{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T17:16:48Z","timestamp":1791047808571,"version":"4.1.0"},"reference-count":106,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2017,11,24]],"date-time":"2017-11-24T00:00:00Z","timestamp":1511481600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Continuous in-home monitoring of older adults living alone aims to improve their quality of life and independence, by detecting early signs of illness and functional decline or emergency conditions. To meet requirements for technology acceptance by seniors (unobtrusiveness, non-intrusiveness, and privacy-preservation), this study presents and discusses a new smart sensor system for the detection of abnormalities during daily activities, based on ultra-wideband radar providing rich, not privacy-sensitive, information useful for sensing both cardiorespiratory and body movements, regardless of ambient lighting conditions and physical obstructions (through-wall sensing). The radar sensing is a very promising technology, enabling the measurement of vital signs and body movements at a distance, and thus meeting both requirements of unobtrusiveness and accuracy. In particular, impulse-radio ultra-wideband radar has attracted considerable attention in recent years thanks to many properties that make it useful for assisted living purposes. The proposed sensing system, evaluated in meaningful assisted living scenarios by involving 30 participants, exhibited the ability to detect vital signs, to discriminate among dangerous situations and activities of daily living, and to accommodate individual physical characteristics and habits. The reported results show that vital signs can be detected also while carrying out daily activities or after a fall event (post-fall phase), with accuracy varying according to the level of movements, reaching up to 95% and 91% in detecting respiration and heart rates, respectively. Similarly, good results were achieved in fall detection by using the micro-motion signature and unsupervised learning, with sensitivity and specificity greater than 97% and 90%, respectively.<\/jats:p>","DOI":"10.3390\/bios7040055","type":"journal-article","created":{"date-parts":[[2017,11,24]],"date-time":"2017-11-24T11:29:33Z","timestamp":1511522973000},"page":"55","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":105,"title":["A Radar-Based Smart Sensor for Unobtrusive Elderly Monitoring in Ambient Assisted Living Applications"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9737-3721","authenticated-orcid":false,"given":"Giovanni","family":"Diraco","sequence":"first","affiliation":[{"name":"National Research Council of Italy, Institute for Microelectronics and Microsystems, 73100 Lecce, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alessandro","family":"Leone","sequence":"additional","affiliation":[{"name":"National Research Council of Italy, Institute for Microelectronics and Microsystems, 73100 Lecce, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pietro","family":"Siciliano","sequence":"additional","affiliation":[{"name":"National Research Council of Italy, Institute for Microelectronics and Microsystems, 73100 Lecce, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2017,11,24]]},"reference":[{"key":"ref_1","unstructured":"United Nations, Department of Economic and Social Affairs, Population Division (2016, October 29). World Population Prospects: The 2015 Revision, Volume II: Demographic Profiles. Available online: https:\/\/esa.un.org\/unpd\/wpp\/Publications\/Files\/WPP2015_Volume-II-Demographic-Profiles.pdf."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Rantz, M.J., Skubic, M., and Miller, S.J. (2009, January 3\u20136). Using sensor technology to augment traditional healthcare. Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, Minneapolis, MN, USA.","DOI":"10.1109\/IEMBS.2009.5334587"},{"key":"ref_3","unstructured":"World Health Organization, Media Centre (2016, October 29). Falls\u2014Fact Sheet. Reviewed September 2016. Available online: http:\/\/www.who.int\/mediacentre\/factsheets\/fs344\/en\/."},{"key":"ref_4","unstructured":"Centers for Disease Control and Prevention (2016, October 29). Injury Prevention & Control: Data & Statistics 2014, Available online: http:\/\/www.cdc.gov\/injury\/wisqars\/."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1024","DOI":"10.1109\/TITB.2012.2203313","article-title":"Virtual caregiver: An ambient-aware elderly monitoring system","volume":"16","author":"Hossain","year":"2012","journal-title":"IEEE Trans. Inf. Technol. Biomed."