Mobile TV
is the latest technology where the TV services are streamed on to the
mobile or hand-held devices. Mobile TV is going to get more and more
prevalent over the next couple years . There is lot of momentum in the
area, even if there are a few commercial products so far.
Already, many mobile
operators offer a selection of television channels or individual shows,
which are streamed across their third-generation (3G)
networks. In South Korea, television is also sent to mobile phones via
satellite and terrestrial broadcast networks, which is far more
efficient than sending video across mobile networks; similar broadcasts
will begin in Japan soon. In Europe, the Italian arm of 3, a mobile
operator, recently acquired Canale 7, a television channel, with a view
to launching mobile- TV broadcasts in Italy in the second half of 2006.
Similar mobile- TV networks will also be built in Finland and America,
and are being tested in many other countries.
At the moment, mobile TV
is mostly streamed over 3G networks. But sending an individual data
stream to each viewer is inefficient and will be unsustainable in the
long run if mobile TV takes off. So the general consensus is that 3G
streaming is a prelude to the construction of dedicated mobile- TV
broadcast networks, which transmit digital TV signals on entirely
different frequencies to those used for voice and data. There are three
main standards: DVB-H (Digital Video
Broadcasting - Handhelds) , favoured in Europe; DMB
(Digital Multimedia Broadcasting), which has been adopted in South
Korea and Japan; and Media FLO , which is
being rolled out in America. Watching TV using any of these
technologies requires a TV -capable handset, of course. Among the three
technologies, DVB-H was officially adopted by ETSI (the European
Telecommunications Standards Institute) as the standard for mobile TV
services in Europe.
Just as there are several
competing mobile- TV technologies, there are also many possible
business models. Mobile operators might choose to build their own
mobile- TV broadcast networks; or they could form a consortium and
build a shared network; or existing broadcasters could build such
networks. Some channels will be given away for free, while others are
for paying subscribers only. The outcome will vary from country to
country, depending on the regulatory environment and the availability
of spectrum. In Italy, 3 bought Canale 7 to get its hands on its
spectrum and its broadcaster's licence; in Britain, Finland and
America, the scarcity of spectrum makes shared networks most likely.
Among the various mobile TV
technologies, the likeliest near-term solution will be to unify under
the ETSI-endorsed DVB-H standard. It is considered to be is the best
delivery system currently available for most markets, according to many
of the operators and vendors.
DVB-H:
DVB-H is a terrestial
digital TV standard that uses less power in receiving client than DVB-T
(DVB Terrestial), and allows the receiving device to move freely while
receiving the transmission, thus making it ideal for mobile phones and
haldheld computers to receive digital TV broadcasting over the digiTV
network (without using mobile phone networks at all) .
The basic DVB-T television standard has been modified to enable the
receivers to be less power hungry, as DVB-T is used in an environment
where power consumption is not a major consideration. This power
reduction has been achieved by time slicing so that the receiver is
only switched on in those time intervals when viewing the channel of
interest. These intervals could be anything between a few milliseconds
and a few seconds. It therefore reduces power consumption by being
switched off for the rest of the time when non-required data is being
transmitted. There is therefore a trade off between the data rate
required for the service and how much this can be packed into short
bursts to save the battery power of the receiver.
Like DMB, DVB-H uses COFDM
but with a bandwidth of either 6, 7, or 8 MHz. Additionally it uses a
range of different types of modulation from QPSK up to 64QAM and this
enables it to have a very high data rate. However it is more
susceptible to signal variations and synchronisation problems.
Additionally higher transmitter powers are required than those needed
for DMB. Also frequencies that are likely to be used have not yet been
allocated but it is thought they might be within the existing
television bands. The wide RF bandwidth also means that current drain
is increased, as wide bandwidth amplifiers are inherently more power
hungry.
As it is really just an
extension to DVB-T, DVB-H uses the same specs DVB-T. Video is normally
encoded with MPEG-2 (but can be encoded with MPEG-1 as well,
although very rarely used) and the standard, just like its
other siblings DVB-C (Cable) , DVB-S (Satellite) and DVB-T, is mostly
used in Europe.
Benefits of
DVB-H:
-
An approved standard
for handheld equipment by ETSI (European Telecommunications Institute)
with a high adoption rate worldwide
-
DVB-H is an open
industry standard that was developed by the DVB Project
, an industry consortium and is currently
being supported by leading companies throughout the wireless industry.
-
It benefits from
existing DVB-T infrastructure components, which reduces initial
investments in many cases
-
It provides the best
user experience in the mobile environment, with an energy saving
handset that is only ‘on’ 10% of the time,
programme guide, soft handover and in-building coverage
-
It offers an
excellent, broadcast-quality picture, because the screen resolution is
of a similar standard to VHS
-
Battery consumption is
reduced by 90% due to time-slicing technology
-
DVB-H comes from the
proven DVB standard used in Europe for standard DTV transmission with a
low power mode for battery-powered devices.
-
Efficient use of
bandwidth enables up to 55 mobile channels plus scalability
-
It is supported by
publicly available air interface specifications helping to drive device
interoperability and market development
-
Its security includes
end-to-end control of stream encryption, generation of decryption keys
and delivery of keys to consumers in a billing-integrated way
-
It will be accessible
by an estimated audience of approximately 300 million mobile users by
2006
Mobile TV
Resources:
DVB Project
Nokia
Mobile TV Forum
Mobile
DTV Alliance
Mobile TV Ready for prime time? : Article
3G Americas: Mobile TV white paper /
Tutorial
About
Mobile TV
DVB-H
Online
Competing Technologies Vie for Mobile TV
Trends
Difference
between DVB-H and DAB (pdf)
Wikipedia
DVB-H
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