Study on feasibility of SATCOM for railway communication

Final Report
the deployment of terrestrial solutions is most feasible and where voice applications are more used),
several SATCOM systems could be chosen as a part of the multi-technology future railway
architecture (since more restrictive criteria disappear or are easier to be achieved due to new
conditions).
2) When not or only partially: can modified off the shelf services and products deliver solutions
for the above mentioned categories?
Currently, it does not exist a regulatory framework where SATCOM solutions could be certified and
homologated for the railway domain. Therefore, solutions technically compliant with railway criteria
shall be updated (if required) in order to comply with these future established regulations.
From the technical point of view, nowadays there exist SATCOM solutions compliant with only data
railway services (i.e. ETCS level 2/3), such as the GEO L-, C-, X- or Ku-band solutions.
A different situation is contemplated for voice services, since most of the SATCOM solutions
analysed are not able to provide them complying with the identified criteria. In fact, only the theoretical
SATCOM solution analysed, the MEO/C-band, is able to provide both voice and data (ETCS)
applications simultaneously. Nowadays there exists a similar solution based on a MEO/S-band system
called ICO, but it has not been analysed because of its near end of life. Anyway, this current solution
reveals that the MEO/C-band solution proposed is feasible from the technical point of view.
SATCOM voice services for railways also require the implementation of the whole set of railway voice
applications, i.e. the ones that are currently in use in the GSM-R system plus the ones considered
within the URS document (mainly those categorised as critical applications), such as voice
communications between train and ground (controller), group calls, railway emergency
communications, shunting voice communications, public emergency calls, etc. But this situation is
exactly the same that for those future railway terrestrial IP communication systems, since currently
only GSM-R is able to provide voice railway services, but in circuit-switched mode. This means that an
implementation of IP voice services for railways shall be implemented regardless of the future IP
communication systems (terrestrials and satellites).
Another important aspect to be considered mainly for voice services (since they are much more
demanding that ETCS applications) is the bandwidth required to satisfy the railway European demand,
since not all the SATCOM solutions are able to provide this demand and/or its geographical
distribution. This point is of high importance and shall be studied in detail with probably the use of
specific tools (such as traffic simulators) before the selection and/or design of the SATCOM solution
for railways.
But in the future communication architecture for railways, which could be composed of terrestrial and
satellite IP systems, some other modified off the shelf services and/or products need to be considered
because of the multi-technology. A clear example of these new services or products is the smartrouter,
which will be capable of changing seamlessly of bearer (i.e. to execute vertical handovers and
without disrupting the IP session established by the previous bearer) according to configuration and
current bearer‘s availability.
Railway specific hard environment and the use of a multi-technology communication architecture could
also require some additional modification(s) in the IP systems selected in order to adapt, for example,
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
Page 179 of 285