SAT E L L I T E C O M M U N I C AT I O N S n
The fight to
save C-band
While C-band continues to serve the
communication needs of the offshore industry,
a battle is underway to safeguard its future
Words: Kevin Tester
43
C
-band was the first
frequency band to be
allocated for remote
communications when
the satellite industry got
off the ground over half a
century ago. And it is still
used heavily today, particularly in the offshore
energy and cruise sectors, where it confers a
number of important benefits over other bands
in terms of resilience, coverage and capacity.
However, this workhorse frequency is now
under threat. Terrestrial mobile operators – the
telcos that bring broadband to your smartphones and tablets – are lobbying hard for the
C-band spectrum to be reallocated for new
mobile services. If the mobile industry gets its
way, it would effectively prevent ships from
using C-band in coastal waters and in the
long-term could even cast a shadow over the
provision of satellite C-band services altogether.
P43-44_TMP_Issue01_Marine Satcoms_F.indd 43
Meeting point
Every three to four years, global regulators
gather at the International Telecommunication
Union’s (ITU) World Radiocommunications
Conference (WRC) to review, and, if necessary,
revise international regulations governing the
use of radio spectrum by all technologies
including satellite. The next meeting – WRC-15
– will be held in Geneva in November 2015.
While that may seem far away, the future of
C-band – Agenda item 1.1 – is already viewed
as a key battleground.
Patrick van Niftrik, vp spectrum management and development EMEA for SES sets the
scene: “The terrestrial mobile telecom industry
is claiming it needs additional spectrum to
satisfy the growing demand for mobile data.
They started by launching a campaign to try to
force satellite service providers to share the
C-band. But sharing is not technically viable.
Since the beginning of this debate, we have
demonstrated through multiple technical
studies that having the two systems operating
in the same frequency band is impossible.
The discussion goes back many years. As it
prepares for 5G, 6G mobile broadband, the
terrestrial telco industry wants to gain rights to
all frequencies below 6Ghz – and ideally wants
those rights on a global basis.
One outcome of WRC 2007 was the so-called
‘footnote to the table of frequency allocations’,
which effectively gave nations the right to use the
contested spectrum for mobile applications,
whilst retaining some protections of neighbour-
Interference caused
by competing services
is not a good
outcome for anyone
Intelsat’s Gonzalo De Dios
15/10/2014 18:17
n SaT E L L I T E C O M M U N I C AT I O N S
ing systems, like satcoms. This was popular
among European countries where C-band is
less widely used. But this piecemeal approach
highlights a fundamental misunderstanding
among regulators in the global nature of C-band.
Each satellite beam offers coverage that is
intercontinental. Switching the service on and off
for individual nations results in Swiss cheesestyle holes that detract from its overall value.
Technical limitations
44
Why can’t satellite and terrestrial mobile play
nicely with C-band? Terrestrial masts emit
high-powered transmissions in every direction.
These interfere with the relatively weak signals
beamed down from a satellite. The amount of
geographical separation it would take for
satellite and wireless terrestrial transmissions
to both function reliably in C-band makes
coexistence impossible.
Despite technological advances
on both sides, the practical
hurdles of getting satellite and
terrestrial mobile to work in
harmony cannot be overcome.
“Mobile still drowns out
satellite on the downlink, whilst
satellite still knocks out mobile on
the uplink. Interference caused by
competing services is not a good
outcome for anyone. The best result is rational
spectrum allocation decisions that maximise
spectrum use,” notes Intelsat’s associate
general counsel Gonzalo De Dios.
“It is not even clear that terrestrial mobile
networks really need this extra spectrum,” he
continues. “For a start, there is already a lot of
spectrum reserved for the mobile sector that is
currently unused. We also believe that the
mobile traffic density assumptions made in the
technical studies they have provided to the ITU
are unrealistic and therefore may have led to
unreliable and misleading data demand forecast.
“The satellite industry is working hard to
maximise the utilisation of existing spectrum
as well as open up new bands for new services.
