Coming Soon: Ultra Wide Band

JScarpace writes: "Robert X. Cringely has a new article in which he talks about Ultra Wide Band (UWB), a new wireless communications technology which may allow wireless networking speeds up to a gigabit per second. Read the article."

Comments

I don't normally say this.. but really.

[mindstrm]

There is a UWB article every couple of months. Nothing has changed in the last few years.

Yes, the technology exists.
No, it's not going to happen any time soon, for what should be obvious reasons.

Re:I don't normally say this.. but really.

[scoove]

No, it's not going to happen any time soon, for what should be obvious reasons.

For those who the reason isn't obvious, much of the controversy with UWB comes from its unlimited use of other people's licensed frequencies, allegedly under the "we don't think it'll interfere too much" rationale. UWB, in that respect, represents the largest theft of frequency since the auctions of the late 90s - stealing pretty much any frequency they want.

There has been substantial analysis of UWB and quite critical findings (see the ARRL's opinion submitted to the FCC - hams in many bands are secondary users and are used to coexisting with primary users, so there's a good reason the ARRL is very concerned about UWB), but instead of addressing it, the UWB lobbyists keep on pushing it forward and getting publicity (quite similar to it showing up on slashdot every once and awhile... who's on the lobby here?).

Unfortunately, the RIAA and peers have done a good job showing how easy it is to steal public or other peoples property when you pay off congress.

But hey, most of the public is technologically illiterate or unconcerned...

*scoove*

Re:I don't normally say this.. but really.

[isdnip]

I hardly think the "property" argument jibes with the "public interest, convenience and necessity" traditional mandate of FCC regulation. Older "narrowband" (and CDMA) licensed services are sensitive to interference from each other. UWB promises not to interfere, so what's the beef? That they didn't pass a Morris Code exam? That allowing phone patches (old amateur radio tradition predating even Carterphone) will take away "the phone company's" guaranteed revenue? That my radio waves can't "overfly" your land without paying your for the privilege?

The debate over UWB centers on the difference between intentional and unintentional transmission. UWB advocates want to be allowed to intentionally transmit at levels *below* those autorized in Part 15 for unintentional radiators. Sounds fair, except of course that the sum of lots of them might seriously raise the noise floor in some portions of the spectrum. That's a valid technical debate, but not a property debate, unless it degrades performance of licensed services.

Cringely, of course, did make major mistakes in his article. UWB doesn't use "ALL" frequencies (the proverbial "DC to daylight"), just a lot more than "traditional" spread spectrum. And its power/range tradeoff is about the same as other spread spectrum. And PCS goes a LOT farther than 1 km, outside of the densest urban enviroments, if its towers are high enough.

(BTW, I have an Extra Class ham ticket, and know the Morse quite well.)

Re:I don't normally say this.. but really.

[scoove]

>I hardly think the "property" argument jibes with the "public interest, convenience and necessity" traditional mandate of FCC regulation.

Fortunately, we're beginning to have Supreme Court rulings changing that annoying trend of stealing people's property under the guise of "public interest." Look at this year's ruling on partial confiscation as an indication of a overdue correction on property rights.

Like it or not, the rules of frequency management are that transmissions in other people's bands is illegal (except in particular permitted circumstances, e.g. emergencies). UWB represents a slippery slope of property theft - allowing tresspass into anyones frequency "as long as they had good intentions."

What's next? Letting me borrow CPU cycles without your authorization because I had a nice intention and wouldn't /really/ slow your web surfing down much? (Oops... I never figured you were going to play Quake... sorry about crashing your game. Look, it's not my fault that you play annoying games that I never tested for. Maybe we ought to ban the games so we don't interfere with my borrowing cycles!).

Actually, this whole "it's not theft if you weren't going to use it" argument you raise is rather interesting - I think it probably represents a significant rationalization used by various thieves in the tech world, though not new nor exclusive to it ("honest officer, we were just borrowing the car while it wasn't used!")

> UWB promises not to interfere, so what's the beef?

Besides the fact that it's not theirs to use? That it steals other people's frequencies? Why hell, go ahead and borrow my wife and car while you're at it, since I wasn't going to use them while I was asleep.

Seriously tho, what if the licensed owners (who paid for their right to use the frequency and received title from the government) wanted to operate similar spread spectrum apps in their allocations? Very similar to the recent partial confiscation case where the farmer could do anything he liked to his property - oh, except for build, farm, drain the wetland, etc. You're stealing this use from the frequency holders.

Also, there has been considerable debate about the "no interference" tests submitted by the applicant by their paid consultants. These tests were limited to examples that were guaranteed to pass, while other critical assessments showing interference were ignored. Which is better: a promise by a commercial interest that wants to steal the entire frequency spectrum and has a definite financial gain, or objective scientists and analysts who've demonstrated no problem in the past coexisting with other services? Can anyone say RIAA?

> That they didn't pass a Morris Code exam?

Were you making a point here, or just confused? Morris the cat? Morris what? Pathetic.

> That my radio waves can't "overfly" your land without paying your for the privilege?

Absurd points that have no bearing on the real issues, as you hopefully already knew when you posted.

> Sounds fair, except of course that the sum of lots of them might seriously raise the noise floor in some portions of the spectrum. That's a valid technical debate, but not a property debate, unless it degrades performance of licensed services.

Aha... "unless" - which is exactly the point brought up by numerous parties. Sort of like saying my theft of your vehicle "isn't a valid debate unless you actually intended on using it at a later date."

Your definition of theft - requiring intent of the entity who was robbed of later using their property - us an odd and disfunctional one. My property taken, regardless of when and how I planned on using it, is theft.

*scoove*

Re:I don't normally say this.. but really.

[ssyreeni]

Now you're confusing a whole lot of completely separate things. I don't think you mean to say DNS entries shouldn't be owned -- in the absence of ownership (more likely a lease from the resolution service owner who then effectively owns the domain names), how could you guarantee that yoursite.com would still point to your site, next week? If the name is not owned, there's nothing to stop anybody from reusing it at will.

What you probably meant to oppose was things like the UDRP, with their connotation that domain names have something to do with registered trademarks, considered "intellectual property". That I have a problem with, too. I think homesteading is the way to go in cyberspace as well, not ownership by fiat of specific bit patterns. No matter the context.

Still another problem with your gut reaction is the idea that only physical things should have property rights attached to them. But even if intellectual property didn't exist, there would still be such things as ownership in usage rights, financial instruments and, you guessed it, scarce immaterial resources like the electromagnetic spectrum. We need such rights in order to put those resources into the best possible use.

AFAICT, what is slowing innovation, here, is not lawyers confused over the proper application of property rights, but bureaucrats regulating innovation out of existence. After all, a market in privately owned radio spectrum would admit UWB and other newer modulation technologies as soon as the price was right. If UWB is so useful, the price would be just that. Interference would simply elevate that price, and give a financial incentive to further develop the technology. That's progress.

Re:I don't normally say this.. but really.

[autopr0n]

I don't think you mean to say DNS entries shouldn't be owned -- in the absence of ownership (more likely a lease from the resolution service owner who then effectively owns the domain names), how could you guarantee that yoursite.com would still point to your site, next week? If the name is not owned, there's nothing to stop anybody from reusing it at will.

Um, a service contract? I mean, I could add an entry to my DNS server saying that 'yoursite.com' pointed to autopr0n.com, and anyone using that for lookups would go there. You don't a domain name, you own a domain name on ICANN's system. Anyone can setup their own systems and do whatever they want to with it. That's what makes your CPU argument a couple posts back lame too. If you want more CPU just go buy some more, you don't need to use other peoples. There is an unlimited supply. There is an unlimited supply of DNS systems people can use to. (and for all practical purposes there is an unlimited number of domain names people can use on ICANN's system)

With radio frequency, there is only a limited space. And while the same is true with land on the earth (the most basic form of property) there is a lot more land then RF.

