A lot of noise about White Spaces

Earlier this week the FCC issued a ruling on ''White Spaces,'' allowing unlicensed devices to operate in certain areas of the radio spectrum allocated to broadcast television.

This ruling affects at least three separate constituencies. First, there are the Internet companies and consumer product manufacturers, who can use this very valuable spectrum to, potentially, blanket the country with always-on wireless Internet connectivity. Next, are the broadcasters''after all, this is effectively coming out of their piece of the pie. Finally, the entertainment industry, worried about how an explosion in unlicensed devices might affect those countless theater systems that use wireless microphones.

I wasn't sure how I felt about this ruling, it is controversial, and in some ways, unprecedented. And I am connected to each of those constituencies; I live a large part of my day online, am grateful when I can pop open my laptop and get connected, frustrated when I cannot. I get my television via broadcast, not cable or satellite. And, with a son who is an actor, I attend theater regularly, and cringe when glitches in a sound system mar a performance.

The White Spaces at issue are the TV channels that, in an analog world, come across as static, in a digital world, simply trigger the screen to display a ''no signal'' message. They prevent broadcast stations in a given market from interfering with each other, and prevent problems at the edges of TV markets, say, for example, in households in New Jersey that pick up signals from both New York and Philadelphia stations. So in New York, for example, channels 2 and 4 are used for broadcast, while channel 3 is a white space; whereas in Philadelphia 3 is an active channel and 4 is a white space. The FCC reasoned that since today's wireless systems are capable of scanning for available channels and selecting only empty frequencies for transmission, such systems, at least at low power, would not interfere with television broadcasts; if they knew ahead of time which frequencies to avoid, they'd have even less of a risk of interfering.

The Commission recognized that interference is a potential problem, relying on a technical report explaining how such interference could be resolved using GPS and a registry of existing signals to prevent new devices from transmitting on those frequencies. Such a system has not been tested directly; and a coalition of Broadway producers and directors led by Dolly Parton was among the groups calling for more tests before issuing a ruling. Other opponents to the ruling included professional sports leagues, Las Vegas casinos, and a coalition of rock musicians, as well as television broadcasters and a long list of senators and representatives. Google led the charge in favor of the ruling.

The ruling as issued includes two different levels of protection against interference. First, there are devices that will use geolocation, that is, have a GPS receiver, use that receiver to determine their location, check a database for active local frequencies, and then lock out those frequencies. Such devices will be legal under the ruling.

Second, devices that don't use geolocation, but instead scan for empty frequencies, are potentially legal, but any designs must be submitted to the FCC for testing before being marketed. Essentially, instead of approving this entire class of devices, the FCC is going to evaluate each device individually.

I spoke to two experts about the topic; one, an expert in the U.S. digital television standard, the other, a specialist in theater sound and lighting systems. I didn't go through standard PR channels to clear the interviews with their employers, so both spoke on the condition I didn't attribute their comments.

To my surprise, actually, both were fairly reassuring. The TV expert said that while building the database of vacant channels will take some doing, the geolocation system seems reasonably safe. Spectrum sensing, he says, has so far failed dismally in testing, so whether this is a reasonable technical option is less clear. One thing he said was not clear from the ruling is whether the frequencies to be opened up involve all the white spaces, or just those in which there is more than one free channel in between active channels. That is, for example, if channels 22 and 25 are active, would both 23 and 24 be up for grabs, or just one of them, and if 36 and 38 are active, would 37 be left as a white space or not. ''If no adjacent channels are allowed, there is a lot less white space than otherwise,'' he says, indicating that that may still be subject to discussion.

I expected my theater expert to be as outraged as Dolly Parton but he told me that he isn't particularly worried. While it's unlikely that the geolocation registry will include every little theater company operating out of a high school gym, he says that the current generation of professional audio equipment is agile enough to deal with interference. In fact, he says, wireless mikes often operate at the same frequencies as local TV broadcasts without significant effects. And manufacturers and distributors of wireless microphones are currently assuring their customers that a ''wireless apocalypse'' is not coming.

Instead, he sees the ruling as an opportunity for the theater community. ''Imagine WiFi everywhere,'' he says, ''we could pump video around,'' generate other special effects.

So I'm somewhat reassured that what's good for Google may indeed be what's good for me.

Photo credit: hungy i


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