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Pradeep Kumar, S., Akash, D., Murali, K., and Shriram, R. (2016, January 30\u201331). Call ambulance smart elderly monitoring system with nearest ambulance detection using Android and Bluetooth. Proceedings of the 2nd International Conference on Science Technology Engineering and Management (ICONSTEM), Chennai, India.","DOI":"10.1109\/ICONSTEM.2016.7560929"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1519\/JPT.0000000000000099","article-title":"Determining Risk of falls in community dwelling older adults: A systematic review and meta-analysis using posttest probability","volume":"40","author":"Lusardi","year":"2017","journal-title":"J. Geriatr. Phys. Ther."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Lord, S., Sherrington, C., Menz, H., and Close, J. (2007). Falls in Older People: Risk Factors and Strategies for Prevention, Cambridge University Press. [2nd ed.].","DOI":"10.1017\/CBO9780511722233"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1007\/BF03324594","article-title":"Concurrent and predictive validity of \u201cgetting up from lying on the floor\u201d","volume":"17","author":"Bergland","year":"2013","journal-title":"Aging Clin. Exp. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1375","DOI":"10.1111\/j.1532-5415.2012.04017.x","article-title":"Critical falls: Why remaining on the ground after a fall can be dangerous, whatever the fall","volume":"60","author":"Bloch","year":"2012","journal-title":"J. Am. Geriatr. Soc."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Noury, N., Fleury, A., Rumeau, P., Bourke, A., Laighin, G., Rialle, V., and Lundy, J.E. (2007, January 22\u201326). Fall detection-Principles and methods. Proceedings of the 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBS), Lyon, France.","DOI":"10.1109\/IEMBS.2007.4352627"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1007\/BF03339872","article-title":"Sleep disordered breathing in the elderly","volume":"12","author":"Janssens","year":"2000","journal-title":"Aging Clin. Exp. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1162","DOI":"10.1016\/0002-9149(89)90871-0","article-title":"Decreased spontaneous heart rate variability in congestive heart failure","volume":"64","author":"Casolo","year":"1989","journal-title":"Am. J. Cardiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/j.ehj.2003.12.003","article-title":"Increased heart rate and reduced heart-rate variability are associated with subclinical inflammation in middle-aged and elderly subjects with no apparent heart disease","volume":"25","author":"Sajadieh","year":"2004","journal-title":"Eur. Heart J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1002\/gps.1439","article-title":"Differences in heart rate variability between depressed and non-depressed elderly","volume":"21","author":"Kooy","year":"2006","journal-title":"Int. J. Geriatr. Psychiatry"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"877","DOI":"10.1002\/ana.24393","article-title":"Heart rate variability and the risk of parkinson disease: The atherosclerosis risk in communities study","volume":"77","author":"Alonso","year":"2015","journal-title":"Ann. Neurol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1159\/000213312","article-title":"Respiration and heart rate variability during sleep in untreated Parkinson patients","volume":"38","author":"Franceschi","year":"1992","journal-title":"Gerontology"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.1007\/s40520-015-0510-5","article-title":"Falls risk assessment for hospitalised older adults: A combination of motion data and vital signs","volume":"28","author":"Baig","year":"2016","journal-title":"Aging Clin. Exp. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1177\/0733464807311435","article-title":"Unobtrusive in-home monitoring of cognitive and physical health: Reactions and perceptions of older adults","volume":"27","author":"Wild","year":"2008","journal-title":"J. Appl. Gerontol."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Nguyen, C., and Han, J. (2014). Time-Domain Ultra-Wideband Radar, Sensor and Components: Theory, Analysis and Design, Springer Science & Business Media.","DOI":"10.1007\/978-1-4614-9578-9"},{"key":"ref_21","unstructured":"Federal Communications Commission (FCC) (2002). Document 00-163. Revision of Part 15 of the Commission\u2019s Rules Regarding Ultra-Wideband Transmission Systems. No. 98\u2013153, FCC."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.medengphy.2016.10.014","article-title":"Review of fall detection techniques: A data availability perspective","volume":"39","author":"Khan","year":"2017","journal-title":"Med. Eng. Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1109\/MSP.2015.2503881","article-title":"Monitoring activities of daily living in smart homes: Understanding human behavior","volume":"33","author":"Debes","year":"2016","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Igual, R., Medrano, C., and Plaza, I. (2013). Challenges, issues and trends in fall detection systems. Biomed. Eng. Online, 12.","DOI":"10.1186\/1475-925X-12-66"},{"key":"ref_25","first-page":"94","article-title":"A survey on automatic fall Detection in the context of ambient assisted living systems","volume":"4","author":"Spasova","year":"2014","journal-title":"Int. J. Adv. Comput. Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1161\/01.CIR.93.5.1043","article-title":"Heart rate variability: Standards of measurement, physiological interpretation, and clinical use","volume":"93","author":"Malik","year":"1996","journal-title":"Circulation"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Hafner, N., and Lubecke, V. (2009, January 3\u20136). Performance assessment techniques for Doppler radar physiological sensors. Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, Minneapolis, MN, USA.","DOI":"10.1109\/IEMBS.2009.5332661"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"315","DOI":"10.4258\/hir.2015.21.4.315","article-title":"Are currently available wearable devices for activity tracking and heart rate monitoring accurate, precise, and medically beneficial?","volume":"21","author":"Nounou","year":"2015","journal-title":"Healthc. Inform. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4373","DOI":"10.1002\/adma.201504366","article-title":"Monitoring of vital signs with flexible and wearable medical devices","volume":"28","author":"Khan","year":"2016","journal-title":"Adv. Mater."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1109\/JBHI.2012.2234129","article-title":"A survey on ambient-assisted living tools for older adults","volume":"17","author":"Rashidi","year":"2013","journal-title":"IEEE J. Biomed. Health Inform."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Min, C., Kang, S., Yoo, C., Cha, J., Choi, S., Oh, Y., and Song, J. (2015, January 7\u201311). Exploring current practices for battery use and management of smartwatches. Proceedings of the 2015 ACM International Symposium on Wearable Computers, Osaka, Japan.","DOI":"10.1145\/2802083.2802085"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3098","DOI":"10.1109\/TKDE.2016.2592527","article-title":"Scalable daily human behavioral pattern mining from multivariate temporal data","volume":"28","author":"Rawassizadeh","year":"2016","journal-title":"IEEE Trans. Knowl. Data Eng."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"22616","DOI":"10.3390\/s150922616","article-title":"Energy-efficient integration of continuous context sensing and prediction into smartwatches","volume":"15","author":"Rawassizadeh","year":"2015","journal-title":"Sensors"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1109\/MPRV.2016.27","article-title":"Floor pressure imaging for fall detection with fiber-optic sensors","volume":"15","author":"Feng","year":"2016","journal-title":"IEEE Pervasive Comput."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Droghini, D., Ferretti, D., Principi, E., Squartini, S., and Piazza, F. (2017). A combined one-class SVM and template-matching approach for user-aided human fall detection by means of floor acoustic features. Comput. Intell. Neurosci.","DOI":"10.1155\/2017\/1512670"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1291","DOI":"10.1109\/TBME.2012.2186449","article-title":"A microphone array system for automatic fall detection","volume":"59","author":"Li","year":"2012","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1109\/TCSVT.2011.2129370","article-title":"Robust video surveillance for fall detection based on human shape deformation","volume":"21","author":"Rougier","year":"2011","journal-title":"IEEE Trans. Circuits Syst. Video Technol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1109\/TSMCC.2008.2008099","article-title":"Resident location-recognition algorithm using a Bayesian classifier in the PIR sensor-based indoor location-aware system","volume":"39","author":"Kim","year":"2009","journal-title":"IEEE Trans. Syst. Man Cybern. Part C Appl. Rev."