An Adaptable Train-to-Ground Communication Architecture Based on the 5G Technological Enabler SDN

Railway communications are closely impacted by the evolution and availability of new wireless communication technologies. Traditionally, the critical nature of railway services, the long lifecycle of rolling stock, and their certification processes challenge the adoption of the latest communication technologies. A current railway telecom trend to solve this problem is to design a flexible and adaptable communication architecture that enables the detachment of the railway services-at the application layer-and the access technologies underneath, such as 5G and beyond. One of the enablers of this detachment approach is software-defined networking (SDN)-included in 5G architecture-due to its ability to programmatically and dynamically control the network behavior via open interfaces and abstract lower-level functionalities. In this paper, we design a novel railway train-to-ground (T2G) communication architecture based on the 5G technological enabler SDN and on the transport-level redundancy technique multipath TCP (MPTCP). The goal is to provide an adaptable and multitechnology communication service while enhancing the network performance of current systems. MPTCP offers end-to-end (E2E) redundancy by the aggregation of multiple access technologies, and SDN introduces path diversity to offer a resilient and reliable communication. We carry out simulation studies to compare the performance of the legacy communication architecture with our novel approach. The results demonstrate a clear improvement in the failover response time while maintaining and even improving the uplink and downlink overall data rates.This research has been supported by the Spanish Ministry of Science, Innovation, and Universities within the project TEC2017-87061-C3-1-R (CIENCIA/AEI/FEDER, UE)

Modelling and Simulation of ERTMS for Current and Future Mobile Technologies

Nowadays, train control in-lab simulation tools play a crucial role in reducing extensive and expensive on-site railway testing activities. In this paper, we present our contribution in this arena by detailing the internals of our European Railway Train Management System in-lab demonstrator. This demonstrator is built over a general-purpose simulation framework, Riverbed Modeler, previously Opnet Modeler. Our framework models both ERTMS subsystems, the Automatic Train Protection application layer based on movement authority message exchange and the telecommunication subsystem based on GSM-R communication technology. We provide detailed information on our modelling strategy. We also validate our simulation framework with real trace data. To conclude, under current industry migration scenario from GSM-R legacy obsolescence to IP-based heterogeneous technologies, our simulation framework represents a singular tool to railway operators. As an example, we present the assessment of related performance indicators for a specific railway network using a candidate replacement technology, LTE, versus current legacy technology. To the best of our knowledge, there is no similar initiative able to measure the impact of the telecommunication subsystem in the railway network availability.The work described in this paper was produced within the Training and Research Unit UFI11/16 funded by the UPV/EHU. This work was supported by the EU FP7-SEC-2011-1 Collaborative Research Project entitled SECurity of Railways against Electromagnetic aTtacks, SECRET Project. This work was also supported by the Spanish Ministry of Economy and Competitiveness through the SAREMSIG TEC2013-47012-C2-1-R project (Contribution to a Safe Railway Operation: Evaluating the effect of Electromagnetic Disturbances on Railway Control Signalling Systems), funded under the call Programa Estatal de Investigación, Desarrollo e Innovación and oriented towards Retos de la Sociedad 2013

Eurobalise-Train communication modelling to assess interferences in railway control signalling systems

The evolution of the railway sector depends, to a great extent, on the deployment of advanced railway signalling systems. These signalling systems are based on communication architectures that must cope with complex electromagnetical environments. This paper is outlined in the context of developing the necessary tools to allow the quick deployment of these signalling systems by contributing to an easier analysis of their behaviour under the effect of electromagnetical interferences. Specifically, this paper presents the modelling of the Eurobalise-train communication flow in a general purpose simulation tool. It is critical to guarantee this communication link since any lack of communication may lead to a stop of the train and availability problems. In order to model precisely this communication link we used real measurements done in a laboratory equipped with elements defined in the suitable subsets. Through the simulation study carried out, we obtained performance indicators of the physical layer such as the received power, SNR and BER. The modelling presented in this paper is a required step to be able to provide quality of service indicators related to perturbed scenarios.The work described in this paper is partially supported by the EU FP7-SEC-2011-1 Col-laborative Research Project entitled SECRET—SECurity of Railways against Electromagnetic aTtacks—and by the EU FP7 Research Project entitled EATS—ETCS Advanced Design Test- ing and Smart Train Positioning System. This work is also supported by the Spanish Min- istry of Economy and Competitiveness through the SAREMSIG TEC2013-47012-C2 project— Contribution to a Safe Railway Operation: Evaluating the effect of Electromagnetic Disturb- ances on Railway Control Signalling Systems. This work is partially produced within the Training and Research Unit UFI11/16 funded by the UPV/EHU