## 7 Performance Evaluation of Multicast R-GOOSE over Public WAN
### Results and Discussion
The number of lost packets is determined by checking the SPDU number in the recorded messages in order to ascertain how many consecutive numbers are missing. Statistical analysis consists of the calculation of key statistical values for the message delays. Table 6 presents delays (mean, 1 st and 99 th centile), packet loss, and the total number of messages transmitted in each configuration for both 5G and 4G communication. According to 5G specification, we expected higher transmission speed in 5G communication. However, 4G communication had better latency characteristics as shown in Table 6. This indicates that the 5G network is not in its full performance in the location of our experiment. The difference could also originate from the fact that our measurement traffic is low-bandwidth communication, and 4G may have better performance in this type of traffic. The authors are not familiar with the performance of 5G versus 4G communication on low-bandwidth traffic. In the following, the statistical analysis results are interpreted. In Table 6, by looking at the 1 st centile values, the best-case performance characteristic of each communication, architecture, or configuration can be evaluated. There does not seem to be a significant difference in the best-performance characteristics between the various tested configurations and only a slight indication that the 5G network could operate faster than 4G. The mean delay values show the average performance characteristics, and they should be considered when the overall performance of an individual configuration is considered. 4G communication seems to perform on average better than 5G with little difference between architectures and configurations. Finally, the 99 th centile value shows us the worst-case performance characteristics which should be considered when the reliability of a configuration is being evaluated for a particular application. Again, the 4G communication performs better than 5G without significant differences between architectures and configurations. Packet loss should also be considered when the reliability of the communication is analyzed. In our test, however, the packet loss was insignificant in all test cases. The communication configurations in Table 6 can be used to transmit R-SV and R-GOOSE messages in various wide-area applications as long as the real-time requirements are met. In each configuration, it is possible to investigate the impact of the communication characteristics (e.g., delay and packet loss) on the real-time requirement of wide-area application. To achieve this, constraints such as max delay should be defined for the measured communication characteristics so that they fulfill the real-time requirement of the application. These real-time requirements are application-specific and determined based on the wide-area monitoring or protection algorithm. The focus of this paper is on R-GOOSE and wide-area protection algorithms. For instance, in GOOSE-based Logic Selectivity and Communication-based LOM, real-time requirements are defined as maximum permissible communication delays, which should be 100 ms and 300 ms for Logic Selectivity and LOM protection algorithms, respectively. Therefore, these values (100 ms and 300 ms) specify the WAN communication constraints (maximum allowable delay) required for each protection application to operate correctly. So, the communication constraints need to be determined on a case-by-case basis. After specifying WAN communication constraints (e.g., maximum allowable delay) based on the application's real-time requirement, it becomes possible to calculate a probability value for the communication reliability in each configuration for a specific wide-area protection application. The reliability can be calculated by analyzing the measurements in each configuration (Table 6) with the defined constraints (e.g., 100 ms and 300 ms delays)in order to determine how communication characteristics meet the specific application requirements.