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With the diversification of industrial Internet of Things applications, there is a growing demand for mobility support in industrial wireless networking environments. However, the routing protocol for low-power and lossy networks is designed based on a static environment and is vulnerable in a mobility environment. Routing protocol for low-power and lossy networks is an Internet engineering task force standard in the low-power and lossy network environments used mainly in industrial environments. In addition, although routing protocol for low-power and lossy networks is based on collection tree protocol and is suitable for data collection and upward traffic transmission, it struggles with downward traffic transmission in terms of control, actuation, and end-to-end transmission. In this article, the problems caused by mobile nodes in routing protocol for low-power and lossy networks are discussed, and a retransmission scheme named IM-RPL is proposed. This retransmission scheme can improve the performance of downward traffic for the mobile nodes by retransmitting the packets to the neighbor nodes, the mobile node’s new parent sets, and relaying them to the mobile node. Its performance is evaluated through an experiment. The results demonstrate that using OpenMote in OpenWSN’s time slotted channel hopping induces a packet reception ratio improvement and a lower transmission delay as compared to standard routing protocol for low power and lossy.

IEEE802.15.4 time-slotted channel hopping (TSCH) is designed to provide reliability even in harsh wireless networks compromised by metal structures and external noise. TSCH provides reliability through coordinated communication based on link schedule however, no policies regarding this are defined by the IEEE802.15.4 standard. 6TiSCH (IPv6 over the TSCH mode of IEEE802.15.4e) provides management policies and link schedule negotiation mechanism that are not defined in the standard, and many studies are based on it. However, in most link-scheduling studies, 6top protocol (6P) for link schedule negotiation remains a premise, and the effect of harsh networks on 6P is rarely considered. Experimental results demonstrate that the performance of 6P is degraded due to the loss of 6P packets and transaction errors. These problems can threaten the fundamentals of existing link-scheduling studies. The main disadvantage of 6P in heavy traffic low-power and lossy networks (LLN)s is that nodes indiscriminately generate 6P requests according to their own demand. In this study, we analyze the performance and problems of 6P in harsh networks and propose parent-initiated 6P transaction and transaction revert methods to overcome such problems. The proposed methods enable stable cell negotiation even in LLNs under heavy traffic load through coordinated transactions of a parent based on the cell requirement of a child. The proposed methods are implemented using OpenWSN, an open-source project that implements the 6TiSCH IoT network stack, and its performance is evaluated through extensive experimentation. The results reveal that the proposed methods improve the success rate of 6P transactions and PDR of data packets by over 100% and 22%, respectively.

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