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Wireless Networking Hardware

New Technology Could Kill WiMax? 263

Posted by Zonk
from the maybe dept.
GolygyddMax writes "Techworld reports that a Florida-based start-up, xG, has developed a technology that's a 1000 times more efficient than WiMax and which could, in theory, lead to wireless LANs being powered by watch batteries. It is still in early development, but this technology could allow anyone to set up as an ISP. This could kill WiMax before it even gets off the ground." From the article: "At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS, but had to take the 50mW base station - and its omnidirectional antenna - on trust, since it was at the top of an 850ft mast. The demonstration will be repeated for the US press next week. The system carried 7.4 Mbit/s per MHz per Watt, said Professor Schwartz. By comparison, GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz per Watt. "
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New Technology Could Kill WiMax?

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  • by PIPBoy3000 (619296) on Friday November 04, 2005 @12:17PM (#13951230)
    Must . . . resist . . . grammar . . . posting . . .
  • by Anonymous Coward on Friday November 04, 2005 @12:18PM (#13951244)
    Since a system like this working with IPv6 could potentially eliminate the need for telecom/cell service providers (since the power reqs are low, it won't be a problem for people to relay each others communications and act as peer to peer links ..using any of the already existing relay reward based schemes).. I could see how cell phone companies would want this technology neutralized.
    • You've been missing the discussions for years that prove that IPV6 is plainly far too much, and that IPV4 needs to be fixed via re-allocation of huge A B and C block and CIDR allocation madnesses that were doled out in the early DARPA days of the Internet.

      What's nice about the posted technology is that its encoding methodology might answer some prayers that neither WiFI or WiMax does. But it's all still unproven, and still far into the future. I like the low battery consumption side of it, as WiFi sucks the
    • This is something I dwell on, from time to time (I posted this comment on "Peer-to-Peer Cell Phones" [slashdot.org] in 2002):

      A small number of people have a direct connection to the internet and share it with anybody within a large range, to wireless devices that not only use it, but also share it to others, thus further extending the range. With enough such devices, an entire metropolitan region can get blanketted in internet access. Sure, the connection would be slow, but eventually, everybody would be connected wire

    • You'll see some legal challenges but not because it competes wil the telephone services. The real challenges will be related to 911. Since the telephone companies are required to provide E-911 data, how will these guys do this? Cell phone companies have invested lots to be able to ensure that when you dial 911 they can tell where you are calling from. WHile this technology isnt perfect yet and will be years before they have 100% compliance, its getting there. Imagine making a 911 call wirelessly via VOiP
      • There is a simple fix for that: use the phone's built-in GPS receiver.

        No consumer-level data network (WiFi, WiMax, etc.) is aware of its location. Since VoIP goes through data networks which may be re-routed through other networks (someone routing calls using SSL to some other machine), it is impossible to determine the exact location based on the traffic's apparent point of origin.

        100% 911-compliant VoIP is unlikely to ever happen because the 'line' is not tied to any fixed infrastructure. Cell phones have
  • by Bastian (66383) on Friday November 04, 2005 @12:18PM (#13951249)
    I am not a radio engineer, but here's what I read from "7.4Mbit/s per MHz per Watt." "At one watt, we can cram 7.4 bits into one cycle of a sine wave. At two watts, we can fit 14.8 bits into one cycle of a sine wave, and so on."

    How does that work?
    • A Watt is a measure of power not the frequency of the carrier wave, i.e. think of this wattage as the amplitude of the sine wave. The frequency has to be much higher than than the number of bits being transmitted per second or at least the resonance modes needed to construct the square pulse from sine waves needs be.
      • by InvalidError (771317) on Friday November 04, 2005 @03:36PM (#13952888)
        Actually, how many bits you can cram in 1Hz of bandwidth depends on the SNR.

        From Shannon: bps = BW * log2(1 + S / N)

        So, with a 30dB SNR you get BW * log2(1+1000) = you could almost encode 10bits of data per Hz of bandwidth... a little under 10Mbps per 1MHz.

        Since this modulation has smaller sidebands, more energy gets packed in a narrower band, enhancing the signal's strength while reducing the amount of noise picked up. It makes sense and I imagined something like this years ago. It looks basically like a single-cycle version of FSK or PSK but I think these should not look quite as clean as they did on their plots. (Well, they did stop at 100kHz resolution.)

