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The Illusion of Spectrum Scarcity
Codeine writes "Presentations
to the Technical Advisory Council (TAC) of the FCC by Vanu Bose "Software
Radio: Enabling Dynamic Spectrum Management" and by David
Reed "How
wireless networks scale: the illusion of spectrum
scarcity." Counterintuitive results from multiuser information theory,
network architectures, and physics: Multipath increases capacity, Repeating increases capacity, Motion increases capacity, Repeating reduces energy (safety), Distributed computation increases battery life, Channel sharing decreases latency and jitter. Highly recommended presentation suggesting that the cost of spectrum management by "exclusive property rights" mandated by the State outweighs the advantages we could obtain
from a new model that acknowledges physics and the 70 years of receiver development since the regulatory model was adopted at the time of the sinking of the Titanic."
Like we need to encourage people to use more capacity! I have more waves buzzing around me already than I know what to do with! I can feel my nuts being sterilized as we speak...err, maybe I should take my Dell lAttitude with 802.11b off my lap.
Yeah, that's better.
On a serious note we really need this, I want technologies that can let my 802.11b network at home work without interfearing with my cordless phone and 2.4gig audio/video transitter and reciever. Right now they all fight for the same spectrum and all lose in someway or another.
-Pete
Soccer Goal Plans
it was better the first time.
"It is a greater offense to steal men's labor, than their clothes"
I want technologies that can let my 802.11b network at home work without interfearing with my cordless phone and 2.4gig audio/video transitter and reciever.
Strangely enough, these are all on unlicenced bands. Sounds like we still need the regulatory bodies to keep the spectrum in some semblance of order.
This is not to say that we shouldn't look into the technologies (quite the opposite). We're just simply not there yet. It would be good to set aside some spectrum for this, though, as a playground for developing new transmission techniques and receiver designs.
"I have opinions of my own, strong opinions, but I don't always agree with them." -- George H. W. Bush
This is a philosophical discussion, but let's also look at the technology.
There are reasons to control. As a licensed radio ham (VA3MVW) I can assure you that if everyone were allowed to broadcast on shortwave ( 30 MHz) we'd have chaos. A kid in Brazil who uses $15 in parts to create a 10W shortwave transmitter can make an entire band unusable in all of Europe. Shortwave covers the world and there is very little bandwith - all of shortwave is only 30 MHz.
The reason things are getting easier now is twofild: technology and physics. Technology, because we can now transmit on GHz frequencies - unheard of just a few years ago. And physics: if you go up in frequency, bandwidth becomes almost infinitely available, antennas become shorter, and range becomes shorter (so less interference).
In other words, good reasons to control low frequencies and good reasons to allow much on wide bands of high frequencies. Which it seems to me is exactly the way it is happening.
Michael
---
BDOS ERR ON A:>
There was a similar article posted on Slashdot a week or so ago.
Yes, advances in technology have greatly increased spectrum efficiency, to the point where we are nearly at Shannon's theoretical limit. But so far, there is nothing at all that indicates we have any way whatsoever of passing those theoretical limits.
Yes, cellular techniques can greatly increase capacity. But the question is - Is the complexity worth the added cost? For some systems, such as the cellular telephone system, the answer is yes. But for others (such as broadcasting), the answer is most definately no. (This may change soon - If we ever get flatrate 3G services, there's a good chance that could replace broadcasting. But that is a LONG way away.)
And let's not forget the huge installed base invested in the old technology. Throwing that all into the junkyard is not worth using newer and more efficient (but much more expensive) technologies.
One of the earlier posters (a ham, like myself) made a number of very good points too. Even with "infinite" spectrum, the FCC has to exist to regulate the airwaves somewhat to prevent interference between stations, especially malicious interference. Someone said it would be nice if their cordless phone didn't kill their WLAN equipment - How would you like it if your neighbor's WLAN equipment was wiping out your cellular calls, and you had no legal recourse whatsoever against him? That's what the FCC is here for.
Anyone who argues that the spectrum is infinite is talking BS. The spectrum itself is infinite, but the USABLE part is not. There are physical limits to which frequencies we can and cannot use. Those limits are expanding rapidly, but resources are still finite.
