A new standard for the digital over-the-air transmission of television signals in the United States will emerge within three years, says Mark Aitken, VP of Advanced Technology of the Sinclair Broadcast Group and the chairman of the ATSC TSG/S4 specialist group responsible for Mobile DTV standardization.
For an industry that completed the transition of full-power stations to DTV in mid-2009, Aitken’s view might seem extreme. But the completion of the June 2009 transition, while fresh, doesn’t involve new technology. “The major elements of that standard — VSB, for instance — are 20 years old. Today, we are living a vision of what was possible 20 years ago,” says Aitken.
Aitken, who delivered a paper last week at the 2011 SMPTE Annual Technical Conference & Exhibition on the future direction of television transmission in the United States, envisions the deployment of a “heteronet,” or heterogeneous network in which digital television broadcasting is overlaid onto the wireless infrastructure to leverage the strength of television — one-to-many transmission of spectrum-hungry video — and that of the wireless Internet and cell networks, namely interactivity.
Aitken points to the work the Femto Forum is doing to make the switchover between a cellular network connection and a femtocell Wi-Fi connection seamless and completely transparent to cell phone users as an example of how a future heteronet involving digital TV transmission and cell sites should be approached.
“My (SMPTE) paper was the other end of that. What I am talking about is a broadcast overlay. It is the extension outside of the home of the download side of the (cell) radio network. It is the inverse of Wi-Fi. A broadcast overlay is about reaching the entire market,” he explains.
But why is a new digital broadcast standard necessary? Couldn’t the same thing be accomplished with the ATSC A/53 advanced television standard and ATSC A/153 mobile standard?
“We have spent all of this time and effort developing a mobile standard, which is good enough for free over-the-air TV, but severely lacks now or in the future to provide the QoS that a paying consumer would expect from any service,” says Aitken.
Despite the ability of gap fillers and distributed transmission to boost signal, there is an inherent problem with today’s digital TV standards, says Aitken. “In a world of distributed transmission and ATSC, while you may well increase the signal level and ability of the mobile device to receive, because of the unquantified performance of (DTV) set-top boxes and what we know about a large part of the set-top boxes because off the NTIA (National Telecommunications and Information Administration) coupon box program, we know having a positive impact on a mobile service will have a negative impact on a fixed service,” he says.
Aitken explains that mobile DTV receivers are equipped with long equalizers and set-top boxes rely on short equalizers. As a result, adding on-channel repeaters and other similar approaches “sort of works for mobile and doesn’t work for fixed reception,” he says.
In the view of Aitken, a new digital television transmission standard designed to fulfill the overlay role not only will overcome this problem but offer wireless carriers an important reason to transition from spectrum competitors to broadcast allies and business partners.
“If we harmonize what we do with those who today are our competitors and leverage and harness the attributes of the standards they use, and if we commit ourselves to taking on a different role, then all of those things are open because of very changed political and technical environment.
“At the end of the day, we will all come to realize that we don’t have a spectrum shortage, we have a myopic view of how spectrum should be used. There is enough spectrum if you have a clear view of how it should be used, but there will never be enough in a one-to-one model.”
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