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Popescu, M., Hotrabhavananda, B., Moore, M., and Skubic, M. (2012, January 21\u201324). VAMPIR\u2014An automatic fall detection system using a vertical PIR sensor array. Proceedings of the 6th International Conference on Pervasive Computing Technologies for Healthcare and Workshops (PervasiveHealth), San Diego, CA, USA.","DOI":"10.4108\/icst.pervasivehealth.2012.248759"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1007\/s10209-010-0197-5","article-title":"Extracting spatiotemporal human activity patterns in assisted living using a home sensor network","volume":"10","author":"Lymberopoulos","year":"2011","journal-title":"Univers. Access Inf. Soc."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Dura-Bernal, S., Garreau, G., Georgiou, J., Andreou, A.G., Denham, S.L., and Wennekers, T. (2013). Multimodal integration of micro-doppler sonar and auditory signals for behavior classification with convolutional networks. Int. J. Neural Syst., 23.","DOI":"10.1142\/S0129065713500214"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"770","DOI":"10.1016\/j.medengphy.2011.02.001","article-title":"Detecting falls with 3D range camera in ambient assisted living applications: A preliminary study","volume":"33","author":"Leone","year":"2011","journal-title":"Med. Eng. Phys."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Iarlori, S., Ferracuti, F., Giantomassi, A., and Longhi, S. (2014, January 9\u201311). RGB-D video monitoring system to assess the dementia disease state based on recurrent neural networks with parametric bias action recognition and DAFS index evaluation. Proceedings of the Lecture Notes in Computer Science (LNCS-2), Paris, France.","DOI":"10.1007\/978-3-319-08599-9_25"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1109\/MSP.2015.2502784","article-title":"Radar signal processing for elderly fall detection: The future for in-home monitoring","volume":"33","author":"Amin","year":"2016","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Balaji, B., Xu, J., Nwokafor, A., Gupta, R., and Agarwal, Y. (2013, January 11\u201315). Sentinel: Occupancy based HVAC actuation using existing WiFi infrastructure within commercial buildings. Proceedings of the 11th ACM Conference on Embedded Networked Sensor Systems, Roma, Italy.","DOI":"10.1145\/2517351.2517370"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Laput, G., Zhang, Y., and Harrison, C. (2017, January 6\u201311). Synthetic sensors: Towards general-purpose sensing. Proceedings of the 2017 CHI Conference on Human Factors in Computing Systems, Denver, CO, USA.","DOI":"10.1145\/3025453.3025773"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1109\/TMTT.2004.823552","article-title":"Range correlation and I\/Q performance benefits in single-chip silicon Doppler radars for noncontact cardiopulmonary monitoring","volume":"52","author":"Droitcour","year":"2004","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Kolakowski, J., Djaja-Josko, V., and Kolakowski, M. (2017). UWB monitoring system for AAL applications. Sensors, 17.","DOI":"10.3390\/s17092092"},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Blumrosen, G., Uziel, M., Rubinsky, B., and Porrat, D. (2010, January 27\u201330). Non-contact UWB radar technology to assess tremor. Proceedings of the XII Mediterranean Conference on Medical and Biological Engineering and Computing 2010, Chalkidiki, Greece.","DOI":"10.1007\/978-3-642-13039-7_123"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"181","DOI":"10.3233\/AIS-170425","article-title":"Estimation of human walking speed by Doppler radar for elderly care","volume":"9","author":"Rui","year":"2017","journal-title":"J. Ambient Intell. Smart Environ."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"2434","DOI":"10.1109\/TBME.2014.2319333","article-title":"Quantitative gait measurement with pulse-doppler radar for passive in-home gait assessment","volume":"61","author":"Wang","year":"2014","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Rahman, T., Adams, A.T., Ravichandran, R.V., Zhang, M., Patel, S.N., Kientz, J.A., and Choudhury, T. (2015, January 7\u201311). Dopplesleep: A contactless unobtrusive sleep sensing system using short-range doppler radar. Proceedings of the ACM International Joint Conference on Pervasive and Ubiquitous Computing, Osaka, Japan.","DOI":"10.1145\/2750858.2804280"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"5717","DOI":"10.1109\/JSEN.2017.2723766","article-title":"People counting based on an IR-UWB radar sensor","volume":"17","author":"Choi","year":"2017","journal-title":"IEEE Sens. J."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"865","DOI":"10.1109\/TBME.2014.2367038","article-title":"Doppler radar fall activity detection using the wavelet transform","volume":"62","author":"Su","year":"2015","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1049\/iet-rsn.2014.0250","article-title":"Radar-based fall detection based on doppler time-frequency signatures for assisted living","volume":"9","author":"Wu","year":"2015","journal-title":"IET Radar Sonar Navig."