Study on feasibility of SATCOM for railway communication

Final Report
GEO Ku-band satellite communication systems are nowadays common systems to provide broadband
data communications to fixed and on-the-move terminals. It is currently a mature technology that
provides service to several markets with high success. That‘s why Ku-band is currently widely used
and it is expected to be a reliable SATCOM solution for the future with new satellites adding
improvements and new features.
Satcom solutions currently deployed to provide non-safety critical services on railways (such as
internet for passengers) are deployed over GEO satellites in Ku-band. For example, 21Net (a
company delivering connectivity solutions for trains based mainly on SATCOM), has based its
solutions deployed over different HSL (High Speed Lines) worldwide on GEO Ku-band solutions. They
have taken advantage of the most convenient satellite in each case (such as for example the
HISPASAT for the Thalys HSL) and the whole SATCOM system including HUB and remote terminals
(initially EMC proprietary solution and subsequently changed to iDirect proprietary solution).
As another example, INDRA is currently participating within the design and deployment of a Satcom
solution for High Speed trains to provide Internet for passenger in Spain (AVE trains). And this solution
also considers the use of a GEO satellite and the Ku-band (such as the HISPASAT 1D or 1E provide).
The system will be based on iDirect proprietary solution.
6.2.12.2 System architecture
GEO/Ku-band solutions have, in general, the system architecture depicted in Figure 32, where the
user link relies on Ku-band. The feeder link could be Ku-band, as well, or different (Ka, for example),
since this link does not represent the limitation part.
Traffic
Control
Centre
Feeder Link
User Link
Ku-band
Train
Stations
WAN
Teleport
RBCs
Figure 32: GEO/Ku-band SATCOM architecture
Regarding the communication solution (basically ground and user segments), it depends on the
equipments selected in each case. Considering as an example the iDirect solution (non-standard but
widely used), it is based on a DAMA system (see section §6.3 for more information about access
schemes) where the access scheme is proprietary and derived from a Time Division Multiple Access
(TDMA) scheme, named Adaptive-TDMA (ATDMA). The ATDMA allows the efficient use of bandwidth
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
Page 88 of 285