Study on feasibility of SATCOM for railway communication

Final Report
GEO / Ku-band
Criterion ID Criterion Evaluation Justification
CRT-TECH-4a
Transfer delay for the proposed satellite system shall be Low.
Note: It refers to the end-to-end (one-way) delay due to the
satellite channel. Therefore, it shall be measured from satellite
transmitter to satellite receiver.
4a: Single-hop required
C (Low)
A GEO satcom solution minimum transfer delay is limited by the distance between
terminal and satellite, which is around 250 ms.
Since a GEO / Ku-band satcom system based on DVB-S2/DVB-RCS2+M
communication standards is broadband, delay related with the data transmission
is negligible in front of the 250 ms due to the GEO satellite.
CRT-TECH-4b 4b: Double-hop required NC
The double hop transfer delay for a GEO solution is not compliant with railway
requirements with independence of the frequency band used, since only
considering the propagation delay to a GEO satellite is around 500 ms.
CRT-TECH-5
Delay jitter of the proposed satcom system shall be Low.
Note: Since this criterion refers to the one-way satellite
channel jitter, it shall be measured from satellite transmitter to
satellite receiver.
C (Low)
Just like previous "opened" GEO satcom solutions, this criterion is marked as a "C
(Low)", since there exist mechanisms to compensate the delay time variations
between packets at IP level, but the lower the orbit the lower the delay jitter.
CRT-TECH-6
Network registration delay for the proposed satcom system
shall be Normal (with similar values of current GSM-R system).
C
Assuming a good network dimensioning according to the estimated throughput,
the registration process of the GEO/Ku-band system based on DVB-S2 / DVB-
RCS2 communication standards can take a "normal" time similar to current GSM-
R performance.
CRT-TECH-7
The call establishment delay for the proposed satcom system
shall be Low.
Note: as a first reference, GSM-R establishment delays can be
considered.
C
In the same way that previous "opened" satcom systems, the call establishment
process of the GEO/Ku-band system based on IP and DAMA access scheme can
be designed in order to assure a low delay similar to the one performed by the
current GSM-R system. It requires the correct dimensioning of the network
resources according to throughput requirements.
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
Page 272 of 285