Enhanced 6P Transaction Methods for Industrial 6TiSCH Wireless Networks

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.