And if cringinly is right, UWB could transform radio frequency from a limited, to an unlimited and free resource for anyone to use. without practically interfering with regular broadcasts. Not allowing people to use it because of the current investments in technology is criminal.

Re:I don't normally say this.. but really.

[scoove]

autopr0n writes:
How can you own a frequency?

Perhaps my use of "licensed owners" wasn't clear enough. The process of licensing conveys ownership and its rights as specified in the license for the duration of the license.

You may want to argue semantics about something licensed not being ownership, but think about what things you usually "own": your land? your house? your car?

All three are technically licensed to you as well. Should you not pay property tax to the government, you lose your land, house and car. Really, you don't have clear and absolute ownership with these items - you just have a license to use them given the terms provided. Terms? On your property? Try building a 1000 foot tower on your land - you own it, right? You'll quickly discover an organization called the FCC explaining how you don't have the right to do that without following their rules. Same with building a landfill, pr0n shop in some areas, etc. All sorts of people have rules that apply to your use of "your property."

I mean, if UWB really can deliver on it's potential, then why the hell should we stime it just so people who have invested in outdated technology can profit?

First of all, UWB may not deliver on its potential. Secondly, who said the rest of the spectrum is outdated technology? Cell companies, microwave operators, hams, military, ISM users, etc. would have a slight disagreement with you. I assume you don't use a cell phone, 802.11b device, pager, etc. since they're outdated?

That's moronic. Look, I mean if you own land and the government wants to put down a highway or a railroad, then they will. They just have to pay you for it.

But what you're arguing for is a highway on my property (spectrum license) without paying me for it, telling me I won't notice the highway and it won't cause me any inconvenience.

Simply put, for one prospective licensee using what some have alleged to be junk commercial science to risk the entire RF spectrum management system is questionable, at a minimum.

The idea that we should hold back a huge technological advance which some have noted interesting parallels to the CueCat and the perpetual motion machines on account of some moronic idea that people can 'own' mathimatical descriptions of b-feild flux is incredibly stupid.

Licensing scarce natural resources (frequency) that are irrespective of manmade political boundries is quite different than owning mathimatical (sic) descriptions.

and per Iguanophobic's note:
I would argue that the government had no right to sell the frequencies in the first place.

Some people aren't comfortable with private ownership, as it deprives them from mooching off of others and limits the ease a parasite can access the product of others hard work.

If you follow the FCC's enforcement actions (detailed on their website), you'll quickly learn the importance of assigning frequencies via license and enforcing that. They routinely deal with mentally unbalanced idiots who find pleasure in jamming other services, cheaters damaging other peoples services by operating on top of their frequency (usually at higher power, destroying the legit user's service), etc.

Think about your cell phone for a second - operating in a licensed band. What if I followed you around and jammed your service every time you went to use your phone, simply because I didn't like you? With no licensing of frequencies, you'd have no recourse - I have as much right to jam you as you do to try to use your service. Or that crummy radio station I don't like... they're going down, baby! (I'd guess that nearly every station has at least one party that doesn't like their broadcast and nothing would be free from interference).

Remember, licenses not only establishes boundries and ownership, but they mandate behavior and provide enforcement should that behavior not be followed within the frequencies as well.

*scoove*

Re:I don't normally say this.. but really.

[scoove]

drinkypoo writes:
There is a sizable difference between me spending money which I earned through my own work, and buying a computer which I personally own, and the available radio frequency bandwidth.

How so? I've bought frequency out of money I earned through my own work as well - licensed microwave paths, for instance, which require a few thousand bucks in path analysis, engineering and application fees.

In fact, it's cheaper to buy a PC than a simple point to point 6 GHz microwave shot.

What gives the FCC the right to sell that off?

I find it funny that as a hard core objectivist, I'm arguing on behalf of the government to regulate (perhaps that's the realist in me coming out). The best answer to your question is probably an Ayn Rand one: a Gun

If you decide you don't have to recognize their right and encroach upon it, you'll eventually discover the extent of their enforcement. Look at all the income tax opponents (Ruby Ridge, anyone?).

I'd like to be able to use some of it to play around

So would I. I can't tell you how disgusted I am that numerous auctions have sold off wonderful frequency, only to have the frequency purchased and sat on by loser incumbants who see it as a cheap way to avoid competition. But I have an option: pay more than they do, or shut up.

and why should I have to pay (ultimately, because of licensing fees and whatnot we all pay) to use the airwaves?

How else would you assign finite property we all share? Give it to friends of the political party in charge? Keep it owned by the government? People like to argue how the current system is unfair, but don't fully explain an alternate.

It sounds like UWB may make most frequencies useless for traditional radio, especially the higher ones, but perhaps it's the right thing to do.

Again, thanks to wonderful PR by the UWB patent holder corporation(s). Many people on /. have provided good links to a sufficient base of analysis debunking both the amazing uniqueness of UWB and its alleged noninterference with other services.

As much as I enjoy Cringley's writing, it's clear that he's a journalist, not a technologist. If you read him for more than entertainment and perspective, you're going to be disappointed.

*scoove*

Re:I don't normally say this.. but really.

[isdnip]

>The process of licensing conveys ownership and its rights as specified in the license for the duration of the license.

Wrong! Licensing conveys RIGHT TO USE, not "ownership". BIG difference. Only some hardcore extreme right wing groups, and perhaps some doctrinaire Libertarians, think otherwise.

Said right to use is not necessarily exclusive. Every gasoline car creates sparks that interfere with radios, but usually below certain limits. Do we ban cars? Do we ban computers, which spew lots of RF? Part 15 defines what we can do without a license. UWB simply modifies that rule to allow intentional radiation at levels below those allowed for unintentional.

Think of it as an easement, if you insist n property analogies. But it's only an analogy, because it's not property.

Re:I don't normally say this.. but really.

[mindstrm]

You are missing the point.
Frequency space is not like cpu cycles. They do not BELONG to anyone. They belong to EVERYONE.
It is a globally limited resource that we all have to share.

If I use a frequency for, say, 2 way radio communication for my security team. Do I care if the noise floor is raised a couple dB? Well.. if I think of it as MY frequency, yes, I do.
But as long as I can do what I licenced that frequency for, I SHOULDN'T.
Remember, a license to a frequency is a license to use it for certain things, not ownership of it.
The airwaves stil belong to the people.

UWB is an alternative to narrowband. Rather than limiting the exact frequencies each person can use, we can all use them all, and we can regulate who can use how much, for instance.. allowing others to take advantage of different wavelengths for different properties.

I mean, comeon... look what we have otherwise.. 2.4 Ghz ISM? Give me a break.. there is a REASON that nobody wants that band, it's dirty as hell compared to others. Microwave ovens, etc, etc.

Positioning

[Cato the Elder]

The idea of UWB making GPS "obsolete" is pretty laughable. The article gives no details on how it works, but since the range is limited, I'm imagining is uses triangulation from a bunch of ground stations. So, OK, all those little GPS receivers to find your way around a city will become obsolete.

But for wilderness and nautical applications, what good is a limited range signal going to do you?

Re:Positioning

[chill]

More likely UWB will compliment GPS nicely. GPS will be used for wilderness, nautical and aviation. UWB will be used to supplement GPS by giving much more accurate measurements in the urban and sub-urban areas -- where 80% of the population lives.

+/- 6 meters isn't good enough for things like parking cars; locating stores/kids in malls; densely populated areas and it really sucks for vertical distances. Yes, differential GPS with ground stations really helps, but UWB could make location-based information and services pervasive.

UWB has a lot of potential.

Re:Positioning

[topham]

Except the only locations where it would likely add enough noise to be a problem would be very high population density areas... like a city. Where GPS doesn't work worth shit. (Tall buildings block the signals, and reflect them, etc.). On the other hand, it would be possible to use cheap UWB transmitters do add the same functionality within such an environment...

