{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T18:57:57Z","timestamp":1771613877813,"version":"3.50.1"},"reference-count":51,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,13]],"date-time":"2023-06-13T00:00:00Z","timestamp":1686614400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Research Foundation of Korea (NRF)","award":["2022R1F1A1074975"],"award-info":[{"award-number":["2022R1F1A1074975"]}]},{"name":"National Research Foundation of Korea (NRF)","award":["20221A10100011"],"award-info":[{"award-number":["20221A10100011"]}]},{"name":"Korea Institute of Energy Technology Evaluation and Planning (KETEP)","award":["2022R1F1A1074975"],"award-info":[{"award-number":["2022R1F1A1074975"]}]},{"name":"Korea Institute of Energy Technology Evaluation and Planning (KETEP)","award":["20221A10100011"],"award-info":[{"award-number":["20221A10100011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Internet of Things (IoT) systems cooperative with unmanned aerial vehicles (UAVs) have been put into use for more than ten years, from transportation to military surveillance, and they have been shown to be worthy of inclusion in the next wireless protocols. Therefore, this paper studies user clustering and the fixed power allocation approach by placing multi-antenna UAV-mounted relays for extended coverage areas and achieving improved performance for IoT devices. In particular, the system enables UAV-mounted relays with multiple antennas together with non-orthogonal multiple access (NOMA) to provide a potential way to enhance transmission reliability. We presented two cases of multi-antenna UAVs such as maximum ratio transmission and the best selection to highlight the benefits of the antenna-selections approach with low-cost design. In addition, the base station managed its IoT devices in practical scenarios with and without direct links. For two cases, we derive closed-form expressions of outage probability (OP) and closed-form approximation ergodic capacity (EC) generated for both devices in the main scenario. The outage and ergodic capacity performances in some scenarios are compared to confirm the benefits of the considered system. The number of antennas was found to have a crucial impact on the performances. The simulation results show that the OP for both users strongly decreases when the signal-to-noise ratio (SNR), number of antennas, and fading severity factor of Nakagami-m fading increase. The proposed scheme outperforms the orthogonal multiple access (OMA) scheme in outage performance for two users. The analytical results match Monte Carlo simulations to confirm the exactness of the derived expressions.<\/jats:p>","DOI":"10.3390\/s23125537","type":"journal-article","created":{"date-parts":[[2023,6,14]],"date-time":"2023-06-14T02:01:40Z","timestamp":1686708100000},"page":"5537","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Exploiting User Clustering and Fixed Power Allocation for Multi-Antenna UAV-Assisted IoT Systems"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1798-2296","authenticated-orcid":false,"given":"Sang Quang","family":"Nguyen","sequence":"first","affiliation":[{"name":"Science and Technology Application for Sustainable Development Research Group, Ho Chi Minh City University of Transport, Ho Chi Minh City 700000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2710-1843","authenticated-orcid":false,"given":"Anh-Tu","family":"Le","sequence":"additional","affiliation":[{"name":"Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City 700000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3175-5698","authenticated-orcid":false,"given":"Chi-Bao","family":"Le","sequence":"additional","affiliation":[{"name":"Faculty of Electronics Technology, Industrial University of Ho Chi Minh City (IUH), Ho Chi Minh City 700000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Phu Tran","family":"Tin","sequence":"additional","affiliation":[{"name":"Data Science Laboratory, Faculty of Information Technology, Ton Duc Thang University, Ho Chi Minh City 700000, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2183-5085","authenticated-orcid":false,"given":"Yong-Hwa","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Data Science, Korea National University of Transportation (KNUT), Uiwang-si 16106, Gyeonggi-do, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2573","DOI":"10.1109\/TWC.2021.3113640","article-title":"Dynamic User Clustering and Optimal Power Allocation in UAV-Assisted Full-Duplex Hybrid NOMA System","volume":"21","author":"Katwe","year":"2022","journal-title":"IEEE Trans. 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