工程科学学报，第41卷，第8期：968-980,2019年8月 Chinese Journal of Engineering,Vol.41,No.8:968-980,August 2019 DOI:10.13374/j.issn2095-9389.2019.08.002;http://journals.ustb.edu.cn 5G超密集网络的能量效率研究综述 马忠贵⑧，宋佳倩 北京科技大学计算机与通信工程学院，北京100083 区通信作者，E-mail:zhongguima@usth.cdu.cn 摘要首先从绿色通信人手，对网络能量效率的国内外研究现状进行了分析.在此基础上，对超密集网络的关键性能指标， 即能量效率的各种定义进行了梳理，为建模莫定了基础。其次，讨论了网络能量效率建模和优化过程中经常使用的4种理论 模型：随机几何、博弈论、最优化理论和分数阶规划.并综述了能效提升的技术，包括高能效部署与规划、高能效基站休眠、高 能效用户关联、高能效资源管理、高能效传输方式.最后，指出未来的可能的技术挑战：网络能效理论与超密集网络体系架构、 超密集小基站高能效覆盖机理、超密集网络的柔性资源匹配机理，移动用户群体行为建模与高能效服务方法.通过研究超密 集网络高能效覆盖机理和柔性资源匹配机理，为未来无线通信网络建模和分析提供设计依据与技术支撑. 关键词能量效率；5G;超密集网络：用户关联；无线资源分配 分类号TN929.5 Survey of energy efficiency for 5G ultra-dense networks MA Zhong-gui,SONG Jia-qian School of Computer and Communication Engineering,University of Science and Technology Beijing,Beijing 100083,China XCorresponding author,E-mail:zhongguima@ustb.edu.cn ABSTRACT Fifth generation (5G)cellular networks are expected to achieve high data rates,reduced latency,increased spectrum efficiency,and energy efficiency.Ultra-dense networks (UDNs),a key enabling technology in 5G cellular networks,are envisioned to support the deluge of data traffic located in hotspots and at cell edges,and to enhance quality of experience of mobile users.UDNs can significantly improve the spectrum efficiency and energy efficiency to achieve sustainability of 5G.However,the deployment of a large number of small cells poses new challenges for energy efficiency.Recently,the energy efficiency of UDNs has become a prime concern in the operation and architecture design owing to environmental and economic effects.Therefore,it is significant to study the energy ef- ficiency of UDNs.This survey provided an overview of energy-efficient wireless communications,and reviewed seminal and recent con- tribution to the state-of-the-art.Therefore,the definitions of energy efficiency,a key performance indicator of the UDNs,are analyzed, which is a foundation for modeling.Four theoretical models,which were often used in the modeling and optimization of energy efficien- cy,were discussed.These models include stochastic geometry,game theory,optimization theory,and fractional programming theory. Energy-efficient techniques of UDNs were also reviewed.These technologies include energy-efficient deployment and planning,a base station sleeping mode,user association,radio resource management,and transmission.Finally,the most relevant research challenges were addressed,including the theory of energy efficiency of UDNs,architecture of UDNs,the high energy efficiency coverage mecha- nism of ultra-dense small base stations,the flexible radio resource matching mechanism of UDNs,group behavior modeling of mobile users,and high energy efficiency service methods.This review of the energy-efficient coverage mechanism and flexible radio resource matching mechanism in UDNs provides design guidelines and potential solutions for analytical modeling of future wireless networks. KEY WORDS energy efficiency;5G;ultra-dense networks;user association;radio resource allocation 收稿日期：2018-07-31 基金项目：国家自然科学基金资助项目(61572074)：中央高校基本科研业务费专项资金资助项目(FRF-GF-18-017B)工程科学学报,第 41 卷,第 8 期:968鄄鄄980,2019 年 8 月 Chinese Journal of Engineering, Vol. 41, No. 8: 968鄄鄄980, August 2019 DOI: 10. 13374 / j. issn2095鄄鄄9389. 2019. 08. 002; http: / / journals. ustb. edu. cn 5G 超密集网络的能量效率研究综述 马忠贵苣 , 宋佳倩 北京科技大学计算机与通信工程学院, 北京 100083 苣通信作者, E鄄mail: zhongguima@ ustb. edu. cn 摘 要 首先从绿色通信入手,对网络能量效率的国内外研究现状进行了分析. 在此基础上,对超密集网络的关键性能指标, 即能量效率的各种定义进行了梳理,为建模奠定了基础. 其次,讨论了网络能量效率建模和优化过程中经常使用的 4 种理论 模型:随机几何、博弈论、最优化理论和分数阶规划. 并综述了能效提升的技术,包括高能效部署与规划、高能效基站休眠、高 能效用户关联、高能效资源管理、高能效传输方式. 最后,指出未来的可能的技术挑战:网络能效理论与超密集网络体系架构、 超密集小基站高能效覆盖机理、超密集网络的柔性资源匹配机理、移动用户群体行为建模与高能效服务方法. 通过研究超密 集网络高能效覆盖机理和柔性资源匹配机理,为未来无线通信网络建模和分析提供设计依据与技术支撑. 关键词 能量效率; 5G; 超密集网络; 用户关联; 无线资源分配 分类号 TN929郾 5 收稿日期: 2018鄄鄄07鄄鄄31 基金项目: 国家自然科学基金资助项目(61572074);中央高校基本科研业务费专项资金资助项目(FRF鄄鄄GF鄄鄄18鄄鄄017B) Survey of energy efficiency for 5G ultra鄄dense networks MA Zhong鄄gui 苣 , SONG Jia鄄qian School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China 苣Corresponding author, E鄄mail: zhongguima@ ustb. edu. cn ABSTRACT Fifth generation (5G) cellular networks are expected to achieve high data rates, reduced latency, increased spectrum efficiency, and energy efficiency. Ultra鄄dense networks (UDNs), a key enabling technology in 5G cellular networks, are envisioned to support the deluge of data traffic located in hotspots and at cell edges, and to enhance quality of experience of mobile users. UDNs can significantly improve the spectrum efficiency and energy efficiency to achieve sustainability of 5G. However, the deployment of a large number of small cells poses new challenges for energy efficiency. Recently, the energy efficiency of UDNs has become a prime concern in the operation and architecture design owing to environmental and economic effects. Therefore, it is significant to study the energy ef鄄 ficiency of UDNs. This survey provided an overview of energy鄄efficient wireless communications, and reviewed seminal and recent con鄄 tribution to the state鄄of鄄the鄄art. Therefore, the definitions of energy efficiency, a key performance indicator of the UDNs, are analyzed, which is a foundation for modeling. Four theoretical models, which were often used in the modeling and optimization of energy efficien鄄 cy, were discussed. These models include stochastic geometry, game theory, optimization theory, and fractional programming theory. Energy鄄efficient techniques of UDNs were also reviewed. These technologies include energy鄄efficient deployment and planning, a base station sleeping mode, user association, radio resource management, and transmission. Finally, the most relevant research challenges were addressed, including the theory of energy efficiency of UDNs, architecture of UDNs, the high energy efficiency coverage mecha鄄 nism of ultra鄄dense small base stations, the flexible radio resource matching mechanism of UDNs, group behavior modeling of mobile users, and high energy efficiency service methods. This review of the energy鄄efficient coverage mechanism and flexible radio resource matching mechanism in UDNs provides design guidelines and potential solutions for analytical modeling of future wireless networks. KEY WORDS energy efficiency; 5G; ultra鄄dense networks; user association; radio resource allocation