Re:Positioning

[scoove]

I'm aware of the analysis indicating GPS could be interfered with or potentially broken (hey, what's a 30 second GPS outage to a landing 747 anyways?), and have seen evidence of other impairments, but haven't seen what potential interference might be applied to 2.4 GHz ISM DSSS and FHSS services.

Has anyone come across references to UWB interference or coexistance with 2.4 spread spectrum systems (e.g. 802.11b)?

Curious that we'd throw out 100 years of frequency management for a commercial licensee/patent holder.

*scoove*

Re:Positioning

[topham]

Please calculate the number of devices required within a 50 meter radius required to create sufficient interference on a specific band to cause a problem EXCLUDING anything -on- said aircraft. (No one has any reason to believe they would be more allowed on planes than cellphones are). Within a few feet there are interference issues. But then, some people find GPS handheld block out their car stereos too.

Re:Positioning

[Skyfire]

+/- 6 meters isn't enough for locating a store in a mall? What mall are you in?

Anyways, differential GPS over IP is plenty enough accuracy for just about any application. You do not need much bandwidth at all to send a correction signal.

Re:Positioning

[topham]

Actually you are very mistaken. Please read the Satelite Navigation news group, several people have described the phenomenon. And there isn't anything unique or special about it. All electronics give off some radio interference to some degree. Typically not enough to cause you to actually lose a radio station on an FM radio. But specific GPS units can, and do if placed close to the antena or stereo. (For some people this shows up when putting the GPS on their dashboard. A common place to put a GPS in a car for it to get a clear signal.). GPS units have also caused interference with each other.
I don't expect the level of interference given off by a GPS is significant enough to worry about, but I was trying to make a point that when arguing that some form of transmitter (intentional) might interfer with GPS that Un-intentional interference is caused by most electronics in close proximity and from everything I have browsed through on UWB seems to indicate the amount of noise is on par with unintentional transmitions. (This includes browsing through an FCC document outlining speed to lock-on with interference & without, distance of transmitters etc.)

of course....

[fluxrad]

if you have a 48" waist...this technology has been out for years.

Re:of course....

[John Harrison]

f you have a 48" waist...this technology has been out for years.

Don't you mean that it has been around for years?

*That* was interesting

[Glorat]

That's one of the more interesting articles I've read about at Slashdot. Unlike our perpetual motion machine, this sounds genuine and not *too* good to be true. High bandwidth, low interference and perfect for that last mile problem! If the technology becomes mainstream, it will be revolutionary

I have questions though:
- Can an enthusiast make one of these "impossibly cheap" devices?
- Are as the article suggests these devices really going to take off within the next year or will they be suppressed as the article suggests other technologies will be.
- Is it really that resistant to interference? We're using so many frequencies at one time, can they really not clash?
- Will it interfere with traditional radio signals? I.e, it seems to clobber other reserved EM frequencies to make use of high bandwidth. Would this mess up our telly or radio?
- Does anyone have experience to say whether this stuff is really as good as it proclaims to be?
- Finally, there must be more downsides than just messing up radio astronomers

Re:*That* was interesting

[3prong]

- Can an enthusiast make one of these "impossibly cheap" devices?

The chips are already being made, and I suppose it won't be too long before someone with a soldering iron could put together a transmitter.

- Is it really that resistant to interference? We're using so many frequencies at one time, can they really not clash?
- Will it interfere with traditional radio signals? I.e, it seems to clobber other reserved EM frequencies to make use of high bandwidth. Would this mess up our telly or radio?

It's a totally different technology than radio. Radio is transmitted via long sine waves of energy. UWB is very short pulses of noise, like an extremely short burst of morse code. Won't have any effect on radio or TV.

Re:*That* was interesting

[Mike Monett]

>I have questions though:

>- Can an enthusiast make one of these "impossibly cheap" devices?

Yes. Schematics and parts are readily available.

>- Are as the article suggests these devices really going to take off within the next year or will they be suppressed as the article suggests other technologies will be.

There is a patent conflict. Thoma McEwan of Lawrence Livermore Labs copied Time Domain's ideas and patented them. Manufacturer's will face litigation expense and could end up paying royalties on both.

>- Is it really that resistant to interference? We're using so many frequencies at one time, can they really not clash?

Yes. Spread Spectrum works now by switching frequencies in a pseudorandom sequence. Receivers that are not on the same sequence cannot hear the transmission.

UWB works on the same principle except it uses time slots instead of frequency slots. Receivers that are not on the same time sequence cannot hear the transmission. As mentioned, UWB is highly secure and difficult to detect for this reason.

>- Will it interfere with traditional radio signals? I.e, it seems to clobber other reserved EM frequencies to make use of high bandwidth. Would this mess up our telly or radio?

Probably, but only if the transmitter is very close (several feet) and you are trying to listen to a very weak signal.

If many transmitters are in use nearby, it may affect GPS by raising the general noise level. GPS works on very weak signals.

- Does anyone have experience to say whether this stuff is really as good as it proclaims to be?

A lot of people have worked on it with good results. Yes, it works.

The antennas have to be specially designed for broadband. They may be larger than practical for handheld phones, but fractal antennas may reduce the size.

- Finally, there must be more downsides than just messing up radio astronomers

It can raise the general background noise level and affect reception of weak signals. However, in an urban environment, there are plenty of signals that already raise the noise level. Radiation from Local oscillators in superhet receivers (probably hundreds of thousands used at different frequencies), cellular phones and other mobile transmitters (this really is bad for radio astronomy), industrial process like arc welding and power conversion, motor starting transients, automobile ignition noise, temperature controllers using bimetallic sensors, light switches, ad infinitum.

Electrical noise pollution is a part of modern society. The noise added by UWB may well be lost in the background noise that already exists.

Mike Monett
mrmonett@yahoo.com

Re:*That* was interesting

[John Miles]

>- Can an enthusiast make one of these "impossibly cheap" devices?

Yes. Schematics and parts are readily available.

Where?

There is a patent conflict. Thoma McEwan of Lawrence Livermore Labs copied Time Domain's ideas and patented them. Manufacturer's will face litigation expense and could end up paying royalties on both.

My understanding is that the court told McEwan to go pound sand last year. Do you have more up-to-date info?

Re:*That* was interesting

[Mike Monett]

>>Yes. Schematics and parts are readily available.

>Where?

Too many places to list. Check the patents - here's a fairly recent list (caution large pdf files):

http://www.aetherwire.com/CDROM/General/numbers. ht ml

Or search Google "uwb receiver".

>My understanding is that the court told McEwan to go pound sand last year. Do you have more up-to-date info?

McEwan claims the patent was reinstated. Fullerton claims it is worthless. I tried to follow both arguments but gave up. It is too confusing and you really have to invest a lot of time. This is the situation that makes investors nervous, or should.

It's probably best to check both sites for the latest info, but it's clear the argument will go on forever.

Mike Monett
mrmonett@yahoo.com

Re:*That* was interesting

[tftp]

Is it really that resistant to interference? We're using so many frequencies at one time, can they really not clash?

Yes. Spread Spectrum works now by switching frequencies in a pseudorandom sequence. Receivers that are not on the same sequence cannot hear the transmission.

But since UWB transmission exists on all frequencies during the time slot, the SS system loses all its advantages. I am sure many users (like military) would not want that.

Why didn't he mention...

[zoid.com]

TimeDomain? They are the leader in the UWB development and hold a bunch of key patents.

http://www.timedomain.com/

Cheers!

Re:Why didn't he mention...

[rbeattie]

Hmmmm... Interesting. The first link on the TimeDomain's website is this LA Times Article about how the FCC is set to aprove the technology next month and how they used UWB during the World Trade Center disaster to look for victims.

Like Johnny used to say: "I, I did not know that."

