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'Whispering' Wireless Internet
Zondar writes "MSNBC is reporting about a new radio filtering technology allows an ISP to use already-occupied frequencies to transmit and receive data. From the article: 'xMax, the latest innovation in broadband communications, is a very quiet radio system that uses radio channels already filled up with noisy pager or TV signals ...' and 'xMax is trespassing radio frequencies, although trespassing is not the right word, because we're allowed to transmit a signal if it doesn't interfere with other, stronger signals...' Too good to be true? Sounds like it would just raise the noise floor, to me."
This is extremely interesting, if not tried before. I wonder what FCC/ologopolies will have to say when someone else starts using their hard lobbied/bribed frequencies.
FP?
Live for the present, learn from the past, and dream of the future!
Yeah, now I RTFA, but I had to get in that early post! Range covers 40 sqmi. Not too bad.
Great, so now we are going to get crosstalk between pagers and e-mail? Getting v14gra on your pager and weird codes from junkies paging their dealers in your e-mail :)
"I need to dump them to a file and diff the whore" -JT
This is just some kind of spread-spectrum technology, nothing new... The signal consists of pseudo-noise. If the receiver knows the key to this pseudo-noise and can synchronize to it, he can decipher the message. This idea and this technology have been around for years.
from the article:
The first xMax network is currently being built in Miami and Fort Lauderdale where one base station can deliver broadband Internet over a 40 square mile area.
But with that much area, you need to start worrying about capacity. What good is it to cover 40 sqmi when you can't get a packet through:
The capacity of that wireless network is not bigger than any other wireless technology, which means that more base stations need to be added if a certain number of people are using the network -- typically several hundreds to a 1,000 users.
"Scientists don't change their minds, they just die." -- Max Planck
Every few years somebody renames ultra wideband CDMA and acts like it's new technology.
I didn't see any mention of the FCC in this article at all, something that may be indicative of a lack of approval from the relevant bodies. It's all very well the inventors/creators saying that this is technically ok, but when the people who are allocated the frequency range this technology operates in have problems with the raised noise or extra signals, or even just object to something else intruding on their licenced spectrum, I wonder what will happen.
Business Voyeur
Check out
http://www.techdirt.com/news/wireless/article/5617
I'm surprised that no-one's actually tried something like this before. What with the prevalence of radios that can adjust themselves to noise conditions, it seems that it would be fairly obvious to build one that could listen to the frequency (or frequencies) it wanted to transmit on and intelligently avoid stomping on other, old-fashioned signals in the vicinity. It's interesting, 'cause I just got done reading about something like this in this rather weird, but oddly compelling book.
What?
You see? You see? Your stupid minds! Stupid! Stupid!
It's all the hassles of DSL but now with NO WIRES!
Radio chips for devices should be in the $5-$6 range when built in volume while base stations will be around $350,000. Those prices are competitive considering the range covered.
1000 transcievers over a 40 square mile area doesn't sound so bad to me. If the population is much denser than that, then wired net access is likely available.
An area of 40 square miles is a circle of radius 3.6 miles (5.8 km). Is that really more than a digital phone tower can manage, for example?
I’m old enough to remember 16K of memory being described as “whopping”
"xMax is trespassing radio frequencies, although trespassing is not the right word, because we're allowed to transmit a signal if it doesn't interfere with other, stronger signals" It's also not trespassing if it's occupying a public band in the first place.
See this article for an explanation of some of the technical details of the system.
Mea navis aericumbens anguillis abundat
If everyone switches to wideband, low-power, densely-coded, mesh-network transmissions, then I suspect that the Earth will become virtually invisible to extraterrestrials who try to use SETI-style, pattern-in-RF methods. With nobody broadcasting at high power on a simple-coded narrow-band carrier, the RF emissions of the planet will become indistinguishable from noise.
I wonder if each civilization goes through a short RF-detectability phase before they so densely pack the spectrum with so many emitters that they become invisible, too.
Two wrongs don't make a right, but three lefts do.
The technical details are sparse but here are two links.
6 3700624 that has a little more information.
In the faq http://www.xgtechnology.com/faq.htm there is a brief description. Note that the spectrum plot shown is basically worthless because it does not show any signal details.
