Optimized Scheduling for TimeCritical Industrial IoT The main requirement of Industrial Internet of Things (IIoT) is reliability with a targeted reliability of above 99.999%. Then come latency and energyefficiency requirements. The next step for the IIoT is to target timecritical applications. Even if IIoT technologies are now adopted worldwide, challenges remain and some of the limits of the technologies are still not fully understood. In this paper, we address TSCHbased (Time Slotted Channel Hopping) Wireless Sensor Networks and study their latency and lifetime limits under realworld conditions. We compute theoretical bounds on the endtoend latency in a perfect radio environment and then in real deployments with unreliable links. We compare the performance of different scheduling algorithms and evaluate the impact of unreliable links on endtoend latency and network lifetime, by means of simulations using traces collected from real deployed TSCH networks.

TSLoRa: Timeslotted LoRaWAN for the Industrial Internet of Things Abstract   Automation and data capture in manufacturing, known as Industry 4.0, requires the deployment of a large number of wireless sensor devices in industrial environments. These devices have to be connected via a reliable, lowlatency, lowpower and low operatingcost network. Although LoRaWAN provides a lowpower and reasonablecost network technology, its current ALOHAbased MAC protocol limits its scalability and reliability. A common practice in wireless networks is to solve this issue and improve scalability through the use of timeslotted communications. However, any timeslotted approach comes with overheads to compute and disseminate the transmission schedule in addition to ensuring global time synchronisation. Affording these overheads is not straight forward with LoRaWAN restrictions on radio dutycycle and downlink availability. Therefore, in this work, we propose TSLoRa, an approach that tackles these overheads by allowing devices to selforganise and determine their slot positions in a frame autonomously. In addition to that, only one dedicated slot in each frame is used to ensure global synchronisation and handle acknowledgments. Our experimental results with 25 nodes show that TSLoRa can achieve more than 99% packet delivery ratio even for the most distant nodes. Moreover, our simulations with a higher number of nodes revealed that TSLoRa exhibits a lower energy consumption than the confirmable version of LoRaWAN while not compromising the packet delivery ratio.