{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T00:22:04Z","timestamp":1760228524374,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,5,17]],"date-time":"2022-05-17T00:00:00Z","timestamp":1652745600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62171002","KJ2019A0554"],"award-info":[{"award-number":["62171002","KJ2019A0554"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Natural Science Foundation Project of Anhui Province","award":["62171002","KJ2019A0554"],"award-info":[{"award-number":["62171002","KJ2019A0554"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Combining Intelligent Reflecting Surface (IRS) with Non-Orthogonal Multiple Access (NOMA) technology is a viable option for increasing communication performance. Firstly, a NOMA downlink transmission system assisted by IRS is established in this study, for maximizing its energy efficiency. Then a Deep Deterministic Policy Gradient (DDPG) algorithm with symmetric properties is used to further optimize the energy efficiency of the system by intelligently adjusting the beam-forming matrix of the access point (AP) and the phase-shift matrix of the IRS. According to the simulation results, the proposed IRS-assisted NOMA downlink network based on the DDPG algorithm presented a considerably higher energy efficiency than the orthogonal multiple access network.<\/jats:p>","DOI":"10.3390\/sym14051018","type":"journal-article","created":{"date-parts":[[2022,5,17]],"date-time":"2022-05-17T08:34:29Z","timestamp":1652776469000},"page":"1018","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Optimal Energy Efficiency Used DDPG in IRS-NOMA Wireless Communications"],"prefix":"10.3390","volume":"14","author":[{"given":"Quanjin","family":"Liu","sequence":"first","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]},{"given":"Jianlan","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]},{"given":"Langtao","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]},{"given":"Songjiao","family":"Bi","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]},{"given":"Wen","family":"Ji","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]},{"given":"Rui","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering and Intelligent Manufacturing, Anqing Normal University, Anqing 246011, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,17]]},"reference":[{"key":"ref_1","unstructured":"Cisco (2020). 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