Open Spectrum: The New Wireless Paradigm

prostoalex writes ""Almost everything you think you know about spectrum is wrong." - starts Kevin Werbach in his working paper Open Spectrum: The New Wireless Paradigm. He touches the possibilities of using open spectrum, and then dwells on such innovative products like software-defined radios, spread spectrum or cooperative wireless networking. Truly informative insight into where the U.S. government stands on the issues of wireless spectrum, where it should be, and how it will benefit society and individuals."

Comments

With public domain frequencies...

[kpansky]

there are some really interesting possibilities. Think of software-defined radio letting you join different wireless networks that are decentralized and encrypted using something ala freenet. If you were to couple unfettered access to wireless frequencies where people's ingenuity sets the standard, and not self-interested corporations.

I would personally love to see open hardware designed to utilize wireless technology available similar to the projects at OpenCores.

If I understand correctly

[drhairston]

While the author is correct in stating that modern advances in digital spread spectrum allow digital signal processors to place multiple signals in the same frequency, he ignores the impact this would have on existing analog technologies which are incapable of this feat. I personally do not wish to be walking down the street the day it starts raining model airplanes.

Re:If I understand correctly

[JaredOfEuropa]

He does suggest to limit this to certain bands, such as the current 2,4GHz band, or to do this in existing bands using extremely low power. Neither should affect existing analog technology such as model airplane transmitters.

The idea that spectrum is a limitless resource is a myth, however. The author does say as much somewhere, but mostly he talks as if the spectrum will bear an unlimited number of users, which is bollocks. Having lots of spread-spectrum devices in the same area and frequency band will affect the performance of these devices. If that was not the case, why the hell would we even need to follow the author's suggestion to open up more spectrum for such use beyod the current 2,4 GHz band?

With that said, current analog transmission technology does not make a good use of the spectrum, and assigning a whole band over a large area to one transmitter is terribly wasteful. While I disagree with the picture the author paints in his article, I endorse his plea to make more use of spread spectrum and to assign more bands to unlicenced use.

Not unless they refactor the laws for tort ...

[LL]

(tort is the legal action against harm within common law jurisdictions). Let's consider a future where individuals have wireless wheelchair, interacting with their environment (like doors/cars/etc). How do you prevent individuals being careless (cf case of leaving a concrete block on road for car to hit)?

Courts (in torts against trespass to chattels w.r.t. deciding spam cases) have rules that having an electronic signal impacting on the computer system is sufficient to be "in contact". Now extend this to a generic wireless world and you can see the potential combinations of potential problems. If my wireless car activates someone elses' garage leading to a theft then are you liable? Medical instrumentation are a major concern, as are anything which records ownership (cf person entering building with wireless and downloading trade secrets).

Wireless will change how we interact provided we can sort out how social responsibilities and obligations are partitioned.

LL

Contradictory

[SiliconEntity]

The paper goes on and on about how WiFi shows that open spectrum works, there's no problem with congestion, no need for ownership or frequency allocation. Then in recommendation 2 we read this:

Improving existing unlicensed bands isn't enough. Most are so narrow and congested that their utility for open spectrum is limited.

So here he's saying exactly the opposite, that congestion is a serious problem for open spectrum! Which is it?

It's also bogus to claim that WiFi proves that open spectrum works. The truth is that WiFi is so sparsely implemented that congestion hasn't yet been an issue. For all the hype, my town of 175,000 people has no wireless public access points. Even in the big cities they're not so close that congestion is a problem.

The article could just as well have used cordless phones and baby monitors (which use the same frequencies) as evidence that open spectrum works. The only difference is that they don't score as high on the hype meter. All these examples prove is that the technology works when the range and distribution of the transmitters is sufficiently limited, which everyone knew already.

Human Nature and The Status Quo

[Iguanaphobic]

It is time to question our long-held assumptions, and explore new policy approaches that could generate tremendous benefits for the American people.

He had me until this sentence. Getting the government to act in the best interests of the American people is not on the agenda. The current licensing scheme guarantees profit for the few. The few, in turn, guarantee $$$ to the government. Anything that threatens this simply will never happen.

Learn from amatuer packet radio ...

[Tjp($)pjT]

There are a host of problems with ad-hoc networking schemes such as this. I have a few solutions to them, but mostly they would be overpriced in the consumer market. One such beast that will start to bite you on the * really hard is hidden transmitter syndrome . This is where your controlling nodes overlap, and say node A is visible to base B and base C but base B and Base C are out of each others range. If B and C don't "hear" each other they can't work in unison without a third party. So when Node A (mobile presumably) hunts for a connection, both B and C try to talk at the same time to A, thus hampering the usable bandwidth. Lots more lessons can be learned by just searcjing for the syndrome and reading the other problems mentioned around it.

What about radio astronomy?

[davecl]

With greater use of the spectrum, and the potential for software defined radios to use any frequency they want to transmit on, we're going to close out the possibility of ground based radio astronomy. This is not a good thing!

Radio astronomy produced many of the basic technologies that todays wireless communications revolution depends on, but is seeing none of the (financial) benefits and is gradually getting squeezed out of its own very limited parts of reserved spectrum. Maybe there should be a 1% levy on all radio licenses dedicated to help astronomers get around this problem and properly police their parts of the spectrum. Or maybe all the money raised from spectrum auctions should be dedicated to establishing space-based astronomy in the radio - probably on the backside of the moon to get away from all the noise!

There are needs for regulation to protect the other users of spectrum that wireless networkers forget about. Total spectrum freedom is not possible or a reasonable goal.

For more information see:

AAS webpages.

Re:What about radio astronomy?

[Celandine]

If you read the document carefully, you'll see that he doesn't advocate complete deregulation, and that radio astronomy is explicitly mentioned as a service that needs protecting.

As extremely broad-band radio astronomy receivers (think GHz rather than tens of MHz) are on the way (e.g. the plans for the EVLA) radio astronomers are going to have to abandon the idea of completely RFI-free bands (already a myth at 1.4 GHz and below) and concentrate on ways of automatically detecting and removing it instead. Of course, large numbers of small, frequency-agile transmitters are pretty much the worst nightmare in this sort of scenario...

With clever use of SDR, they might not notice

[Gerry Gleason]

Particularly with the 'underlay' concept, if you could quitely start using spectrum in ways that don't interfere with existing uses, who would know? In the regulatory space, spectrum license holders are always arguing against new uses because they *might* interfere with their bands even though there is precious little evidence that there would be problems.

Of course, this is the big conceptual problem with Open/Free Source SDR in general. Recieving is fine, but as soon as you want to transmit, the FCC wants to regulate the device. Now you are getting into the same problems you have with Open Source and DRM, if the end user has control, they can circumvent any controls by taking them out and recompliling. Buggy or malicious software could interfere in a big way, although the range of the interference would be limited by limiting the power of the transmitter which couldn't be easily overriden.

I like the paper's analogy to ships on the ocean, and I think it is very accurate for spectrum use. Most of the time you can put on the autopilot and sleep without much danger, but you'd better be on watch to adjust your course when you're near the shipping lanes. In any location, most of the spectrum will be silent most or even all of the time, and most modern recievers are pretty good at cancelling interference, so nobody will even notice if you use nearby frequencies.

The TV bands have all kinds of space in them, and there is all sorts of interference already unrelated to unlicensed transmitters. I'm still using my TV antenna in an urban area, and the big problem is multipath interference from all the large steel frame buildings. I wouldn't have any way to know that unused channels were being used for underlay digital comm., and I wouldn't care much either.