You Don’t Have to Be Einstein to Understand Broadcasters Are Efficiently Using Spectrum
A bad combination last night — catching up on reading the latest in the broadcast spectrum debate followed by a book on the life and sayings of Albert Einstein. Fell asleep, and dreamed of walking the tree-lined streets of Princeton with the Great Professor, discussing spectrum policy. It went something like this:
Me: It’s frustrating — we’re getting the facts out there about television broadcasters being extremely efficient spectrum users but the message just isn’t sinking in. Almost every other day somebody criticizes broadcasters for “squatting” on spectrum. It’s unsubstantiated rhetoric from the uninformed, but the future of broadcasting is at stake.
Einstein: “I never think about the future — it comes soon enough.”
Me: Well, the future may be coming pretty fast now for serious consideration of broadcast spectrum reallocation. The selling job for how simple it would be to reallocate spectrum from television broadcasting to mobile broadband ignores a lot of important details, but a lot of people are buying into it.
Einstein: “Everything should be made as simple as possible, but no simpler.”
Me: Exactly. Here’s an example of an argument about the inefficiency of broadcasting that is just way too simple to be true. The argument goes like this: Broadcasters have 294 MHz of spectrum available in Washington DC — 49 channels between channel 2 and channel 51 — and…
Einstein: But there are 50 channels between channel 2 and channel 51.
Me: Sorry, I shouldn’t have over-simplified. Channel 37 doesn’t count — it’s reserved for radio astronomy. Anyway, we have to deal with these armchair analysts who will argue that there are 49 broadcast channels available in Washington DC but there are only about a dozen or so television stations, so the rest of the spectrum is being wasted.
Einstein: Oh, I see what you mean. So they ignore the fact that stations that operate on the same channel have to be a certain minimum distance apart so they won’t interfere with each other. And in congested areas, like the East Coast, the distance between cities is such that you just can’t re-use the same channels in nearby cities, so the total number of channels needed is a lot more than the number of stations in a given city.
Me: You catch on quick. And that’s true for operating on adjacent channels too, since television receivers don’t have the ability to perfectly filter out station signals in nearby cities that use adjacent channels, although you can use adjacent channels for stations in the same city. But that means, for example, you can’t use the same channels or adjacent channels in Baltimore and Washington DC, since they’re only about 40 miles apart. And if you add a third city close by, and a fourth, those 49 television channels don’t really go very far, not when you’re dealing with the over 1700 stations in the country. So this attempt at a common sense theory that broadcasting could get by with far fewer channels without reducing the number of stations or reducing the service areas of those stations just doesn’t fit the facts.
Einstein: “If the facts don’t fit the theory, change the facts.”
Me: That’s about the size of it.
Einstein: The adjacent channel angle is interesting. How close adjacent channel stations can be to each other would be determined by the relative ability of receivers to reject those unwanted adjacent channel signals, no? Are the interference rejection characteristics of the receiver population well known and reliable?
Me: Not to a great degree of certainty. Funny you should mention receiver characteristics though. The FCC has never adopted mandated receiver standards for wireless services. But an official at the National Telecommunications and Information Administration (NTIA), which oversees government use of spectrum, just sent a letter to the FCC telling them that when designing new wireless services that will share the use of spectrum with other services, “one of the key steps in any analysis is identifying the interference protection criteria (IPC) of the incumbent receivers.” They also said “the FCC should seek comment on how the IPC values should be specified for incumbent receivers, and the specific IPC values to be used.”
Current and former technical FCC officials also talked about the need for receiver standards recently and noted that the topic of receiver standards is one that will be addressed, and recommendations made, by the FCC Technological Advisory Council — hey, I’m a member of that group. The second public meeting of the Technological Advisory Council is on Wednesday of this week.
In addition, NAB President and CEO Gordon Smith just sent a letter to key Congressional leaders pointing out that the FCC is starting to take notice that knowledge of receiver performance for rejecting interfering signals is critical to making the most efficient use of spectrum in designing wireless services. Frankly, all this newfound interest in exploring obligations for receiver manufacturers to meet performance standards for the sake of efficient spectrum planning is a rather refreshing new approach.
Einstein: “We cannot solve our problems with the same thinking we used when we created them.”
Me: I’m not sure whether you’re being cynical or ironic, but I certainly agree with the sentiment. And I’m sure you’ll appreciate that it’s really hard not to be cynical about politicians and regulators insisting that a broadcast spectrum re-allocation process will be all-voluntary for broadcasters. Participating in incentive auctions, assuming that Congress authorizes them, might be voluntary actions. But to clear the significant nationwide spectrum swath desired by the mobile broadband providers, broadcast stations will need to be re-packed, or re-located, into a smaller band of spectrum, and voluntary is not the word to describe that wide-scale operation of forcing stations to change channels.
Re-packing the television channels to create cleared spectrum for mobile broadband without harming the incumbent broadcast service, if it’s possible at all, is a computationally intense math problem for really fast computers. The FCC is developing this capability but all they’ve produced so far was released last June and showed really poor results — only one 6 MHz channel could be cleared nationwide by re-packing the existing broadcasters. We’ve been waiting to see more refined results, or at least a detailed description of the Allotment Optimization Model’s algorithm for re-packing, but nothing has been made available so far. If the computer model has something significant to offer, that would be a basis for further quantitative analysis. Otherwise, this is more of a political debate.
Einstein: “Politics is for the present but an equation is for eternity.”
Me: That boils it down to the essentials. By the way, did you really say “Everything should be made as simple as possible, but no simpler?”
Einstein: Well, it’s certainly been attributed to me by a lot of people. What I really said was:
“It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.”
But it essentially means the same thing, if you reduce the words to being as simple as possible, but no simpler.
Me: That’s definitely irony, right? Well, it was nice chatting with you today, even though it’s just a dream. I am infinitely indebted to you for your time and your insight about spectrum policy.
Einstein: “Only two things are infinite; the universe and human stupidity, and I’m not sure about the former.”
Me: I’m not touching that one.