A Novel Technique to Parameterize Congestion Control in 6TiSCH IIoT Networks
Kushal Chakraborty, Aritra Kumar Dutta, Mohammad Avesh Hussain, Syed Raafay Mohiuddin, Nikumani Choudhury, Rakesh Matam, Mithun Mukherjee
TL;DR
This work tackles congestion in 6TiSCH IIoT networks using RPL by introducing an Exponential Weighted Queue Occupancy Factor (EWQOF) that dynamically assesses node congestion via exponential smoothing over recent queue backlogs. A concurrent parent selection and swapping mechanism computes a composite score $PS(P_i) = Rank(P_i) + ETX(n_i,P_i) + \eta \times QOF(P_i)$ and uses a congestion metric $\beta(n_i)$ to decide when to switch parents, all while applying the HDLAC criterion to prevent oscillations. The approach is evaluated in MATLAB against a Max QOF baseline, showing 6–30% throughput gains, 4–10% improvements in PDR, 15–60% fewer swaps, and notable energy savings, especially in larger networks. The findings demonstrate that EWQOF effectively mitigates congestion-induced packet loss and control overhead, offering a practical congestion-control enhancement for RPL-based 6TiSCH LLNs in industrial settings.
Abstract
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.