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For several years, the digital dividend has been a
hot issue extensively discussed by broadcasters and
operators of telecommunication and other services.
Apparently, there is a lot at stake for these industries
and, therefore, also for end-users. The crucial role of
governmental bodies in this process is also evident.
Some important choices have been already made;
however, further decisions are still to be taken.
This article considers hopes and concerns that
have been voiced in regard to the digital dividend
and looks at the activities of telecommunication administrations
on this issue.
What is the digital dividend?
Digital compression systems now available for
digital television systems allow the transmission
of several (up to six, depending on the coding and
modulation techniques) standard digital television
channels of acceptable quality in the radio-frequency
spectrum previously used by a single analogue channel.
Typically, there are four or five terrestrial analogue
services in a given region, so their digitization
into a single digital television channel will considerably
reduce the overall use of spectrum.
A number of Recommendations from ITU’s
Radiocommunication Sector (ITU–R) dealing with
coding, compression and modulation techniques for
digital terrestrial television broadcasting have indirectly
contributed to the process that is finally yielding
the digital dividend. For example, the pioneering
Recommendation ITU–R BT.798 stipulates "that
digital television terrestrial broadcasting should fit in
the channels (6, 7 and 8 MHz) intended for analogue
television emission in the VHF/UHF bands”. This
Recommendation, forbidding the bandwidth used
for digital programmes to go beyond the analogue channel bandwidth, paved the way for the development
of sophisticated digital compression techniques.
The amount of spectrum in the VHF and UHF
bands that is above that nominally required to accommodate
existing analogue programmes, and that
might be thus potentially freed up in the switchover
from analogue to digital television, is defined as the
digital dividend. This is illustrated in Figure 1.
How can the dividend be used?
The amount of spectrum to be released in the
switchover depends primarily on national peculiarities
such as the geography and topography of a
country, the degree of penetration of cable and/or
satellite television services, requirements for regional
or minority television services, and spectrum usage
in neighbouring countries. The amount also depends
on the digital television technology being implemented
to replace analogue services. Therefore, the size
of the digital dividend will vary from region to region,
and from country to country.
The range of users to which the digital dividend
spectrum can be opened is wide and includes additional
terrestrial broadcasting services, mobile multimedia
applications, mobile communications, and
wireless broadband access systems. Broadcasters can
significantly expand their services to potentially include
delivery of new interactive and high-definition
television programmes. Mobile television, being a
good example of a convergent service,
is also a promising potential user of the
digital dividend spectrum.
New potential users that do not belong
to the broadcasting family of applications
consider the dividend spectrum
as an opportunity to respond to
the growing demand for new wireless
communication services. These would
include delivery of ubiquitous broadband
Internet access to areas not yet reached
by landlines, thus helping to overcome
the digital divide. Moreover, there might
also be a possibility for broadband access
in the empty spaces between television
channels in a particular region, for example
in white spaces (temporally and/or geographically
unused television channels).
The digital dividend spectrum is located between
200 MHz and 1 GHz. These frequencies possess superior
signal propagation characteristics to those at,
for example, 2.4 GHz. The industry has expressed interest
in using these lower frequencies to facilitate
provision of coverage and thus to achieve an optimal
balance between transmission capacity and operational
range. This would mean that less infrastructure
would be required to provide wider mobile coverage,
all resulting in lower costs for communication services,
especially in rural areas.
Spectrum issues in accessing the benefits of the digital dividend
If the digital dividend is to be utilized by mobile
services, a worldwide (or at least region-wide) frequency
harmonization is a required condition. Such
harmonization would create enormous benefits in
terms of social impact and increased productivity. In
particular, mobile operators and equipment manufacturers
would be able to address a large market,
leading to economies of scale and preventing high
costs for handsets.
The possibility of harmonization depends primarily
upon the timing and coordination of the analogue-todigital
switchover process; the digital dividend spectrum
will be fully available only after analogue switchoff.
