{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T16:39:56Z","timestamp":1783010396297,"version":"3.54.6"},"reference-count":39,"publisher":"Institute of Electrical and Electronics Engineers (IEEE)","license":[{"start":{"date-parts":[[2025,1,1]],"date-time":"2025-01-01T00:00:00Z","timestamp":1735689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/legalcode"}],"funder":[{"name":"German Federal Ministry of Education and Research (BMBF) in the course of the 6G Research hub for Open, Efficient and Secure Mobile Communication Systems (6GEM) Research Hub","award":["16KISK038"],"award-info":[{"award-number":["16KISK038"]}]},{"name":"Program \u201cNetzwerke 2021,\u201d an initiative of the Ministry of Culture and Science of the State of Northrhine Westphalia"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IEEE Access"],"published-print":{"date-parts":[[2025]]},"DOI":"10.1109\/access.2025.3621763","type":"journal-article","created":{"date-parts":[[2025,10,15]],"date-time":"2025-10-15T17:40:14Z","timestamp":1760550014000},"page":"179200-179215","source":"Crossref","is-referenced-by-count":1,"title":["Hierarchical Multi-Grid OMP for Ultra-Resolution Channel Estimation in THz UM-MIMO Systems"],"prefix":"10.1109","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-4086-7782","authenticated-orcid":false,"given":"Akram","family":"Najjar","sequence":"first","affiliation":[{"name":"Institute of Digital Signal Processing, University of Duisburg-Essen, Duisburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0410-9030","authenticated-orcid":false,"given":"Mohammed","family":"El-Absi","sequence":"additional","affiliation":[{"name":"Institute of Digital Signal Processing, University of Duisburg-Essen, Duisburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9679-5968","authenticated-orcid":false,"given":"Thomas","family":"Kaiser","sequence":"additional","affiliation":[{"name":"Institute of Digital Signal Processing, University of Duisburg-Essen, Duisburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"263","reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1109\/WCNC61545.2025.10978220"},{"key":"ref2","volume-title":"The Next Hyper Connected Experience for All","year":"2020"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1109\/COMST.2024.3385908"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.1109\/JMW.2022.3228118"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1109\/MCOM.2014.6736750"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.1109\/PIMRC.2013.6666272"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.1109\/MCOM.2015.7010533"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1109\/IWMTS51331.2021.9486830"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2023.3338814"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.2013.130213"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1109\/TCOMM.2013.090513.120848"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.2017.2725682"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.2009.091009"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2016.2520930"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.1109\/JSTSP.2014.2334278"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2017.2713357"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.2017.2720038"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.1109\/RACE.2015.7097290"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1109\/TCOMM.2016.2557791"},{"key":"ref20","doi-asserted-by":"publisher","DOI":"10.1109\/TVT.2020.2963847"},{"key":"ref21","first-page":"1","article-title":"Hierarchical sparse channel estimation for massive MIMO","volume-title":"Proc. WSA; 22nd Int. ITG Workshop Smart Antennas","author":"Wunder"},{"key":"ref22","doi-asserted-by":"publisher","DOI":"10.1109\/TVT.2018.2842724"},{"key":"ref23","doi-asserted-by":"publisher","DOI":"10.1109\/LWC.2023.3284491"},{"key":"ref24","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2021.3100073"},{"key":"ref25","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2017.2768579"},{"key":"ref26","doi-asserted-by":"publisher","DOI":"10.1109\/LCOMM.2024.3436917"},{"key":"ref27","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2025.3539001"},{"key":"ref28","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.2021.3071851"},{"key":"ref29","doi-asserted-by":"publisher","DOI":"10.1109\/GLOCOM.2018.8647269"},{"key":"ref30","doi-asserted-by":"publisher","DOI":"10.1109\/TGCN.2023.3317829"},{"key":"ref31","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2025.3551144"},{"key":"ref32","doi-asserted-by":"publisher","DOI":"10.1109\/JSAC.1987.1146527"},{"key":"ref33","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2015.2401560"},{"key":"ref34","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2013.072313.121581"},{"key":"ref35","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2018.2871960"},{"key":"ref36","volume-title":"Fundamentals of Statistical Signal Processing, Volume I: Estimation Theory","author":"Kay","year":"1993"},{"key":"ref37","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2014.011714.130846"},{"key":"ref38","doi-asserted-by":"publisher","DOI":"10.1109\/TCOMM.2022.3146400"},{"key":"ref39","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2018.2818281"}],"container-title":["IEEE Access"],"original-title":[],"link":[{"URL":"http:\/\/xplorestaging.ieee.org\/ielx8\/6287639\/10820123\/11204008.pdf?arnumber=11204008","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,24]],"date-time":"2025-10-24T04:49:20Z","timestamp":1761281360000},"score":1,"resource":{"primary":{"URL":"https:\/\/ieeexplore.ieee.org\/document\/11204008\/"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025]]},"references-count":39,"URL":"https:\/\/doi.org\/10.1109\/access.2025.3621763","relation":{},"ISSN":["2169-3536"],"issn-type":[{"value":"2169-3536","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025]]}}}