# An Energy Efficient Routing Approach for Cloud-Assisted Green Industrial IoT Networks
Thus, to ensure the QoS requirements, the routing approach in the industrial network needs to determine reliable data transmission and also consider the node's constraints because routing decisions can influence overall network performance. Currently, the industrial wireless network is still in the preliminary stages of network design, routing protocols, and deployment. However, IoT-based applications are having a significant impact on today's industries by leveraging cutting-edge technologies and standards. The WirelessHART, LoRa, and NB-IoT are some of the major wireless communication technologies used in the IIoT scope. WirelessHART and LoRa rely on an unlicensed frequency band, whereas NB-IoT uses a licensed spectrum. Because of the harsh environment and ultra-high reliability requirements of industrial wireless networks, these standards adopt the IEEE802.15.4 because they require a dedicated physical layer, and it supports many commercial off-the-shelf chips [5]. Furthermore, industrial network infrastructure can also be structured based on several enabling technologies such as cloud computing [8], big data [9], and Blockchain [10; 11; 12]. Since connectivity plays a crucial role in industrial network design to enable interconnection between heterogeneous systems, IIoT infrastructure relies on short-range wireless communications such as ZigBee, Wi-Fi, Bluetooth, and Radio-frequency identification [13]. In an industrial environment, connecting the physical working system with real-world network systems like the Internet or cloud is essential to enrich IIS. However, typical wireless sensor networks (WSNs) cannot interact with the Internet or cloud because some protocols of WSNs do not use the IP protocol [14]. Thanks to the contributions of the working group of IETF for IPv6 over low power wireless personal area networks (6 LoWPAN) that made possible the integration of the constrained wireless network with an IP based network or the Internet [15]. It is standardized as the technique to implement IPv6 over IEEE 802.15.4 networks. 6 LoWPAN is developed to enable an IoT device with IP communication functionality by adding the adaptation layer between data-link and network layer. As a result, the implementation of an industrial emergency monitoring system (IEMS) is possible by integrating IIS with the 6 LoWPAN industrial wireless network. Furthermore, to provide the routing solution, IETF has developed a particular routing specification named IPv6 routing protocol for low power and lossy networks (RPL) to be used in resource-constrained networks such as 6 LoWPAN [16]. In addition, RPL is intended to overcome different routing requirements of various application domains, namely urban application, industrial application, and home and building automation [17]. IoT devices run RPL to easily communicate with IP-based networks or the Internet through various links such as IEEE 802.15.4, power-line communication, and Bluetooth; therefore, RPL is often considered as routing protocol for IoT, and it can be applied in IEMS. Since LLNs is an important infrastructure in the IIoT ecosystem, the main challenge is efficient resource utilization and the design of routing strategy. In multi-hop IIoT network infrastructure, the node performs a dual role as sender and forwarder; therefore, for each node, routing is the key functionality for efficient data delivery over a network. In addition, the routing protocol contributes to determining energy efficiency and communications reliability as well. Thus, for the IIoT network to be an energy-efficient, routing approach is an important part because routing protocol plays an important role in making efficient use of limited network resources. For most of the IIoT applications, the large number of sensor devices are typically deployed in harsh environmental situations, making it difficult to reach the device for battery recharge or replacement.