APB chats with Dr Peter Siebert, executive director of the DVB Project, on the merits of DTT, and how a new digital terrestial network architecture can potentially hasten the demise of analogue TV.
In the April 2017 issue of APB, the argument put forth was this: if broadcasters were to harness the full benefits of emerging technologies such as 4K/Ultra HD (UHD), 8K, virtual reality (VR) and IP, all roads start with digital.
Today, that position has not weakened; on the contrary, the case for broadcasters to complete the transition to digital terrestrial television (DTT) is perhaps stronger than it has ever been.
While broadcast TV started with analogue terrestrial transmission, which for a long time was the preferred way to receive TV signals, many countries have now switched off analogue signals and commenced digital terrestrial transmission, notes Dr Peter Siebert, executive director of the DVB Project.
He tells APB: “Digital can offer more choices, better video and audio quality, and because of additional metadata, greater ease-of-use. Whereas these advantages apply to all delivery schemes, there are additional benefits for the terrestrial platform.
“It is the easiest to set up for the end-user — no cable connection is necessary and no satellite dish needs to be installed and pointed. For portable in-door reception, a simple rod antenna may give reception in any room of the household, without the need for heavy indoor networking. Furthermore, DTT is the only broadcast platform supporting mobile reception, at least as a best effort service.”
Where Europe is concerned, the analogue switch off (ASO) has been a long gone conclusion in many countries. Some have gone further by making a second DTT transition, going from DVB-T and MPEG-2 to DVB-T2 and H.264 or HEVC/H.265, Dr Siebert points out.
He highlights Germany as a case in point, where 2017 saw the introduction of the country’s second-generation DTT system, which utilises DVB-T2 and HEVC/H.265 to bring HD and more services to the end-user. “To plan the transition, the relevant stakeholders came together in a round table approach,” Dr Siebert describes. “A wide range of interest groups participated in the planning: public and private broadcasters, network operators, the consumer electronics and retail industry, German regulators and even consumer organisations representing the interest of the end-users.”
All relevant aspects were discussed and agreed during the round table discussions, including: business cases, frequency planning, transition scenarios, transmission parameters, AV coding, receiver specification and perhaps of most relevance, financing and time schedules.
Compliance of the TV receivers and sets to the new specification was then demonstrated by a logo, defined and administered by the round table. This was closely followed by an intensive marketing campaign informing end-users about the changes to come.
Within a nine-hour period on March 29 last year, the switchover to the new system took place without any major flaws, Dr Siebert reports. “There are, of course, many ways for the transition to a new system, and Germany can only serve as an example,” he emphasises. “Nevertheless, there may be elements of the German approach that could be considered for other regions, such as Asia-Pacific.”
According to the Asia-Pacific Broadcasting Union (ABU), as of January this year, only a meagre five countries in the Asia-Pacific region have completed a full ASO. Calling this a “surprising statistic”, Dr Siebert says: “Only a handful of countries [in APAC] have gone through ASO, while others appear to be struggling with their DTT transition, even as people in the region have continued to embrace digital broadcast TV.”
While he acknowledges that each country in APAC needs to define its own road to DTT and ASO, there appears to be no major obstacles standing in the way of the DTT transition. “Digital services via cable and satellite are popular, and as well, there are commercial DTT networks in many countries in APAC,” Dr Siebert explains. “There is certainly no shortage of inexpensive receiver equipment based on DVB specifications (the majority of countries in Asia-Pacific have chosen DVB standards for their DTT transition), and the region has plenty of experienced engineers with the know-how to set up DTT networks.”
In today’s digital age where viewing habits continue to evolve, it is imperative that broadcasters are armed with the mechanisms to interact, get analytics and build loyalty among audiences — all of which are difficult to achieve without going digital, because analogue transmission lacks return paths that can be integrated with modern broadcast services.
For broadcasters who are running digital services alongside analogue ones, they need to give due consideration to the actual costs of running simulcast operations — is this truly economically viable and sustainable over a long period of time?
A new digital terrestial network architecture, however, may well allow broadcasters to make a more cost-effective transition to DTT. WiB, or Wideband Broadcast, is a new DTT architecture with the potential to reduce Opex and Capex for a terrestrial network, and to increase the bandwidth for a given set of frequencies.
Dr Siebert details: “Before WiB, the typical approach for terrestrial network planning is to not reuse the same frequencies for adjacent transmitters, because, except for single frequency networks (SFNs), the receiver would see the signal as noise”
The WiB approach, however, is based on the concept that all transmitters in a network use all available frequencies, which means that there will be interference from adjacent transmitters. “To compensate for the interference, a very robust modulation scheme like QPSK needs to be used, resulting in a lower data rate in the typical 8MHz channel,” Dr Siebert continues. “Consequently, the bandwidth needs to be increased to wideband channels beyond the usual 6MHz or 8MHz bandwidth. Furthermore, additional interference reduction measures, like directional antennas or Layer Division Mutiplexing (LDM), are needed.”
To further analyse the potential of WiB, the DVB Project has set up a special Study Mission Group (SMG). And while the DVB Project’s work on WiB is at an early stage, first simulations have demonstrated that with WiB, transmission power can be reduced by up to 90%. “This would result in significant Capex and Opex cost savings for terrestrial networks. Furthermore, it seems to be possible that the overall capacity of a network could be increased with the new concept,” Dr Siebert reports, while highlighting that more research is required to identify and confirm WiB’s full potential.
“Assuming that the current prediction on reduced power and increased capacity are confirmed, WiB will be the first technology after DVB-T2 to significantly improve DTT networks, and could play a major role in spectrum discussions and network planning in the years to come,” he
concludes.