Study on feasibility of SATCOM for railway communication

Final Report
Inmarsat 4 (BGAN) - Inmarsat 6 (ICE)
Criterion ID Criterion Evaluation Justification
CRT-TECH-6
Network registration delay for the proposed satcom system
shall be Normal (with similar values of current GSM-R system).
NC
Inmarsat 4 (BGAN) terminals requires "2 registration processes" to be able to use
Packet Switched services.
Each I-4 satellite can generate 19 wide beams and more than 200 narrow spotbeams.
These beams can be quickly reconfigured and focused anywhere on Earth
to provide extra capacity where needed.
The BGAN system requires 2 step connection process. The first step is to Register
with the Network, which is opening a wide beam connection with one of the I-4
satellites. After registration, the BGAN terminal's phone and SMS messaging
services are operational (Circuit Switched). The BGAN may place or receive voice
calls or sms messages to anyone in the world.
The second step is opening a Data Session (Packet Switched), such as a
connection to the Internet. When this happens, the BGAN terminal is connecting to
a Narrow Beam of the same I-4 satellite.
In addition, within the terminal comparison study performed by TelAstra [RD-22], it
is shown that the registration time of the BGAN IsatPhone Pro takes a lot of time
(between 72 to 120 seconds) because it needs first to fix its position by means of
the GPS system. Despite this first acquisition is expected to be improved, it is only
the first step of the registration process (in fact satphones only executes this first
step since they only provide service by means of the Circuit Switched system.
Doc.Nº: SRAIL-FNR-010-IND
Edit./Rev.: 1/1
Date: 16/02/2017
Page 234 of 285