# Performance of 5G Trials for Industrial Automation
## 5G Performance for Industrial Control  
In our latency measurements of industrial traffic over a 5G network, we assumed fixed message sizes with periodic transmission intervals. Periodic messages with an inter-arrival time of 8, 16, and 32 ms have been evaluated as they would be in industrial control processesusing protocols such as PROFINET, CIP, etc. We obtained at least 100,000 samples for each measurement in order for our measurement results to have sufficient statistical significance. The standard deviation for each percentile value shown for a given packet size in the UL or DL direction with different inter-packet periodicity intervals generally varied from 0.3 ms to 1.2 ms in the results presented in this section. Different message sizes were considered: 100 bytes (as shown in Figures 5 and 6) and 1024 bytes (as shown in Figures 7 and 8). A first observation is that for the typical small message sizes for industrial control [1], the MBB-focused 5G system as deployed today can achieve low average latencies: 3.7-6.9 ms in uplink and 5.2-6.2 ms in downlink. This is visible from the median latency in Figures 5-8 When the message size is increased by a factor of approximately 10, the latency increase is rather small. What becomes apparent is that the latency increases significantly when considering the 99 th percentile or even the 99.9 th percentile values. In other words, a 5G system focused on MBB services has very good average performance, but this performance cannot be necessarily guaranteed with high reliability. For uplink, the latency that can be provided for 99% of the transmissions increases from the median value by 1.05-4.1 ms when small messages that are 100 bytes in size are transmitted. For large messages of 1024 bytes in size, the corresponding latency increase is between 3-10.6 ms. The equivalent latency value increase in the downlink is 4.7-4.8 ms for 100 bytes messages and 5.5-5.8 ms for large 1024 bytes messages. The latency guarantees at higher levels of 99.9% lead to a latency increase from the median uplink value of 1.5-9.4 ms for small messages and 6.5-12.8 ms for large messages. In the downlink, the corresponding increases in latency are 5.8-8.8 ms for small messages and 6.1-9.3 ms for large messages. Figure 8: Downlink latency for 1024-bytes messages and different reliability percentiles (median, 99 th percentile, 99.9 th percentile). Figure 7: Uplink latency for 1024-byte messages and different reliability percentiles (median, 99 th percentile, 99.9 th percentile). Based on those results, it can be concluded that MBB-based 5G systems are primarily designed and configured to provide good average latency performance while providing stringent guarantees on the latency bounds has not been the focus. We investigated two different 5G devices in the measurement setup, which are shown in the green and blue graphs in Figures 5-8 and are marked as device A and device B. It is noteworthy that the latency performance can differ substantially between devices, even if both 5G devices use the same 5G modem chipset (i.e., Qualcomm x55). For example, in the uplink, Device B has a 2.9 ms lower median latency and a 4.6 ms higher latency for the 99.9 th percentile. In general, the differences in the latencies between the two devices are in the range of up to 6 ms. The 5G network can be configured in various ways. In particular, during uplink, the link can be configured with higher link robustness, while medium access times can be reduced by pre-scheduling. Figures 5 and 7 show the impact of the RAN configuration on the latency performance.