{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,7]],"date-time":"2026-03-07T18:09:36Z","timestamp":1772906976775,"version":"3.50.1"},"reference-count":23,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2021,9,16]],"date-time":"2021-09-16T00:00:00Z","timestamp":1631750400000},"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>In this paper, we use satellite-assisted and multi-group multicast mechanisms to relieve ground traffic pressure and improve data transmission efficiency of cell-free massive MIMO systems. We propose to estimate channel state information (CSI) by common pilot scheme. Given the estimated CSI, we derive the closed-form expressions of achievable rate with maximum ratio transmission (MRT) and zero-forcing (ZF) precoding. The correctness of the closed-form expressions is verified through simulations. The results show that with the help of satellite and multicast, the average system spectrum efficiency (SE) can be significantly improved.<\/jats:p>","DOI":"10.3390\/s21186222","type":"journal-article","created":{"date-parts":[[2021,9,22]],"date-time":"2021-09-22T03:47:35Z","timestamp":1632282455000},"page":"6222","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Satellite-Assisted Cell-Free Massive MIMO Systems with Multi-Group Multicast"],"prefix":"10.3390","volume":"21","author":[{"given":"Jiamin","family":"Li","sequence":"first","affiliation":[{"name":"National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China"}]},{"given":"Lingling","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Southeast University, Nanjing 210096, China"}]},{"given":"Pengcheng","family":"Zhu","sequence":"additional","affiliation":[{"name":"National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China"}]},{"given":"Dongming","family":"Wang","sequence":"additional","affiliation":[{"name":"National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China"}]},{"given":"Xiaohu","family":"You","sequence":"additional","affiliation":[{"name":"National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,16]]},"reference":[{"key":"ref_1","first-page":"IV","article-title":"Interagrated terrestrial-satellite networks: Part two","volume":"15","author":"Kuang","year":"2018","journal-title":"China Commun."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5550","DOI":"10.1109\/ACCESS.2019.2963223","article-title":"Convergence of satellite and terrestrial networks: A comprehensive survey","volume":"8","author":"Wang","year":"2020","journal-title":"IEEE Access"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.dsp.2021.102995","article-title":"On the spectral efficiency of cell-free large-scale MIMO non-orthogonal multiple access systems","volume":"111","author":"Zhang","year":"2021","journal-title":"Digit. 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