Unmasking Fresnel-Zone Limitations for Robust Respiration Sensing in Cell-Free Massive MIMO

Unmasking Fresnel-Zone Limitations for Robust Respiration Sensing in Cell-Free Massive MIMO | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Unmasking Fresnel-Zone Limitations for Robust Respiration Sensing in Cell-Free Massive MIMO Haoqiu Xiong, Jialun Kou, Zhuangzhuang Cui, Yang Miao, Sofie Pollin This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7466079/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Wireless signals can sense subtle physiological motion, such as human respiration, but their reliability is often undermined by Fresnel-zone limitations where amplitude or phase information collapses. We show that distributed Cell-Free Massive MIMO (CF-mMIMO) architectures provide a natural remedy, yet naive fusion of heterogeneous measurements leads to a new challenge of blind fusion. Here we present a unified framework that resolves both issues. At the single-AP level, we reveal that respiration induces arc-like trajectories in the IQ plane and introduce Circle Fitting (CF) and principal component analysis (PCA) to unmask Fresnel-zone limitations. At the multi-AP level, we design adaptive fusion strategies, including weighted antenna combining (WAC) and PCA fusion, to align distributed observations efficiently. Simulations and experiments on a 64-antenna testbed show that PCA consistently outperforms conventional approaches at the single-AP level, while PCA-WAC achieves the best trade-off between accuracy and scalability at the multi-AP level. This work establishes a practical foundation for robust, unobtrusive respiration monitoring and advances the role of integrated sensing and communication (ISAC) as a core capability of 6G networks. Physical sciences/Engineering Physical sciences/Mathematics and computing Physical sciences/Physics 6G Integrated sensing and communication cellfree massive MIMO respiration monitoring Fresnel zone Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 24 Nov, 2025 Reviews received at journal 05 Nov, 2025 Reviews received at journal 18 Oct, 2025 Reviewers agreed at journal 28 Sep, 2025 Reviewers agreed at journal 25 Sep, 2025 Reviewers invited by journal 23 Sep, 2025 Editor assigned by journal 03 Sep, 2025 Submission checks completed at journal 03 Sep, 2025 First submitted to journal 26 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7466079","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":524485770,"identity":"123c367f-14af-49fe-88ca-c819b16d82eb","order_by":0,"name":"Haoqiu Xiong","email":"","orcid":"","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"Haoqiu","middleName":"","lastName":"Xiong","suffix":""},{"id":524485772,"identity":"469755be-77af-4bdd-aacd-d479eab78943","order_by":1,"name":"Jialun Kou","email":"","orcid":"","institution":"KU 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