Here is a magazine article http://www.mwee.com/showArticle.jhtml?articleID=1
Note the following: In the first is the statement that Shannon's theorem is not violated but no justification is given. In the second it says that most power is put in the carrier. Both of these statements should raise red flags. Be skeptical!
If you know the characteristics of a signal exactly, you can recover it from below quite a bit of noise. One of the experiments I have my students do is to recover a signal 20 dB below the noise. It is trivially easy to do. The amount of data you can send, on the other hand, is approximately zilch.
Shannon's law describes the amount of data you can send as a function of the signal to noise ratio. As long as you are willing to put up with low bit rates it is no problem to use a signal below the noise floor.
Several of the posters have assumed that these guys have re-invented cdma. That's not necessarily the case (although it might be).
I believe when you typed:
I wonder what FCC/ologopolies will have to say when someone else starts using their hard lobbied/bribed frequencies.
You meant to type:
I wonder what FCC/ologopolies will have to say when we starts using our hard lobbied/bribed for frequencies.
Get your Unix fortune now!
http://www.wirelessnetdesignline.com/howto/uwb/163 103775
An xMax-enabled system has several advantages of over a UWB network. Primarily, whereas UWB emissions require several gigahertz of spectrum, the "narrowband" version of xMax only requires sidebands on the order of several megahertz. The carrier synchronous nature of xMax also bests UWB, which uses thousands of pulses to represent one symbol.
Paradoxically, UWB is often designed as a PAN technology for use in the 3.1- to 10.6- GHz range and other limited uses in higher bands (24 GHz), leading to potentially high transmitter density. Given the amount of power emitted into adjacent bands, the cumulative likelihood of interference is high. In contrast, xMax is designed as a WAN technology, leading to a low transmitter density and lower interference potential. FCC rules also prohibit UWB applications from using spectrum below the 3.1-GHz band, whereas xMax is designed for sub-GHz use.
Lastly, xMax is a more efficient, agile system that requires as little as 6 MHz for broadband data transmission and can frequency-hop to vacant spectrum. As stated, the xMax signal is carrier-synchronous, making detection easier. UWB, on the other hand, doesn't use a carrier; timing must be embedded in the information, requiring large contiguous swaths of spectrum. Note that UWB requires higher signal power when measured using equivalent resolution bandwidth.
Lobbyists for spectrum license holders have written thousands of pages of F.C.C. comments ridiculing proposals to allow low-power transmissions (whispering) within their frequency bands. For example, highpower TV broadcasters argue that such low-power unlicensed underlays for uses such as WiFi would create harmful interference with their signals and lead to an inefficient allocation of resources. By lobbying against unlicensed underlays, they hope to hinder potential competitors and create a vast new market for themselves.
(It's never too late to join the Renaissance)
mod both parents up
I wouldn't be surprised if this is another thing to stomp all over the HF bands and raise the background noise level a lot. With this and BPL, you might as well say goodbye to 30 mhz.
On key piece of information I go looking for in new wireless schemes like this is how much information a "cell" can carry. For example, from memory a GSM cell carries about 400 kbps, a 3G cell carries 4 Mbps, a WiMax cell about 70 Mbps. The figure gives you a feel for how useful the technology will be for broadband.
If you follow the links already posted here, you will see it has FCC approval, it travels a looong way at low power levels, the chip set is expected to be under $10, has bugger all side-band interference, and so on. All well and good, but its useless if it can't carry information at broadband speeds. As far as I can tell that is the one figure they aren't not revealing.
I am not a radio guru, so there is probably some perfectly good reason why they have not published it. It would be nice to know what it is. It would also be nice to know what power is consumed by the thing. A long distance unlicensed transmitter that can be powered by a lithium battery for months (like bluetooth) sounds like it would be very useful.
Here's an important clue, from their FAQ: "The narrowband channel allocation that xMax uses to coordinate reception of its wideband xG Flash Signal is not the system's information-bearing bandwidth."
So, it's a very narrowband pilot signal plus low level wideband signal with some new filtering/shaping tricks and maybe frequency agility on the wideband part.