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Jokanovic, B., Amin, M., and Ahmad, F. (2016, January 2\u20136). Radar fall motion detection using deep learning. Proceedings of the IEEE Radar Conference (RadarConf), Philadelphia, PA, USA.","DOI":"10.1109\/RADAR.2016.7485147"},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Erol, B., Amin, M.G., and Boashash, B. (2017, January 8\u201312). Range-Doppler radar sensor fusion for fall detection. Proceedings of the IEEE Radar Conference (RadarConf), Seattle, WA, USA.","DOI":"10.1109\/RADAR.2017.7944316"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"959","DOI":"10.1016\/S0140-6736(71)90274-1","article-title":"Contactless apnoea detector based on radar","volume":"298","author":"Caro","year":"1971","journal-title":"Lancet"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"306","DOI":"10.1007\/BF02478126","article-title":"Contactless respiration monitoring of infants","volume":"14","author":"Franks","year":"1976","journal-title":"Med. Biol. Eng."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"1530","DOI":"10.1109\/PROC.1975.9992","article-title":"Noninvasive microwave measurement of respiration","volume":"63","author":"Lin","year":"1975","journal-title":"Proc. IEEE"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"618","DOI":"10.1109\/TMTT.1979.1129682","article-title":"Microwave apexcardiography","volume":"27","author":"Lin","year":"1979","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1002\/bem.2250130610","article-title":"Microwave sensing of physiological movement and volume change: A review","volume":"13","author":"Lin","year":"1992","journal-title":"Bioelectromagnetics"},{"key":"ref_63","doi-asserted-by":"crossref","unstructured":"Greneker, E.F. (1997, January 21\u201325). Radar sensing of heartbeat and respiration at a distance with security applications. Proceedings of the International Society for Optical Engineering (SPIE), Orlando, FL, USA.","DOI":"10.1049\/cp:19971650"},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Kim, K.-B., Suh, J.-S., Shin, D.-H., and Park, S.-O. (2014, January 16\u201323). High sensitivity doppler radar system for detecting respiration and heart rate using improved isolation technique. Proceedings of the 31th URSI General Assembly and Scientific Symposium (GASS), Beijing, China.","DOI":"10.1109\/URSIGASS.2014.6930091"},{"key":"ref_65","doi-asserted-by":"crossref","unstructured":"Petkie, D.T., Benton, C., and Bryan, E. (2009, January 13\u201317). Millimeter-wave radar for vital signs sensing. Proceedings of the International Society for Optical Engineering (SPIE), Orlando, FL, USA.","DOI":"10.1117\/12.818927"},{"key":"ref_66","unstructured":"Vinci, G., Lindner, S., Barbon, F., Hofmann, M., Fischer, G., Kissinger, D., and Koelpin, A. (November, January 31). 24 GHz six-port medical radar for contactless respiration detection and heartbeat monitoring. Proceedings of the 9th European Radar Conference (EuRAD), Amsterdam, The Netherlands."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"2046","DOI":"10.1109\/TMTT.2013.2256924","article-title":"A review on recent advances in doppler radar sensors for noncontact healthcare monitoring","volume":"61","author":"Li","year":"2013","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"2076","DOI":"10.1109\/TMTT.2013.2252185","article-title":"IR-UWB radar demonstrator for ultra-fine movement detection and vital-sign monitoring","volume":"61","author":"Schleicher","year":"2013","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"3143","DOI":"10.1109\/TMTT.2008.2007139","article-title":"Random body movement cancellation in doppler radar vital sign detection","volume":"56","author":"Li","year":"2008","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_70","doi-asserted-by":"crossref","unstructured":"Hu, X., and Jin, T. (2016). Short-range vital signs sensing based on EEMD and CWT using IR-UWB radar. Sensors, 16.","DOI":"10.20944\/preprints201608.0206.v3"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"1565","DOI":"10.1364\/BOE.6.001565","article-title":"DistancePPG: Robust noncontact vital signs monitoring using a camera","volume":"6","author":"Kumar","year":"2015","journal-title":"Biomed. Opt. Express"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/j.bspc.2014.03.004","article-title":"Non-contact heart rate and heart rate variability measurements: A review","volume":"13","author":"Kranjec","year":"2014","journal-title":"Biomed. Signal Process. Control"},{"key":"ref_73","unstructured":"TIME DOMAIN (2016, July 14). Pulson\u00aep410 Radar Kit (27 May 2015). Available online: http:\/\/www.timedomain.com\/."