## 4 Performance Results and Discussion
### Evaluation of Setup 3: 5G URLLC Test System and 5G Mid-Band System  
The results of Setup 3, using one 5G mid-band and one 5G mmW connection, are shown in Figure 12. The end-to-end latency of the individual UEs one and two are given in Figure 12a,b as a distribution over time. UE1 with a mean latency of 6.51 ms and UE2 with 0.72 ms. The combined transmission after elimination on Switch 2 is shown in Figure 12c, with an average latency of 0.72 ms. The mean latency and the 99.99% value for the overall pipeline are the same as for the URLLC values, the same as the latency over time diagram shown in Figure 12c. Since the URLLC has much shorter transmission times than the mid-band deployment, the messages always arrive earlier than the messages from UE1. Therefore, the messages from router 1 are always eliminated and have no impact on the  
Figure 11: Latency of the wireless transmission. (**a**) Latency for packets sent by 5G UE1 (mid-band NSA), (**b**) latency for packets sent by 5G UE2 (mid-band SA), and (**c**) latency of the first packet arriving at Switch 2.  
overall performance of the setup. Only if there are packet losses in the URLLC testbed is the mid-band message not eliminated. As a result of Setup 3, FRER has a large impact if being used for systems with similar performance but has almost no impact if systems with different performances are used. The low latency and high reliability of the URLLC testbed are outperforming the 5G mid-band system, therefore making the frame replication obsolete. Evaluation of Setup 4: Redundant Transmission via 5G Mid-Band Deployment and 5G mmW System Deployment  
The results of Setup 4, using one mid-band and one mmW connection, are shown in Figure 13. The end-to-end latency of the individual UEs one and two are given in Figure 13a,b as a distribution over time. UE1 with a mean latency of 6.60 ms and UE2 with 3.32 ms. The combined transmission after elimination on Switch 2 is shown in Figure 13c, with an average latency of 3.31 ms. Again, the mmW system has a shorter transmission time than the mid-band deployment. Therefore, the messages arrive earlier than the messages from UE1. The mid-band system is only used to equalize spikes occurring in the mmW transmission, reducing the mean latency and jitter compared to the sole mmW performance. This has a high impact on the 99.99% values, which dropped from 12.30 ms for UE1 and 8.13 ms for UE2 to 7.36 ms. However, this equalization can only happen if the latency spike is not caused by the 5G system, which is shared by both communication streams. Figure 12: Latency of the wireless transmission. (**a**) Latency for packets sent by 5G UE1 (mid-band), (**b**) latency for packets sent by 5G UE2 (URLLC), and (**c**) latency of the first packet arriving at Switch 2. Figure 13: Latency of the wireless transmission. (**a**) Latency for packets sent by 5G UE1 (mid-band NSA), (**b**) latency for packets sent by 5G UE2 (mmW NSA), and (**c**) latency of the first packet arriving Switch 2. As a result of Setup 4, FRER has a limited impact if used for systems with different performances. Since the mmW system has a higher performance than the mid-band system, the mid-band system is used as the primary communication path only in the case of a latency spike. Evaluation of Setup 4 with Introduced Disturbances: Redundant Transmission via 5G Mid-Band Deployment and 5G mmW System Deployment  
To further evaluate the benefit of FRER for 5G communication, a second measurement using Setup 4 has been performed. This time, disturbances, in the form of a metal plate put in front of the antennas of UE2, have been introduced. The metal plate blocking the transmission partly simulates a workpiece or a metal housing of the milling machine blocking partly the signal. Outside the machine, this blocking can be caused by a crane, an autonomous guided vehicle (AGV), or a metal workpiece passing or being placed in front of the UE.