation for Statistics and Data Analysis, Chapman and Hall."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"864","DOI":"10.1109\/TIM.2013.2283546","article-title":"Flexible Indoor Localization and Tracking Based on a Wearable Platform and Sensor Data Fusion","volume":"63","author":"Colombo","year":"2014","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1002\/navi.7","article-title":"A New Loosely Coupled DCM Based GPS\/INS Integration Method","volume":"59","author":"Edwan","year":"2012","journal-title":"Navig.-J. Inst. Navig."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1346","DOI":"10.1109\/TBME.2006.875664","article-title":"Quaternion-Based Extended Kalman Filter for Determining Orientation by Inertial and Magnetic Sensing","volume":"53","author":"Sabatini","year":"2006","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1109\/TMC.2007.1017","article-title":"Kernel-Based Positioning in Wireless Local Area Networks","volume":"6","author":"Kushki","year":"2007","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Bar-Shalom, Y., Li, X.-R., and Kirubarajan, T. (2001). Estimation with Applications to Tracking and Navigation, Wiley.","DOI":"10.1002\/0471221279"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"334","DOI":"10.3390\/s16030334","article-title":"An Anchor-Based Pedestrian Navigation Approach Using Only Inertial Sensors","volume":"16","author":"Gu","year":"2016","journal-title":"Sensors"},{"key":"ref_29","first-page":"794","article-title":"Joint Access Point Selection and Local Discriminant Embedding for Energy Efficient and Accurate Wi-Fi Positioning","volume":"6","author":"Deng","year":"2012","journal-title":"KSII Trans. Internet Inf. Syst."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Mo, Y., Zhang, Z.Z., Lu, Y., Meng, W.X., and Agha, G. (2014). Random Forest Based Coarse Locating and KPCA Feature Extraction for Indoor Positioning System. Math. Probl. Eng., 850926.","DOI":"10.1155\/2014\/850926"},{"key":"ref_31","unstructured":"Zou, D.Y., Meng, W.X., and Han, S. (2013, January 7\u201310). Euclidean Distance Based Handoff Algorithm for Fingerprint Positioning of WLAN System. Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC) 2013, Shanghai, China."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Li, F., Zhao, C., Ding, G., Gong, J., Liu, C., and Zhao, F. (2012, January 5\u20138). A Reliable and Accurate Indoor Localization Method Using Phone Inertial Sensors. Proceedings of the 14th ACM International Conference on Ubiquitous Computing, Pittsburgh, PA, USA.","DOI":"10.1145\/2370216.2370280"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Jahn, J., Batzer, U., Seitz, J., Patino-Studencka, L., and Boronat, J.G. (2010, January 15\u201317). Comparison and Evaluation of Acceleration Based Step Length Estimators for Handheld Devices. Proceedings of the 2010 International Conference on Indoor Positioning and Indoor Navigation (IPIN), Zurich, Switzerland.","DOI":"10.1109\/IPIN.2010.5646888"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"21518","DOI":"10.3390\/s150921518","article-title":"Heading Estimation for Indoor Pedestrian Navigation Using a Smartphone in the Pocket","volume":"15","author":"Deng","year":"2015","journal-title":"Sensors"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1109\/TBME.2004.840727","article-title":"Assessment of Walking Features from Foot Inertial Sensing","volume":"52","author":"Sabatini","year":"2005","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3605","DOI":"10.3390\/s120303605","article-title":"On the Statistical Errors of RADAR Location Sensor Networks with Built-In Wi-Fi Gaussian Linear Fingerprints","volume":"12","author":"Zhou","year":"2012","journal-title":"Sensors"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/9\/1427\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:30:06Z","timestamp":1760211006000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/9\/1427"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,9,5]]},"references-count":36,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2016,9]]}},"alternative-id":["s16091427"],"URL":"https:\/\/doi.org\/10.3390\/s16091427","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,9,5]]}}}