The pilot is strong, easy to find, on a known frequency, shaped to occupy minimum bandwidth, and carries low-bitrate control info - like where and when to find the "flash" information-bearing carrier. It also may be a system clock reference (why not?). Being a clock reference would allow for more fancy demodulation techniques (yielding better BER performance) to be used on the other signal, because the lack of need to do clock recovery from the weak "flash" carrier.
I'm a BSEE- not so strong in signal and noise theory. Is it possible that the added frequencies would add noise, but the noise frequencies would be above audio range? ...
In a short period of time, we will switch to laser and other directed communications for long range and mesh systems for short range. The only major signals going out will be the ones we intentionally send out. Likewise, SETI will probably never detect a stray signal if our civilization is any indication. The time period that an alien civilization would be smart enough to use powerfull radio, but dumb enough not to use something better is on the order of centuries which is a blink in a galactic timescale. SETI will most likely detect directed radio (or maybe laser) transmissions that would have been designed to act as pings from aliens. These directed signals would be targets at stars that the aliens know would be able to support life (as they define it) rather than just being very loud and undirected.
The speed I would think- could be anything up to the speed of light, limited by factors that normally bottleneck tcp.
if they say broadband, they mean broadband, which is anything faster than 56kB.
Even if it's slow like isdn, it will still ad to the luster of having access points everywhere, which can only be good.
I would like to take a guess and say it will compete with wimax, etc, but be slower because it will have to default to whomever has first usage rights on whatever particular Frequency it happens to be on when it gets *bumped*.
of course with spread spectrum and digital, along with the fact that this could conceivably have the WHOLE HF, down to .001 hz, we may be entering into an area where cheap or even free InterNet service is right around the corner.
I will gladly loose all of life's battles.. in order to win the war..
Talking about beautiful, brilliant women should ALWAYS be on topic here at /.
I mod everyone down who says "I'll get modded down for this." I hate to disappoint.
Mod all three... no wait, screw them; mod ME up!
The point is lower power. Since signal decreases as a square of distance, even small reductions in transmit power will have a dramatic difference in the noise signature of the Earth at multi-light-year distances. Ultra wideband allows lower power.
As an aside, the transition to heavily encoded packet RF also reduces our signature to ET. Anyone with a long enough wire and a speaker can pick up analog TV or radio and recognize it as synthetic. Can the same be said for highly dense encrypted digital traffic? Even my 56k modem sounds like white noise to me.
Build a man a fire, he's warm for one night. Set him on fire, and he's warm for the rest of his life.
Maybe I just don't get it. Can someone explain how exactly this is funny?
because he actually got first post.
Any in-band energy except for the desired signal is noise and WILL degrade the reception of the signal. If you put enough of these whispering signals in someone's band you will obliterate their signal.
No matter what kind of clever modulation and encoding you have, you are ultimately limited by noise. People tend to treat things like cdma and bluetooth as though they cause no interference and are not interfered with. That is simply not the case. In fact there are a goodly number of organizations who have banned bluetooth from their premeses because they are worried about interference.
Of course that is not to say that some people aren't using noise as a convenient support for an ulterior motive. That does not, however, make the noise issue less real.
As a previous poster pointed out, this sounds a lot like VMSK - a well debunked modulation scam.
. htm
Here's another: http://www.sec.gov/litigation/litreleases/lr15898
"Never give a sucker an even break." (W.C. Fields)
This reminds me of people in the ham radio community that do extremely low-wattage radio contacting, also known as running "QRP". One major difference, whilst you might be able to hear morse code decently at 2 watts, across the ocean and down the continent from another person, I doubt that a complicated hiss of an internet connection could be sustained using near noise-level strength signals. I mean, what kind of bandwidth are we talking about here? With all the packets that would be dropped, and resent, it'd be like surfing the internet on your TRS-80.. but i guess if you're like my friend "slow is a whole lot better than full stop". So i guess frustration is easier than being calm and being able to do what you expect on your connection. Oh well! It just doesnt seem like this will go anywhere. Thought i'd add my $00.02 73 DE KI4GMB
although trespassing is not the right word, because we're allowed to transmit a signal if it doesn't interfere with other, stronger signals...