In this respect, the GE06 Agreement (adopted in
Geneva at the ITU Regional Radiocommunication
Conference 2006) calls for the transition to be completed
by 17 June 2015 for the countries in Region 1
(except Mongolia) and the Islamic Republic of Iran.
In Europe, many countries will close down their analogue
television transmissions by 2012.
The situation is quite different in Region 3, where
some countries have made their plans for the analogue
switch-off, while others are only considering
this possibility. Moreover, different analogue standards
and different channel rasters are used across
Region 3. Another constraint is that broadcasting
channels are scattered on a non-contiguous basis
across the whole UHF band. Though digital terrestrial
television services have been introduced in some
countries of Region 3, they are based on different
standards (DVB-T, ATSC, ISDB-T, DMB-T), all using a
different channel raster. In contrast, a single standard
(DVB-T) is chosen in the countries that are contracting
members of the GE06 Agreement.
It should be noted here that parts of the UHF
band are also allocated to primary terrestrial services
other than broadcasting. Protection of other primary
services may limit the ability to use the digital dividend
in some countries.
ITU activities
The World Radiocommunication Conference 2007
(WRC-07) allocated the upper part of the UHF band
(790–862 MHz) to the mobile service in Region 1 as
from 2015, and allowed some countries of this region
to use this allocation immediately, under certain
conditions. These conditions include protection of
the GE06 Agreement and all its future developments.
Countries that wish to implement mobile services
in the band 790–862 MHz are required to protect
broadcasting services against harmful interference.
Also, before putting mobile services into operation,
agreements from neighbouring countries must be
obtained.
These ITU allocations open up the possibility
(but not the obligation) of choosing for the digital
dividend up to 72 MHz of spectrum (18 per cent of
the UHF television band) currently allocated to the
broadcasting service. It should be said that 320 MHz
(82 per cent of the UHF television band) is being reserved
predominantly for the broadcasting service in
Region 1.
Furthermore, WRC-07 identified the UHF frequencies
allocated to the mobile service on a primary
basis in all three ITU regions for use by administrations
wishing to implement International Mobile
Telecommunications (IMT). This can be considered as
a signal to industry to develop equipment for worldwide
use.
However, recognizing the potential for interference
between the mobile service and other primary
services in the band 790–862 MHz, WRC-07 decided
that ITU would conduct technical studies on sharing
among the mobile and other allocated services in the
band in Regions 1 and 3. The results of these studies
will be reported to the World Radiocommunication
Conference 2012 (WRC-12) under Agenda item 1.17,
in order to ensure the adequate protection of services to which this frequency band is allocated, and
take appropriate action.
In view of the complexity and importance of the
issues related to Agenda item 1.17, a dedicated Joint
Task Group 5-6 (JTG 5-6) was established. It studies
how the mobile service can share the relevant band
with the broadcasting, aeronautical radionavigation
and fixed services. Recognizing that there is a
lot at stake with respect to the future of the digital
dividend, administrations are attaching much importance
to the activities of the group, whose work is
scheduled for completion in May 2010.
End of the story — or a new beginning?
The digital dividend arises from the ability of digital
compression systems to allow the multiplexing of
several television programmes and their transmission
over the spectrum previously used by a single analogue
television channel. It means that the process of
gaining access to the digital dividend spectrum is still
progressing, as more advanced digital terrestrial television
standards for infrastructure and for compression
(e.g. the second generation of digital terrestrial
television broadcasting transmission systems), offering
higher bit rate capacity per Hz than existing systems,
are being gradually developed and introduced.
The digital dividend spectrum can be used for innovative
services, from improved and new interactive
television broadcasting to mobile communications
and wireless broadband Internet access. Only
a fair and well-balanced distribution of this spectrum
among different information and communication
technologies will deliver the full social and economic
benefits of the digital dividend, thus maximizing its
value for all users. This can only be achieved by effi
cient and effective spectrum management. All concerned
sectors need clarity on this issue when developing
their strategies for the coming years.
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