ASAP: a decentralized slot reservation policy for dynamic 6TiSCH Networks in Industrial IoT

In Industrial Internet of Things (IIoT) networks, endnodes may disconnect or become no longer reachable, due to manifold causes, such as battery discharge, network interference and/or packet collisions. Overall, this could lead to low Quality of Service (QoS) levels. To satisfy application requirements, i.e., reliability, it is mandatory to continuously monitor connectivity and properly managing disconnections, without causing signaling overhead. The optimization of the exchange of messages can be pursued thanks to dedicated communication slots, eventually rescheduled in cases of deletion, replacement or dynamic reassignments. This solution lowers energy consumption while accounting for a number of improvements in network operative conditions. In this work, network formation optimization mechanisms for IPv6 over the TSCH mode of IEEE 802.15.4 (6TiSCH) networks are analyzed in real use cases in which the number of nodes in the network varies over time. Once the network was fully connected, a performance analysis has been carried out in order to measure typical networks parameters, such as latencies and Packet Loss Ratio (PLR). The study has proven the effectiveness of dedicated slots dynamic assignment. In particular, it has been measured a sensible reduction of latencies and losses of information. The obtained results pave the way towards robotics-aided set up of Internet of Things (IoT) networks in industrial contexts.