-Russ

more info

[Syre]

Here's a FAQ from the Ultra Wideband Working Group.

It's not clear that it will be allowed to be deployed widely, since it may in fact interfere with the spectrum allocated for other uses. As the U.S. Governmetn's Ultrawideband (UWB) Signal Characterization Project says:

Many claims have been made that UWB communication transmitters can effectively share spectrum with existing users. Some of these claims have not been independently verified.

We'll have to wait and see...

I Think I'm Missing Something

[Trillian_1138]

I have a question about wireless vs wired communications systems. I am admitadly next-to clueless about telecommunications in general, but I'd always thought it would be faster and cheaper to send data over physicals wires, period. How does it work that this technology (UWB) can send data faster and cheaper than physical lines?

I'm assuming there's some key point I'm missing, but I don't know what. (If I did, I presumably wouldn't be missing it any longer...)

-Trillian

Re:I Think I'm Missing Something

[Afrosheen]

Ever try to wire a house, a building, a metroplex? It's horribly expensive and fraught with licensing, deals with the city/builder, permits, yada yada.

With wireless, you throw up an antenna and a power source, and go on about your business.

Re:I Think I'm Missing Something

[Afrosheen]

True, but consider having to dig up streets all over a metroplex or through a downtown area. It's all relative, and overall, wireless is cheaper and easier to implement. Here in Dallas there are wireless radio retransmitters on almost every light post. Look carefully around your area, you may notice these little dudes also.

Re:I Think I'm Missing Something

[Kwil]

I'm no engineer, but what little reading on it I've done suggests it works like this:

Think about your normal physical line. It sends data in a sequential form.. first a 1, then a 0 , then a 1, then a 0 and so on. Now admitted, it does this ridiculously fast but it's still sequential. (This is a huge simplification, btw, but it's the general gist)

Now UWB is using a whole bunch of frequencies to send those ones and zeros, but each frequency carres a different bit. So the first frequency carries a 0, the second carries a 0, the third carries a 1, the fourth carries another 1, and so on. The trick is, it sends these all at the same time and it's up to the receiver to not only know exactly WHEN those frequencies will be carrying information to it, but put them together into the proper sequence of bits.

It's the difference between getting hit by a steady, narrow stream of water, and getting hit by a single tidal wave. They'll both get you wet, but one will do it a lot faster.

So that's the faster.

The cheaper is that a physical line requires a way to code and decode the information and.. well.. a physical line. Which means you have to pay for the line, you have to pay for running line through cities and into people's houses, you have to pay for when a bad weatherstorm comes and a tree busts the line, you have to pay licensing fees to lay all this line, etc.

UWB requires a more sophisticated coder and decoder, but since it doesn't require a line and microchips are so cheap these days, this comes out to be a much lower cost - especially if the FCC lets it go unregulated.

Now as to how it avoids interfering with each other, I really don't know, because if you have enough of these devices, you would think that sooner or later *some* of them in the same area will be sending at the same time.

Re:I Think I'm Missing Something

[WolfWithoutAClause]

Its cheaper because you don't need some hairy ape running around digging and drilling and laying wires.

It's faster only if its short distance- then you can get many megabits/second. Long distance you can too, but then you take up too much bandwidth over a wide area.

Even the UWB takes up bandwidth, but because it steals such a small amount from the existing fixed bands you can mostly get away with it; and the total power is very low, and any interference is only likely to be over a short distance anyway.

Re:I Think I'm Missing Something

[AnotherBlackHat]

You're not completely wrong - it is faster and cheaper to use wires than wireless, ignoring the cost of running the wires. Current "cheap" UWB claims 40-60Mbps, and is considerably more expensive than 100baseT (100Mbps) Ethernet. Gigabit UWB may happen in the future, but gigabit-over-wire exists today. The only reason people don't use it (much) is gigabit over fiber optic is cheaper still.

The key point you're missing is the cost of running the wires, which can be extremely high. I've seen estimates over $500,000 a mile in cities, and even in rural areas it's over $15,000 per mile. And that's ignoring state and local laws which can and do tax almost anything that makes money.

--- "He's making money and I'm not getting any" - far too many people.

UWB _IS_ spread spectrum

[Anonymous Coward]

It's not a successor but a kind of spread sprectrum. There are other inaccuracies in the article: it's spectral power density is low, not it's power. It does not violate any information-theoretic rule (some people still don't seem to grasp the difference between a law of the state and the laws of nature :-). You still need good enough SNR. And the limitations to the number of multiple access are just the same as with concentrated spectrum transmission, except that you have "graceful degradation" of the QoS. In my country, BTW, UWB is permitted for military use only. Yes, it's hard to detect, but not impossible at all. Commercial UWB is explicitly outlawed. Not that I'm happy with this legislation, though...

Seti Etc.

[Alien54]

The biggest losers, though, would appear to be the radio astronomers. Just as the light pollution from street lamps made work harder for astronomers with optical telescopes, UWB will raise the noise threshold for the radio astronomers.

Not only that, but what if all of the Alien Civilizations are already using the equivalent of UWB for all of their interstellar communication? This is going to be really hard for SETI to deal with.

;-)

Re:Seti Etc.

[hashashin]

Honestly, I don't see UWB (as described in the article) as a huge threat to radio astronomers. With the limited range of UWB (hundreds of feet for a fast connection, 1km for a reliable one) and the tendency of astronomers to locate their observatories far from population centers, not to mention the parabolic dish antennae, I don't imagine that it will significantly influence their results.

Security, not bandwidth

[kenneth_martens]

What's most appealing about UWB is not it's promise of high bandwidth, but it's promise of a secure wireless protocol. According to the article, "UWB is pretty much immune to eavesdropping, is equally immune to interference or jamming, and because its broad frequency range includes the ultra-low frequencies used to communicate with submerged submarines, UWB can be used easily in buildings and even underground." With all the problems with the inherently insecure 802.11b wireless protocol, UWB sounds mighty appealing based on security alone, and when you consider its greater bandwidth that makes it doublely attractive.

Better security and more bandwidth? It sounds too good to be true. (It also sounds expensive.) Here's to hoping it's for real.

Re:Security, not bandwidth

[hpa]

because its broad frequency range includes the ultra-low frequencies used to communicate with submerged submarines, UWB can be used easily in buildings and even underground.

Bullshit.

There is so little bandwidth in those low frequencies that you can hardly talk about "ultrawideband"! If it wasn't clear that he doesn't know what he was talking about beforehand, that statement should have made it clear.

"Ultrawideband" is really not anything other than a marketing name for direct-sequence spread spectrum (DSSS). It has been rebranded in no small part in order to attempt to get the FCC and similar regulatory agencies to allow it to be spread across already allocated radio bands (where they become part of the noise floor) rather than confined in between narrowband applications.

All of this really isn't anything particularly earth-shattering. The standard electromagnetic spectrum frequency domainis given by a Fourier transform of the electromagnetic wave using sine waves as base functions. Spread-spectrum technologies simply create a new "frequency domain" use a different set of base functions. They are resistant to interference or jamming only because most sources of interference or jamming operates in the standard frequency domain, not in the "alternate" one. 802.11b actually uses direct-sequence spread spectrum (spread across a fairly wide 2.4 GHz band officially used for industrial applications and microwave ovens) already -- the security added by DSSS is automatically removed by the fact that you can buy 802.11b-compatible waveform correlators for a few hundred dollars at any electronics store. Sorry guys, you still need encryption.

Re:Security, not bandwidth

[WolfWithoutAClause]

It isn't just DSSS, I think the UWB bit may refer to picosecond pulses to maximise the bandwidth.

Re:Security, not bandwidth

[cats-paw]

"Ultrawideband" is really not anything other than a marketing name for direct-sequence spread spectrum (DSSS).

That is not true. It is a different communications scheme. You need to go read up.