Damn right it's not the right word, and it wouldn't be even if it weren't legal to transmit on those same freqs. You can't trespass on frequencies because frequencies are not anyone's property. We gotta shake off this relentless trend of treating rights and licenses as property. To use a more familiar example, nobody "owns" music, not even the composer. Rights holders don't own anything at all, they merely control the rights to do specific things for a limited time.
The distinction isn't semantic nitpicking, it's very important because treating rights as property gives the copyright control industry an unfair advantage in any public discussions about rights issues. They like to play the part of the plucky little old lady chasing down a purse snatcher, or the outraged homeowner defending his castle against burglars and government goons. They get away with it because the public has been taught to overlay the simple and familiar concept of property on much more complicated issues. Treat rights as what they are -- temporary conditions set by the government -- and various rights and DRM issues suddenly require a lot more thought, which they should.
little girl: "There is no floor."
- Calling Hedy Lamarr a "scientist" is a bit of a stretch. If you read her autobiography, she sounds more like a very vain and scatterbrained barbie doll. (Not to mention, bisexual, which makes the book really *hot*)
- First of all, she didnt seem to have a clue that radio waves don't make it very far in water. Water, eswpecially salty water, conducts electricity, which shorts out radio waves.
- How is the transmitter supposed to sync up with the receiver?
- The local oscillators of that era were not too stable-- you couldnt depend on a LC tuned oscillator to stay on frequency, especially given the temperature, humidity, and vibrations inherent in a torpedo.
- Most jammers already assume there's going to be some manual frequency hopping, so they used a braod-spectrum noise source to cover a wide swath of spectrum.
So as often is the case, nothing to see here.Wireless Regional Area Networks. IEEE is developing a standard for a cognitive radio-based PHY/MAC/air_interface for use by license-exempt devices on a non-interfering basis in spectrum that is allocated to the TV Broadcast Service.
...it's on a standards track.
.com days.
Until then, it's just some crazy joe's propriatary protocol that will fail due to lack of market acceptance. I mean it's not like this hasn't been tried before. Just look at Breezecom or Alvarion or whatever they're calling themselves this week. Prior to a widely accepted IEEE wireless standard, Breezecom was a market leader... now just about *EVERY* 802.11* chip foundry/reseller is bigger than they every were (and it happened in a faction of the time it took Breezecom to build (and lose) their market).
Put that modulation/protocol on a standards track, make the radios frequency agile, allow the carrier to use both licensed / unlicensed bands and you *MIGHT* have something worth writing about.
Hell, even WiMax is looking like is going to be a pooch screwer... and that's *ON* a "standards" track. Companies driving current standards tracks seem to not understand that cheap, interoperable client end radios everywhere are what made WiFi what it is today.
Looks like it's going to be an 802.11a/b/g world for a very long time (unless IEEE gets their groove back). I'm sure parallels can be drawn with the ethernet standard(s) back in the near pre-boom
Oh, and while I enjoy a few moments of flaming *RANT*, if the FCC had any balls, they'd open up frequency space with better propagation characteristics. Until then, the FCC will continue to prove themselves to be nothing more than the corporate bitch that they are.
... if that transmitter would have an output a little higher, say 1.21 GigaWatt, then we could just leap to another time where aliens are here!
Now where did I put my Flux capacitor...
To Terminate, or not to Terminate, that's the question - SCSIROB
No wait...that was Hedley Lamar.
Oh, a wed wose...how owdinawy.
Give the Governor harumpf!
We covered this a week ago at Techworld, from an interview with Joe Bobier, who invented the technology.
There are a couple of interesting things about this. On one level, it's a UWB-like system that promises to do longer distance, by the use of a narrowband licenced channel for a timing signal.
So far, it's only been demonstrated indoors (and that's the basis of its support by Stuart Schwartz, the Princeton professor). The people involved have a history that I am still disecting.
All of which makes me want to wait and see how it works in the proposed wide-area demonstration. Peter Irrelevantly to this discussion, I had a Slashdot post on xMax accepted over the 4 July weekend, that never appeared on Slashdot.