The Year of the Spectrum
by Robert Bell
New York City, December 3, 2012--For better or worse – and mostly for better, I think –2012 has been the Year of Spectrum. We have seen a series of amazing announcements about step-changes in the number of megabits we can run through a given amount of satellite spectrum.
In 2007, the research firm NSR coined a new term, “high-throughput satellite” (HTS). Until 2012, high throughput was pretty much synonymous with the Ka band of frequencies, able to deliver more bits per hertz due to their shorter wavelengths and re-use of frequencies among spotbeams, from Wildblue and ViaSat-1 to Eutelsat’s KA-SAT, Hughes’ Jupiter, and Ka-band payloads on Avanti, Arabsat, Jabiru, SES, Inmarsat and O3B space-craft. But then Israel’s Novelsat and Belgium’s Newtec introduced modulation technologies that began a well-publicized race toward higher and higher speeds: 250, 310, 500 Mbps and beyond. And in June, Intelsat said that its next generation of EPIC spacecraft would be high-throughput satellites employing the frequency re-use and architecture of the Ka-band birds in a mix of frequencies: hemi or regional beams in C- and spotbeams in Ku- and Ka-bands. No longer an outlier, the HTS design has now gone mainstream.
In WTA’s Teleports in a Gigabit World report, we said that it is only a matter of time before one of these wizards announces the ability to put a gigabit per second through a transponder. As ViaSat founder Mark Dankberg put it in that report, “What we are doing is to give you lots and lots of bandwidth to make your customer happy. You are no longer trying to squeeze high per¬formance out of a small amount of resource, and you are suddenly in a whole new world.”
But this brave new world also brings new challenges – and radio frequency interference is certainly one. The harder we push the spectrum to meet the world’s apparently limitless demand for bandwidth, the worse interference is likely to grow as an issue.
I was recently in Dubai for the annual meeting of the Satellite Interference Reduction Group and saw a startling presentation. SES and Intelsat have recently upgraded their capabilities for capturing information on interference and its sources, and showed the meeting their first results. They confirmed something I suspected ever since I did interviews for two of WTA’s What Customers Want reports, one on the media market and the other on enterprise. I learned that interference is a big issue for broadcasters, because they occupy full transponders carrying programming that earns them revenue. In response to a question about interference, enterprise customers basically said “what interference?” Their needs are met by fractional slices of bandwidth, and the impact of interference on them is not sufficient to get their attention. So the early results announced by the satellite operators were startling but hardly a surprise: broadcast traffic, including SNG, generates only a tiny percentage of persistent interference. By far the biggest source is VSAT carrying enterprise traffic. Which means that, no matter how hard broadcasters work on reducing the interference they cause, they can’t fix what they mostly haven’t broken.
And finally, in 2012, we began looking forward to 2015, when the World Radiocommunications Congress reconvenes and the mobile industry once again comes, like Oliver Twist, saying “Please, sir, may I have some more?” The satellite industry did a good job of defending C-band from land-grabs at the last WRC, and will have to repeat the performance in 2015.
The prospect of 2014 makes the following year-end news item a comfort.
Two professors at the University of California at Riverside have developed a new method that doubles the efficiency of wireless networks. Mobile traffic operates today in half-duplex mode: it sends on one channel and receives on another. A full-duplex circuit sends and receives simultaneously on the same channel, doubling the efficiency. Except that we don’t know how to do it in 3G and 4G. Professors Yingbo Hua and Ping Liang have developed a solution called time-domain transmit beamforming, which prevents the simultaneous incoming and outgoing signals in a full-duplex circuit from interfering with each other. It apparently does so in a manner consistent with existing mobile technologies. Doctors, call your patent attorney.
Don’t’ you know there’s a spectrum crunch? The people want mobile voice and data, and we need your bandwidth now! By 2015, maybe not so much. A Happy New Year to you and yours.
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Robert Bell is Executive Director of the World Teleport Association, which represents the world's most innovative teleport operators, carriers and technology providers in 20 nations. He can be reached at: rbell@worldteleport.org