        As far as the signal generation goes, I am guessing they used an FPGA to drive an ADC and DAC for their prototypes and their 50mW is only the DAC's power output, not the entire receiver/transmitter power. They insist a lot on the signal's power but they say nothing about the system used to generate, transmit, receive and decode the signal.
    • by Wesley Felter (138342) <wesley@felter.org> on Friday November 04, 2005 @12:26PM (#13951346) Homepage
      It probably doesn't work. Like everything else, the RF field is full of snake oil created by people who don't quite understand what they're doing. The stuff always demos well, but it never quite makes it into production.
    • by jonesboy_damnit (773676) on Friday November 04, 2005 @12:29PM (#13951369)
      From TFA:

      "xMax is unconventional," said Stuart Schwartz, professor of electrical engineering at Princeton Universithy, who has scrutinised xG's demonstration set-up, speaking at the xMax demonstration. "It is clever and innovative, but it is not magic. It uses single cycle modulation, and needs much less power than other technologies."
      Single-cycle modulation is the invention of xG's chief technology officer Joe Bobier, with backing from Mooers Branton, a merchant bank, whose founder Rick Mooers also serves as xG's chief executive. The modulation scheme alters the frequency of individual cycles of the carrier wave, which has the effect of introducing very low power side-bands to the signal.


      My take is that they're using the difference in frequency between the carrier frequency and the generated sideband frequency to represent a value (ie. +10kHz = 0001; +15kHz = 0010; etc.). This seems awfully similar to the SSB modulation commonly used in shortwave radiocommunications to me.

      Since they're operating in the license-free 900mHz ISM band, it also *must* implement some sort of frequency-hopping (or direct sequence, I suppose) spread spectrum stuff in order to be legal. Could be kind of an interesting technology. I'd like to play with a couple of the radios and a good spectrum analyzer to see what it looks like.

      In the interests of full disclosure, IANARE (but I played one at a job once for awhile).

      -Matt
      • by fatboy (6851)
        Since they're operating in the license-free 900mHz ISM band

        Not a good band to be operating in for weak signal type stuff. The 300Watt paging transmitters operating in that band could cause them some trouble without the use of a helical front end on their receiver.
        • by rot26 (240034) *
          Not a good band to be operating in for weak signal type stuff. The 300Watt paging transmitters operating in that band could cause them some trouble without the use of a helical front end on their receiver.

          That's the whole point. It's fairly conventional technology, but they've developed MAGIC TECHNOLOGY at the reciever that filters out the BAD signals (i.e. NOISE). Low operating frequency plus incredibly low S/N ratio equals efficiency equals range. They state on their website that they don't violate S
      • My take is that they're using the difference in frequency between the carrier frequency and the generated sideband frequency to represent a value (ie. +10kHz = 0001; +15kHz = 0010; etc.). This seems awfully similar to the SSB modulation commonly used in shortwave radiocommunications to me.

        Actually this seems awfully similar to FSK (frequency shift keying) to me. And I am not sure that I trust it:

        The modulation scheme alters the frequency of individual cycles of the carrier wave, which has the effect of i

    • That's the smell of BS.

      Anyone else check their shoes? I think slashdot stepped in it again with this article.

      If I'm wrong, then I will shut my piehole. ;)

    • Its all BS. Basically there is a standard MHz and a standard wattage that you really can't deviate much from. As well seval signals are being sent in neighboring MHz. Anyways the guy sent a 3.7Mbit/s signal using 1/20th of a watt using 900Mhz. To make the assumption that if use 20 times the wattage you could do anything but improve the distance/signal loss is rediculus.
      • Of course, with twice as much power the S/N ratio can be twice as much, giving you more bandwidth. I'm not certain how much more bandwidth, as that depends on the current S/N ratio.
      • by jonesboy_damnit (773676) on Friday November 04, 2005 @12:42PM (#13951485)
        Actually, increasing the transmit power *can* buy you greater data rates, as long as your data rate is limited by signal-to-noise ratio.

        For example, let us build (in our minds) a transmitter/receiver pair which can encode/decode one symbol every second. OK? Every second we send one symbol (effectively a magic combination of waves which means something to a demodulator) from the transmitter, and every second we decode one symbol at the receiver.

        If we have lousy SNR, we might only be able to differentiate between the most distinct two states of the transmitter (one bit per symbol: either 1 or 0), since all the noise impinging on our signal looks an awful lot like the more subtle states (or even worse, completely obstructs all states, making decoding impossible). This gives us a data rate of 1bps.

        If we can increase the signal level at the receiver, thus increasing SNR (assuming we're not distorting the living hell out of our transmission, natch) but increasing our transmitter's output, we might be able to encode *two* bits per symbol (00, 01, 10 or 11) by adding two more symbols to the constellation. By doing this, we haven't increased our symbol rate (still only one symbol every second), but we *have* doubled our throughput.

