The future of European digital terrestrial broadcasting will be imperiled if decisions taken at the recent World Radio Communications (WRC-12) conference are implemented without change.
This warning has been sounded by German DVB-T operator Media Broadcast in the latest fallout from the WRC-12 conference, which awarded extra spectrum to mobile communications in parallel with DVB-T. This followed an unexpected intervention at WRC-12 by Middle Eastern and African countries calling for a second digital dividend to be awarded to mobile communications, which are more important for them than terrestrial broadcasting. As Europe is in the same spectral zone, this would affect its terrestrial services, which in some countries, including France, Germany, the UK and Italy, are a major distribution medium for Free-To-Air premium channels. There are also some pay DVB-T services, especially in France, Italy and some countries of the Nordics and eastern Europe.
The African and Middle Eastern move was justified partly on the grounds that it would harmonize spectrum allocation around the world, bringing the Europe/MiddleEast/Africa zone into line with the Far East and the Americas. This all dates back to the last WRC-07 conference when the first digital dividend was awarded, and represents a continuation of the debate over allocation of the crucial UHF bands at frequencies below 1GHz, particularly in the 698MHz to 806MHz and 790MHz to 862MHz ranges (referred to respectively as the 700MHz and 800MHz ranges). These bands are highly prized because signals propagate over longer distances at these than at higher frequencies above 1GHz, with superior indoor coverage, which is valuable for both cellular and digital terrestrial services.
The digital dividend has been liberated by analogue switch off, reducing the amount of bandwidth needed to transmit a given number of channels. But then, the advent of HD, along with growth in number of channels, increased demand for digital terrestrial capacity just at the time cellular services were also clamoring for ever more bandwidth. So, at WRC-07, a compromise was struck whereby the 800MHz band was allocated on a co-primary basis to both mobile and digital terrestrial services, while in most of the Americas and Asia, both the 700MHz and 800MHz bands were carved up this way.
Co-primary means that the bandwidth is shared with equal rights over interference mitigation, so, for digital terrestrial, this entailed additional costs for replanning of spectrum. This was generally considered justified on the basis that the societal benefits of making spectrum below 1GHz available for use by mobile broadband services would outweigh the cost of replanning digital terrestrial television networks, and would result in net gains for national economies. However, in Europe, the preservation of the 700MHz exclusively for digital terrestrial services was in turn justified on the basis that these were major sources of premium TV viewing. Since 2007, however, mobile networks have expanded enormously in Africa and the Middle East, while digital terrestrial transmission is relatively much less important. Furthermore, mobile services have expanded greatly in capacity and have experienced unprecedented growth in demand, fuelled by the more recent arrival of tablets as well as smartphones consuming ever greater amounts of unicast video.
At the same time many governments have made commitments to superfast broadband connectivity at speeds up to 50Mb/s that they have realized they cannot meet by deployment of fiber, or any wired medium, alone, and will need wireless to deliver to more rural locations. This requires more spectrum, especially in the sub-GHz band for the greater range. Against this background, it is easy to see where the African and Middle Eastern countries are coming from.
But, a key part of Media Broadcast’s argument, which is echoed not just by the European Broadcast Union (EBU) but also by many members of the National Association of Broadcasters (NAB) in the U.S., is that the world can never operate on unicast wireless alone, and there will have to be a balance with broadcast services that are inherently more efficient for one to many communications. There will also be a role for broadcasting content in very crowded locations, such as big sports events, as well as for distributing vital information in large-scale emergencies. We have only to look back to what happened in events such as last year’s Japanese Tsunami to see that.
The present proposal would mean that about one-third of the 700MHz spectrum currently assigned to DVB-T in Europe would be made available in parallel to mobile services, meaning they would share that band. This, according to Media Broadcast and many other operators, will endanger the future of DVB-T, given there will be demand for higher bit rates to support emerging versions of HD, which will cancel out any further efficiency savings. Furthermore, there will be increased risk of interference from mobile services at the point of reception.
Already about 20 percent of the DVB-T spectrum had been handed over to mobile as a result of the first digital dividend awarded after 2007.
Media Broadcast makes the further point that these sub 1GHz UIHD bands are more essential for digital terrestrial than for mobile wireless, because of their superior range and penetration. The majority of mobile cells are in urban and semi-urban areas where distances are much smaller and the need is to have good propagation and large capacity in areas of high building density, where frequencies above 1GHz work well.
This last point, though, is less relevant for the current debate in the wake of WRCD-12, since the Middle Eastern and African countries want to use mobile services over longer ranges in sparsely populated regions to a greater extent than Europe.
Media Broadcast’s main point though is that innovation and investment in DVB-T require long term frequency planning and assurances that spectrum allocations will not change. The first dividend had been expected and was reasonable, but operators had received little warning that there would be a second one. This point has strong backing throughout Europe. As a result, it is not yet clear whether the compromise reached will be implemented in Europe, and what further negotiations will take place before the next world radio conference in 2015.