{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:24:26Z","timestamp":1760243066566,"version":"build-2065373602"},"reference-count":38,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2015,6,17]],"date-time":"2015-06-17T00:00:00Z","timestamp":1434499200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Localization as a technique to solve the complex and challenging problems besetting line-of-sight (LOS) and non-line-of-sight (NLOS) transmissions has recently attracted considerable attention in the wireless sensor network field. This paper proposes a strategy for eliminating NLOS localization errors during calculation of the location of mobile terminals (MTs) in unfamiliar indoor environments. In order to improve the hidden Markov model (HMM), we propose two modified algorithms, namely, modified HMM  (M-HMM) and replacement modified HMM (RM-HMM). Further, a hybrid localization algorithm that combines HMM with an interacting multiple model (IMM) is proposed to represent the velocity of mobile nodes. This velocity model is divided into a high-speed and a low-speed model, which means the nodes move at different speeds following the same mobility pattern. Each moving node continually switches its state based on its probability. Consequently, to improve precision, each moving node uses the IMM model to integrate the results from the HMM and its modified forms. Simulation experiments conducted show that our proposed algorithms perform well in both distance estimation and coordinate calculation, with increasing accuracy of localization of the proposed algorithms in the order M-HMM, RM-HMM, and HMM + IMM. The simulations also show that the three algorithms are accurate, stable, and robust.<\/jats:p>","DOI":"10.3390\/s150614298","type":"journal-article","created":{"date-parts":[[2015,6,17]],"date-time":"2015-06-17T11:19:34Z","timestamp":1434539974000},"page":"14298-14327","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["An Indoor Mobile Location Estimator in Mixed Line of Sight\/Non-Line of Sight Environments Using Replacement Modified Hidden Markov Models and an Interacting  Multiple Model"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9132-374X","authenticated-orcid":false,"given":"Jingyu","family":"Ru","sequence":"first","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chengdong","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zixi","family":"Jia","sequence":"additional","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yufang","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yunzhou","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nan","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Information, Northeastern University, Shenyang 110819, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,6,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Xia, D., and Vlajic, N. (2006, January 7\u201310). Near-optimal node clustering in wireless sensor networks for environment monitoring. Proceedings of the 2006 Canadian Conference on Electrical and Computer Engineering, Ottawa, ON, Canada.","DOI":"10.1109\/CCECE.2006.277300"},{"key":"ref_2","unstructured":"Virone, G., Wood, L., Selavo, Q., Cao, L., Fang, T., Doan, Z.H., R. Stoleru, S.L., and Stankovic, J.A. (2006, January 2\u20134). An advanced wireless sensor network for health monitoring. Proceedings of the 1st Transdisciplinary. Conference on Distributed Diagnosis and Home Healthcare (D2H2), Arlington, VA, USA."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Lee, S.H., Lee, S., Song, H., and Lee, S.H. (2009, January 18\u201321). Wireless sensor network design for tactical military applications: Remote large-scale environments. Proceedings of the IEEE Military Communications Conference, Boston, MA, USA.","DOI":"10.1109\/MILCOM.2009.5379900"},{"key":"ref_4","unstructured":"Ares Zurita, B., Park, P.G., Fischione, C., Speranzon, A., and Johansson, K.H. (2007, January 2\u20135). On power control for wireless sensor networks: System model, middleware component and experimental evaluation. Proceedings of the 2007 European Control Conference (ECC), Kos, Greece."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1109\/SURV.2009.090103","article-title":"A survey of indoor positioning systems for wireless personal networks","volume":"11","author":"Gu","year":"2009","journal-title":"Commun. Surv. Tutor. IEEE"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1067","DOI":"10.1109\/TSMCC.2007.905750","article-title":"Survey of wireless indoor positioning techniques and systems","volume":"37","author":"Liu","year":"2007","journal-title":"IEEE Trans. Syst. Man Cybern. Part C Appl. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"262","DOI":"10.1109\/TITS.2012.2213815","article-title":"GPS localization accuracy classification: A context-based approach","volume":"14","author":"Drawil","year":"2013","journal-title":"IEEE Trans. Intell. Transp. Syst."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Zhong, Z., and He, T. (2007, January 6\u20139). MSP: Multi-sequence positioning of wireless sensor nodes. Proceedings of the 5th International Conference on Embedded Networked Sensor Systems, Sydney, Australia.","DOI":"10.1145\/1322263.1322266"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Zhong, Z., and He, T. (2009, January 4\u20136). Achieving range-free localization beyond connectivity. Proceedings of the 7th ACM Conference on Embedded Networked Sensor Systems, New York, NY, USA.","DOI":"10.1145\/1644038.1644066"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1109\/LCOMM.2004.835319","article-title":"The Cram\u00e9r\u2013Rao bounds of hybrid TOA\/RSS and TDOA\/RSS location estimation schemes","volume":"8","author":"Catovic","year":"2004","journal-title":"IEEE Commun. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1109\/MCS.2009.935569","article-title":"Kalman filtering in wireless sensor networks","volume":"30","author":"Ribeiro","year":"2010","journal-title":"IEEE Control Syst."},{"key":"ref_12","unstructured":"Chen, H.Y., Deng, P., Xu, Y.J., and Li, X.W. (2005, January 23\u201326). A robust location algorithm with biased extended Kalman filtering of TDOA data for wireless sensor networks. Proceedings of the IEEE International Conference on Wireless Communications, Networking, and Mobile Computing, Wuhan, China."},{"key":"ref_13","first-page":"1","article-title":"Indoor mobile localization in wireless sensor network under unknown NLOS errors","volume":"2013","author":"Cheng","year":"2013","journal-title":"Int. J. Distrib. Sens. Netw."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Caballero, F., Merino, L., Maza, I., and Ollero, A. (2008, January 19\u201323). A particle filtering method for wireless sensor network localization with an aerial robot beacon. Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), Pasadena, CA, USA.","DOI":"10.1109\/ROBOT.2008.4543271"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1007\/s00779-010-0357-x","article-title":"EDIPS: An Easy to Deploy Indoor Positioning System to support loosely coupled mobile work","volume":"15","author":"Vera","year":"2011","journal-title":"Person. Ubiquit. Comput."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1525","DOI":"10.1109\/TSP.2006.889978","article-title":"Hidden Markov models for radio localization in mixed LOS\/NLOS conditions","volume":"55","author":"Morelli","year":"2007","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1157","DOI":"10.1109\/TVT.2008.928649","article-title":"Mobile location estimator in a rough wireless environment using extended Kalman-based IMM and data fusion","volume":"58","author":"Chen","year":"2009","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1109\/TVT.2005.861207","article-title":"Time-of-arrival based localization under NLOS conditions","volume":"55","author":"Chan","year":"2006","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3597","DOI":"10.1109\/TWC.2009.080415","article-title":"UDP identification and error mitigation in TOA-based indoor localization systems using neural network architecture","volume":"8","author":"Heidari","year":"2009","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1438","DOI":"10.1109\/TAES.2013.6557997","article-title":"NLOS identification and mitigation for mobile tracking","volume":"49","author":"Yu","year":"2013","journal-title":"IEEE Trans. Aerosp. Electro. Syst."},{"key":"ref_21","unstructured":"Chen, P.C. (1999, January 21\u201324). A non-line-of-sight error mitigation algorithm in location estimation. Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC), New Orleans, LA, USA."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Marano, S., Gifford, W.M., Wymeersch, H., and Win, M.Z. (December, January 30). Nonparametric obstruction detection for UWB localization. Proceedings of the 2009 IEEE Global Telecommunications Conference, Honolulu, HI, USA.","DOI":"10.1109\/GLOCOM.2009.5425460"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1109\/JSAC.2010.100907","article-title":"NLOS identification and mitigation for localization based on UWB experimental data","volume":"28","author":"Marano","year":"2010","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1622","DOI":"10.1109\/TIE.2011.2165462","article-title":"Toward robust indoor localization based on Bayesian filter using chirp-spread-spectrum ranging","volume":"59","author":"Wang","year":"2012","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Merino, L., Caballero, F., and Ollero, A. (2010, January 18\u201322). Active sensing for range-only mapping using multiple hypothesis. Proceedings of the IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Taipei, China.","DOI":"10.1109\/IROS.2010.5650442"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1065","DOI":"10.1109\/LCOMM.2011.080811.111087","article-title":"Improving RSS-based ranging in LOS-NLOS scenario using GMMs","volume":"15","author":"Wang","year":"2011","journal-title":"IEEE Commun. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"999","DOI":"10.1109\/TVT.2003.814222","article-title":"Location of mobile terminals using time measurements and survey points","volume":"52","author":"McGuire","year":"2003","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3801","DOI":"10.1109\/TSP.2008.920145","article-title":"A jump Markov particle filter for localization of mobile terminals in multipath indoor scenarios","volume":"56","author":"Nicoli","year":"2008","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3002","DOI":"10.1109\/TWC.2006.04747","article-title":"Robust mobile location estimator with NLOS mitigation using interacting multiple model algorithm","volume":"5","author":"Liao","year":"2006","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1424","DOI":"10.1109\/TMC.2010.105","article-title":"Mobile location estimation using fuzzy-based IMM and data fusion","volume":"9","author":"Yang","year":"2010","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3398","DOI":"10.1109\/TSP.2011.2138702","article-title":"Robust MT tracking based on M-estimation and interacting multiple model algorithm","volume":"59","author":"Hammes","year":"2011","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1109\/TWC.2006.1611097","article-title":"Analysis of wireless geolocation in a non-line-of-sight environment","volume":"5","author":"Qi","year":"2006","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_33","first-page":"1","article-title":"CRLBs for WSNs localization in NLOS environment","volume":"22","author":"Huang","year":"2011","journal-title":"EURASIP J. Wirel. Commun. Netw."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2243","DOI":"10.1109\/TSP.2013.2251341","article-title":"TOA-based robust wireless geolocation and Cram\u00e9r-Rao lower bound analysis in harsh LOS\/NLOS environments","volume":"61","author":"Yin","year":"2013","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_35","unstructured":"Morelli, C., Nicoli, M., Rampa, V., and Spagnolini, U. (2006, January 14\u201319). Particle filters for RSS-based localization in wireless sensor networks: An experimental study. Proceedings of the 2006 IEEE International Conference on Acoustics, Speech and Signal Processing, Toulouse, UK."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"916","DOI":"10.4028\/www.scientific.net\/AMM.373-375.916","article-title":"Improved D\/TA and information fusion based on HMM indoor localization","volume":"373","author":"Ru","year":"2013","journal-title":"Appl. Mech. Mater."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1109\/36.739074","article-title":"Multitarget detection\/tracking for monostatic ground penetrating radar: Application to pavement profiling","volume":"37","author":"Spagnolini","year":"1999","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1109\/LSP.2005.845598","article-title":"Capacity and complexity of HMM duration modeling techniques","volume":"12","author":"Johnson","year":"2005","journal-title":"IEEE Signal. Process. Lett."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/6\/14298\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:48:01Z","timestamp":1760215681000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/6\/14298"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,6,17]]},"references-count":38,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2015,6]]}},"alternative-id":["s150614298"],"URL":"https:\/\/doi.org\/10.3390\/s150614298","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2015,6,17]]}}}