        Make sense?

        -Matt
        • by tessaiga (697968) on Friday November 04, 2005 @01:17PM (#13951750)
          If we have lousy SNR, we might only be able to differentiate between the most distinct two states of the transmitter (one bit per symbol: either 1 or 0), since all the noise impinging on our signal looks an awful lot like the more subtle states (or even worse, completely obstructs all states, making decoding impossible). This gives us a data rate of 1bps. If we can increase the signal level at the receiver, thus increasing SNR (assuming we're not distorting the living hell out of our transmission, natch) but increasing our transmitter's output, we might be able to encode *two* bits per symbol (00, 01, 10 or 11) by adding two more symbols to the constellation. By doing this, we haven't increased our symbol rate (still only one symbol every second), but we *have* doubled our throughput.
          You're missing the point. Yes, you can increase data rate by increasing power. However, by quoting a data rate per watt, they're claiming that power increase required is linear in the increase in data rate. It's well known that an exponential increase in power is required [wikipedia.org] to increase your data rate. OP was pointing out that the data rate they reported has to be at a specific power level, and that you'd quickly discover it's not going to be very feasible to increase the data rate significantly beyond that by increasing power (contrary to what that "per watt" statistic suggests).
      • Not really, consider that the signal sent is digital but the transport is analog, you could assign values to frequency shifts, phase shift and amplitude levels. Greater power permits greater amplitude, depending on the resolution of the A/D converter at the other end, greater amplitude can lead to more information channels. A 16bits A/D could therefore have a theoretical 65536 channels into which information could be extrated from frequency shifts and phase shifts, hence greater power=more information.

        Of co
    • The "per watt" rating refers to power. The signal improves due to increased power because the signal is clearer, and therefore there is less interference and packet loss. As for the 7.4 bits per sine wave, I'm as stumped as you. Maybe they use harmonics or something.
      • an EE here at work says you can fit multiple bits into a sinewave - the more you try to cram into a single cycle the elss flexible it becomes
      • An easy way to look at that is Amplitude Modulation (AM). Lets pretend that you have REALLY good signal to noise ratio - basically no noise. Use 44.1 KHz of bandwith, transmit CD quality sound, and you can get 44.1 KHz * 16 bits/Hz out of it.

        Of course, in reality you use the time domain as well as the amplitude domain, but that is the idea.
        • Use 44.1 KHz of bandwith, transmit CD quality sound, and you can get 44.1 KHz * 16 bits/Hz out of it.

          I am an EE, but my major is Power Engineering. But IIRC from my (short) telecomunication theory course, there is some limit of bits per hertz you can get. I really doubt if 44.1kHz bandwitdh could give you 44.1kHz*16bits.

          Is there such bitrate/bandwidth limit or I am wrong?

    • I am also not a radio engineer, but I'd imagine that it's calculated this way: Say you've got 1MHz of bandwidth (You 'own' the radio spectrum between 9MHz and 10MHz.) On that one band, you can transmit 7.4Mbps with a transmitter that uses one watt of power. If you double the Wattage, you double the bandwidth. If you get another MHz, you double the bandwidth again.

      GSM uses 890-915MHz for phone transmit and 935-960MHz for base transmit, so this system could transmit 185Mbps with one watt, or 18.5Gbps with 10

    • What they are actually saying is that it takes xwatts to transmit 7.4mbit/s over 900mhz. If you divide x by 900, then divide the transfer rate by that, and play with the numbers a bit you wind up with the "value" of 1 watt. Its usefully for compairing efficiencies, but it doesn't imply that you can simply increase the wattage to gain frequency or transfer speed. Its a formula that describes a senerio, not defines it.

      -Ruck
    • by TheSync (5291)
      7.4 Mbps per MHz per Watt is a silly way of saying things. The key is signal to noise at the receiver, which depends on signal loss and noise in the received spectrum where you are seeking the signal.

      On their site, xG has a plot of bit error rate versus Eb/No [xgtechnology.com] (the energy in a bit over the spectral noise power, which is related to carrier-to-noise ratio as Eb/No=C/No - 10log(data rate)). It appears to perform as well as BPSK (binary phase shift keying). Although it doesn't make it clear how many bits per
    • "At one watt, we can cram 7.4 bits into one cycle of a sine wave.

