Deterministic communication is required for applications of several industry verticals including manufacturing, automotive, financial, and health care, etc. These applications rely on reliable and time-synchronized delivery of information among the communicating devices. Therefore, large delay variations in packet delivery or inaccuracies in time synchronization cannot be tolerated. In particular, the industrial revolution on digitization, connectivity of digital and physical systems, and flexible production design require deterministic and time-synchronized communication. A network supporting deterministic communication guarantees data delivery in a specified time with high reliability. The IEEE 802.1 TSN task group is developing standards to provide deterministic communication through IEEE 802 networks. The IEEE 802.1AS standard defines time synchronization mechanism for accurate distribution of time among the communicating devices. The time synchronization accuracy depends on the accurate calculation of the residence time which is the time between the ingress and the egress ports of the bridge and includes the processing, queuing, transmission, and link latency of the timing information. This paper discusses time synchronization mechanisms supported in current wired and wireless integrated systems.

翻译：确定性通信是制造业、汽车、金融、医疗等多个垂直行业应用的必要条件。这些应用依赖于通信设备之间可靠且时间同步的信息传递，因此无法容忍数据包传输中的大时延波动或时间同步误差。特别是，数字化转型、数字与物理系统互联以及柔性生产设计等工业革命需求，要求实现确定性与时间同步的通信。支持确定性通信的网络能够以高可靠性在指定时间内完成数据投递。IEEE 802.1 TSN任务组正致力于制定通过IEEE 802网络提供确定性通信的标准，其中IEEE 802.1AS标准定义了用于在通信设备间精确分配时间的时间同步机制。时间同步精度取决于驻留时间的精确计算——驻留时间定义为桥接设备入端口与出端口之间的时间间隔，包含时序信息的处理时延、排队时延、传输时延以及链路时延。本文探讨了当前有线与无线集成系统中支持的时间同步机制。