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

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!

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...

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

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."

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.

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

[Anonymous Coward]

UWB boxes don't switch frequencies, but you're sort of on the right track. They simply use *very narrow* pulses, which in the frequency domain have an "ultra wide bandwidth". IIRC our friend Bob made mention of this.

Someone in a previous post also posited UWB is nothing more than remarketed spread spectrum. It's definitely not DSSS, but I'd say a distant cousin. UWB relates to DSSS only in that both achieve robustness and discourage detection by intentionally spreading the signal in the frequency domain. There are no separate spreading and payload modulations with UWB, though. UWB trades the functional complexity of a DSSS radio with more simple, but much higher precision parts, to achieve tight timing requirements.

According to a digital signals textbook I own, there are three main "flavors" of spread spectrum systems - frequency hoppers, direct sequence and time hoppers. I've never seen a commercial time hopper radio, but have read the US military at least experimented with them. UWB is time hopping (information transmitted in pulse timing - I believe also can be called pulse position modulation), combined with the use of picosecond or even femtosecond-range pulses. Very short pulses also allows for lots of pulses per second... hence the ability to potentially offer high data rates.

It's been about 3-4 years since I worked in the wireless field, but even then UWB was being actively talked about, tested, and Time Domain the company was doing demos. Typical signal bandwidths were on the order of 2-3 GHz, occupying spectrum between 1 and 4 GHz. The occupied bandwidth was determined by a bandpass filter and little else. And that's all one needs, since the rest of the radio is all done in timing of the pulses.

Another interesting technical challenge of UWB (which ties in with the preceding paragraph) is the antennas. Physically constructing antennas that present a good impedance match across a wide range of frequencies and have good phase/group delay characteristics, let alone be an efficient radiator is *tough*. This is a knotty engineering problem for any long range use of UWB technology. In that respect, I feel 1km range for UWB is not as practical as Mr. Cringley makes it sound. However, for very short range, inefficient antennas can be good enough, and that's where I believe we'll see the first applications.

It's closer than you think. The 10+ GHz Ethernet technologies now making their way into the mainstream will make the necessary technology a commodity. The engineering veep of a well-known wireless vendor once told me the (relatively) cheap 2.4 GHz stuff we now know and love was made possible by the mass production of PCS (1.9 GHz) parts, antennas, etc. - then adapted to 2.4.

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: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*

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: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.

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

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.

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

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

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.

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.

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.

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 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