Study on feasibility of SATCOM for railway communication

Final Report
Each satellite is controlled by means of 2 different Satellite Access Stations (SAS), which provide
backup with automatic switchover. These SAS are separated hundred of kilometers in order to also
offer site diversity.
The ground segment provides SASs and also a multiprotocol label switching (MPLS) infrastructure
that interconnects all Inmarsat L-band and Ka-band resources. The ground segment also provides
secure enclaves for supporting Customer-specific equipment and services.
Both user link and feeder link uses Ka-band, which allows high bandwidth but limited types of
terminals, since the use of directive antennas is required (handhelds are not allowed).
Figure 33 shows GX architecture taking into account only one of the three satellites.
Feeder Link
Ka-band
User Link
Ka-band
GX SAS 1
Traffic Control
Centre
Train Stations
Railway
Network
RBCs
GX users
Redundancy
Switch-over
GX SAS 2
Network
Operator
Control
Transport
Network
Figure 33: Global Xpress architecture for railways
Following subsections describes with more details the three segments of this architecture.
6.2.13.2.1 Space segment
GX space segment is composed (at this moment) of 3 Inmarsat-5 GEO Ka-band satellites, which
provide high-speed mobile broadband communications with global coverage by means of 89 fixed
spot beams and 6 steerable high capacity spot beams (each satellite).
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
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