The EBU has just released a paper entitled “DTT Quo Vadis” by Ulrich Reimers of Germany’s Braunschweig Technical University. The paper focuses on the future prospects for classical terrestrial broadcasting in Germany. It makes interesting reading, as it predicts the possible termination of terrestrial broadcasting by the end of the decade. Germany is well-served by satellite and cable services, with the result that DVB-T viewing averages only 12.5 percent of viewing, falling as low as 3 percent in one state. The public broadcasters use DVB-T, but the commercial broadcasters shun the service, as the low viewing figures make it a poor business proposition.
Some countries are moving from DVB-T to T2 to enable the carriage of HDTV over terrestrial RF channels. With free-to-view HD available via satellite in Germany, DVB-T is used at higher field strength than in many countries to permit viewing on portable receivers. So, if Germany moved to DVB-T2, it would be to support mobile receivers, rather than terrestrial HD broadcasting to fixed receivers with roof-top antennas.
German stations are now questioning the long-term viability of DVB-T, and are looking to new technologies like Dynamic Broadcasting, which allows interworking between broadband wireless, IP networks and broadcast. It also envisages STBs being preloaded with non-live programming, typically overnight, to make best use of bandwidth. Dynamic Broadcasting does not use fixed channel allocations, but adapts depending on the type of content and viewer demand. The mobile and portable receivers will be served via LTE and LTE-Advanced and Wi-Fi.
However, the cellular network is essentially a unicast system. Reimers describes a possible method by which to overcome the limitations of cellular networks for broadcast video. A proposed standard, Tower Overlay, runs a large point-to-multipoint (P2MP) cell over a number of smaller LTE-Advanced cells using techniques like single-frequency networking. Unicast traffic uses the LTE cells, and video “broadcast” could use the P2MP overlay cell. This concept is being actively pursued for eventual presentation to the 3rd-Generation Partnership Project (3GPP). To understand more, look for the paper on the EBU website.
Combine this with Dynamic Broadcasting, and you achieve a smart network, using fiber, satellite, Wi-Fi and cellular systems. The system’s smart nature allows spectrum to be managed in a way that’s just not possible with the fixed allocation of RF channels to conventional broadcast.
Now the business models in Germany are not the same as elsewhere. In some countries, terrestrial viewing is an essential part of broadcast operations. But in emerging nations, concepts like tower overlay, using cellular networks, may well prove a more cost-effective route than building out a broadcast network separate from mobile services.
Back in the middle of the last century, handheld communicators were a thing of science fiction. The spectrum available easily served the handful of TV channels in a city. The ubiquity of video and TV everywhere has turned spectrum into a scarce resource, and this forward-looking paper from Reimers looks at innovative solutions — some existing, some for development.
One thing is certain: Countries outside Germany are also going to have to actively pursue alternative means to meet the demands from the public for more mobile video and data services. Emerging cellular technology provides one answer for mobile-TV broadcast reception.
—David Austerberry, editor