{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,14]],"date-time":"2026-03-14T11:40:31Z","timestamp":1773488431471,"version":"3.50.1"},"reference-count":65,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2019,7,15]],"date-time":"2019-07-15T00:00:00Z","timestamp":1563148800000},"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>The rapidly increasing interest from various verticals for the upcoming 5th generation (5G) networks expect the network to support higher data rates and have an improved quality of service. This demand has been met so far by employing sophisticated transmission techniques including massive Multiple Input Multiple Output (MIMO), millimeter wave (mmWave) bands as well as bringing the computational power closer to the users via advanced baseband processing units at the base stations. Future evolution of the networks has also been assumed to open many new business horizons for the operators and the need of not only a resource efficient but also an energy efficient ecosystem has greatly been felt. The deployment of small cells has been envisioned as a promising answer for handling the massive heterogeneous traffic, but the adverse economic and environmental impacts cannot be neglected. Given that 10% of the world\u2019s energy consumption is due to the Information and Communications Technology (ICT) industry, energy-efficiency has thus become one of the key performance indicators (KPI). Various avenues of optimization, game theory and machine learning have been investigated for enhancing power allocation for downlink and uplink channels, as well as other energy consumption\/saving approaches. This paper surveys the recent works that address energy efficiency of the radio access as well as the core of wireless networks, and outlines related challenges and open issues.<\/jats:p>","DOI":"10.3390\/s19143126","type":"journal-article","created":{"date-parts":[[2019,7,16]],"date-time":"2019-07-16T02:23:16Z","timestamp":1563243796000},"page":"3126","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":67,"title":["A Survey on Recent Trends and Open Issues in Energy Efficiency of 5G"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8650-1479","authenticated-orcid":false,"given":"Muhammad","family":"Usama","sequence":"first","affiliation":[{"name":"School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6787-8457","authenticated-orcid":false,"given":"Melike","family":"Erol-Kantarci","sequence":"additional","affiliation":[{"name":"School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1109\/MCOM.2017.1600788","article-title":"Energy Efficiency Challenges of 5G Small Cell Networks","volume":"55","author":"Ge","year":"2017","journal-title":"IEEE Commun. Mag."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1109\/JSAC.2016.2550338","article-title":"A Survey of Energy-Efficient Techniques for 5G Networks and Challenges Ahead","volume":"34","author":"Buzzi","year":"2016","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"330","DOI":"10.1016\/j.compeleceng.2013.10.013","article-title":"Energy-efficiency analyses of heterogeneous macro and micro base station sites","volume":"40","author":"Lorincz","year":"2014","journal-title":"Comput. Electr. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"5965","DOI":"10.1109\/ACCESS.2017.2696025","article-title":"Energy Efficiency of Small Cell Networks: Metrics, Methods and Market","volume":"5","author":"Zhang","year":"2017","journal-title":"IEEE Access"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1355","DOI":"10.1109\/ACCESS.2016.2549641","article-title":"Power Optimization in 5G Networks: A Step Towards GrEEn Communication","volume":"4","author":"Abrol","year":"2016","journal-title":"IEEE Access"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Ryoo, S., Jung, J., and Ahn, R. (2018, January 15\u201318). Energy efficiency enhancement with RRC connection control for 5G new RAT. Proceedings of the 2018 IEEE Wireless Communication and Networking Conference (WCNC), Barcelona, Spain.","DOI":"10.1109\/WCNC.2018.8377115"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"955","DOI":"10.1109\/TWC.2017.2772897","article-title":"Energy Efficiency in Cache-Enabled Small Cell Networks with Adaptive User Clustering","volume":"17","author":"Hajri","year":"2018","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Zhang, J., Zhang, X., Imran, M.A., Evans, B., and Wang, W. (2016, January 4\u20138). Energy Efficiency Analysis of Heterogeneous Cache-Enabled 5G Hyper