DSSS works by mixing a wide bandwidth PN sequence with a low BW data stream.

UWB communicates by accurately positioning pulses in time.

FCC to approve this next month

[plasticquart]

LA Times Story here

From the article:

"The Federal Communications Commission still is negotiating with opponents, but Bruce A. Franca, acting chief of the FCC's office of engineering, said he is hopeful that an accord can be reached and that the FCC will approve the technology next month."

School Glue GEL

[Graymalkin]

Ultra wide band communication isn't so damn fancy conceptually. The problem is is practically difficult. It works on the same principals as regular sized band radio transmission with the small difference of not splitting the band into channels. Channels are just time slots you set your transciever to listen to or send on which arej ust portions of a band. With UWB there's no channel designations so reception and transmission frequencies can be all over the specified band. It sounds like a good idea because there are not channels to occupy or share with others and your beeps all over a band can be construed as static rather than interference. A random beep in the middle of a frequency used for aviation radio isn't going to crash a plane as it is catagorized as static.

The problem with implimenting UWB is getting the electronics to move fast enough. In order for me to send lets say my voice over UWB I need electronics in my transmitter that can switch really quickly between enough frequencies in order to give me the aggregate bandwidth to send my voice signal. Easy you say modern CDMA cells phones already do that. Granted they make the most of their radio spectrum by splitting up data over the entire band but they are splitting up big chunks of data over a limited band. UWB transceivers will have to switch fast enough where a single radio blip might only be half a word or a quarter of a word and switch over a much higher range of frequencies.

In order to have a gigabit of bandwidth your transceiver would have to switch frequencies in excess of a billion times a second (not merely transmit at a billion hertz). It takes x electronic clock cycles to switch the electronics to switch frequencies you'd have to have electronics working at xgigahertz in order to send a gigabit of data. In a handheld unit? Not likely in the next couple years no matter how fast microprocessors get. Companies have just recently been able to build circuits that can switch at 10GHz it will still be a little while before actual logical circuits can be mass produced and run on batteries. Handheld devices are going to have the same amount of information throughput as they have now even if the radio band they work on is a good portion of the radio spectrum. There is alot of engineering left before UWB is really a viable solution to any problem but it is still a cool concept and I hope these problems get worked out sooner than later.

Re:School Glue GEL

[Graymalkin]

You make a good point about antennas which I didn't mention but is very pertienent because not all antennas send or receiver well at all frequencies. The sky high expectations of UWB technologies providing gigabit upon gigabit of data throughput is a bit ridiculous when you figure in the actual physics of the system. UWB is most effective when you use predetermined bands but widen them considerably over conventional channel arrangement techniques. This limits the amount of interference a prevelance of these devices WOULD actually make. It would be rare for a handful of devices ever to send enough bit pulses to cause perceptable interference in electrical equipment but millions and millions of devices all doing the same thing will statistically cause enough interference on one band that narrowband equipment or electrical devices will register it and it will cause problems. Cringly also talks about antennas that need no tuning, millions of tiny antennas all broadcasting radio pulses with no concern for tuning out harmonics is a crappy idea.

As for 2.4GHz phones being made from 1.9GHz parts that is mostly due to the similar antenna and electrical requirements of transmitting on the two different bands. The phones are also operating under the same principals so they have the same bandwidth requirements whether they are transmitting on 2.4 or 1.9GHz. The digitalized voice signal needs a certain amount of throuput no matter what frequency it is eventually transmitted over. Adapting current technologies for UWB is a bit more difficult because it requires VERY high precision electronics in order to make the whole thing feasible. A PCS or GSM cell phone can miss out on a small chunk of data without the phone HCF. An UWB receiver needs to have pretty incredible reception and timing characteristics because the natual SN ratio is just enormously high. I think we're still several years away from marketable products using UWB.

Re:School Glue GEL

[BeBoxer]

I was going to mod the parent down, but I figured it is better to correct misinformation. You need to go read up on how UWB actually works. It absolutely does not require the transmitter to "switch frequencies". It does not attempt to transmit a little bit of information on lots of different frequencies. Rather, it transmits little bits of information on all frequencies at once. Doing this is not hard. Rather, it is trivial.

You see, in many ways UWB is just like the very first radio tranmissions. The first radios were "spark gap" transmitters, which basically generated RF by creating a little arc of electricity. Doing this creates a little burst of energy which is spread across most of the RF band. You can still hear this effect by trying to listen to AM radio during a lightning storm. Each lightning strike sends out a burst of RF which you can hear on any AM modulated radio. It wipes out all the AM stations, and I guarantee you that the lightning is not using any fancy electronics to "change frequencies". You don't notice the interference as much other radios, such as FM, because they use more advanced modulation techniques. So, the noise from lightning doesn't usually manage to turn into actual audible interference. But if you are listening to a weak signal and the lightning is close, it will still fade out when the noise from the lightning overpowers the signal from the radio station.

Back to UWB, the basic 'unit' of transmission is not unlike the signal generated by a spark gap transmitter or a lightning strike. In order to transmit a bit, the transmitter sends the wide-band pulse either a little bit early or a little bit later than expected. The receiver knowns exactly in time when the next pulse should show up. It has a bit of circuitry which can detect whether the pulse shows up early or late, and spit out a 1 or a 0 accordingly. If the pulse never shows up, nothing gets output. The circuits involved are actually fairly simply. Certainly simpler than a frequency-hopping radio which does work the way you described. Actually, I think you've gotten your wish for "these problems get worked out sooner than later." I say this because I think they have working hardware now. It's not on the market, but it would be if the FCC approval came thru.

Of course, the claims that UWB won't interfere with existing RF users, or with itself, is pretty close to BS. UWB definitely creates interference for other radios, it just a question of whether or not it's enough interference to be noticable. But it will definitely raise the noise level for pretty much every other RF band, so it's safe to assume that the potential of problems exists.

UWB will also interfere with itself. If you are the only user, your fine. But as soon as more than one person is using it, you are going to start finding out that pulses from other transmitters are showing up times which set your receivers correlator off erroniously. If a lot of people are using it in the same area, you are going to get more and more errored bits showing up at the receiver. These can be worked around by using error correcting codes at a higher layer, but it's still interference. Folks who think it can't be jammed are full of it too. One of the papers mentioned that the radios might have a duty cycle as low as 1% or less. If I build a radio that starts spitting pulses out at a 50% duty cycle or some such, I can probably get everyone elses receiver to go nuts trying to deal with all of my extraneous pulses. Maybe I'll need 100 radios running at 50% duty cycles, but it can be done.

As another poster mentioned, eavesdropping will still be quite possible for most applications. It might be hard to detect UWB if you know nothing a priori about the signal. But, anybody who is using it already has a receiver which knows everything it needs to know to pick up signals! It's just like 802.11. It might be hard to pick up a FHSS 802.11 radio if you know nothing about the signal. But if you go out and buy an 802.11 receiver for $100, you can pick up the signal just fine. To some extent this can be worked around by using cryptographically secure PRNG's to generate your timing signals. Then only folks who know the 'key' will be able to pick up the signal. But I can guarantee you that consumer UWB gear will not under any circumstances use secure PRNG's if for no other reason than it would make it a real pain in the ass to set the stuff up to work properly.

Re:School Glue GEL

[Graymalkin]

I probably do need to read a bit more on the UWB transmitters because I was under the impression they were just an extension of FHSS transmission systems. That's how I've seen it explained in several cases, this is the first time I've ever had someone relate UWB to spark-gaps. At least I was right about the BS being thrown about UWB being interference proof.

Bah! TANSTAAFL.

[phliar]

This keeps coming up every so often.

UWB is ... a series of very short electrical pulses ... on ALL frequencies simultaneously.

UWB requires ultra-low power... [it is] a signal that can't be detected and doesn't interfere.

Here goes: Bullshit!

