Deterministic communications are essential to meet the stringent delay and jitter requirements of Industrial Internet of Things (IIoT) services. IIoT increasingly demands wide-area wireless mobility to support Autonomous Mobile Robots (AMR) and dynamic workflows. Integrating Time-Sensitive Networking (TSN) with 5G private networks is emerging as a promising approach to fulfill these requirements. In this architecture, 5G provides wireless access for industrial devices, which connect to a TSN backbone that interfaces with the enterprise edge/cloud, where IIoT control and computing systems reside. TSN achieves bounded latency and low jitter using IEEE 802.1Qbv Time-Aware Shaper (TAS), which schedules the network traffic in precise time slots. However, the stochastic delay and jitter inherent in 5G disrupt TSN scheduling, requiring careful tuning of TAS parameters to maintain end-to-end determinism. This paper presents an empirical study evaluating the impact of 5G downlink delay and jitter on TAS scheduling using a testbed with TSN switches and a commercial 5G network. Results show that guaranteeing bounded latency and jitter requires careful setting of TAS transmission window offset between TSN switches based on the measured 5G delay bounded by a high order p-th percentile. Otherwise, excessive offset may cause additional delay or even a complete loss of determinism.

翻译：确定性通信对于满足工业物联网（IIoT）服务严苛的延迟与抖动要求至关重要。IIoT 日益需要广域无线移动性以支持自主移动机器人（AMR）和动态工作流。将时间敏感网络（TSN）与 5G 专网融合正成为一种满足这些需求的有前景的方法。在此架构中，5G 为工业设备提供无线接入，这些设备连接至 TSN 骨干网，后者与企业边缘/云（IIoT 控制与计算系统所在之处）对接。TSN 通过 IEEE 802.1Qbv 时间感知整形器（TAS）实现有界延迟与低抖动，该整形器在精确的时间槽中调度网络流量。然而，5G 固有的随机延迟与抖动会破坏 TSN 调度，需要仔细调整 TAS 参数以维持端到端的确定性。本文通过一个包含 TSN 交换机和商用 5G 网络的测试平台，开展了一项评估 5G 下行链路延迟与抖动对 TAS 调度影响的实证研究。结果表明，要保证有界延迟与抖动，需要基于以高阶 p 百分位数界定的实测 5G 延迟，仔细设置 TSN 交换机之间的 TAS 传输窗口偏移。否则，过大的偏移可能导致额外的延迟，甚至完全丧失确定性。