Study on feasibility of SATCOM for railway communication

Final Report
11. CONCLUSIONS AND RECOMMENDATIONS
11.1 MAIN FINDINGS
This section provides findings regarding technical, multi-technology and non-technical criteria
based on the SATCOM solutions‘ assessment carried out in section §9.
11.1.1 Findings regarding technical criteria
After analysing the SATCOM solutions in previous sections, the following conclusions have been
drawn:
o
o
o
After the technical & functional criteria assessment, the theoretical system MEO/C-band is the
best-positioned SATCOM solution.
Other well-positioned SATCOM solutions (although with more requirements scored as non- or
partial-compliant) are GEO/L-band (e.g. IRIS FOC), GEO/S-band and GEO/C-band.
The most demanding criteria for SATCOM solutions are:
Availability for critical applications
Transfer delay between SATCOM remote terminals
The use of handhelds
These conclusions have been drawn after the assessment of only SATCOM solutions (i.e. without
considering the behaviour of gap fillers and/or additional terrestrial systems) and by taking into
account data and voice applications. If only data applications (i.e. ETCS) were considered, some
criteria would not be necessary (such as the use of handhelds) and some others could be easier to
comply by SATCOM solutions due to the reduced data rate (such as the link availability):
o
o
o
When voice applications are not considered, data rate decreases and, therefore, link
availability is largely increased.
SATCOM communications will only consist of single hop connections (between ground
stations and on-board SATCOM terminals). In this way, the transfer delay is reduced
compared to with that of the double hop connectivity required for user-to-user (voice)
connections.
SATCOM handhelds, the most demanding type of terminals, would therefore no longer be
required.
This hypothesis makes more feasible GEO solutions operating at low frequency bands (L, S and C
bands), since their main constraints are the delay on double hop connections and the absence of
handhelds.
It is worth mentioning that in the long term, the concept of operation in railways could change and
voice services could be replaced by data applications, making possible the use of SATCOM solutions
to support services currently provided by voice and data applications using only data. In addition, in
the long term, there may be a SATCOM solution complying with both voice and data services (such as
the MEO/C-band solution), being also possible this way to offer a SATCOM solution compliant with all
the criteria identified.
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
Page 170 of 285