6
NEWS & VIEWS
September 2016
Which second-generation DTT
standard suits your needs better?
by dr peter siebert
When the DVB-T2 standard was published in 2009, it was the first, and for
some time the only, second-generation
Digital Terrestrial Transmission (DTT)
standard. Because of its superior spectral
efficiency and its operational flexibility,
DVB-T2 has become very successful,
especially in Asia-Pacific countries that
have predominantly embraced T2 technology.
Now, with ATSC 3.0, there is another
second-generation DTT specification
and the obvious question is: What are
the relevant differences between ATSC
3.0 and DVB-T2? Before answering this
question, I want to congratulate our
colleagues at ATSC. Over the past three
years, they have brought the relevant
experts together and have created a
remarkable DTT specification which is
a marked advance on its predecessor,
ATSC 1.0.
The physical layer of ATSC 3.0 has
reused the basic building blocks from
DVB-T2, which are OFDM and LDPC
Forward Error Correction
Codes. First comparisons
based on simulations for an
AWGN channel have demonstrated a performance
improvement of about
1dB, mainly resulting from
using non-uniform constellations and advanced
LDPC codes.
These tools provide improved performance at the cost of higher complexity. 1dB is for sure an improvement but it
is not in the same range as the transition
from a first- to a second-generation
standard, which in the case of DVB was
about 6dB.
There are additional new tools in
ATSC 3.0, including MIMO. So far, DVB
has purposely not made such a move
for T2, because to date there has been
no commercial demand for it. Obviously,
operators are also concerned about the
more complex and expensive network
infrastructure. Furthermore, ATSC 3.0
extends the operational range beyond
256 QAM by introducing 1024 QAM and
4096 QAM. This allows for more bits per
symbol but at the price of a higher S/N
requirement, which will again result in a
more expensive network.
When looking at the higher layers,
❝In summary, I see one
fund