},{"key":"ref_74","unstructured":"The MathWorks (2017, November 18). (November 2017) Signal Processing Toolbox User\u2019s Guide. Available online: http:\/\/www.mathworks.com\/access\/helpdesk\/help\/toolbox\/signal\/."},{"key":"ref_75","doi-asserted-by":"crossref","unstructured":"Moulton, J., Kassam, S., Ahmad, F., Amin, M., and Yemelyanov, K. (2008, January 26\u201330). Target and change detection in synthetic aperture radar sensing of urban structures. Proceedings of the IEEE Radar Conference (RADAR), Rome, Italy.","DOI":"10.1109\/RADAR.2008.4721104"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"3192","DOI":"10.1109\/TGRS.2009.2019728","article-title":"Spatial filtering for wall-clutter mitigation in through-the-wall radar imaging","volume":"47","author":"Yoon","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"1589","DOI":"10.1109\/TGRS.2008.916212","article-title":"Refocusing through building walls using synthetic aperture radar","volume":"46","author":"Dehmollaian","year":"2008","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"29","DOI":"10.2528\/PIERB09060903","article-title":"Analysis of clutter reduction techniques for through wall imaging in UWB range","volume":"17","author":"Verma","year":"2009","journal-title":"Prog. Electromagn. Res. B"},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"1913","DOI":"10.3390\/s90301913","article-title":"Sea clutter reduction and target enhancement by neural networks in a marine radar system","volume":"9","year":"2009","journal-title":"Sensors"},{"key":"ref_80","doi-asserted-by":"crossref","unstructured":"Mohsin Riaz, M., and Ghafoor, A. (2012). Through-wall image enhancement based on singular value decomposition. Int. J. Antennas Propag., 2012.","DOI":"10.1155\/2012\/961829"},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"783","DOI":"10.1109\/JSTARS.2013.2259801","article-title":"Advanced signal processing for vital sign extraction with applications in UWB radar detection of trapped victims in complex environments","volume":"7","author":"Li","year":"2014","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1109\/TAES.2006.1603402","article-title":"Micro-Doppler effect in radar: Phenomenon, model, and simulation study","volume":"42","author":"Chen","year":"2006","journal-title":"IEEE Trans. Aerosp. Electr. Syst."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"2600","DOI":"10.1109\/78.782222","article-title":"Computing the discrete-time analytic signal via FFT","volume":"47","author":"Marple","year":"1999","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1109\/10.81568","article-title":"Reconstruction of sequential cardiac in-plane displacement patterns on the chest wall by laser speckle interferometry","volume":"38","author":"Singh","year":"1991","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_85","doi-asserted-by":"crossref","unstructured":"Tan, H., Qiao, D., and Li, Y. (2012, January 19\u201320). Non-contact heart rate tracking using Doppler radar. Proceedings of the IEEE International Conference on Systems and Informatics (ICSAI), Yantai, China.","DOI":"10.1109\/ICSAI.2012.6223372"},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1109\/TASSP.1980.1163359","article-title":"Time-frequency representation of digital signals and systems based on short-time Fourier analysis","volume":"28","author":"Portnoff","year":"1980","journal-title":"IEEE Trans. Acoust. Speech Signal Process."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"4135","DOI":"10.1109\/TIT.2010.2050935","article-title":"On the analytic wavelet transform","volume":"56","author":"Lilly","year":"2010","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"2745","DOI":"10.1109\/78.482123","article-title":"The chirplet transform: Physical considerations","volume":"43","author":"Mann","year":"1995","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1109\/MSP.2013.2267931","article-title":"Empirical mode decomposition-based time-frequency analysis of multivariate signals: The power of adaptive data analysis","volume":"30","author":"Mandic","year":"2013","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"903","DOI":"10.1098\/rspa.1998.0193","article-title":"The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis","volume":"454","author":"Huang","year":"1998","journal-title":"Proc. R. Soc. Lond. A Math. Phys. Eng. Sci."