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）服务严格的时延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）与动态工作流。将时间敏感网络（TSN）与5G专网相融合，正成为满足这些需求的一种前景广阔的方法。在该架构中，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/云平台对接，IIoT控制与计算系统即部署于此。TSN通过IEEE 802.1Qbv时间感知整形器（TAS）实现有界时延与低抖动，该整形器在精确时隙中调度网络流量。然而，5G固有的随机时延与抖动会破坏TSN调度，需要精细调整TAS参数以维持端到端确定性。本文通过搭建包含TSN交换机和商用5G网络的测试平台，实证评估了5G下行链路时延与抖动对TAS调度的影响。结果表明，要保证有界时延与抖动，必须基于以高阶p百分位数界定的实测5G时延，审慎设置TSN交换机间的TAS传输窗口偏移量。否则，过大的偏移量可能导致额外时延，甚至完全丧失确定性。