Future trends and expected technological evolution - Three generations approach of future communications satellite
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Future trends and expected technological evolution - Three generations approach of future communications satellite
The need of communications satellite will be
unchanged in the future, because of the feature of
satellite communications’. Considering the necessity
of satellite communications in the future,
three generations of communications satellites
were proposed. The capacity of each generation
communications satellite is given in Table 1.
Namely, in 2000-2010 the first generation communications
satellite (1G-sat) has capacity of 5-
50 Gbps, in 2010-2020 the second generation
communications satellite (2G-sat) has capacity of
5O-500 Gbps and in 2020-2030 the third generation
communications satellite (3G-sat) has capacity
of 0.5-5 Tbps.
The reasons why such large capacity satellite has
been proposed are as follows: First, in order to
develop a harmonious infrastructure with terrestrial
communications systems for mitigation
of disaster, the satellite capacity should be increased
along with the terrestrial capacity,
although the complete follow up is impossible,
because the capacity of satellite communications
need be increased to accommodate some capacities
of terrestrial communications. Second, it
is assumed that the satellite should share at least
1% of the backbone network capacity. Paradoxically
speaking, the future satellite should have
such a high capacity to survive in the competition
with the terrestrial systems.
The capacity of the terrestrial backbone network
increases tremendously year by year: A prediction
is shown in Fig. 1. The capacity of a single
fiber as a backbone network, shown in the upper
part of Fig. 1, is about 400 Gbps-5 Tbps in the
2000-2005 time frame and it will increase to 2.5
Tbps-40 lbps around 2010. A dotted thick bold
line shows the extrapolation, considering that
there could be a limitation in the capacity of a
single optical fiber cable, around one Peta bit per
second.
Each generation of communications satellite is
shown in Fig. 1. As far as 1G satellite is concerned.
the WINDS satellite has 1.2
Gbps/channel and the total capacity is estimated
to be about 6 Gbps. On the other hand, the ip-
STAR is plammd to have total 40 Gbps capacity,
to be launched in 2003. Therefore, it is reasonable
to assume that several to several tens of
Giga bit per second (5-50 Gbps) is the total capacity
of the 1G satellite. As for the 2G satellite,
we believe that the capacity will increase by an
order of magnitude (10 times). Therefore, the
total capacity per satellite will be several tens to
several hundreds Giga bit per second (50-500
Gbps) for the 2G satellite. A range of several
hundreds to several thousands of Giga bit per
second capacity (500 Gbps-5 Tbps) is taken to
be the total capacity of the 3G satellite in order
to survive in the future IT environment. The
capacity of the 3G satellite could not be realized
by a conventional satellite. Therefore, a GE0
platform will become necessary and a technical
breakthrough is needed.
The generation change of a unit for ten years, as
shown in Table 1, seems to be too long in the
recent times so-called ‘Dog Y&‘. One generation
of 10 years may be long, but it must be reasonable
because it may be about a generation of
infrastructure. A communications satellite means
that it provides fixed, broadcast and mobile satellite
communications. [1]
References
[1] T.Iida
"Cost consideration for future communications satellite".