Cellular Networks. Proceedings of the 2016 IEEE Global Communications Conference (GLOBECOM), Washington, DC, USA.","DOI":"10.1109\/GLOCOM.2016.7841790"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"5869","DOI":"10.1109\/TWC.2017.2716948","article-title":"Energy-Spectral Efficiency Tradeoffs in 5G Multi-Operator Networks With Heterogeneous Constraints","volume":"16","author":"Aydin","year":"2017","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Rehan, S., and Grace, D. (2015, January 6\u20139). Efficient Joint Operation of Advanced Radio Resource and Topology Management in Energy-Aware 5G Networks. Proceedings of the 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall), Boston, MA, USA.","DOI":"10.1109\/VTCFall.2015.7390914"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1049\/iet-com.2018.5448","article-title":"Green 5G enabling technologies: An overview","volume":"13","author":"Zhang","year":"2019","journal-title":"IET Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1343","DOI":"10.1587\/transcom.2016FGP0004","article-title":"Fronthaul Constrained Coordinated Transmission in Cloud-Based 5G Radio Access Network: Energy Efficiency Perspective","volume":"100-B","author":"Sun","year":"2017","journal-title":"IEICE Trans."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Kitanov, S., and Janevski, T. (2017, January 6\u20138). Energy efficiency of Fog Computing and Networking services in 5G networks. Proceedings of the IEEE Eurocon 2017\u201417th International Conference on Smart Technologies, Ohrid, Macedonia.","DOI":"10.1109\/EUROCON.2017.8011159"},{"key":"ref_14","first-page":"5121302","article-title":"5G Communications: Energy Efficiency","volume":"2017","author":"Demestichas","year":"2017","journal-title":"Mob. Inf. Syst."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1109\/MSP.2014.2335093","article-title":"Toward Energy-Efficient 5G Wireless Communications Technologies: Tools for decoupling the scaling of networks from the growth of operating power","volume":"31","author":"Cavalcante","year":"2014","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2779","DOI":"10.1007\/s11277-017-4324-y","article-title":"Downlink Massive MIMO Systems: Achievable Sum Rates and Energy Efficiency Perspective for Future 5G Systems","volume":"96","author":"Isabona","year":"2017","journal-title":"Wirel. Pers. Commun."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1109\/MWC.2016.1500374WC","article-title":"Energy Efficiency in Massive MIMO-Based 5G Networks: Opportunities and Challenges","volume":"24","author":"Prasad","year":"2017","journal-title":"IEEE Wirel. Commun."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Nawawy, N.A., Mohamed, N., Dziyauddin, R., and Sam, S.M. (2018, January 24\u201326). Functional Split Architecture for Energy Efficiency in 5G Backhaul. Proceedings of the 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN), Kuching, Malaysia.","DOI":"10.1109\/TAFGEN.2018.8580483"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Rizvi, S., Aziz, A., Jilani, M.T., Armi, N., Muhammad, G., and Butt, S.H. (2017, January 14\u201317). An investigation of energy efficiency in 5G wireless networks. Proceedings of the 2017 International Conference on Circuits, System and Simulation (ICCSS), London, UK.","DOI":"10.1109\/CIRSYSSIM.2017.8023199"},{"key":"ref_20","unstructured":"Aligrudic, A., and Pejanovic-Djurisic, M. (2014, January 9\u201311). Energy efficiency metrics for heterogenous wireless cellular networks. Proceedings of the 2014 Wireless Telecommunications Symposium, Washington, DC, USA."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Bouras, C., and Diles, G. (2017, January 29\u201331). Energy efficiency in sleep mode for 5G femtocells. Proceedings of the 2017 Wireless Days, Porto, Portugal.","DOI":"10.1109\/WD.2017.7918130"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2932","DOI":"10.1109\/TWC.2018.2804397","article-title":"Sector and Site Switch-Off Regular Patterns for Energy Saving in Cellular Networks","volume":"17","author":"Beitelmal","year":"2018","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.comcom.2014.02.010","article-title":"On interdependence among transmit and consumed power of macro base station technologies","volume":"50","author":"Lorincz","year":"2014","journal-title":"Comput. Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1109\/TCOMM.2016.2638906","article-title":"Interference-Aware Energy Efficiency Maximization in 5G Ultra-Dense Networks","volume":"65","author":"Yang","year":"2017","journal-title":"IEEE Trans. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1561\/0100000088","article-title":"Energy Efficiency in Wireless Networks via Fractional Programming Theory","volume":"11","author":"Zappone","year":"2015","journal-title":"Found. Trends Commun. Inf. Theory"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.comcom.2018.08.005","article-title":"Energy efficiency maximization oriented resource allocation in 5G ultra-dense network: Centralized and distributed algorithms","volume":"130","author":"Li","year":"2018","journal-title":"Comput. Commun."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Boumard, S., Harjula, I., Kanstr\u00e9n, T., and Rantala, S.J. (2018, January 26\u201329). Comparison of Spectral and Energy Efficiency Metrics Using Measurements in a LTE-A Network. Proceedings of the 2018 Network Traffic Measurement and Analysis Conference (TMA), Vienna, Austria.","DOI":"10.23919\/TMA.2018.8506529"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4264","DOI":"10.1109\/ACCESS.2017.2688584","article-title":"Energy Management in LTE Networks","volume":"5","author":"Kanwal","year":"2017","journal-title":"IEEE Access"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Yusoff, R., Baba, M.D., and Ali, D. (2015, January 10\u201311). Energy-efficient resource allocation scheduler with QoS aware supports for green LTE network. Proceedings of the 2015 IEEE 6th Control and System Graduate Research Colloquium (ICSGRC), Shah Alam, Malaysia.","DOI":"10.1109\/ICSGRC.2015.7412474"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Feng, Y., Shen, X., Zhang, R., and Zhou, P. (2016, January 14\u201316). Interference-area-based resource allocation for full-duplex communications. Proceedings of the 2016 IEEE International Conference on Communication Systems (ICCS), Shenzhen, China.","DOI":"10.1109\/ICCS.2016.7833655"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Wen, K., Chen, Y., and Hu, Y. (2017, January 13\u201316). A resource allocation method for D2D and small cellular users in HetNet. Proceedings of the 2017 3rd IEEE International Conference on Computer and Communications (ICCC), Chengdu, China.","DOI":"10.1109\/CompComm.2017.8322620"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Qi, Z., Fan, J., Ji, P., Xia, F., Huang, X., and Zhao, S. (2017, January 25\u201327). Highly Energy-Efficient Resource Allocation in Power Telecommunication Network. Proceedings of the 2017 International Conference on Computer Systems, Electronics and Control (ICCSEC), Dalian, China.","DOI":"10.1109\/ICCSEC.2017.8446827"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Yen, C., Chien, F., and Chang, M. (2018, January 27\u201330). Cooperative Online Caching in Small Cell Networks with Limited Cache Size and Unknown Content Popularity. Proceedings of the 2018 3rd International Conference on Computer and Communication Systems (ICCCS), Nagoya, Japan.","DOI":"10.1109\/CCOMS.2018.8463254"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1109\/MWC.2017.1600121WC","article-title":"Economical Energy Efficiency: An Advanced Performance Metric for 5G Systems","volume":"24","author":"Yan","year":"2017","journal-title":"IEEE Wirel. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Vu, T.X., Chatzinotas, S., and Ottersten, B. (2017, January 3\u20136). Energy-efficient design for edge-caching wireless networks: When is coded-caching beneficial?. Proceedings of the 2017 IEEE 18th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Sapporo, Japan.","DOI":"10.1109\/SPAWC.2017.8227689"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Erol-Kantarci, M. (2015, January 9\u201312). Content caching in small cells with optimized uplink and caching power. Proceedings of the 2015 IEEE Wireless Communications and Networking Conference (WCNC), New Orleans, LA, USA.","DOI":"10.1109\/WCNC.2015.7127804"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Zhou, X., Lu, Z., Gao, Y., and Yu, Z. (2014, January 14\u201316). An Effective Cooperative Caching Scheme for Mobile P2P Networks. Proceedings of the 2014 International Conference on Computational Intelligence and Communication Networks, Bhopal, India.","DOI":"10.1109\/CICN.2014.96"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1109\/MVT.2015.2508319","article-title":"Resource Sharing in 5G Contexts: Achieving Sustainability with Energy and Resource Efficiency","volume":"11","author":"Georgakopoulos","year":"2016","journal-title":"IEEE Veh. Technol. Mag."