Study on feasibility of SATCOM for railway communication

Final Report
NPV in the long term. GEO/Ka-band offers a good competitive edge in economic terms in the same
class as a moderately conservative LTE estimate.
In addition, the modularity and the OPEX-intensive economic model proposed by SATCOM solutions
offer the possibility of a gradual implementation. In stark contrast, LTE implies that in general a small
number of infrastructure managers should have to make strong initial investments to deploy terrestrial
infrastructure, and with little room for a scaled deployment, requiring instead a comprehensive landbased
infrastructure to provide initial operating capability. All this makes LTE a more financiallydemanding
solution compared with that of SATCOM broadband candidates.
As a result, SATCOM solutions can be implemented at a rather low and progressive initial investment
in select rail services to fulfil the current demand, hence providing a solid platform to stand as either a
stop-gap measure for more investment-demanding solutions, or as initial proof-of-concept and
progressively ramped-up services for full-scale deployment in their own right.
1.7 GENERAL CONCLUSIONS AND RECOMMENDATIONS
Figure 7 shows the complete compliance matrix of technical, multi-technology and non-technical
criteria for the eleven SATCOM systems evaluated. This matrix shows that all the SATCOM solutions
assessed have more than one criterion not compliant plus some partial compliant, as well. It means
that there is not any SATCOM system fully compliant with current criteria identified. This is
mainly because GSM-R voice requirements become the main barrier for SATCOM, due principally to
the fact that their values are out of the scope of any current SATCOM solution (in terms of availability,
latency and even capacity for the whole European demand). Therefore, it is strongly recommended to
reconsider such requirement‘s values (i.e. latency and availability) taking into account the safety
cases 4 for these scenarios where SATCOM could be working standalone (e.g. remote/rural areas).
Having a look of the complete compliance matrix in more detail, it can be observed that:
- All the solutions are compliant with the multi-technology criterion, meaning that all of them can be
integrated within a FRMCS consisting of several communications systems (i.e. heterogeneous
technologies) and allowing the convergence of networks that would enable a multi-link scenario.
- The system technically best evaluated (the MEO/C-band solution) is also the worst evaluated
non-technically. It is because of the MEO/C-band is nowadays only a theoretical solution 5 .
- The IRIS FOC solution has a similar behaviour than the MEO/C-band, since its technical
evaluation is highly positive (only with a bad grade on the double-hop delay). In addition, this
solution is currently planned, although from 2025.
4
It is worth mentioning that a similar situation have been considered in the aeronautical environment, where ATM (Air Traffic
Management) applications requirements are classified according the airspace domain, such as the APT/TMA (Airport/Terminal
Manoeuvring Area), ENR (En Route) and the ORP (Oceanic, Remote and Polar). For example, in the areas where SATCOM is the
only mean of communications (i.e. ORP), QoS requirements (e.g. latency) are relaxed, and not only to make possible the use of
SATCOM where no other terrestrial system is available, but also because the specific features of these domains (in terms of number
of users, operations required, etc) make possible this relaxation keeping the safety case. For the contrary, in APT/TMA, it is
mandatory the presence of, at least, two different links, i.e. multilink (LDACS/VDL2, AeroMACs).
5
Despite the MEO/C-band is only a theoretical solution, a similar solution exists nowadays. It is a MEO/S-band (ICO), which is
currently reaching its end of life.
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
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