Study on feasibility of SATCOM for railway communication

Final Report
Etc.
MEO
LEO
O3b
Iridium Next (ongoing)
6.2.14.1 System architecture
Table 18: Ka-band satellites/constellations
The GEO/Ka-band SATCOM system architecture is the same that the GEO/Ku-band architecture,
where the only difference is in the frequency band used. Figure 37 shows a general GEO/Ka-band
SATCOM system architecture, where the user link uses the Ka-band. The feeder link could also use
the Ka-band or a different one, since this link does not represent the limitation part.
Traffic
Control
Centre
Feeder Link
User Link
Ka-band
Train
Stations
WAN
Teleport
RBCs
Figure 37: GEO/Ka-band SATCOM architecture
The communication solution (ground and user segments) in this case is the same that in Ku-band
(except for the RF and antenna equipments). It means that at designing phase it can be analysed
which SATCOM solution (standard or proprietary) is more convenient for a specific solution.
6.2.14.2 High Throughput Satellites (HTS)
One interesting feature of Ka-band (although the band a priori it is not a constraint) is currently the
increase of a type of satellites capable to provide many times the throughput of a traditional FSS
satellite for the same amount of allocated frequency on orbit. These satellites are named High
Throughput Satellites (HTS), and are able to increase throughput radically (and reducing this way the
cost per bit delivered) by means of defining multiple spot beams and frequency reuse techniques.
And although HTS are not only specific of Ka-band, the fact is that the amount of bandwidth available
(and of course the characteristics of the band) make this band a good candidate to be used on HTS.
A HTS is defined as a satellite that uses a large number of small spot beams distributed over a
particular service area. These spot beams provide high signal strength and signal gain (EIRP and
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
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