CoSiNeT: A Lightweight Clock Synchronization Algorithm for Industrial IoT

Recent advances in the industrial internet of things (IIoT) and cyber-physical systems drive Industry 4.0 and lead to advanced applications. The adequate performance of time-critical automation applications depends on a clock synchronization scheme used by control systems. Network packet delay variations adversely impact the clock synchronization performance. The impact is significant in industrial sites, where software and hardware resources heavily contribute to delay variations and where harsh environmental conditions interfere with communication network dynamics. While existing time synchronization methods for field IIoT end-devices, e.g., Simple Network Time Protocol (SNTP), provide adequate synchronization in good operating conditions, their performance degrades significantly with deteriorating network conditions. To overcome this issue, we propose a scalable, software-based, lightweight clock synchronization method, called CoSiNeT, for IIoT end-devices that maintains precise synchronization performance in a wide range of operating conditions. We have conducted measurements in local network deployments such as home and a university campus in order to evaluate the proposed algorithm performance. The results show that CoSiNeT matches well with SNTP and state-of-the-art method in good network conditions in terms of accuracy and precision; however, it outperforms them in degrading network scenarios. In our measurements, in fair network conditions, CoSiNeT improves synchronization performance by 56% and 73% compared to SNTP and state-of-the-art method. In the case of poor network conditions, it improves performance by 76% and 74%, respectively.