This subtopic presents an example illustrating the use of the SLS template proposed in the 5G-ACIA White Paper “Service-Level Specifications (SLSs) for 5G Technology-Enabled Connected lndustries.”
The example involves an OT customer aiming to deploy a 5G system for two shopfloor use cases: one involving automated guided vehicles (AGVs) or mobile robots, and the other involving motion control. These use cases are described in more detail below. The overall system requirements are listed in Table 1.
Table 1: Example system level
| Attribute | Discussion | |
| System Level | Network availability | 99.9 % |
| Cell availability | 99.9 % | |
| Service area | Indoor on workshop floor as well as raw material storage area | |
| QoS monitoring | Yes: system and service-level KPI monitoring (e.g., latency, user experienced data rate, handover rate),
monitoring interval: 1 second |
The first use case concerns an AGV on the shop floor, which may be responsible for delivering goods to different stations. In this example, the AGV includes an application-layer fault tolerance mechanism. While operating, the AGV sends a status packet to the control system every 100 ms. If it does not receive a response packet during 500 consecutive milliseconds, it sends a disconnection alarm. When the AGV is idling, it sends a status packet once every second. If a response packet is not received within five consecutive seconds, the system assumes that the connection to the AGV has been lost. This could lead to consequences such as: the AGV shutting down and ceasing to transport materials, potentially bringing production to a halt. Additionally, the AGV traffic controller may shut down the entire area where the AGV was last located due to its unknown state, which could lead to congestion or a stoppage in production. See Table 2 for example requirements related to this use case.
The second use case involves a motion control system, which is responsible for controlling moving and/or rotating parts of machines. This type of use case imposes very demanding requirements on system performance in terms of latency, reliability, and determinism. Because of the stringent latency requirements, the industrial application layer may not be able to tolerate any packet loss. A failure in such motion-control use cases typically results in the entire production line shutting down and leads to reduced operational efficiency. See Table 2 for example requirements related to this use case.
Table 2: Example SLS for the AGV and motion control use cases
| Attribute | Discussion AGV | Discussion Motion Control | |
| System Level | Communication service availability | 99.9999 % | 99.9999 % |
| Communication service reliability | 1 year | 10 years | |
| End-to-end latency | 100 ms | 1 ms | |
| Transfer interval | 100 ms | 1 ms | |
| Survival time | 500 ms | 0 ms | |
| Message size | 500 bytes | 64 bytes | |
| Mobility | 4 km/hour | N/A | |
| Positioning service | Yes, accuracy: 1 m | No | |
| User plane protocol | IP | TSN | |
| Time synchronization precision | N/A | 900 ns |
