The Industrial Internet of Things (IIoT) refers to the use of interconnected smart devices, sensors, and other technologies to create a network of intelligent systems that can monitor and manage industrial processes. 6TiSCH (IPv6 over the Time Slotted Channel Hopping mode of IEEE 802.15.4e) as an enabling technology facilitates low-power and low-latency communication between IoT devices in industrial environments. The Routing Protocol for Low power and lossy networks (RPL), which is used as the de-facto routing protocol for 6TiSCH networks is observed to suffer from several limitations, especially during congestion in the network. Therefore, there is an immediate need for some modifications to the RPL to deal with this problem. Under traffic load which keeps on changing continuously at different instants of time, the proposed mechanism aims at finding the appropriate parent for a node that can forward the packet to the destination through the least congested path with minimal packet loss. This facilitates congestion management under dynamic traffic loads. For this, a new metric for routing using the concept of exponential weighting has been proposed, which takes the number of packets present in the queue of the node into account when choosing the parent at a particular instance of time. Additionally, the paper proposes a parent selection and swapping mechanism for congested networks. Performance evaluations are carried out in order to validate the proposed work. The results show an improvement in the performance of RPL under heavy and dynamic traffic loads.

翻译：工业物联网（IIoT）是指利用互联智能设备、传感器及其他技术，构建能够监控和管理工业流程的智能系统网络。6TiSCH（基于IEEE 802.15.4e时隙跳频模式的IPv6）作为关键使能技术，可在工业环境中实现物联网设备间的低功耗、低延迟通信。作为6TiSCH网络事实上的路由协议，低功耗有损网络路由协议（RPL）存在若干局限性，尤其在网络拥塞时表现突出。因此，亟需对RPL进行改进以应对该问题。针对随时间动态变化的流量负载，所提机制旨在为节点寻找合适父节点，使其能够通过拥塞最轻、丢包最少的路径将数据包转发至目的地，从而在动态流量负载下实现拥塞管理。为此，本文提出一种基于指数加权概念的新型路由度量方法，该方法在特定时刻选择父节点时，会考虑节点队列中数据包的数量。此外，本文还提出了面向拥塞网络的父节点选择与交换机制。为验证所提方案的有效性，进行了性能评估。结果表明，在高动态流量负载下，RPL的性能得到显著提升。