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Advancing Cellular Backhaul Through SatelliteRichard Deasington, Director, Market Development, iDirect
The mobile industry is at an important cross-
roads. With new technology emerging every
day, mobile operators are rapidly moving from
GSM standard 2nd generation (2G) networks to
3rd generation (3G) and 4th generation (4G) net-
works. With these changes, however, come
challenges. While 2G networks offered primari-
ly voice connectivity, 3G and 4G networks are
much richer and more complex, offering Internet
access, video, and much more. As such, they
deliver a significantly greater volume of data.
In major urban areas, there is the infrastructure
to support all of this data, but in rural areas, it
is much harder for mobile operators to backhaul
3G and 4G data affordably. Fortunately, there is
a solution. Mobile operators that have used
advanced satellite technology to backhaul 2G
traffic are discovering that it is also a viable
solution for backhauling more complex and
bandwidth-heavy 3G and 4G voice and data.
This article will examine how satellite delivers
cellular backhaul for 3G and 4G, the ways that
satellite has evolved in the last several years to
be more efficient and affordable, and the impli-
cations that the expansion of 3G and 4G cellular
services has had on the Asia-Pacific region.
Advancing Cellular Backhaul Through SatelliteOver the past decade, mobile technology has
been advancing at a phenomenal rate and
nowhere have these changes been felt more
strongly than in the developing world where
mobile devices are the primary way that individ-
uals access the Internet. In a 2010 report, Cisco
projected that mobile data traffic would grow
from 14 million to 788 million users by 2015 - a
26-fold increase. With an ever-increasing num-
ber of subscribers transitioning from 2G mobile
phone networks to 3G and 4G technology, we’re
coming closer to that reality. For mobile opera-
tors, however, tapping into rural communities is
easier said than done.
A key challenge preventing mobile operators
from delivering 3G and 4G service to developing
regions, including many areas in Asia-Pacific, is
backhauling rural network traffic. Because
these regions are often remote and cut off from
terrestrial communications, it can be difficult for
mobile operators to backhaul cellular data
affordably. While this was less of a concern
with previous mobile technology, which was pri-
marily focused on voice communications, 3G
and 4G mobile provide voice, video, and Internet
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18 Quarterly Newsletter Q2•2012 19
access, which accounts for significantly greater
data volume.
Fortunately, there is a solution for mobile opera-
tors, and it’s one that they’re already familiar
with: satellite. Mobile operators can look to sat-
ellite as a solution for growing 3G and 4G net-
works in rural areas in the same way that they
used it to grow 2G networks. Furthermore,
because of significant recent advances in satel-
lite technology, mobile operators can leverage
satellite solutions even more efficiently than
before.
To understand how mobile operators can use
satellite technology for 3G and 4G, it’s impor-
tant to revisit how satellite helped mobile oper-
ators manage 2G data. The legacy approach for
backhauling cellular data relied on a technology
called SCPC (Single Channel Per Carrier). This
technology extends an E1 (or T1) fractional link
from the Base Station Controller (BSC) site to
the Base Transceiver Station (BTS) using a pair
of devices called SCPC modems. This solution
was effective for sites that had a high level of
traffic, but was operationally inefficient for
more remote and rural locations.
Because the capacity of the satellite link
between two SCPC modems has to be configured
for peak usage – which typically occurs for only a
few hours on the busiest day of the year – it ends
up costing mobile operators significant money in
wasted bandwidth. The shift in the market that
enabled mobile operators to backhaul data via
satellite more efficiently came in the mid-2000s
with the deployment of IP technology instead of
TDM (Time Division Multiplex) links.
As cellular data began to become more complex,
IP networks offered more efficiency to operators
by providing the ability to share capacity
between multiple sites rather than having a
fixed amount per site, as in a TDM network.
Concurrent to this change in the mobile industry
was a shift to IP in the satellite industry.
IP-based satellite networks use a concept called
TDMA (Time Division Multiple Access) to share
bandwidth across many sites. Through TDMA
technology, it is possible to allocate satellite
bandwidth on demand, based on the real-time
requirements of each site. When you pool band-
width like this, it creates a significant “trunking
gain” – requiring up to 80% less capacity on a
per site basis.
Modern carrier-class satellite systems built for
IP traffic are highly compatible with newer
IP-based 2G, as well as IP-based 3G and emerg-
ing 4G networks. Additionally, there have been
several other key technical innovations in the
satellite industry that made backhaul over satel-
lite an especially compelling option for 2G and
continue to make it a viable solution for 3G and
4G mobile operators.
The first key innovation supporting backhaul
over satellite was the move to the second gen-
eration of the Digital Video Broadcasting stan-
dard, or DVB-S2. This transition has made
TDMA networks significantly faster, particularly
when fine-tuned for maximum efficiency. The
addition of Adaptive Coding and Modulation
(ACM) technology makes satellite even more
efficient.
ACM enables each remote to operate at its
most efficient coding and modulation scheme at
any moment, depending on its location within
the satellite contour, antenna size and atmo-
spheric conditions. In practical terms, ACM
ensures that satellite connectivity will be unin-
terrupted by sudden weather changes in regions
where rain fade was previously a problem and
allows the satellite links to be configured on the
basis of optimal operation under clear sky con-
ditions instead of having to assume worst-case
conditions.