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Arbi, A., and O\u2019Farrell, T. (2015, January 8\u201312). Energy efficiency in 5G access networks: Small cell densification and high order sectorisation. Proceedings of the 2015 IEEE International Conference on Communication Workshop (ICCW), London, UK.","DOI":"10.1109\/ICCW.2015.7247604"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Dinh, T.H.L., Kaneko, M., and Boukhatem, L. (2019, January 11\u201314). Energy-Efficient User Association and Beamforming for 5G Fog Radio Access Networks. Proceedings of the 2019 16th IEEE Annual Consumer Communications & Networking Conference (CCNC), Las Vegas, NV, USA.","DOI":"10.1109\/CCNC.2019.8651884"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2758","DOI":"10.1109\/JSAC.2017.2726398","article-title":"Resource Allocation in Energy-Cooperation Enabled Two-Tier NOMA HetNets Toward Green 5G","volume":"35","author":"Xu","year":"2017","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Benjebbour, A., Saito, Y., Kishiyama, Y., Li, A., Harada, A., and Nakamura, T. (2013, January 12\u201315). Concept and practical considerations of non-orthogonal multiple access (NOMA) for future radio access. Proceedings of the 2013 International Symposium on Intelligent Signal Processing and Communication Systems, Naha, Japan.","DOI":"10.1109\/ISPACS.2013.6704653"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Rabee, F.A., Davaslioglu, K., and Gitlin, R. (2017, January 24\u201325). The optimum received power levels of uplink non-orthogonal multiple access (NOMA) signals. Proceedings of the 2017 IEEE 18th Wireless and Microwave Technology Conference (WAMICON), Cocoa Beach, FL, USA.","DOI":"10.1109\/WAMICON.2017.7930242"},{"key":"ref_44","unstructured":"Choi, J. (2016, January 27\u201330). On the spectral efficient nonorthogonal multiple access schemes. Proceedings of the 2016 European Conference on Networks and Communications (EuCNC), Athens, Greece."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1109\/MCOM.2018.1800179","article-title":"Non-Orthogonal Multiple Access: Achieving Sustainable Future Radio Access","volume":"57","author":"Yang","year":"2019","journal-title":"IEEE Commun. Mag."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1109\/LCOMM.2019.2892468","article-title":"Mode Selection Between Index Coding and Superposition Coding in Cache-Based NOMA Networks","volume":"23","author":"Fu","year":"2019","journal-title":"IEEE Commun. Lett."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3170","DOI":"10.1109\/TWC.2016.2517626","article-title":"Energy-Efficient 5G Outdoor-to-Indoor Communication: SUDAS over Licensed and Unlicensed Spectrum","volume":"15","author":"Ng","year":"2016","journal-title":"IEEE Trans. Wirel. Commun."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"44939","DOI":"10.1109\/ACCESS.2019.2907798","article-title":"Optimized Energy Aware 5G Network Function Virtualization","volume":"7","author":"Lawey","year":"2019","journal-title":"IEEE Access"},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Al-Quzweeni, A., El-Gorashi, T.E., Nonde, L., and Elmirghani, J.M. (2015, January 5\u20139). Energy efficient network function virtualization in 5G networks. Proceedings of the 2015 17th International Conference on Transparent Optical Networks (ICTON), Budapest, Hungary.","DOI":"10.1109\/ICTON.2015.7193559"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1109\/MCOM.2016.7452271","article-title":"Network function virtualization in 5G","volume":"54","author":"Abdelwahab","year":"2016","journal-title":"IEEE Commun. Mag."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Al-Quzweeni, A., Lawey, A., El-Gorashi, T., and Elmirghani, J.M.H. (2016, January 10\u201314). A framework for energy efficient NFV in 5G networks. Proceedings of the 2016 18th International Conference on Transparent Optical Networks (ICTON), Trento, Italy.","DOI":"10.1109\/ICTON.2016.7550698"},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Xiao, Y., Zhang, J., and Ji, Y. (2018, January 26\u201329). Energy Efficient Placement of Baseband Functions and Mobile Edge Computing in 5G Networks. Proceedings of the 2018 Asia Communications and Photonics Conference (ACP), Hangzhou, China.","DOI":"10.1109\/ACP.2018.8596134"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1586","DOI":"10.1109\/ACCESS.2014.2381215","article-title":"Energy Efficiency Benefits of RAN-as-a-Service Concept for a Cloud-Based 5G Mobile Network