{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,29]],"date-time":"2025-10-29T13:44:38Z","timestamp":1761745478474,"version":"build-2065373602"},"reference-count":26,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2021,6,20]],"date-time":"2021-06-20T00:00:00Z","timestamp":1624147200000},"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":["No.61971450","No.61801521"],"award-info":[{"award-number":["No.61971450","No.61801521"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004735","name":"Natural Science Foundation of\u00a0Hunan Province","doi-asserted-by":"publisher","award":["No.2018JJ2533"],"award-info":[{"award-number":["No.2018JJ2533"]}],"id":[{"id":"10.13039\/501100004735","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100010031","name":"Postdoctoral Research Foundation of China","doi-asserted-by":"publisher","award":["No.2019M652895"],"award-info":[{"award-number":["No.2019M652895"]}],"id":[{"id":"10.13039\/501100010031","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100014472","name":"Scientific Research Foundation of Hunan Provincial Education Department","doi-asserted-by":"publisher","award":["No.18B517"],"award-info":[{"award-number":["No.18B517"]}],"id":[{"id":"10.13039\/100014472","id-type":"DOI","asserted-by":"publisher"}]},{"name":"the Science and Technology on Antenna and Microwave Laboratory","award":["No.61424020309"],"award-info":[{"award-number":["No.61424020309"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>In this paper, we propose a spectrum-sharing protocol for a cooperative cognitive radio network based on non-orthogonal multiple access technology, where the base station (BS) transmits the superimposed signal to the primary user and secondary user with\/without the assistance of a relay station (RS) by adopting the decode-and-forward technique. RS performs discrete-time energy harvesting for opportunistically cooperative transmission. If the RS harvests sufficient energy, the system performs cooperative transmission; otherwise, the system performs direct transmission. Moreover, the outage probabilities and outage capacities of both primary and secondary systems are analyzed, and the corresponding closed-form expressions are derived. In addition, one optimization problem is formulated, where our objective is to maximize the energy efficiency of the secondary system while ensuring that of the primary system exceeds or equals a threshold value. A joint optimization algorithm of power allocation at BS and RS is considered to solve the optimization problem and to realize a mutual improvement in the performance of energy efficiency for both the primary and secondary systems. The simulation results demonstrate the validity of the analysis results and prove that the proposed transmission scheme has a higher energy efficiency than the direct transmission scheme and the transmission scheme with simultaneous wireless information and power transfer technology.<\/jats:p>","DOI":"10.3390\/e23060785","type":"journal-article","created":{"date-parts":[[2021,6,20]],"date-time":"2021-06-20T22:00:02Z","timestamp":1624226402000},"page":"785","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Performance Analysis and Optimization of a Cooperative Transmission Protocol in NOMA-Assisted Cognitive Radio Networks with Discrete Energy Harvesting"],"prefix":"10.3390","volume":"23","author":[{"given":"Hui","family":"Wang","sequence":"first","affiliation":[{"name":"School of Computer Science and Engineering, Central South University, No. 932 Lushannan Road, Changsha 410083, China"}]},{"given":"Ronghua","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Computer Science and Engineering, Central South University, No. 932 Lushannan Road, Changsha 410083, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6993-5347","authenticated-orcid":false,"given":"Kun","family":"Tang","sequence":"additional","affiliation":[{"name":"Guangdong Provincial Key Laboratory of Millimeter-Wave and Terahertz, School of Electronic and Information Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, China"},{"name":"Pazhou Lab, No. 248 Pazhouqiaotou Street, Guangzhou 510220, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8220-8424","authenticated-orcid":false,"given":"Jian","family":"Dong","sequence":"additional","affiliation":[{"name":"School of Computer Science and Engineering, Central South University, No. 932 Lushannan Road, Changsha 410083, China"}]},{"given":"Shaowei","family":"Liao","sequence":"additional","affiliation":[{"name":"Guangdong Provincial Key Laboratory of Millimeter-Wave and Terahertz, School of Electronic and Information Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, China"},{"name":"Pazhou Lab, No. 248 Pazhouqiaotou Street, Guangzhou 510220, China"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Babu, V.S., Deepan, N., and Rebekka, B. 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