Railway applications are in continuous evolution with the aim of offering a more efficient, sustainable, and safer transportation system for the users. Generally, these applications are constantly exchanging information between the systems onboard the train and the trackside through a wireless communication. Nowadays, Global System for Mobile communications-Railway (GSM-R) is the technology used by European Train Control System (ETCS), but it is becoming obsolete. Therefore, alternatives for this technology have to be found for the different railway applications. Its natural evolution is to move forward with the latest technology deployed: Long-Term Evolution (LTE), which the Public Land Mobile Networks (PLMN) have already deployed. Therefore, testing the performance of this communication technology in the railway environment could be useful to assess its suitability and reduce the cost of railway network dedicated deployment. In order to do that, a methodology to characterize the communication environment is proposed. The main goal is to measure geolocated impairments of any communication channel in a railway environment being able to determine its behavior of the different communication technologies and find out possible coverage issues. Moreover, it could help in the selection of suitable communication technology for railway. This paper presents a brief description of the communication for railways and its QoS parameters for performance measuring. Afterward, the testing methodology is described, and then, the communication channel measurement campaign on a real track in Spain where the railway environment is variable is presented (tunnels, rural/urban area…). Finally, the measurements and results on this real track in Spain are shown. The results provide suitability of the 4G technologies based on the delay requirements for the implementation of ETCS over it.

Communication technologies are in continuous evolution and as well, the different applications making use of them. In order to succeed with the roll-out of the communication-based applications, it is required that the communications technologies are intensively tested and validated before deployment. Current strategies for testing and validation cover field tests and laboratory tests. Railways is also taking advantage of the communication technologies evolution, and therefore, there is a need for having testing and validation strategies adapted to the railway environment, especially for safety-critical applications. Field tests and laboratory tests also apply in Railways. In the frame of laboratory tests, this paper includes an overview of different network emulators existing currently in the market. Furthermore, an analysis of the gaps of the network emulators with regards to the needs of the railways environment is also included. The goal of this paper is to show that network emulators are a flexible cost-effective solution for communication technologies testing purposes. Additionally, this paper also shows that there is a need to adapt current emulators to the railway environment in order to test and validate the future railway applications based on communication technologies. INDEX TERMS IP Communication, Laboratory testing, Network Emulator, Railways, Wireless Communications I. INTRODUCTION Nowadays, communication technologies are in continuous evolution, offering a higher performance that allows getting further services. In order to adopt these new services, the communication technology in use has to be tested to ensure the required performance. However, due to the time constraints and cost of infrastructure deployment, the real performance of new communication technologies are not simple to be tested. Railways is also aiming to move forwards in this field of the communication technologies to make railways more efficient, safer and profitable [1], even if the main stakeholders interested in the deployment of these new communication technologies are mobile operators. Future railway services are pushing restrictive requirements such as large bandwidth (high data rate transmission capabilities) [2] and low latency [3]. To research these type of requirements (among others) in the railway communication field, some European projects were built, such as Shift2Rail [4] and FRMCS [5]. Shift2Rail project covers the future adaptable communications for railways, but also several different topics such as train integrity, interconnections between the different components inside the train car apart from the communication technologies. FRMCS project is also analyzing new mobile communications capabilities for railways. With regard to validation, particularly, Shift2Rail includes in its innovation program, a research activity related to the development of a new laboratory test framework, which comprises simulation tools and testing procedures for carrying out open tests with clear operational rules and simple certification ...