Specifically in C-band we want to accommodate innovations on the ESV side that allow
better use of spectrum. Our fear is that due to is
a lack of understanding some administrations
think C-band is obsolete and only supporting
legacy services. But that’s not the case: it is not
under-utilised or wasted spectrum.”
Unrealistic forecasts
De Dios questions the spectrum demands
being made by the mobile industry: “They are
justified largely by expectations of future
growth. Warehousing spectrum for predicted
growth is not a good strategy until you have
extracted the most juice from existing capacity.
Moreover, some of their assumptions are
dubious and we are seeing new dynamics. For
instance, mobile traffic is increasingly being
offloaded on to other bands like Wifi, itself a
technology which is evolving rapidly at the
moment. Such developments would diminish
the appetite for cellular mobile.”
Ahead of WRC-15 the satcoms
industry is responding to the
threat with its own lobbying
activities, spearheaded by the
Global VSAT Forum (GVF) and
the Satellite Spectrum Initiative
(SSI). Individual operators, like
SES, are also undertaking further
technical studies.
The goal is to preserve that harmonised
use of spectrum. C-band has certain characteristics that cannot be replicated simply by
switching to other bands, such as Ku or Ka. For
example, it prevails in equatorial regions and
other areas with high precipitation, which would
degrade the performance of higher frequencies
(like Ku and Ka again). Further C-band typically
offers ubiquitous reach across entire continents
and oceans within a single beam, which coupled
with its high availability, make it highly attractive
for applications in the offshore business.
Closer approach
Yet, later in proceedings, members of the WRC
will consider provisions aimed at liberalising
the use of maritime C-band and Ku-band closer
to shore. To minimise the risk of interference
with other spectrum users, VSAT antennas
300km
Within territorial waters a vessel has to coordinate with shorebased authorities on how satcoms equipment can be used
P43-44_TMP_Issue01_Marine Satcoms_F.indd 44
installed on ships (or Earth Stations on Vessels
(ESVs) as they known in WRC parlance) are
subject to regulations which dictate how close
to shore they may be operated.
Last updated in 2003, these are now
overdue a review in light of the technological
advances made in antenna design that have
attenuated disruptive emissions and the fact
that VSAT on ships is much more common
than before. The gist of the 2003 rules is that
within territorial waters (300km) a vessel has
to coordinate with shore-based authorities on
how satcoms equipment can be used. Like
IMO’s rulings, the ITU’s regulations are ratified
into law by individual nations. As such, there is
considerable variation in the implementation
between countries.
Intelsat’s de Dios explains: “This lack of
consistency can cause a headaches for ships
approaching a new port. As the regulation
currently stands it is based on maximum
transmit power levels that were typical a
decade ago. Power intensities have dropped
markedly since then. Taking this into account,
you could substantially reduce the distance at
which an antenna can be operated without
causing interference. Relaxing the regulations
would also reduce the burden on shoreside
authorities, as they would have fewer ESVs
[Ed: ie, vessels] to track in their waters.”
De Dios believes that in the lower ESV
power range, operation could become
permissible at 60-70km without coordination.
Yet, considered together, the two agenda items
– 1.1 proposing limits on C-band when mobile
is pre-eminent and 1.8 allowing the use of
C-band antennas closer to shore – are
seemingly at odds.
New normal
Going forward, fending off assaults for
spectrum is likely to be a recurring issue
for the satellite industry. Spectrum is a scarce
commodity, which is in greater demand than
ever before following the meteoric rise of
mobile broadband. But, says de Dios, the
communications ecosystem should be
considered as a whole, not application by
application. “In many cases satellite and
mobile complement each other. Satellite
supports mobility as a seller of backhaul,
for trains and planes as well as aboard ships.
If spectrum is allocated indiscriminately in
favour of one application, the ecosystem
becomes unbalanced, and the maritime
operators will ultimately be the ones that
suffer,” he concludes.
15/10/2014 18:17