In Broadcast - April 2015 - 44

44

www.inbroadcast.com | Vol: 5 - Issue 4 | April 2015

InMedia

Taking Terrestrial TV Regional
With DVB-T2
By Carl Walter Holst, CEO, Appear TV

T

errestrial operators face the
problem of being squeezed
between wide content offering of payTV operators and the niche offerings of
OTT services.
One important tactic in terrestrial's
play-book is the regionalisation of its
content services, which is enabled by
the DVB-T2 standard.
The
following
three
options
balance an individual operator's
infrastructures and needs:
Option 1 uses traditional regional
head-ends generating full T2MI
streams with regional content. This
method provides maximum ﬂexibility
and does not require regional
backhaul.
It makes all content available at
a regional site, where the gateways
create a T2MI stream. PLP replacement
need not be used. The T2MI stream
is distributed from the regional site
directly to the transmitters within the
SFN.
This approach is simple to manage,
however potential disadvantages
arise from the need to have complex
equipment
(gateways)
at
the
regions with the potential support
implications it may cause. Additionally,
a distribution mechanism must exist
from the regional gateway to all of the
transmitter sites in the SFN.
Option 2 uses centralised T2MI
signal generation together with PLP
replacement to ﬁnalise the signal at
the transmitter edges. The central
location of the
T2 gateways provides an efﬁcient
means for satellite delivery. All
regional content must be backhauled.
The beneﬁts are efﬁcient distribution
and ﬂexible regional PSI/SI handling.
This scenario uses only two PLPs, of
which one is a common PLP. Regional
PLPs carrying local content are created
at the central headend together with
the primary national stream. At the
transmitter sites, the national PLP and
correct regional PLP are merged.
Synchronisation takes place prior
to merging utilising T2MI framing
information to align the streams, the
content of the common PLP is then
added by the receiver to the service
contained in the primary PLP.

This has the following implications
and beneﬁts - it provides optimal
bandwidth usage and regional streams
do not carry L1 signalling data or
timestamps.
Good PSI/SI management and low
bandwidth usage are just two of
the reasons why Appear TV would
recommend this approach it when
using satellite distribution to feed the
transmitters.
Option 3 is a distributed method
(non-backhaul)
that
utilises
independent regional T2 gateways
together with "PLP replacement"
at the edge. This method provides
efﬁcient distribution, but at the cost
of a less ﬂexible PSI/SI regionalisation
model, since every PLP replacement
operation
must
be
performed
deterministically.
A central gateway is used to
generate the main PLPs (usually
only one), which will carry national
content directly to the transmitter
sites. Additionally, further PLPs
may be created at the national site,
either with content for that region
or with no content at all (a simple
place holder). Gateways placed at
regional studios create local PLP's
with content for that region. This is a
completely deterministic process and
all transmitter sites perform the same
operation at the same time, producing
an output that is suitable for SFN
operation.
A key advantage is that regionally
generated streams can be distributed
to transmitter sites with minimum of
bandwidth overhead. This is a method
well suited to satellite distribution in
cases where there is no possibility for
regional content backhaul.
In conclusion, the mechanism that
is best for a particular operator will
depend upon individual circumstances
and future plans.
It will depend upon what the
objectives are and what distribution
infrastructure exists to achieve it.
The ﬂexibility of the Appear TV
portfolio of end-to-end DVB-T2
solutions will ensure that you obtain
the best regionalisation architecture,
whatever your infrastructure plans and
future aims and goals.

Option 1: Traditional regional head-ends

Option 2: Centralised T2MI signal generation

Option 3: Independent regional T2 gateways
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