# Railway Wireless Communications Channel Characterization
## 7 Conclusions  
The technology and transportation sectors are in continuous evolution to provide the best experience to the final user. Therefore, new applications and technologies are being implemented and deployed. Among those new developments, it can be stated that CCT has been proven to be a powerful tool that supports the methodology proposed for the communication channel characterization methodology. This methodology can bring the needed information to help understand the behavior of communication technologies in the railway environment and its suitability to migrate the dedicated communication to the public services. This is achieved by analyzing the impairments by means of parameters that normally describe a communication channel such as RTT, bandwidth, or packet loss. Thanks to the special innovative feature of continuous testing, the possibility of measuring these parameters along the whole track is realized. In comparison with the current tools in the market, the CCT is an adaptable tool due to its modularity, allowing the integration of other technologies already deployed but not included or in development. Furthermore, the chance of exchanging the communication antennas in the CCT allows for a possible study of antenna selection for the final user to be carried out due to the feature of plugging different antennas. Additionally, non-communication expert users, such as maintenance operators, are able to use the CCT due to the special easy usage offered by CCT. The proposed methodology brings the possibility of finding out how a given application will work in a real scenario, reducing the learning curve corresponding to the test configuration and visualization of the results.  
Obtained results can help to determine why the communication channel varies along the track, e.g., due to the surrounding environment. The effects of the track environment in a selected technology are shown because of the mapping of the measured value with its corresponding location in each moment. Additionally, communication issues can be found  
Figure 12: KSR vs. RTT measured value.  
in any track due to the deployed technology itself or due to the environment that affects the communication channel. With this methodology, these critical areas are identified, which could be a relevant point to be analyzed in the transportation control systems regarding safety issues. Moreover, CCT can also show where an application will have the required QoS, comparing the results with the target KSRs.  
In conclusion, this methodology permits both knowing how the communication channel is along the track by means of measuring the performance of the technology (QoS) and determining if a given application would behave correctly at each point of the track in a user-friendly way. Additionally, it provides the characterization of the on-site communication channel for a specific real case having as result inputs for laboratory testing, which will enable shifting the real world to the laboratory environment.  
Conceptualization, N.F.-B., J.G. and J.M.; methodology, N.F.-B., J.G. and J.M.; software, N.F.-B., I.M. and J.A.; validation, N.F.-B. and J.A.; formal analysis, N.F.-B., J.G. and J.A.; investigation, N.F.-B., J.G. and J.M.; writing--original draft preparation, N.F.-B.; writing--review and editing, N.F.-B., J.G., I.M., J.A. and J.M.; visualization, N.F.-B.; supervision, J.M. and J.G.; project administration, J.M. and J.G.; funding acquisition, J.M. All authors have read and agreed to the published version of the manuscript.  
This research has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No: 826141: [[https://projects.shift2](https://projects.shift2) rail.org/s2r_ip2_n.aspx?p=X2 RAIL-3]([https://projects.shift2](https://projects.shift2) rail.org/s2r_ip2_n.aspx?p=X2 RAIL-3) (accessed on 19 September 2021).  
Not applicable.  
The authors declare no conflict of interest.