He (or whoever he got this story from) needs to read a little bit of signal processing. Yes, it sounds very nice, and you can build it, and it's all true... if there's only one such device. You see, what this does to other users of spectrum is raise the noise floor just a bit. No big deal.

But what happens if there's a whole bunch of these devices? Well, let's say you're an FCC licensed user of spectrum. You've been allocated a certain bandwidth. Your channel capacity depends on the bandwidth and the noise floor. If your noise floor goes up, your channel capacity goes down.

Where did that lost channel capacity go? It's being used by these "UWB" devices. As evil as the FCC is, we do need some arbiter of the EM spectrum.

TANSTAAFL, folks. Go read Shannon.

Cringely is an idiot.

Re:Bah! TANSTAAFL.

[Afrosheen]

And what better arbiter of the EM spectrum than this kook?

Re:Bah! TANSTAAFL.

[raving_cock]

He's right. CDMA transmits below thermal noise, and it still needs to have its own band. Maybe if they're low power and short range, they can work and be unlicensed, but forget it for any kind of power. You may be able to get signal out of low power over range with directional antennae, but you can't punch through or bounce off material. No cell phones or radios certainly. Also, don't forget, the broader the band you take signal from, the wider and faster a A/D converter you need, and that can eat power.

More UWB articles - Tech and Regulatory

[billstewart]

There's an article on UWB on Dave Farber's Interesting-People List, posted from The451.com with content from Janos Gereben and Dewayne Hendricks.

There's a longer article on Hendricks's work in This month's Wired, talking about UWB, unwiring Tonga, and using Indian Reservations to try out radio technology because their sovereign nation status may be a useful regulatory hack as well as because they need better communications on the rez.

Re:REally?

[xanadu-xtroot.com]

(isnt that what AOL members reply with?) :)

Nope, more like:

/\/\3 70!

NOT

[Lumpy]

Until they can demo it with the current "bandwidth limitless" carrier frequency called laser light it's nothing but hot air. Come on, point to point laser links are horribly slow compared to a fiber. It should be easy to do this with a laser as the technology already exists, they just have to add error correction and other fixes for natural distortion and interference. (Of which there is much less on a laser link than a RF path.)

Before they go screaming about what might be,they need to try making what we have work right.

the noise can be calculated

[cats-paw]

But that doesn't mean that it's not subject to a lot of political bullshit. Here ya go :

UWB : 1uW in 5GHz BW => 200E-18 W/Hz

US Digital Cell phone BW is 30kHz

total intercepted noise in a 30kHz BW : 6E-12W => -82dBm

Assume 40dB path loss from UWB device to cell device : -122 dBm. Which is generous, if the guy standing next to you is using a UWB device the path loss is more like -30dB.

Thermal noise floor kTB = 1.38E-23 x 300 x 30kHz
That's 124E-18 W => -129 dBm

So my cell phone sensitivity just lost 7dB which will cut the range by 1/2 and that's for 1 UWB device.

Guess what happens when there is 10 of them ?
Guess what happens if I need 10uW.

Brian

Re:the noise can be calculated

[guygee]

Ever hear of a "notch filter"?

Frequency Bandwidth and Information Bandwidth

[guygee]

I think several (highly modded) contributors to this discussion are confusing
the concepts of information bandwidth and frequency bandwidth. Ultra-wideband
refers to the bandwidth in the frequency domain, which is only indirectly
connected to the concept of information bandwidth, in that a wide band in
the frequency domain translates to narrow pulse in the time domain. Coding
techniques also strongly affect the ultimate information bandwidth of the
system. UWB is nothing like IEEE 802.11b,
which operates in the narrow 2.4 GHz - 2.483 GHz band.

I have been working on a project for US Army STRICOM,
in which we are using 8 UWB devices manufactured by
Time Domain Inc. to perform position location. These devices
operate at 1.9 GHz center frequency with a 2 GHz bandwidth,
which translates to a 500 ps pulsewidth.
We have a short conference paper on UWB simulation, accepted for presentation
to the 2002 IEEE Antenna and PropagationSociety Symposium,
which you can access
here. Speaking in general and rather simplistic terms, the information
bandwidth of such a system would depend of the time frame over which you
will allocate these 500 ps slots to listen for the transmission of 1 bit
of information. For example, if we choose a 5 ns time frame, then we
could theoretically obtain 200 Mb/s information bandwidth, while (ideally)
allowing for 10 channels of operation. Of course, the previous analysis
neglects the need for redundancy, and you may want to choose a time slot
over which to listen for a pulse different than the pulsewidth itself, but
I think the discussion gives one a good idea about how to relate information
bandwidth to frequency domain bandwidth in a simple communication system.

Established industries.

[Restil]

First of all, the scare that industries will vanish overnight due to newfangled technology is an unwarranted one. Granted, over time new technology will slowly replace older. Industries need to learn to adapt and grow. The market for horsedrawn carrages isn't what it used to be, but the introduction of the car wiped that industry out. But it didn't happen overnight. Even if cars are built that get 100 miles to the gallon, there will be a brief period of time when those cars cost more than the general variety. And not everybody is going to instantly trash their current cars and start buying up the new ones. The reduction in fuel requirements will be offset by the purchase of more vehicles now that people can afford it. It all works out. And if production is less, you lay off people. And natural resources last longer. Its all good.

Bandwidth is the same way. The dialup ISP will slowly go away, but "slowly" is the key word here. Business will adapt. And if they don't, they die. It happens. Tech related businesses are USED to going out of business. And the smart businesses will find a way to embrace the new technology before it destroys them. Then the next big thing will hit.

And there's always the possiblity that there are problems with the technology we aren't aware of when its more a theory than widespread in practice. Sounds cool to me. I can't wait to get 1gbps to my home! :)

-Restil

No Free Lunch!

[Detritus]

Having a snazzy acronym does not repeal the laws of physics and communications engineering. There is no such thing as free bandwidth. Increase the data rate, the range decreases. Increase the power, the range increases and the noise floor goes up, degrading every other user's SNR.

UWB is the modern equivalent of the spark-gap transmitter, which was banned many years ago. It is like dumping your old motor oil in the city water reservoir. If a few people do it, nobody notices. If everyone does it, the reservoir becomes a toxic waste dump.

Not certain (I'm no engineer either), but...

[BlackGriffen]

I think that UWB devices don't interfere with each other because you would need two waves to hit at the same time and in the same place, right on the receiver, to actually notice the interference. Otherwise, the interference would be there, you just couldn't detect it from where you where. Because of the short duration (they sound almost like fourier approximations of dirac delta spikes), this coincidence is extremely unlikely. Even with thousands of devices on a single block, they probably wouldn't interfere with each-other any more often/severely than current noise.

The reason they wouldn't interfere with standard receivers, I think, is that the duration of the spike is so short that the signal will barely have time to propagate down the antenna (light travels about 1 foot every nanosecond, electricity travels slower, so the signal may barely reach the end of a 1 foot antenna). Even if a signal was passed on by the antenna, the receiver probably doesn't run at high enough frequency to notice (to notice a nanosecond pulse requires that the receiver can resolve that small of a time scale, i.e. it can operate around the GHz range).

All this makes me wonder how the signal is detected at all, even if the receiver knows when to look. I also have to wonder because of the pulses have nanosecond widths, the position of the device has a significant effect on wether it's timing is synced with the signal (i.e. since light travels about a foot in a nanosecond, a shift in the position will lead to a shift in the timing). Perhaps the device listens starts listening 2 nanoseconds early to 2 nanoseconds late, and broadcasts often enough so that it can adjust the timing?

Just some thoughts from a physics undergrad.

Worldwide Mobile Communications Device?

[martyb]

I sure hope we've learned from the incompatible mobile phone protocols that have developed over the years (GSM, CDMA, etc.). Unfortunately, I'm not optimistic given what I've read so far.

