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back to article WTF is... White Space radio networking?

2012 will be the year White Space radio starts delivering networks of unprecedented speed and range, but if it works then White Space will also change how radio is used across the spectrum. The first commercial radio networks utilising White Space are already running, but in eagerness to associate White Space with the ever- …

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DVB-T and ISDB-T already fix the main problem...

The whole issue with adjacent TV transmitters wasting spectrum by having to transmit on different frequencies is already addressed by single frequency network support in the DVB-T and ISDB-T standards. In principle, all countries which use these standards can efficiently pack all of their terrestrial TV broadcasting into a well defined chunk of spectrum - eliminating the need for location based white space detection altogether. Of course the US decided to use ATSC instead, so that's not a solution that's open to them...

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Mushroom

Simple Answer

It's a fantasy that will damage TV reception for 100,000s of people.

An evil genie that should never be let out of the box. Apart from the fact that even if done as planned it's a disaster of epic proportions, people will disable the geo database lookup, the data base will be inadequate and people will add too powerful aerials or amplifiers.

We don't need this Yuppie DIY outdoor WiFi. Proper protected dedicated Licensed Spectrum is the only solution that works.

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WTF?

Re: Simple Answer

"Yuppie DIY outdoor WiFi"

Did you throw some fridge magnet words up in the air and copy them however they landed?

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Happy

Re: Simple Answer

I like the irrelevant but pejorative association with Yuppies, maybe Pikey-Fi is a term you could introduce? The rest of the post is quite poor. I cannot see users needing to flout the regulations, as there is a legal and adequate means to get the bandwidth desired. The costs of look-up are a free market and will be cheap, and are only required for roaming - where monster aerials would be cumbersome.

I see it as a return of what is "ours" - for our use and for free.

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Boffin

SFN

You can't do very large regions with SFN. Go read how it works. The difference of arrival of signal from two transmissions can't exceed symbol guard time.

SFN doesn't enable so called "White space". It just simplifies planning at some locations.

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Boffin

Re: SFN

If you choose your guard interval appropriately, any 'late' signal which falls outside the guard period will be sufficiently attenuated due to the extra propagation distance that you can just treat it as background noise. Under those circumstances, there is no theoretical limit to the area you can cover with an SFN.

It's not a case of single frequency networks enabling "white space". On the contrary, the more efficiently you use the TV broadcast spectrum the less white space there is - to the point where it doesn't make economic sense to even worry about it.

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Re: SFN

ISTR Spain operates a mix of national SFN networks as well as MFN regional networks and national networks.

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The mathematics behind this concept are awesome

As transmitter power goes down, aggregate bandwidth - bandwidth per square km goes up, way up. So with a 100,000 watt TV transmitter, you have a bandwidth of 6 Mhz spread over hundreds of sq km. Break that into cells 100 m across, and bandwidth goes up by a factor of well over a million. Total power used also drops - even a million wifi routers only use about 50,000 watts.

You can even break these 100m cells down, as a microwatt powered transmitter (say on a phone inside a house) can use a 10m cell size. Combine that with all the other windows of bandwidth and the fact that as power goes down, battery life goes up along with bandwidth, and you can see the end of comm wires for many devices.

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Re: The mathematics behind this concept are awesome

Were we to apply that logic to other infrastructure, we would discover that we don't need motorways, because a thousand five-foot-wide country lanes can hold more cars.

If I raise my voice loud enough, I can manage communications within a 100m radius without needing any RF spectrum at all. The useful things about data networking concern getting information not from within the immediate location I'm in (I've eyes and ears for that), but from somewhere very far away.

Current femtocell technology almost invariably relies on wired backhaul. What's the magic behind whitespace radio going to be? Probably the same - unless you fancy using your battery to forward everyone else's packets. Hype, hype, hype...

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Re: The mathematics behind this concept are awesome

Agreed that it's hype.

It's sort-of-but-not-very-much like the hoary old one about the bandwidth of a 747 full of DAT tapes. It's truly massive. The latency, however.......

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Paris Hilton

Real-time databases = real-time costs

I suspect that these geo-location awareness and frequency information aggregation systems will cost to operate, and hence wind up costing the end users. Is this expected to be deployed in the home? If we move completely to an all white-space wireless society, including at home -- as I doubt we'll retire the ISM bands, this probably isn't likely -- that means you pay for the privilege to operate a wireless network anywhere, whether home or business. As well, it means a central database of all wireless devices which has the potential to defy privacy.

