# A Network-Based Method to Analyze EMI Events of On-Board Signaling System in Railway
## 4 Case Study
### Analysis and Discussion
#### 4.3.1 Path A
Thus, the path \(v_{2}\to v_{14}\to v_{17}\) that the propagation characteristics could be  
Figure 11: Measurement setup and results for \(A_{v2}\) of the node \(v_{2}\). (**a**) Setup description of the on-site measurement in Chinese high-speed railway; (**b**) The result of the pantograph arcing. Figure 12: The attribute model of the edge \(e_{14\text{-}17}\) by a simplified model for the connection between node \(v_{2}\) and \(v_{17}\). analyzed according to the model above. Furthermore, the electric field at the \(v_{17}\) position could be obtained by this model. However, it is different from the real environment in the high-speed railway. To get the actual signal for the next segment in the path, the signal is measured at the node of \(v_{17}\) and the result is shown in Figure 13. The pulse received at the \(v_{17}\) position is in Figure 13a and it has the same trends in Figure 11b. The port voltage received at the antenna cable of the module node \(v_{26}\) is shown in Figure 13b. Thus, the analysis process indicates the feasibility of the path \(v_{2}\to v_{14}\to v_{17}\) in the EN model. 3. \(A_{v26}\) of the node \(v_{26}\)  
To complete the case analysis, a downlink of LTE-R is established in Matlab for evaluating the path \(e_{17\text{-}26}\) as shown in Figure 14. Since the throughput is an important criterion for evaluating the communication system, the throughput, as a basic index, is chosen as the attribute \(A_{v26}\) of node \(v_{26}\). Thus, the path \(v_{2}\to v_{14}\to v_{17}\to v_{26}\) could be complete after the study above. Figure 14: The structure of the downlink model. Figure 13: The results at node \(v_{17}\). (**a**) The pulse received at the antenna position in the EMU (**b**) The port voltage received at the antenna cable of the module node \(v_{26}\). In the downlink model of \(e_{17\text{-}26}\), PDSCH (Physical Downlink Shared Channel) with modulation of 64 QAM is selected for downlink simulation by the single antenna transceiver and the carrier frequency is 450 MHz with FDD standard [26]. The channel is AWGN and the bandwidth is 5 MHz. The port voltage received after the node \(v_{17}\) at the cable end in Figure 13b is added to the transmission channel. The relationship between the throughput and SNR (Signal to noise ratio) is shown in Figure 15 with the blue line. The throughput decreases when the disturbance caused by the pantograph arcing from the node \(v_{2}\). In Figure 15, the measurement result is from the work in Reference [25]. It indicates the result is consistent with the simulation in \(e_{17\text{-}26}\). It is based on the FTP (File Transfer Protocol) to measure the throughput of the LTE-R system in an experimental high-speed railway line in Shenyang, China. The on-board and wayside terminal will transfer a 100 MB file when the train passes through the coverage area of the network. Then, the device calculates the maximum number of bytes per second and we fit the relationship between the downlink throughput and the SNR. The measurement results verify the validity of the simulation of the path \(v_{17}\to v_{26}\). Thus, the EMI event of \(v_{2}\to v_{14}\to v_{17}\to v_{26}\) in the EN model of the OTCS has been analyzed and the results show that the pantograph arcing disturbance will affect the performance of communication.