A second important development was the inte-
gration of TDMA and SCPC technology onto a
single networking platform. This innovation,
pioneered by iDirect, allows mobile operators to
use an SCPC Return channel when they need to
sustain fairly constant capacity, or to switch to
a TDMA link when throughput is more variable.
This flexibility takes away the guess-work from
network deployment – having to predict which
sites will be high-traffic in advance of their roll-
out.
Combining TDMA and SCPC on one platform not
only saves bandwidth but also lowers up-front
capital expenses by eliminating the need to
implement different types of ground infrastruc-
ture. Rather than sending a team to physically
swap a remote modem, a mobile operator can
switch modes from a central NOC using the
same hardware in the field. This is a powerful
incentive for mobile operators, particularly in
the Asia-Pacific region where rural subscribers
may be in areas where geographies and topog-
raphies make deployment difficult.
A third key development in the mobile industry
that has made cellular backhaul over satellite
appealing is the introduction of small cell/femto-
cell technology. Mobile operators are already
familiar with small cells as a means of offload-
ing data from the wireless network to the terres-
trial network, but they also offer the ability to
cost-effectively expand a wireless service area.
Many vendors are offering small cell platforms,
power amplifiers, power supplies and outdoor
enclosures to produce packages that can sup-
port 30 – 60 voice calls plus HSPA data traffic
and backhaul that traffic using any available IP
connectivity – including carrier-class satellite.
Compared to macro-cell solutions, which have
to be mounted on high towers and are expen-
sive to deploy and maintain, the price of these
small cell packages are significantly lower and,
combined with a low-cost remote satellite rout-
er, allow mobile operators to expand coverage
into rural areas quickly and economically.
Small cell solutions are challenging the tradi-
tional models that were used by mobile vendors
by developing new systems that incorporate the
entire 3G core network on the same server plat-
form that hosts the small cells. The effect of
this is to release mobile operators from the
need to operate large and extremely expensive
proprietary 3G core networks and replace them
with much lower cost soft-switches. These
devices allow scaling to much smaller networks
– even to allow entirely separate networks to
be operated in a building, ship or aircraft.
Given the game-changing potential of femtocell
technology, mobile operators that are already
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IP-Based Cellular Network
20 Quarterly Newsletter
invested in Femto-gateways for core operations
in major cities are naturally interested in lever-
aging their existing investment to support rural
coverage.
Mobile Data Statistics in AsiaOne important characteristic of satellite tech-
nology as it relates to cellular backhaul is that
satellite can be integrated easily with existing
terrestrial networks. When you consider mobile
data usage trends in Asia, it is easy to see how
this can be a valuable benefit.
According to research from the International
Telecommunication Union1, South Korea and
Japan are ranked number one and number two
worldwide in mobile broadband penetration,
with 91 and 87.8 percent penetration respec-
tively. The ITU also found that, by the end of
2011 there were 6 billion mobile subscriptions
worldwide – roughly 87 percent of the world
population.2 Of those 6 billion mobile subscrip-
tions, 4.5 billion came from the developing
world, with adoption in China and India driving
much of the growth. Unsurprisingly, the top
three mobile operators in the world are from
these two countries (China Mobile, China
Unicom, and Bharti Airtel India, according to
Portio Research3).
In countries like this, which have large and
highly populated urban areas, there is a high-
level of telecommunications infrastructure
already in place in major cities. While extending
this infrastructure to rural areas with terrestrial
technology can be complicated and costly, sat-
ellite presents a strong complementary solution
that can overcome geographic barriers and
extend mobile network from cities to remote
areas affordably and efficiently.
ConclusionAs wireless communications technology contin-
ues to evolve and operators are able to offer
greater and more sophisticated high-speed
wireless data services to customers, they need
a solution that can backhaul data efficiently and
affordably. Because satellite can reach places
that no terrestrial technology can, it is the ideal
solution for mobile operators to reach remote
and rural areas that are lacking 3G and 4G cov-
erage. Additionally, as satellite technology con-
tinues to evolve with the development of band-
width management breakthroughs and integra-
tion with small cell technology, it is becoming
easier to deploy and significantly more afford-
able to manage.
By using satellite to extend cellular coverage to
remote and rural areas in Asia-Pacific, where
mobile technology continues to be the primary
way that individuals access the Internet, mobile
operators are able to expand their customer
base while also facilitating important economic
and social change by improving access to infor-
mation.
Richard Deasington has more than 25 years of experience in the telecommunications industry, holding senior level positions in
R&D and Engineering working closely on voice, data and transmission network systems. In his current role as Director of Market
Development for iDirect, Richard is currently responsible for leading iDirect’s engineering and sales efforts for GSM backhaul solutions.
Prior to joining iDirect, Richard held Managing Consultant position at PA Consulting Group and later Questus Ltd where he focused on
mobile systems: GSM and 3G systems in particular. He has been involved in a large range of mobile related activities from architecting
the world’s first shared 3G network to leading the design of a range of network planning tools. Richard has written several well-known
books and published many articles on subjects ranging from 3G power amplifier efficiency to network sharing and push-to-talk. Richard
holds a Bachelor of Science degree with Honors in Computer Science with Biology from the University of London.
1 http://www.itu.int/ITU-D/ict/facts/ 2011/material/ICTFactsFigures2011.pdf
2 http://www.itu.int/ITU-D/ict/statis-tics/at_glance/KeyTelecom.html
3 http://www.portioresearch.com/Ranking09.html