A final point - The increased complexity of cellular systems means reduced reliability. Their reliability is extremely high, but still, it is more likely to fail than other technologies, such as point-to-point radio, which will always have its place even though cellular phones are beginning to replace two-ways in many areas. 9/11 is an example - Despite being a theoretically higher-capacity system than "low-tech" NBFM two-way radio, the cellular system in NYC was quickly rendered useless by a combination of infrastructure damage and overloading. For at least a month and a half (I don't remember the exact time period), amateur radio (ham) operators provided a significant portion of the emergency communications capacity near the former Twin Towers.
retrorocket.o not found, launch anyway?
I think that bandwidth could be used a lot more efficently. Right now we are treating the spectrum like the analog medium it is. But a digital treatment is more justified. If we were to break everything up into packets, use reapeaters what not, we could achieve a far more efficent utilization of the airwaves. Nearly all bandwidth is allocated to something. But at the same time, most of it is unused at one instant. Using packets like the internet does could do a far better better job of utilization.
HOWEVER, it would require more control, not less. The government would need to mandate all radio equipment manufactors meet new standards (much more rigorous than they do now). All legacy equipment would need to be replaced. New laws would need to be drafted to regulate the medium better.
But so much more is possible. We're using an abundant natural resource like cavemen, and we could do better.
Two (or more) radio transmitters on the same frequency within range of the same receiver will interfere with each other to the extent that usually one of them will not be heard well (or at all). The idea of "software radio" changes nothing unless every transmitter conforms to the same sets of rules and knows exactly where all the other transmitters are and what they are doing.
Even at microwave frequencies someone with a baby monitor on all the time at 2.4gHz will likely cause you problems with your WiFi network if it's close enough; or between you and the main antenna. One unmanaged device would be enough to create problems for everyone in its vicinity even using the software radio methods.
Government regulation of radio frequency spectrum was designed to minimize interference and create "bands" where users could reasonably expect the service they want to be located. Otherwise you would have to search through 10gHz of spectrum to find NBC news. Their concept of "software radio" only works if these radios know every source of possible interference in a geographical area and moves in the right way to avoid it. Who determines which way is the right way seems to me to be important and I'd much rather have a government entity do it.
In addition, the implementation of this system would pretty much require that all the other transmitters be confiscated and destroyed to keep them from mucking up the works.
No one ever had to evacuate a city because the solar panels broke!
If I set up a 138db WW II vintage air raid siren in my back yard for fun and start testing it out -- in all likelihood I'll be dealt with by the local authorities who will be called in by just about everyone in a 1km radius.
On the other hand, if I'm talking to my neighbor over the back fence and some Feds showed up to stop our "noise" the local authorities (presuming this is a jurisdiction that doesn't receive a lot of Federal subsidies) would likely arrest them.
Seastead this.
The trouble is is that you are talking about the technology of 60 to 70 years ago. The point the article makes is that in the modern world it is just an anachronism, rather like a lot of what the government does. Technology has moved on and there isn't a call for the solutions of 70 years ago - solution that in all fairness were enforced by governments ultimately grabbing hold of the medium for propaganda in the run up to WWII. Merely because ham radio was ruined by "the tradgerdy of the commons" doesn't mean that all non-government wavebands have to be commons. In fact, can you think of a single common not held there by a government agaency anyway? Freeing the spectum from the FCC would not necessarliy give way to a commons, any more than property would revert to commons without the IRS. In fact life would be a lot easier.
The point is, everyone should have access to the airwaves. It should not be based on how much money you have. No one has any right to claim they own the air or the airwaves, just as no one has the right to claim they own their air: that's bullshit.
This is sort of like saying "Forget traffic laws, let anyone who wants to get a vehicle and drive it any way they want." Sounds great until someone drives a tank across your front lawn. There might be laws against trespass, but the damage has already been done by the time the tank tread prints are in the grass.
Spectrum regulation isn't some cheesy artifact the government dreamed up to make your life miserable. Among other things, it means you can make radios that tune between 530 and 1700 kHz instead of having to guess where the broadcast band might be. It keeps people from plopping down TV operations right in the middle of a band used for medical telemetry.
I'm not saying the currect system is perfect or anything, but there are valid reasons why some of it (especially the lower areas where broadcasters can be heard across the country or around the globe) still needs to be.
Someone you trust is one of us.