Dividing the digital dividend

01 Dec 2010

The government’s recent Digital Dividend Green Paper details its planned approach to digital switch-over. Broadcast Australia has responded with two proposed scenarios which specify options to optimise the utilisation of the digital dividend.

A recent government Digital Dividend Green Paper details its immediate goals following digital switch-over—planned to be completed by year-end 2013. The key points covered include the provision of six digital TV (DTV) channels to be available throughout Australia, a digital dividend of 126MHz (from 694 to 820MHz), and the  desire for this spectrum to be available as soon after digital switch-over as possible.

 According to Steve Farrugia, Broadcast Australia Engineering Director, most of the digital dividend will be used by the telecommunication companies for 4G uplink and downlink services. “However, the precise way the liberated spectrum is allocated will have subtly different implications for the future of the broadcast industry,” he said. “We have responded to the green paper with a proposal of two possible scenarios for spectrum planning.”

 Raising the standard

Both scenarios cater for six in-home DTV channels, three TV-channels’ worth of spectrum available for future Australia-wide digital radio, plus one ‘spare’ channel that can be used either for mobile TV or a further in-home DTV service. The principal difference is that Scenario Two features less spectrum ‘wasted’ through the use of guard-bands, thereby freeing-up a spectrum block of 21MHz. See Figure 1.

 “While both scenarios will allow Australia to transition from the current digital video broadcasting terrestrial (DVB-T) standard to DVB-T2—the next generation standard—Scenario Two would make this far easier,” says Steve. “Scenario One relies on using the single ‘spare’ channel to effect this transition, whereas Scenario Two can utilise the entire 21MHz block—equivalent to three channels—for the same purpose.”

 The importance of a future migration to DVB-T2 cannot be overstated, as this will allow 50 per cent more bandwidth per channel compared with DVB-T. If this is combined with a transition from MPEG2 to MPEG4 encoding, a single channel can carry more than double the number of programs than currently possible.

 Poised for action

“Scenario Two definitely represents the optimal choice for the broadcasting industry,” said Steve. “This will facilitate the most seamless future transition to DVB-T2. Moreover, once DVB-T2 transition is completed, Scenario Two opens-up 21MHz of spectrum for further services—in effect, a second ‘mini digital dividend’.”

 However, the telecommunication companies would most likely favour Scenario One, as this will enable them to better coordinate international standards. “We await the government’s decision, before we can begin to make the changes necessary for digital switch-over,” said Steve. “A decision by the government on how the spectrum will be restacked is expected early in 2011.”

 

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