Though UWB sends its signal over "all frequencies", it depends on sending out the information at "certain times" (like an extremely fast clock, as best as I understand). It seems to me that if the USA comes up with a standard to clock that at one rate, and other countries at other rates, we'll end up with the same mess we have with current mobile phones.

Or are we likely, because the FCC is considering approving it as an unregulated use of the spectrum, to end up with each mobile phone manufacturing company coming up with its own variation and we'll end up with yet another variant on the old beta vs VHS battles?

What are the chances we can finally get a single world-wide standard that would allow a single mobile phone to work anyplace in the world?

Faster vs. Fast Enough, Far Enough, Interference

[billstewart]

As other people have said, if you've got the wire, using wire is cheaper, but running wires costs money. The big change with some of the newer wireless technologies is that they're starting to go fast enough and far enough to be useful. 10kbps connections are fast enough to run voice on, and paging, and sometimes email, but not something you'd run real computing over. Metricom's ~30-100kbps was better - but the tradeoffs of how many users fit in a given area, how far it goes, and how many microcells it needs didn't quite work for them. But 802.11b, at "11" Mbps, is really fast enough for many networking applications, and distance-limited enough that lots of people in a city can use it without overly stepping on each other's bandwidth needs - you can use it for typical office data applications and voice phones, though you'll still need a feed to the outside world that's usually wired. Inside an office building, run by the end users, it's a win; adapting it to be a public wide-area service is a different game economically, with different competition, and perhaps folks like BAWUG or Starbuck's Coffee will succeed. But those applications still require an upstream feed, and the cost of using a wired feed is enough that the economics are still dodgy for free service, and the market for paid service hasn't taken off quite fast enough. 802.11a, at 55Mpbs, is even more useful for office LANs; we'll see if it can provide upstream feeds for WANs.

What UWB technologies can offer is that they increase the number of users and amount of bandwidth that can operate in the same space without interfering with each other, and they also have sufficiently entertaining options for directional data and longer distances that it might be possible to build a meshed distribution network that's got enough horsepower to be self-sustaining without lots of wired access points. That not only makes it more viable for wireless users to access services on each others' machines, but also to get better economies of scale sharing upstream bandwidth - N users on a 45Mps T3 connection get much more effective capacity than N/28 users on a 1.544Mbps T1 connection, plus you save the costs of running lots of small connections to lots of individual cells (the access costs for a T3 are typically about 10 times the access costs for a T1, and you get 28 times the bandwidth, plus you also have more users who'll be sending data to each other instead of to the outside world.)

UWB.ORG is a front for Time Domain, Inc.

[Animats]

UWB.ORG claims to be an organization of companies that want the FCC to approve ultrawideband transmission. But when we look in the WHOIS database, we get:

Registrant:

• Time Domain Corp (UWB2-DOM)
• 
  7057 Old Madison Pike
  Huntsville, AL 35806
  US

  Domain Name: UWB.ORG
  

I thought that hype looked familiar.

You have questions, we have answers

[Animats]

I have questions though:

• Can an enthusiast make one of these "impossibly cheap" devices?
  Yes, but not "impossibly cheaply". The "really cheap" part assumes custom ICs have been developed and produced in large quantities. The parts cost of the radio in a cell phone is about $10. So there's no big price breakthrough here.
• Are as the article suggests these devices really going to take off within the next year or will they be suppressed as the article suggests other technologies will be.
  Probably not. It's not that great a technology. Ordinary spread spectrum systems have most of the same advantages, without blithering all over the RF spectrum.
• Is it really that resistant to interference?
  Only if the receiver is really good. It's tough to build an untuned receiver that won't saturate when there's some big signal in the neighborhood. Unclear how well Time Domain has actually done in that area.
• Will it interfere with traditional radio signals?
  If the power is high enough, or there are enough of the things, yes. The FCC is very worried about this, with reason. Spread spectrum is only allowed in bands that don't have anything important, but UWB will overlap important stuff.
• Does anyone have experience to say whether this stuff is really as good as it proclaims to be?
  It can't live up to Cringley's hype; that's physically impossible. It might lead to better wireless LANs.

This isn't really a technical breakthrough at all. It's more of a political gimmick to take spectrum away from incumbents who are underutilizing it. For example, you could probably run spread-spectrum cellular telephony on top of existing UHF TV stations, and nobody would notice. There's be a little more snow on screen, that's all. But the broadcasters scream if somebody suggests something like that. This is an end run around that political objection.

the UWB landgrab

[markj02]

There is only so much bandwidth to go around. You can allocate it one way or another. We have chosen to allocate it by frequency channels. That's simple and low-tech.

UWB doesn't give you any unused spectrum, it just degrades that the spectrum there is uniformly for everybody else. In small amounts, that may not be a problem, but in big amounts it is. Think of it like trash: the occasional piece of paper on the street isn't a problem, but if everybody dumps their garbage on the sidewalk, it's a big problem.

If UWB were ever widely deployed, you can think of it as generating noise kind of like one billion light switches turned on and off many times per second. It's best to put a stop to that before it starts. Or, if we are going to throw out frequency based allocation, let's do it consciously (and let's wait for the UWB patents to run out before we do it).

Re:the UWB landgrab

[markj02]

overlaying multiple different modulation methods on the same frequency bands can lead to better aggregate utilization of the total bandwidth.

Only if the individual modulation methods aren't using their allocated bandwidth optimally. Of course, for historical and practical reasons, they don't. But the same technology that makes UWB feasible also allows more efficient utilization of spectrum within our current allocation system.

Trying to use UWB on top of the existing allocations in order to achieve better overall utilization seems like saying "we'll just park this car in your front yard--you aren't using the space for anything important anyway".

Deadborn. Let me explain why.

[Thor Ablestar]

Because the CDMA (UWB is CDMA) signals are not orthogonal. If you use the traditional radio you use the filters that ideally don't let other channels pass in, and really suppress them as well as needed.

But for the CDMA it's not true. The signals are not ortogonal. Other channels appear to be like a noise, and the only method I know to make them fully ortogonal is the one that is used in CDMA cellular phone - use of special code sequences that produce really terrible spectrum with a lot of narrow peaks.

Then, the fundamental power laws come into existence. To transmit a bit you need some energy to be received, and this energy cannot be decreased. If you spread the energy over the spectrum, the spectral density will be decreased but the energy itself will not. You needed 600 mW for AMPS and you still need it for CDMA.

Then, for instance, if you transmit 1 mbit/s over 1 MHz channel to 1 kilometer, you will need about 10 dB over the noise (Or less, if your coding scheme is really good). If you spread the signal over 1 GHz, the s/n at receive end will be about -20 dB and your receiver will be able to recover it. But on 100 m from the transmitter the s/n will be 0 dB - quite an interference for anything using any part of the 1-GHz band. In 10 meters it will be 20 dB and nobody will be able to use the band at all. So the CDMA towers command the phones to adjust the power levels in less than 1 dB increments to keep them equal. It cannot be done in usual conditions.

Limitations of UWB

[XNormal]

Ultrawideband cannot be used to communicate from your car.

A pulse width of 1 nanosecond translates to about 1 foot. A car travels many times that distance in a second. In a free space environment such as ground-to-air communication it is possible to compensate for this, but in a typical urban environment with many reflections it is probably impractical to track so many different propagation paths that chance so rapidly.

Narrowband communication is less susceptible to this problem. Multiple paths that differ by less than one bit time do not affect the receiver too much (although they have a certain probability of fading).

The processing gain of UWB is very high, but not infinite. A cellular phone transmitting too close to a UWB receiver *will* jam it. Combining the two in a single device is probably not practical. Filtering this frequency range will not help either: the notch filter may look OK in the frequency domain but in the time domain it creates too much ringing for UWB to work correctly.

