Ultra HD - TELE-satellite International Magazine

as many bits per second in a given bandwidth
as is physically possible. Further
improvement in spectral efficiency is
practically impossible. So, if we ever hope
to see DVB-C3, the potential improvement
won’t be related to efficiency but
rather to something else.
It must be already obvious to our readers
that today’s DVB-C receiver will not
be able to receive the future DVB-C2
signal. DVB-C2 is not backward compatible
with DVB-C. Of course a DVB-C2
receiver will be able to receive the new
and the old standard, similar to DVB-S/
S2 equipment.
A very interesting feature of DVB-C2
(identical to that of DVB-S2 and DVB-T2)
is its ability to carry not only DVB transport
streams with MPEG2/4 video but also
the so-called generic stream which was
developed specifically to transport Internet
IP data. IP data can be sent either on
its own or in combination with an MPEG
stream. The concept called Physical Layer
Pipe (PLP) was developed for this purpose
and because of this, DVB-C2 becomes a
■
transparent data link for all kinds of digital
information
This extra flexibility is important
because when combined with DOCSIS
it enables the broadcaster to smoothly
switch to more interactive services
(unicasting, on-demand content, etc.).
DVB-C2 was late compared with DVB-S2
and DVB-T2. Implementation of “older
brothers” was often combined with the
introduction of HD and MPEG4. In such
cases it was easier to make a decision
about the extra cost necessary for
the upgrade. Since HD and MPEG 4 are
already present in many cable headends
and end-user boxes, the operators might
wonder if the increase in efficiency alone
justifies the switch to DVB-C2.
Fortunately, DVB-C2 is similar to DVB-T2
so the chipset prices should be comparable
to existing solutions. Most likely T2
chips will simply be re-engineered for C2
compliance. Hopefully, at some point in
the near future, the same tuner would be
able to receive both DVB-C2 and DVB-T2,
but we are still waiting to see that. It took
Table 2. After upgrading from DVB-C 256-QAM to DVB-C2 1024-QAM it becomes possible to send roughly 20 Mbps more data in the same channel
while keeping the same C/N (no need to boost signal power). If we decide to switch to DVB-C2 4096-QAM and increase the C/N by 5 dB, we could then
send 30 Mbps more!
12 TELE-satellite — Global Digital TV Magazine — 08-09/2010 — www.TELE-satellite.com
four years for DVB-S2 to become commercially
available after the specification
was frozen so it may also take a few years
for the cable standard.
The future of DVB-C2 will look much
brighter when it is adopted as a physical
layer by the forthcoming new DOCSIS 4
standard; this is very likely to happen.
However, even now, many of the leading
cable network operators in Europe
have declared their intention to immediately
introduce DVB-C2. Among them
are; YouSee (Denmark), Numericable
(France), Kabel Baden Württemberg, Unitymedia,
Kabel Deutschland (Germany),
Ziggo (The Netherlands), ZON (Portugal),
ONO (Spain) and Com Hem (Sweden).
They supply more than 35 million homes
which in turn translates to 35 million
DVB-C2 set-top-boxes. DVB-C2 is almost
certainly on the roadmaps of many IC and
equipment manufacturers worldwide.
For more information on DVB-C2 you
can check out the DVB organization at:
www.dvb.org, www.dvb-h.org, www.
mhp.org and www.dvbworld.org.