# An Adaptable Train-to-Ground Communication Architecture Based on the 5G Technological Enabler SDN
## Abbreviations  
The following abbreviations are used in this manuscript: \begin{tabular}{l l}
5G & Fifth-generation \\ ACS & Adaptable communication system \\ AP & Access point \\ CCE & Control center equipment \\ CCTV & Closed-circuit television \\ DisPaC & Disjoint Path-Computing \\ E2E & End-to-end \\ eNB & evolved Node B \\ EPC & Evolved packet core \\ GSM-R & Global System for Mobile--Railway \\ LTE & Long-term evolution \\ M2M & Machine-to-machine \\ MAC & Media access control \\ MME & Mobility management entity \\ MPLS & Multiprotocol Label Switching \\ MPTCP & Multipath Transmission Control Protocol \\ MQTT & Message Queuing Telemetry Transport \\ OBE & Onboard equipment \\ OF & OpenFlow \\ ONOS & Open Network Operating System \\ OVS & Open vSwitch \\ PCE & Path computation element \\ QoS & Quality of service \\ SDN & Software-defined networking \\ S/P-GW & Serving/Packet-data-network Gateway \\ T2G & Train-to-ground \\ VLAN & Virtual local area network \\ WMN & Wireless mesh network \\ \end{tabular} 
\end{table}
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* IEC (2018) IEC 61375-2-6. _Electronic Railway Equipment--Train Communication Network (TCN)--Part 2-6: On-Board to Ground Communication_; International Electrotechnical Commission (IEC), May 2018. Available online: [[https://webstore.iec.ch/publication/33737](https://webstore.iec.ch/publication/33737)]([https://webstore.iec.ch/publication/33737](https://webstore.iec.ch/publication/33737)) (accessed on 11 June 2019). * ISO/IEC 20922.