This one happens to be correct

[XNormal]

There are other inaccuracies in the article: it's spectral power density is low, not it's power.

There are many errors in the article, but this one is not entirely incorrect: in practice, USB does use lower power than narrowband. UWB is not suceptible to fading so it does not need the large fading margin required by narrowband radio.

With narrowband communication the SNR fluctuates widely because of Raleigh fading - different reflection paths interfering either constructively or destructively. You need a large fading margin (extra power) to ensure robust communication.

With ultrawideband (i.e. bandwidth approaching center frequency) there is no Raleigh fading and the signal power does not fluctuate so much, even in environments with severe multipath reflections. This translates to as much as 20db savings of real transmission power.

UWB antennas

[XNormal]

The antennas have to be specially designed for broadband. They may be larger than practical for handheld phones, but fractal antennas may reduce the size.

Not any wideband antenna is good for UWB. UWB uses time-hopping modulation. This requires a very short antenna ringing time. The antennas cannot be large and they cannot be complex. The UWB antennas I have seen look ridiculously simple - a short piece of wire or a square of metal. That does not mean that they are simple to design!

Fractal antennas may be good *wideband* antennas but they are probably bad for time-hopping.

Almost free lunch

[XNormal]

Yes, Cringely doesn't understand 99% of the technology he writes about. That does not make the technology bullshit.

UWB is real. It's as close as it gets to a free lunch, and Claude need not turn in his grave.

you can build it, and it's all true... if there's only one such device

Not correct. UWB devices share the spectrum just fine. In fact, it's a far superior way to share the spectrum than narrowband frequency allocations.

The problems start when different devices use very different power levels: GPS uses extremely low levels, TV stations use very high levels and almost anything is at very high levels if you are close enough to the transmitter.

Spectrum sharing by frequency allocation provides very good separation between bands that use widely differing power levels. It's not too difficult to build filters that reject out-of-band interference by 100db or more. With ultrawideband, the rejection of unwanted signals cannot exceed 40-50db. UWB will work very well if all narrowband communications below 1GHz are shut down. Since that will never happen it will probably remain limited to very low power levels and certain niche applications.

Here's what might happen if all narrowband transmissions *are* shut down:

UWB cells for "last 10 miles" delivery, combined with long range fiber and satellite infrastructure could bring 100kbps to almost any person on earch and 10mbits/second to anyone living in a city. The terminals will use very little power and can have long battery life. Location tracking with 20 centimeter accuracy will be available anywhere in a city, including indoors.

How is all this possible with just 1GHz of bandwidth? The utilization efficiency of spectrum should not be measured in bps/Hz but rather in bps/Hz/square Km. Today's cellular infrastructure uses a very crude form of frequency reuse to optimize this capacity. IS-96 CDMA barely begins to utilize the real advantages of spread spectrum with a bandwidth of 1.25MHz. With 1GHz of spread spectrum things start to look different. And it's not just the bandwidth: 1GHz at a center frequency of 15GHz can only be use for line-of-sight communication. If the 1GHz band has a center frequency of 700MHz it has much better propagation and is immune to fading.

Of course, this will never happen. But not because it is mathematically or technologically impossible.

Huh?

[autopr0n]

How can you own a frequency?

I mean, if UWB really can deliver on it's potential, then why the hell should we stime it just so people who have invested in outdated technology can profit? That's moronic. Look, I mean if you own land and the government wants to put down a highway or a railroad, then they will. They just have to pay you for it.

The idea that we should hold back a huge technological advance on account of some moronic idea that people can 'own' mathimatical descriptions of b-feild flux is incredibly stupid.

UWB de-mystified

[icarumba]

For a discussion of UWB from a technology company that has been active in the field for over 13 years, check out these links:

UWB Frequently Asked Questions

History of UWB technology [from perspectives of 4 experts in field]

Various papers and presentations on UWB technology

Multispectral Solutions' submissions to FCC UWB proceeding

Hrm?

[autopr0n]

According to the artical, the military is already using UWB. I don't know why they would care, I don't see why UWB would cause problems for SS, and anyway, I'm sure the military would be using good digital encryption for anything important now.

Good Technology, but Long Way to Go

[GroundBounce]

I have had some exposure to companies working on UWB. There are currently two primary markets being targeted by UWB: position and tracking (including through-wall radars used by the military and law enforcement), and communications.

So far, the primary focus seems to have been on the position and tracking side. Primarily, this is because with out FCC approval, the only markets that could be targeted for an actual product are markets where it is possible to get a waiver - military and law enforcement are two such areas.

The current crop of chips that these systems are built on are very expensive and power-hungry. Because of the sub-nanosecond nature of the pulses, fairly exotic and relatively expensive technologies are required to both generate the pulses (which must not only be fast, but also properly shaped so they don't contain too much energy in certain areas of the spectrum), and to receive them.

In terms of communication capabilities, the current technology is not anywhere near the information bandwidth vs. range quoted in the article

Next generation chipsets will both increase performance and reduce power and cost, but these chips are still in the early planning stages. I wouldn't expect too many cheap, mainstream products in 18 months - it will probably take longer than that.

The technology clearly differentiates itself in the position and tracking area, with accuracies that are difficult or impossible to achieve with narrowband technolgies. The communications market, however, is extremely cost sensitive, and the road is littered with cases where the best technology didn't necessarily win, for a large number of reasons.

The companies championing UWB, such as Time Domain, are working hard to make both the technoloy and FCC approval a reality, and over time UWB will probably find significant markets, although it may not completely change the face of the earth overnight.

Time Domain dubious I'm afraid

[horza]

Last time I looked at Time Domain and did a little background reading I became *very* skeptical of them. I later spoke to someone high up in the Radio Agency (the people who approve/disapprove the use of radio spectrum in the UK) and he told me he had investigated them and hell would freeze over before they were allowed to operate over here. I think it will be an interesting proof of concept for the forseeable future.

Phillip.

Re:No Free OS

[Detritus]

) take a wait and see approach.

Because the electromagnetic spectrum is already polluted by unintentional radiators, due to lax regulation by the FCC. These devices don't go away until they break or are replaced, which may be decades.

The electromagnetic spectrum is a finite resource. There are ways of using it more efficiently. There is no magic wand that will create more spectrum. That means that somebody, such as the FCC, has to allocate it to the competing uses and demands.

Some of the hype behind UWB is the modern equivalent of perpetual motion, a promise to provide something for nothing.

Re:Leave Dubya out of this

[Dr. Spork]

He is an idiot, but perhaps you are right, he neither knows or cares one bit about frequency allocations. Still, he is the one who appoints the head of the FCC, and guess what: it's Colin Powell's son, an unellected pro-big-buisiness right-winger who thinks there's nothing finer than corporate welfare for the companies that bought off the administration (er--"purchased frequencies"). So this is not a low blow. In fact, this administration is the single biggest hinderance to any progress on the UWB. We should be looking to replace them with some people who might act in the interest of the public.

Inverse Square Law

[GroundBounce]

The raising of the noise floor for narrowband users (and other UWB users for that matter) is a concern, but I think the effect has been overestimated a bit. It is true that many UWB transmitters in a close area will measurably degrade the noise floor for other radios operating in that local area, but the RF energy falls off as at least 1/r^2, and in UWB it is very small to begin with (the UWB emissions actually meet part 15 specs for unintentional emissions).

Once you are very far at all from a group of UWB transmitters, their ourtput will not affect the noise floor beyond what would otherwise be the current noise floor to any measurable amount. In this sense, it's not quite as bad as the trash analogy. If UWB is used for short range indoor comm applications (e.g., in-home video distribution and networking), any increase in the noise floor caused by the equipment in one house would be nonexistent four or five housed down the street.

In other words, for short range UWB applications, the local noise floor will only be affected by those UWB transmitters within a certain relatively short distance, not by all the UWB transmitters in the country.