Through The Looking Glass, Our Vanishing Spectrum – Part II

There’s so much heat on in the spectrum and broadband areas today, LBA asked the Curmudgeon to expand a bit on his last posting’s spectrum musings.

In the last blog post we identified the looming potential problem of total consumption of the radio frequency spectrum.   If we want to head this off, we need to begin with some guidance about how we should rationally allocate and use the spectrum  — for what sorts of things should it be used, for what other sorts of activities should it not be used?  What should we be doing with it today and what should we not be doing?  And the emphasis is on….

We will start with a living chap who, although not particularly well known as such, may be one of the most significant telecommunications visionaries that this country has produced.  The curious thing is that he is not an engineer or a scientist; he was trained as an architect.   His name is Nicholas Negroponte.  (Yes, you have heard that family name previously: older brother John Negroponte was a US ambassador to the United Nations).  Today, Nicholas is one of the guiding forces behind the “One Laptop per Child” movement which seeks to provide a $100 (maximum cost) functioning laptop computer to each school child in Third World nations.

Nicholas has held a number of significant assignments, but the one that will interest us here is his serving as a founder and the first Director of MIT’s Media Laboratory, back in the 1980s and 1990s.  The Media Lab was (and still is) a place where many new and revolutionary ideas about the mass media and telecommunications were/are proposed, debated, and in some cases reduced to practice.  A book by Stuart Brand with the name “The Media Lab” documents much of the early history of the place, and although now dated it is still worth a reading.  You may find surprising the percentage of the Lab’s predictions from those early days of communications and computing that have now come into commonplace use.

Among many other novel ideas flowing from Negroponte and the Media Lab, he proposed a fundamental communications concept which, to the Curmudgeon’s way of thinking, is simply brilliant in its simplicity and universality.  In just a few words it lays out the basic guidance for the rational uses to which the radio frequency spectrum ought to be put.  By rights it should be known as Negroponte’s Law, although the Curmudgeon is not certain that this identification has been designated.  But it has been called the Negroponte Switch (switch as in “change-over,” not switch as in “make and break circuit element”).

At the fundamental, bedrock level, as paraphrased here, Negroponte teaches:

Telecommunications services which are FIXED in nature (i.e., where the receiver is at a stationary location) should preferentially be transmitted by wired circuits; telecommunications services which are MOBILE in nature need to be transmitted by wireless circuits (i.e., by radio).

What an elegant idea!  It’s one of those simple little concepts for which it might be said, “anyone could have thought of it!”  And nobody except Negroponte actually did.

It says that, in a world of limited spectral resources, let’s use the radio spectrum for transmission only where and when we need it, and avoid using it where other choices are available.  That principle is, truly, the Ursprung of spectrum conservation!

So, as Negroponte did, let’s apply it toward rationalizing today’s telecommunications world and, noting some caveats along the way (for there are some valid practical exceptions that need to be made), let’s see how well we’ve done at meeting the target.

Let’s begin with broadcasting, but we’ll have to be a bit more specific: we’ll treat aural and video broadcasting separately, and leave text broadcasting for a later time.  Video broadcasting — it is a fixed or a mobile service?  Viewers generally sit in rooms in front of stationary receivers.  And the Negroponte Law choice for television?  To a huge extent, it’s a fixed service, so it goes to the wires for transmission!  We don’t need to tie up huge chunks of radio spectrum with basic television distribution; there’s enough wire line capacity in most places to handle that chore.  In fact, the only reason that television broadcasting has spectrum allocations is an historical one: after World War II, when television broadcasting was first authorized, the use of the radio spectrum was the ONLY way in which it could be easily and cheaply mass-distributed!  That’s no longer the case.

Now for the exceptions.  There are some rural, sparsely-populated areas of the country where it is economically infeasible to “hang cable.”  These may still need RF distribution, either from local translators or by limited satellite service.  And there is some developing interest in broadcasting to cellular telephones, although the acceptance of this by the public is not yet really known.  But this is a special, bandwidth-limited television signal.  Consequently some bandwidth-limited frequency allocations may be needed for “cellular television.”  Overall, though, the traditional over-the-air broadcast television distribution system needs to be “sunsetted” and eventually removed from the radio frequency spectrum!  To what purposes the liberated spectral resources might be allocated is quite a different matter, one which will be considered later.

Aural broadcasting: Most people listen to broadcast radio primarily while driving automobiles or using public transit services, or on small portable receivers while doing other things such as jogging, gardening, or working around their homes.  Radio certainly is a mobile service and it should keep its access to the radio frequency spectrum.  But there is also some true fixed broadcast usage:  “Internet radio” is expanding.  It consists of both live and previously-broadcast program streams from on-air broadcasters and also the independent audio streams from Internet-only program distributors.  As is the bulk of all Internet traffic, Internet radio is primarily distributed by wire transmission.  Since, in a general sense, wire line transmission is not capacity constrained as is the RF spectrum, the Internet can host a very large number of “radio” stations without jeopardizing a national resource.  Thus it is a “good” place for the expansion of aural broadcasting, although there will always be a need for radio frequency transmission as well.

One additional caveat: per the discussion in an earlier blog posting, the United States has parallel broadcast radio services, on “AM” and “FM” bands.  There is no longer a need for both services, and one of them should relinquish its spectral allocation (a mandate which is easy for a telecommunications theorist to deliver, but there are practical accommodations that will need to be implemented as well.)  VHF FM radio, especially as it gradually transitions into full digital broadcasting, has the clear technological lead.  It also has the majority of the listeners, and it has the capacity of absorbing much of the current content of AM radio as well.  Thus, AM radio should be “sunsetted,” and its spectrum refarmed.

Print space is short, and we will continue the Negroponte’s Law examination of other radio spectrum users in subsequent posts.  For now, though, once you see how the game is played, you might want to try it by yourself.

What do you think?

“Let’s keep the universe safe for RF!”

The Old RF Curmudgeon