Fine Time Measurement Based Synchronization for Industrial Wireless/Wired Networks

Industrial environments, e.g., factory plants, rely on equipment that is usually interconnected via Ethernet/Time Sensitive Networking, thus supporting critical requirements of industrial applications, e.g., bounded latency in the order of milliseconds, low jitter. To achieve such requirements, tight time synchronization across all wired networked devices is ensured via the Precision Time Protocol (PTP) at a Local Area Net-work (LAN) level. However, industrial networks are changing, currently integrating new wireless standards such as Wi-Fi 6/7. While PTP can also be used to support time synchronization across wireless networks, it is a point-to-point UDP based protocol, and Wi-Fi integrates specific time synchronization mechanisms, that are better suited to achieve accurate and tight time synchronization across wireless. One of such mechanisms is the Fine Time Measurement (FTM) protocol. Aiming at con-tributing to a time synchronization solution across wireless/wired networks, this paper proposes a time synchronization approach based on an PTP to FTM mapping, and provides results for the evaluation of the approach. The evaluation is carried out on a novel ns-3 deterministic wireless/wired framework, and the experiments rely on values that were collected from our wireless/wired deterministic testbed. Results achieved show that FTM is a promising candidate to provide accuracy in a backward compatible way to IEEE 1588IPTP, and in a way that better suits the wireless shared medium.