},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1109\/TBME.2013.2288319","article-title":"Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature doppler radar sensor","volume":"61","author":"Hu","year":"2014","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_92","doi-asserted-by":"crossref","unstructured":"Mostafanezhad, I., Boric-Lubecke, O., Lubecke, V., and Mandic, D.P. (2009, January 3\u20136). Application of empirical mode decomposition in removing fidgeting interference in doppler radar life signs monitoring devices. Proceedings of the 31st IEEE Engineering in Medicine and Biology Society (EMBC), Minneapolis, MN, USA.","DOI":"10.1109\/IEMBS.2009.5333206"},{"key":"ref_93","first-page":"1355","article-title":"Micro-Doppler character analysis of moving objects using through-wall radar based on improved EEMD","volume":"32","author":"Wang","year":"2010","journal-title":"J. Electron. Inf. Technol."},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"1897","DOI":"10.1109\/JSEN.2013.2238376","article-title":"Cancellation of unwanted doppler radar sensor motion using empirical mode decomposition","volume":"13","author":"Mostafanezhad","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1146\/annurev.fluid.31.1.417","article-title":"A new view of nonlinear water waves: The Hilbert spectrum","volume":"31","author":"Huang","year":"1999","journal-title":"Annu. Rev. Fluid Mech."},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1109\/TIM.2013.2275243","article-title":"EMD-based filtering using similarity measure between probability density functions of IMFs","volume":"63","author":"Komaty","year":"2014","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_97","unstructured":"Axiomtek (2015, February 15). eBOX530-820-FL Fanless Embedded System Datasheet. Available online: http:\/\/www.axiomtek.it."},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1016\/j.irbm.2008.08.002","article-title":"A proposal for the classification and evaluation of fall detectors","volume":"29","author":"Noury","year":"2008","journal-title":"IRBM"},{"key":"ref_99","doi-asserted-by":"crossref","unstructured":"Vlaeyen, E., Deschodt, M., Debard, G., Dejaeger, E., Boonen, S., Goedem\u00e9, T., Vanrumste, B., and Milisen, K. (2013). Fall incidents unraveled: A series of 26 video-based real-life fall events in three frail older persons. BMC Geriatr., 13.","DOI":"10.1186\/1471-2318-13-103"},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/S0140-6736(12)61263-X","article-title":"Video capture of the circumstances of falls in elderly people residing in long-term care: An observational study","volume":"381","author":"Robinovitch","year":"2013","journal-title":"Lancet"},{"key":"ref_101","unstructured":"(2017, September 28). HEPTAGON. Available online: http:\/\/hptg.com\/industrial."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"246","DOI":"10.1016\/j.enbuild.2015.01.043","article-title":"People occupancy detection and profiling with 3D depth sensors for building energy management","volume":"92","author":"Diraco","year":"2015","journal-title":"Energy Build."},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1016\/j.gaitpost.2013.07.003","article-title":"In-home hierarchical posture classification with a time-of-flight 3D sensor","volume":"39","author":"Diraco","year":"2014","journal-title":"Gait Posture"},{"key":"ref_104","doi-asserted-by":"crossref","unstructured":"Diraco, G., Leone, A., and Siciliano, P. (2011, January 27\u201330). Geodesic-based human posture analysis by using a single 3D TOF camera. Proceedings of the IEEE International Symposium on Industrial Electronics (ISIE), Gdansk, Poland.","DOI":"10.1109\/ISIE.2011.5984351"},{"key":"ref_105","unstructured":"SMARTEX (2017, March 01). Wearable Wellness System. Available online: http:\/\/www.smartex.it\/en\/our-products\/232-wearable-wellness-systemwws\/."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"1002","DOI":"10.1109\/JBHI.2013.2274479","article-title":"An online one class support vector machine-based person-specific fall detection system for monitoring an elderly individual in a room environment","volume":"17","author":"Yu","year":"2013","journal-title":"IEEE J. Biomed. Health Inform."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/7\/4\/55\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:51:09Z","timestamp":1760208669000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/7\/4\/55"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,11,24]]},"references-count":106,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2017,12]]}},"alternative-id":["bios7040055"],"URL":"https:\/\/doi.org\/10.3390\/bios7040055","relation":{"has-preprint":[{"id-type":"doi","id":"10.20944\/preprints201710.0115.v1","asserted-by":"object"}]},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,11,24]]}}}