“MUST EVERYTHING BE MOBILE?” A Radioman’s Paean to the Wired Telecommunications Circuit
The US economy, juiced by the national popular culture, is about to commit another major telecommunications blunder! The title of this piece gives a clue to it. Since there is no way to stop or to prevent the developing blunder, it might be of some use at least to understand what we are doing.
American consumers, gleefully aided and abetted by the commercial carriers, have become besotted by the concept of “wireless.” Thus the public now demands that its communications and entertainment pastimes must become “untethered!” They want to take everything they do (voice, text, movies, e-mail, games, television, search, music, navigation, Web browsing, photographs, home video, and perhaps even remote control over their kitchen coffee pots) along with them on their persons—– everywhere and forever. They want “permanently-connected Web-direct to the belly-button!” They want it twenty-four hours a day and even more if they could just fit the time in! They want it all, even though they don’t have either the background or the interest to understand the future ramifications of this wish.
Would it shock you, Gentle Reader, to discover that the Curmudgeon has a slightly different “take” on this? That his fifty years as a radioman provides a perspective that a frenetic teenager or a (formerly) upwardly-mobile “Twenty Something” doesn’t have? That all the narcotic-like addictiveness of the latest “Belt Toyz” looks somewhat different when viewed in the context of the history and the engineering realities of telecommunications? (And just to settle a point, yes the Curmudgeon has used most of the Toyz in his business life, and found them more of a distraction than a benefit.)
Certainly, as a society we have the technical skill to take every existing telecommunications service and application and to port them all onto wireless platforms. Or, at least we could try to do so. Whipped up by consumer hysteria and a hype-driven feeding frenzy, we can gloriously “burn” the radio frequency spectrum and continue to do so until the Nth+1 “must have” mobile application collides with an empty resource locker. And that is precisely our looming public policy crisis: there just isn’t enough radio spectrum to give every person in America unlimited “mobility” for every possible application that he or she might ever want.
Let’s say it again, just to be sure that everybody gets it: “WE DON’T HAVE ENOUGH RADIO SPECTRUM TO PROVIDE THE PUBLIC WITH EVERY FUNCTION THAT IT THINKS IT WANTS TO USE VIA A MOBILE PLATFORM” Well, we might possibly have enough spectrum if we zeroed out all the existing licensed radio users: Public Safety, Maritime Mobile, Business, Aeronautical Mobile, Military, Amateur, Broadcasting, fixed microwave and satellite, all levels of government, and more. Does anyone want to propose doing that to facilitate “universal texting?”
Some rationality, in the guise of humble common sense, is desperately needed to sort matters out here. Which of the myriad of telecommunications systems now in use or coming along absolutely requires “wireless?” And which ones can be beneficially entrusted to the humble fixed land line circuit (which includes both metallic and glass transmission media)?
The Curmudgeon spent much of his career working in various aspects of the art and science of what was then called “radio” and now is known as “wireless.” He has always stood in awe of the wonder of the transmission of information through free space by electromagnetic waves! But that doesn’t mean that he is in any way ignorant or dismissive of the virtues of the land line telecommunications channel! He would be one of the first to admit that there are many practical circumstances under which the use of a wired telecommunications channel would be preferable to a wireless channel. For, in the final analysis, the limited amount of available “wireless” capacity should be reserved primarily for those specific applications where “you just can’t get it done any other way.”
Fixed land line communications channels have a number of inherent advantages over wireless channels, of which only two of their pluses can be highlighted in the available space. The first advantage is their very high path availability, which is defined as the percentage of a channel’s total operating time during which the channel is fully functional and available for its designated use. In a properly engineered land line circuit, path availability asymptotically approaches 100%. In the very best wireless circuits, path availability approaches “five nines,” or 99.999%. That figure translates into a wireless channel maximum outage time of about five minutes per year. Do you think that “only five minutes” is a trivial amount of unavailable channel time? Ask a stock broker what five minutes of outage would mean to his operations! And in the Public Safety mobile radio world, which is a fairly good model for the emerging “consumer mobile device” environment, the path availability is at best only 95%, and even reaching that figure requires some expensive engineering designs.
The public’s expectations for electronic communications have been conditioned by almost a century of its use of wired channels or, in the special case of wireless broadcasting, signals which are generally always tens of decibels above the ambient noise level. Consumers expect 100% path availability; they don’t know how to deal with lower-quality channels. And if they don’t like “dropped” cellular telephone calls now, how well will they do with dropped mobile Web pages, dropped music streams or movies, etc.?
A second advantage of wired channels is their spectral bandwidth availability. We can see that there isn’t a nearly sufficient amount of available RF spectrum to handle the total job of “broadbanding America.” (And led by the politicized FCC, the “broadbanding job” is being pushed onto the RF spectrum largely because doing it in RF is “cheap and quick” compared to hanging cable! RF capital investments are smaller, and the profits begin rolling in more rapidly.) But “wires” always have abundant internal spectrum available, limited only by the ingenuity of engineers to use it. Each copper pair in a cable, each glass fiber in a bundle, has available for use within itself the entire radio frequency domain, or the equivalent capacity in the time domain. And the adjacent wire pair or fiber contains another complete and independent universe that adds to the available resources!
The end uses that the public makes of communications channels are not a legitimate topic for an engineering discussion; ethically as engineers “we can’t go there.” But careful thought should be given before a consumer application that could be satisfied “on the wires” is instead dumped onto the RF spectrum. Do we really need to do this? Do we really want to burn up our very limited public resources for just a “nice to have” application? Are we about to create the radio spectrum equivalent of a deep-water blowout?
Of course this discussion will have absolutely zero effect on the forthcoming public policy decisions; the Curmudgeon well understood this even as he wrote it. In the marketplace, “popular” always trumps “thoughtful,” and the United States is, above everything else, a vast market! We as a country will blithely squander our resources and then, looking back in time, we will wonder why we did it. But to the Curmudgeon, destroying the RF spectrum solely in the name of chicness and a quick profit makes as much sense as slaughtering panda bears for their meat! “Wireless” is not a toy: it’s a very limited resource and a tool! And this fundamental view will never change.
Please consider for a moment, when you reach for your wireless iTrinket, that the terms “conservation” and “conservative” derive from the same language root, which root means “to protect from harm or destruction!”
What do you think?
“Let’s save the universe for RF”
The Old RF Curmudgeon