TSN over 5G: Building a Deterministic Ecosystem
Time-Sensitive Networking (TSN) is moving from theory into practical deployment across industrial environments. At Cumucore, we see a clear shift: deterministic communication is no longer confined to wired Operational Technology (OT) networks, it is extending into mobile domains through 5G. This evolution is critical for enabling coordinated automation between mobile robots, fixed systems, and emerging humanoid platforms.
First target Use Cases: Synchronization as the Enabler
Consider a warehouse or factory floor where autonomous mobile robots (AMRs) and fixed robotic arms must operate in tight coordination. For example, unloading and loading operations require precise timing alignment latency alone is not the issue; synchronization is.
The same applies to humanoid robotics. Before two humanoids can collaborate on a task, they must share a common time reference. Without a unified clock, even low-latency communication cannot guarantee deterministic behaviour.
This is where TSN over 5G becomes essential.
Why TSN over 5G?
There are two fundamental requirements in these systems:
- Reliable communication for mobile robots
- Precise time synchronization between mobile robots
These two functions could be done separately but TSN over 5G introduces a more efficient paradigm: using the same communication channel to deliver both data and synchronization. This reduces architectural complexity and aligns mobile systems with deterministic OT environments.
Understanding the Dual-Clock Model
Deploying TSN over 5G requires a clear understanding of timing architecture. In practice, two distinct clocks are involved:
Clock A – Network Synchronization
This clock ensures base station alignment. In private mobile networks—particularly TDD-based systems—base station synchronization is mandatory to manage interference and enable seamless handovers for mobile robots. Without this, mobility and seamless handover break. Clock is also used in NW-TT to have a timestamp for the TSN traffic and DS-TT to have a same time reference. See the picture below.
Clock B – Application Synchronization
This is the TSN time delivered to applications. It is transported via the user plane as part of TSN flows. This clock governs how robots, controllers, and systems coordinate their actions.
These clocks may:
- Originate from the same source (e.g., grandmaster), or
- Be derived from different sources (e.g., GNSS for Clock A and a TSN grandmaster for Clock B)
Designing how these clocks are delivered is a key system-level decision.
OT System Integration: The Role of the Application Function
Integration with OT systems is not plug-and-play. The Application Function (AF) acts as the control interface between the automation system and the 5G network. It manages TSN synchronization flows between the grandmaster clock and applications running on devices such as mobile robots.
However, OT ecosystems are fragmented across protocol domains:
- Siemens → Profinet
- Mitsubishi → CC-Link
- Rockwell → EtherNet/IP
Each protocol stack requires a dedicated AF implementation to correctly map TSN behaviour into the 5G system. This is not just a technical nuance, it is a deployment constraint that must be addressed early.
5G System Requirements for TSN
Delivering TSN over 5G is not a feature toggle, it is an end-to-end capability requiring alignment across all components:
Core Network
- Network Slicing and QoS management
- Capability to generate dataflows from OT system
- Support for Ethernet PDU sessions
- User Plane Function (UPF) with Network TSN Translator (NW-TT)
Transport Network
- Deterministic traffic handling with prioritization and QoS enforcement
Radio Access Network (Base Station)
- Support for SIB9 (System Information Block 9) to deliver Clock A to DS-TT
User Equipment (UE)
- Ethernet PDU support
- SIB9 information handling capability
- Device-side TSN Translator (DS-TT)
Each element must be validated as part of a coherent system—not in isolation.
End-to-End Performance: Where Projects Succeed or Fail
While standards define the building blocks, real-world deployments expose the complexity of integration. TSN over 5G spans three domains:
- 5G network
- OT network
- Clock source infrastructure
There are multiple configuration paths within each domain, and not all combinations yield deterministic performance. Achieving a robust solution requires careful system design, including:
- Clock source selection and distribution strategy
- Mapping between TSN and 5G QoS models
- Protocol-specific AF implementation
- End-to-end latency and jitter budgeting
Closing Perspective
TSN over 5G is not just about extending Ethernet into wireless—it is about enabling a new class of coordinated, mobile automation systems. As robotics evolves toward mobility and collaboration, synchronization becomes the defining requirement.
The ecosystem is ready from a standards perspective. The challenge and the opportunity lies in engineering these components into a cohesive, deterministic system.
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