Infrastructure","volume":"2","author":"Sabella","year":"2014","journal-title":"IEEE Access"},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Ren, Y., Phung-Duc, T., Chen, J., and Yu, Z. (2016, January 4\u20138). Dynamic Auto Scaling Algorithm (DASA) for 5G Mobile Networks. Proceedings of the 2016 IEEE Global Communications Conference (GLOBECOM), Washington, DC, USA.","DOI":"10.1109\/GLOCOM.2016.7841759"},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Phung-Duc, T., Ren, Y., Chen, J., and Yu, Z. (2016, January 12\u201315). Design and Analysis of Deadline and Budget Constrained Autoscaling (DBCA) Algorithm for 5G Mobile Networks. Proceedings of the 2016 IEEE International Conference on Cloud Computing Technology and Science (CloudCom), Luxembourg City, Luxembourg.","DOI":"10.1109\/CloudCom.2016.0030"},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Abdullaziz, O.I., Capitani, M., Casetti, C.E., Chiasserini, C.F., Chundrigar, S.B., Landi, G., and Talat, S.T. (2017, January 12\u201315). Energy monitoring and management in 5G integrated fronthaul and backhaul. Proceedings of the 2017 European Conference on Networks and Communications (EuCNC), Oulu, Finland.","DOI":"10.1109\/EuCNC.2017.7980760"},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Klapez, M., Grazia, C.A., and Casoni, M. (2018, January 10\u201313). Energy Savings of Sleep Modes Enabled by 5G Software-Defined Heterogeneous Networks. Proceedings of the 2018 IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI), Palermo, Italy.","DOI":"10.1109\/RTSI.2018.8548508"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1109\/MWC.2016.1500356WC","article-title":"Machine Learning Paradigms for Next-Generation Wireless Networks","volume":"24","author":"Jiang","year":"2017","journal-title":"IEEE Wirel. Commun."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Miozzo, M., Giupponi, L., Rossi, M., and Dini, P. (2017, January 19\u201322). Switch-On\/Off Policies for Energy Harvesting Small Cells through Distributed Q-Learning. Proceedings of the 2017 IEEE Wireless Communication and Networking Conference Workshops (WCNCW), San Francisco, CA, USA.","DOI":"10.1109\/WCNCW.2017.7919075"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1002\/ett.2891","article-title":"Duty cycle control with joint optimisation of delay and energy efficiency for capillary machine-to-machine networks in 5G communication system","volume":"26","author":"Li","year":"2015","journal-title":"Trans. Emerg. Telecommun. Technol."},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Li, Z., Lu, Z., Wen, X., Jing, W., Zhang, Z., and Fu, F. (2015, January 6\u20139). Distributed Power Control for Two-Tier Femtocell Networks with QoS Provisioning Based on Q-Learning. Proceedings of the 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall), Boston, MA, USA.","DOI":"10.1109\/VTCFall.2015.7390896"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1109\/JSAC.2016.2544601","article-title":"Energy-Efficient Power Control of Cognitive Femto Users for 5G Communications","volume":"34","author":"Park","year":"2016","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"ref_63","doi-asserted-by":"crossref","unstructured":"AlQerm, I., and Shihada, B. (2017, January 8\u201313). Enhanced machine learning scheme for energy efficient resource allocation in 5G heterogeneous cloud radio access networks. Proceedings of the 2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), Montreal, QC, Canada.","DOI":"10.1109\/PIMRC.2017.8292227"},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Fern\u00e1ndez-Fern\u00e1ndez, A., Cervell\u00f3-Pastor, C., and Ochoa-Aday, L. (2017). Energy Efficiency and Network Performance: A Reality Check in SDN-Based 5G Systems. Energies, 10.","DOI":"10.3390\/en10122132"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1109\/MWC.2015.7096297","article-title":"Recent advances in energy-efficient networks and their application in 5G systems","volume":"22","author":"Wu","year":"2015","journal-title":"IEEE Wirel. Commun."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/14\/3126\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:05:58Z","timestamp":1760187958000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/14\/3126"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,7,15]]},"references-count":65,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2019,7]]}},"alternative-id":["s19143126"],"URL":"https:\/\/doi.org\/10.3390\/s19143126","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,7,15]]}}}