“LIFE, THE UNIVERSE, AND EVERYTHING…” THE FUTURE OF THE RF SPECTRUM Part 2
Last time we began a discussion about some of the factors (mostly human-created) which could limit the future usability of the RF spectrum. The first two were spectrum-use saturation and the spread of poorly-designed, RF-radiating digital devices. In this post we’ll conclude the Curmudgeon’s list with three more possible factors, and then toss it open for additions by the readers.
The third area that could affect future successful use of the spectrum is the failure to adopt comprehensive digital standards in the US. Certainly some strong nationwide standards that affect the use of the RF spectrum do exist already: ATSC, WiFi, WIMAX (to some extent). But in other RF-dependent areas they do not; the “poster child” for this is digital cellular telephone/PCS. With competing standards comes inherently inefficient use of allocated spectrum. Either two (or more) different digital protocols require duplicate, independent spectral allocations for a given application, or else when two or more standards can co-share a frequency band they will probably do so less efficiently than would a fully-loaded allocation for a single standard.
This has seldom been a problem with analog protocols; usually one of several competing standards quickly prevails. Thus an inexpensive wireline analog telephone will work successfully anywhere in the US, and delivered residential electrical power is always specified as 120 volts (r.m.s.), 60 Hertz! Why must the inability to adopt comprehensive digital standards penalize consumers with higher prices and equipment obsolescence, and afflict the RF spectrum with inefficient and redundant spectral allocations?
The fourth area, as alluded to above, is the growing inability of the FCC to regulate and to enforce usage standards for the RF spectrum. There are two different areas here, and the first is the increasing loss over time (i.e., the past several decades) of the Commission’s ability to perform spectrum management in an engineering-centric manner. Political and economic attacks on the Commission from bellowing hordes of LEPs (lawyers, economists, and politicians, aided and abetted by the major spectrum-consuming industries and their highly-paid lobbyists) have left the Commission today in the posture of a badly wounded prairie dog, lying listless in the tall grass surrounding its burrow and watching the vultures circling overhead. Every politician, every lobbyist for a trade group or manufacturer, “just must have his way,” no matter the cost and no matter the long-term damage to a critically loaded spectrum. It’s the “tragedy of the commons” writ large, and the current US economy doesn’t seem to deal competently and successfully with that sort of thing.
Second, there is the withering of the FCC’s Enforcement Bureau, which is directly responsible for “keeping the law in Dodge City.” As the size and influence of the overall Commission has declined in part because of the actions of LEPs, the EB has taken a large share of the cutbacks. Their limited resources need to be carefully husbanded, and their attention is generally directed first at matters involving “safety of life and property.” Anything else is handled on an “as resources become available” basis, with emphasis on those of these secondary problems that may result in a high-profile, newsworthy action. As a consequence, Broadcast Service pirate operators and stations are only eventually taken down by the EB, then to reappear in an endless cycle. Enforcement actions involving international relations drag on for years without resolution. And shrieking digital devices are almost never investigated.
What does all of this Commission impotence indicate? A future with weak Rules and little policing of the spectrum. Or, in other words, incipient bedlam. And we’ve seen that before: prior to the establishment of the first Federal Radio Commission, there was effectively only very minimal regulation of the spectrum. The mess that developed in this unregulated and un-policed era directly resulted in the establishment of the Federal Radio Commission in 1927! And we could do it all again, if present trends continue.
The fifth area comes from a very unexpected direction: global warming! Setting aside the “skeptics” who apparently have their own (overtly political) ax to sharpen, and noting that the earth has been in its current global warming cycle for about 1.5 centuries (which is a minuscule time-period on the geological time scale, and such warming cycles are a not-uncommon event during the earth’s long history), warming could cause problems for radio spectrum users. But how?
A warmer earth (and atmosphere) will produce climate changes (for example, Mediterranean olive trees have been recently imported into the United Kingdom) and, to an extent, climate does affect EM field propagation. Warmer air in the layer just above the surface of the earth (resulting from the so-called temperature inversion weather phenomenon) results in a slight decrease in the index of refraction of the atmosphere at these heights and a consequent slight increase in the speed of EM waves, principally observed at VHF and above. The component of the waves moving through the (warmer) atmosphere at several thousand feet above ground level travels slightly faster than the component moving through the air just above the surface of the (cooler) ground. This often results in a “bending” of the composite EM wave front toward the ground (i.e., wave refraction). As a consequence VHF/UHF/microwave transmissions bend to follow the curvature of the earth and thus travel somewhat beyond the optical horizon. This is the mechanism of “tropospheric ducting,” a well-known radio phenomenon.
With a warmer earth there may well be an increase in the number and duration of the tropospheric ducts, and thus somewhat longer average operating distances for VHF/UHF/microwave radio systems than the distances that their original licensing had envisioned. This may not produce a major effect on spectrum usage, but it is a phenomenon which can have a deleterious effect on specific installed systems and applications.
Given all the above (and other potential problems, to be contributed by readers in the Comments section), usage of the RF spectrum in future years looks problematic at best. As an example of the current “blind leading the lame into the swamp” cultural view, the Curmudgeon recently noted (with amusement) the predictions of a young technology “guru” about the next decade in computing. “Oh, in the next ten years the PC will fade into complete oblivion. Everything will be done with mobile computing. There will be no need for PCs.” Presumably by “everything” he meant the usual mix of consumer entertainment digital files plus low information content text and voice communication transmissions. Nevertheless, it’s difficult to see how complex financial and engineering spreadsheets or PhotoShop edits will be done on a cellular telephone. Nor had the “guru” ever considered the ramifications of his bold prediction on the RF spectrum, which will certainly take the hit. Quid est demonstrandum!
Of course there are the possibilities of unanticipated future technological advances which might then permit much greater information density per Hertz of bandwidth than is now available and which would then alleviate much of this concern. The FCC seems to be counting on these advances, as they order the shrinking of the occupied bandwidths of existing spectrum users (for example, the “Re-farming” of the Land Mobile Services) But these future developments currently lie outside the range of the Curmudgeon’s vision, and “scheduled breakthroughs” are, at best, a poor basis on which to perform planning.
The bad news is that we humans may well need to make adjustments in our lifestyles and commerce to adjust to a future of spectrum resource scarcities and limitations, but that’s probably going to be true for many other areas of life as well. The good news is that the RF spectrum will endure and will survive all of man’s attempts to tinker with and to abuse it and, if just allowed a modicum of respect, will be ready to provide service again.
What do you think; what are your additions to the list?
“Let’s keep the universe safe for RF!”
The Old RF Curmudgeon