Cellular networks have changed the world we are living in, and the fifth generation (5G) of radio technology is expected to further revolutionise our everyday lives by enabling a high degree of automation, through its larger capacity, massive connectivity, and ultra-reliable low-latency communications. In addition, the third generation partnership project (3GPP) new radio (NR) specification also provides tools to significantly decrease the energy consumption and the green house emissions of next generations networks, thus contributing towards information and communication technology (ICT) sustainability targets. In this survey paper, we thoroughly review the state-of-the-art on current energy efficiency research. We first categorize and carefully analyse the different power consumption models and energy efficiency metrics, which have helped to make progress on the understanding of green wireless networks. Then, as a main contribution, we survey in detail —from a theoretical and a practical viewpoint— the main energy efficiency enabling technologies that 3GPP NR provides, together with their main benefits and challenges. Special attention is paid to four key enabling technologies, i.e., massive multiple-input multiple-output (MIMO), lean carrier design, and advanced idle modes, together with the role of artificial intelligence capabilities. We dive into their implementation and operational details, and thoroughly discuss their optimal operation points and theoretical-trade-offs from an energy consumption perspective. This will help the reader to grasp the fundamentals of —and the status on— green wireless networking. Finally, the areas of research where more effort is needed to make future wireless networks greener are also discussed.

中文翻译：

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5G 无线接入网络能源效率调查：大规模 MIMO、精益载波设计、睡眠模式和机器学习


蜂窝网络改变了我们生活的世界，第五代 (5G) 无线电技术有望通过其更大的容量、大规模连接和超可靠的低功耗实现高度自动化，从而进一步彻底改变我们的日常生活。 - 延迟通信。此外，第三代合作伙伴计划（3GPP）新无线电（NR）规范还提供了显着降低下一代网络的能源消耗和温室气体排放的工具，从而有助于实现信息和通信技术（ICT）的可持续发展目标。在这份调查报告中，我们全面回顾了当前能源效率研究的最新进展。我们首先对不同的功耗模型和能效指标进行分类并仔细分析，这有助于对绿色无线网络的理解取得进展。然后，作为主要贡献，我们从理论和实践的角度详细调查了 3GPP NR 提供的主要能效支持技术及其主要优势和挑战。特别关注大规模多输入多输出（MIMO）、精益载波设计、先进空闲模式等四项关键使能技术以及人工智能能力的作用。我们深入研究它们的实施和操作细节，并从能源消耗的角度深入讨论它们的最佳操作点和理论权衡。这将帮助读者掌握绿色无线网络的基础知识和现状。最后，还讨论了需要付出更多努力以使未来无线网络更加绿色的研究领域。