The last few decades have witnessed an explosive growth of the Internet-of-Things (IoT) systems, which provide ubiquitous sensing and computing services. When adopted in industrial and manufacturing environments, IoT is referred to as the industrial IoT (IIoT), which has attracted increasing research attention. Energy efficiency is one of the most important research topics in green IIoT, as 1) the limited resource can significantly affect the lifetime of IIoT systems and 2) massive sensors, devices, machines keep consuming a considerable amount of energy, and increasing the carbon footprint. In this article, we present a comprehensive survey on energy-efficient communications and computation mechanisms in IIoT systems (such as smart grids). We categorize the existing works, review, discuss, and compare the works to explore their pros and cons. We also discuss the open issues and research challenges, considering the recent 5G communications and edge computing trends.

中文翻译：

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节能工业物联网：概述和未解决的问题

过去几十年见证了物联网 (IoT) 系统的爆炸式增长，它提供无处不在的传感和计算服务。在工业和制造环境中采用时，物联网被称为工业物联网 (IIoT)，它引起了越来越多的研究关注。能源效率是绿色 IIoT 中最重要的研究课题之一，因为 1) 有限的资源会显着影响 IIoT 系统的寿命；2) 大量传感器、设备、机器不断消耗大量能源，并增加碳足迹. 在本文中，我们对 IIoT 系统（如智能电网）中的节能通信和计算机制进行了全面调查。我们对现有作品进行分类，回顾、讨论和比较作品，以探索它们的优缺点。