{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T14:13:17Z","timestamp":1766758397584,"version":"3.48.0"},"reference-count":26,"publisher":"Institution of Engineering and Technology (IET)","issue":"1","license":[{"start":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T00:00:00Z","timestamp":1766707200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["92067201"],"award-info":[{"award-number":["92067201"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["ietresearch.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["IET Communications"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>As a cornerstone of the internet of things, massive grant\u2010free random multiple access (MGFRMA) has attracted wide attention in recent years. However, due to lack of coordination, it is difficult to remove access collisions among randomly activated users, which makes the existing solutions unsatisfactory. To solve the issue, this paper introduces cognitive radio (CR) and preamble delay (PD) to reduce access collisions, together with non\u2010orthogonal multiple access (NOMA) to improve spectrum efficiency, and then develops a CR\u2010NOMA\u2010PD\u2010based MGFRMA scheme. First, a three\u2010step MGFRMA protocol is advanced. It helps users to obtain the channel occupancy state before uplink transmission with spectrum sensing so as to consciously avoid access conflicts. Then, an optimisation strategy for jointly selecting access channel and power level is designed according to the sensing results. The competitive transmission scheme with PD is formulated, based on which uplink signals are well modelled. Finally, a multi\u2010user detection algorithm involving channel filtering, power level detection, preamble detection, and data recovery is proposed. The performance of the CR\u2010NOMA\u2010PD\u2010based MGFRMA scheme is also analysed and simulated. Simulation results indicate that the proposed scheme improves the access ratio of users and system overload capacity significantly compared to the existing schemes. It also has better robustness and scalability.<\/jats:p>","DOI":"10.1049\/cmu2.70124","type":"journal-article","created":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T14:11:05Z","timestamp":1766758265000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Massive Grant\u2010Free Random Access Scheme Based on Spectrum Sensing and Preamble Delay"],"prefix":"10.1049","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7591-4232","authenticated-orcid":false,"given":"Jing","family":"Zhang","sequence":"first","affiliation":[{"name":"Jiangsu Province Key Lab of Wireless Communications and Internet of Things, School of Communications and Information Engineering Nanjing University of Posts and Telecommunications  Nanjing China"}]},{"given":"Zhuang\u2010Zhuang","family":"Wei","sequence":"additional","affiliation":[{"name":"Jiangsu Province Key Lab of Wireless Communications and Internet of Things, School of Communications and Information Engineering Nanjing University of Posts and Telecommunications  Nanjing China"}]},{"given":"Yu\u2010Qi","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Accounting Chongqing Technology and Business University  Chongqing China"}]},{"given":"Hong\u2010Xu","family":"Gao","sequence":"additional","affiliation":[{"name":"China Post Construction Technology Co., Ltd  Nanjing China"}]},{"given":"Hai\u2010Tao","family":"Zhao","sequence":"additional","affiliation":[{"name":"Jiangsu Province Key Lab of Wireless Communications and Internet of Things, School of Internet of Things Nanjing University of Posts and Telecommunications  Nanjing China"}]},{"given":"Hong\u2010Bo","family":"Zhu","sequence":"additional","affiliation":[{"name":"Jiangsu Province Key Lab of Wireless Communications and Internet of Things, School of Communications and Information Engineering Nanjing University of Posts and Telecommunications  Nanjing China"}]}],"member":"265","published-online":{"date-parts":[[2025,12,26]]},"reference":[{"key":"e_1_2_12_2_1","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2020.3010271"},{"key":"e_1_2_12_3_1","doi-asserted-by":"publisher","DOI":"10.1109\/MWC.001.1900494"},{"key":"e_1_2_12_4_1","doi-asserted-by":"publisher","DOI":"10.1109\/MCOM.2016.7565189"},{"key":"e_1_2_12_5_1","doi-asserted-by":"crossref","unstructured":"F.MehmetiandT. F.La Porta \u201cModeling and Analysis of mMTC Traffic in 5G Base