# Railway Wireless Communications Channel Characterization
## 6 Deployment Example  
The CCT can measure any communication channel in any railway track, helping to go forward in the decision of migrating from current technologies to new ones because of the current capabilities. Moreover, the tool can help a specific user develop a railway application on how this application behaves in a specific track due to the network deployed and the railway environment. As shown in Section 2, CCT measures different parameters, some of which, depending on the application to be used, will be more critical than others. For example, regarding the requirements of each application indicated in [18], ETCS is a critical application, for which the minimum requirements are a data rate of 4 kbps and a latency of 3.5 s [18], but only a probability of data loss less than \(10^{-4}\)[30]. However, a real-time critical video application needs a minimum data rate of 5 Mbps as the amount of data for video streaming tends to be higher than ETCS, the constant delay should not exceed 0.1 s, and the acceptable packet loss should be around 4% [31]. As an example of the tests and results given by the CCT, a test campaign has been carried out in a specific track placed in Spain, more specifically, in the track Ciudad Real-Cerro Negro. This track has several railway environments causing different effects on the desired signal. During the test campaign, the different parameters that the CCT is capable of measuring have been tested: RTT, jitter, bandwidth, throughput, radio frequency values such as RSSI, and packet loss. However, the results shown are from one of the available parameters: RTT. The rest of the parameters have the same visualization options, but the RTT results are shown as an example. Additionally, the results correspond to a part of the whole track mentioned before, being this sub-track placed between Almonacid de Toledo and Mora and the wireless technology provided by the Vodafone network operator. The environment that was identified for this specific track where the train is passing through is mainly a suburban area, as Figure 5 shows. Some results obtained by the testing of the different parameters are shown in this section using the visualization part of the CCT, that is, CCT CI. Apart from these interesting values obtained from the test campaign measurement, the powerful CCT system can provide more information that helps the user understand what happened during the test campaign, such as the cells from the network operator that the agent was attached to or the technology measured in each point. The CCT allows the user to both configure the test and visualize the results. The visualization functionality permits the user to know the quality of the communication channel while on-site testing for each location in the track, as Figure 4 shows. As Figure 6 shows, the RTT is, in general, around 100 ms. However, there are some points in the track that have different values, being greater than the average. This effect could be because of the environment affecting the communication channel or the proximity to the cell. Figure 5: Measured track: Ciudad Real-Cerro Negro. Furthermore, the tool can generate a coverage map to find out the lack of coverage or the available technologies in the specific track, as Figure 7 shows. In this specific case, the CCT had total LTE coverage in the track, resulting in no vertical handovers and no disconnections from the fact of switching the technology. Moreover, this tool allows both comparing different tests between each other and comparing the same test with different conditions (min and max values changed) at the same moment as Figure 8 shows or in different tests. Furthermore, the CCT CI can show statistics results, that is, the results of a given test sent by the user or the results of the different tests performed in a given track as Figure 9 shows.