Thought it doesn't necessarily have to be centralized. A white-space awareness infrastructure could be built consisting of many databases coordinating amongst each other, possibly by region, and querying the back-end list of frequency assignments from the FCC or OFCOM. Wireless devices vendors could maintain a list of servers which provide mapping, published by HTTP/S or DNS, for devices to coordinate. Given the right amount of openness, enterprises or even home users could run their own white-space awareness (WSA) server(s) and configure the devices to query those in favor of the vendor-supplied list.

Some kind of simple caching could be involved at the device and WSA interface to allow for connectivity and service disruptions.

Paris, defying privacy for years.

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Mushroom

I have my doubts

I have some strong doubts about all this. It's one of those things that sounds reasonable and only moderately complex in theory, but in practice is fiendishly difficult.

Having said that, 3G mobile works surprisingly well (most of the time) and that is horribly complicated. It took years and millions of pounds/euros to get it working, but the end result is there.

One issue does jump out immediately though - The fact that it relies on a database that you need to access in real time. Presumably this database connection will be via the internet and assumes, I'm guessing, that you actually have an internet connection. But if you had an internet connection you probably wouldn't need the wireless connection in the first place for most applications!

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Boffin

Re: I have my doubts

3G networks use dedicated licensed spectrum Each operator plans their own spectrum, or with a RAN the Network Manager manages the Pooled spectrum.

The Spectrum isn't shared with a Broadcast service. So called "white space" is an illusion.

The "Database" is a clumsy attempt to solve the "hidden transmitter syndrome". Just because this sounds cool, or allows licence free kit or is very clever doesn't make it a good idea.

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Anonymous Coward

Not so much a "freak of meteorology"

Just ask amateurs operating on 144MHz just how Sporadic-E propagation (which is presumably what the "freak of meteorology" refers to) occurs and I suspect this one will ramp up on the problem list.

Mr Average only notices when he starts getting French stations on the FM band. It's a mega-opening when that happens.

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WTF?

White Space...WTF?

The term is used in the first three paragraphs before it is defined. Perhaps a bit of an overview would be a good idea?

I consider myself fairly up on technology, and in the US, "White Space" has been used as a term to describe the spectrum (700-800 MHz) vacated by the TV broadcasters when they switched over to digital and moved lower in the UHF TV band . The level of the article is fairly low (not all that techy) so your readers probably aren't up on the nuances of WTF "White Space" actually is. A bit more of a definition would be nice, before you start getting excited about all the networking you might be able to do there...

.

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Re: White Space...WTF?

No, the vacated spectrum is NOT "White space", that's the "Digital Dividend".

So called "White space" is the effect caused by the fact that if C23 for example is used for a Station, it can't be reused at the next city, but at a further city. At the intermediate location you are not ensured any reception on C23. But SOME people may have larger poles and Aerials and get either C23 depending which way it's pointed. The Fantasy of "White Space" radio is the idea that at certain locations you can re-use the in use channel because

a) No-one here is using it.

b) you won't interfere with the further off places that do use it.

Both assumptions are false.

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Put on your mu-metal cap

And consider that _they_ (you know who, nudge, nudge, wink wink) are gung-ho for whitespace because it will be rife with "cheaters" who ignore the databases or pollute them with false data, or simply use a few hundred times the allowed power. Most of us will consider this a bad thing, but then we would (like those who make excuses for porn-scans and junk-touchingl) support "vitally needed new legislation" making it illegal for anyone, anywhere, to build or operate anything capable of emitting R.F. (except CFL bulbs, those are grandfathered) unless it is subject to control by "the authorities". Eventually, possession of a 1929 copy of The Radio Amateur's Handbook will be a one-way ticket to the gulag.

Have a nice day.

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Joke

So if we take this to allow....

Your children to play in the center divide of a freeway (aka motorway in the UK). I mean that the space is not used normally, so it is nice and available, and we need to accommodate children with play spaces. Look the government already owns the space and it isn't being used, and allowing playgrounds in center divides of freeways would put the space to "good use".

Sounds about as logical as white space networking.

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Whitespace is a great idea!

Spectrum management seems to be based on finances rather than intelligence. A complete disregard to potential interference, a desire to make as much cash per MHz and cost engineered receiver front-ends which are as wide as a barn door are a recipe for problems.

Our Glorious Regulator has no real interest in doing it's regulatory job and is more interested in generating revenue and telling Jeremy Clarkson he's a very naughty boy.

Gigabit VHF PLT has been demonstrated to interfere with FM and DAB, yet is being allowed onto the market unchecked. White Space has the potential to cause problems on a massively grand scale.

I'm really considering the options of setting up a company to help those affected by interference and grabbing some of the £10k-per-household mitigation honey pot and retiring early :)

-.-

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Trollface

Humph....

"... without interfering with Eastenders..."

But if it could be guaranteed to do so, I'd be all for it.

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