Stations \u201d inProceedings of the 2022 IEEE 19th Annual Consumer Communications & Networking Conference (CCNC)(IEEE 2022) 652\u2013660.","DOI":"10.1109\/CCNC49033.2022.9700727"},{"key":"e_1_2_12_6_1","doi-asserted-by":"publisher","DOI":"10.1109\/MVT.2019.2921208"},{"key":"e_1_2_12_7_1","doi-asserted-by":"publisher","DOI":"10.1109\/COMST.2018.2835558"},{"key":"e_1_2_12_8_1","doi-asserted-by":"publisher","DOI":"10.1109\/TVT.2021.3096259"},{"key":"e_1_2_12_9_1","doi-asserted-by":"publisher","DOI":"10.1109\/JIOT.2018.2869003"},{"key":"e_1_2_12_10_1","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2011.111611.110350"},{"key":"e_1_2_12_11_1","doi-asserted-by":"publisher","DOI":"10.1109\/TVT.2015.2418811"},{"key":"e_1_2_12_12_1","doi-asserted-by":"publisher","DOI":"10.1109\/ACCESS.2021.3109242"},{"key":"e_1_2_12_13_1","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2015.2417873"},{"key":"e_1_2_12_14_1","doi-asserted-by":"publisher","DOI":"10.23919\/JCC.ea.2021\u20100807.202302"},{"key":"e_1_2_12_15_1","doi-asserted-by":"publisher","DOI":"10.1109\/JIOT.2023.3247801"},{"key":"e_1_2_12_16_1","doi-asserted-by":"publisher","DOI":"10.1109\/TWC.2019.2929126"},{"issue":"3","key":"e_1_2_12_17_1","doi-asserted-by":"crossref","first-page":"1557","DOI":"10.1109\/TWC.2020.3034308","article-title":"An Approach to Preamble Collision Reduction in Grant\u2010Free Random Access With Massive MIMO","volume":"20","author":"Choj J.","year":"2021","journal-title":"IEEE Transactions on Wireless Communications"},{"key":"e_1_2_12_18_1","doi-asserted-by":"publisher","DOI":"10.1109\/LWC.2020.2974724"},{"key":"e_1_2_12_19_1","doi-asserted-by":"publisher","DOI":"10.1109\/COMST.2020.2996032"},{"key":"e_1_2_12_20_1","doi-asserted-by":"crossref","unstructured":"H.Jiang Q. M.Cui andY.Gu \u201cDistributed Layered Grant\u2010Free Non\u2010Orthogonal Multiple Access for Massive MTC \u201d inProceedings of the IEEE 29th Annual International Symposium on Personal Indoor and Mobile Radio Communications(2018) https:\/\/doi.org\/10.1109\/PIMRC.2018.8580806.","DOI":"10.1109\/PIMRC.2018.8580806"},{"issue":"8","key":"e_1_2_12_21_1","first-page":"2606","article-title":"Grant\u2010Free Random Access Scheme for MTC Based on Multi\u2010Power Level and Multi\u2010Preamble","volume":"45","author":"Wang J. W.","year":"2023","journal-title":"System Engineering and Electronics"},{"key":"e_1_2_12_22_1","doi-asserted-by":"publisher","DOI":"10.1109\/JIOT.2021.3081535"},{"key":"e_1_2_12_23_1","doi-asserted-by":"publisher","DOI":"10.1109\/JSTSP.2025.3533115"},{"key":"e_1_2_12_24_1","doi-asserted-by":"publisher","DOI":"10.1109\/TIFS.2025.3544957"},{"issue":"7","key":"e_1_2_12_25_1","doi-asserted-by":"crossref","first-page":"6369","DOI":"10.1109\/JIOT.2020.2972274","article-title":"Deep Reinforcement Learning for Throughput Improvement of Uplink Grant\u2010Free NOMA System","volume":"7","author":"Zhang J. Z.","year":"2020","journal-title":"IEEE Internet of Things Journal"},{"issue":"20","key":"e_1_2_12_26_1","doi-asserted-by":"crossref","first-page":"15349","DOI":"10.1109\/JIOT.2021.3064872","article-title":"Resource\u2010Hopping\u2010Based Grant\u2010Free Multiple Access for 6G\u2010Enabled Massive IoT Networks","volume":"8","author":"Han S. J.","year":"2021","journal-title":"IEEE Internet of Things Journal"},{"key":"e_1_2_12_27_1","doi-asserted-by":"publisher","DOI":"10.1109\/MCOMSTD.001.1900015"}],"container-title":["IET Communications"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/ietresearch.onlinelibrary.wiley.com\/doi\/pdf\/10.1049\/cmu2.70124","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T14:11:07Z","timestamp":1766758267000},"score":1,"resource":{"primary":{"URL":"https:\/\/ietresearch.onlinelibrary.wiley.com\/doi\/10.1049\/cmu2.70124"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,26]]},"references-count":26,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,1]]}},"alternative-id":["10.1049\/cmu2.70124"],"URL":"https:\/\/doi.org\/10.1049\/cmu2.70124","archive":["Portico"],"relation":{},"ISSN":["1751-8628","1751-8636"],"issn-type":[{"value":"1751-8628","type":"print"},{"value":"1751-8636","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,26]]},"assertion":[{"value":"2025-01-06","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-12-16","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-12-26","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70124"}}