      Not quite. It suggests they can cram 7.4 bits into a 1Hz wide channel.
      For example in theory you could descide to represent data using a carrier which
      at any instant in time can be at one of 256 different power levels. That gives
      you eight bits per symbol. To keep the frequency components of the signal within
      a 1HZ channel you have to change the power level slowly which liits the symbol rate. For this to work you need the signal to noise ratio to
    • by Guysmiley777 (880063) on Friday November 04, 2005 @01:54PM (#13952039)
      It's easy. 7.4Mbit/s per MHz per Watt -> 23.1LOC/hh/kg (Libraries of Congress per hogshead per kilogram) -> 1,225Gbit/HP-ft-lb/AU. Once you get past the fact that you are comparing meaningless numbers, you can pretty much make up whatever you want.
    • "At one watt, we can cram 7.4 bits into one cycle of a sine wave. At two watts, we can fit 14.8 bits into one cycle of a sine wave, and so on." How does that work?

      The easiest way (to explain) to make it work is to assume that for each period you change the amplitude of the sine wave, e.g. you transmit a sine wave of 1V, 2V, 3V... or 128V. At the receiver you measure the amplitude (number from 1 to 128) and this would allow you to transmit 7 bits. At the same time you can transmit cosine waveforms and pla

  • It's you! (Score:3, Funny)

    by tnk1 (899206) on Friday November 04, 2005 @12:18PM (#13951252)
    Launch all ZiG 1000 times for efficent Justice!
  • by Jim Morash (20750) on Friday November 04, 2005 @12:19PM (#13951266)
    Three orders of magnitude better than GSM or EVDO? There is no way this is true. What a load of bul^H^H^H marketing!
    • When I saw this on the front page - with the thing about the 850 ft tower it IMMEDIATELY brought the phrase "Any suitably rigged demo is indistinguishable from magic".

      There have been cases of this before - very convincing demos done that have turned out to be snake oil, or perhaps have the kernel of truth behind them (and the demo used to drum up capital - at which point the inventors HOPED they could make the technology actually do what the rigged demo showed).

      Basically, I'll believe it when you can buy it
  • by Brunellus (875635) on Friday November 04, 2005 @12:20PM (#13951276) Homepage

    wait, WiMAX was alive in the first place? Either I'm actually living under a rock, or I haven't seen any significant real deployments of the technology outside of pilot programs. So from where I sit, WiMAX can't be killed, because it's not alive.

  • by CyricZ (887944) on Friday November 04, 2005 @12:20PM (#13951278)
    They need to sign a contract with a large transportation provider in Europe and Japan, so as to provide this service on all buses, trains and other public transport vehicles. That would give people the incentive needed to purchase the hardware necessary to take advantage of this new system.

  • by Mille Mots (865955) on Friday November 04, 2005 @12:20PM (#13951284)
    Infinium Systems [phantom.net] announced the addition of wireless gaming to the panoply of features included in their phantom Phantom Gaming Console.

    --
    Who knows what evil lurks in the hearts of men?
    The ShadowPhantom knows!

    • The funny thing about the Phantom is that it's basically an XP PC, and they can't get it out the door. How much R&D needs to be done to get a fairly standard PC shipped? They might claim it's the backend that needs most work, but it's just a network server that sends you files. They've been doing that since the inception of digital communications.

      I don't know, I think the Phantom would be a cool toy to have. But after years and years it's just stupid now.

      Let's not even mention Duke Nukem - that
  • by rsborg (111459) on Friday November 04, 2005 @12:21PM (#13951289) Homepage
    From TFA:
    not unlike a cordless phone base station, operating in the unlicensed - and crowded - 900MHz band, to send a 3.7Mbit/s data signal to a radius of 18 miles across the suburbs of Miami
    and this:
    Before any of this happens, more demonstrations are needed, to show the system is robust against interference and multipath, and can operate in an area more crowded than 18 miles of swamp. It will also need to be approved by the FCC and other regulators round the world.
    Those are BIG if's. Most likely, if it can withstand a moderate amount of interference, this will mainly be used to support other technologies.

    Yeah, an immersive internet would be awesome... but this thing still has some issues to be resolved.

    • RF engineering is nothing new. If they use a low power/high propigation (low) frequency, they run into interferance unless they are using very directional equipment. If they are using a high frequency (high power/low propigation), then they will need higher xmit power. These variables will not change.

      What does change are advancements in modulation, DSP's, antennas, equipment cost etc.

  • More details here (Score:5, Informative)

    by Anonymous Coward on Friday November 04, 2005 @12:21PM (#13951295)
    Lots more details in this article [zdnet.co.uk], and photo's here [zdnet.co.uk]. Looks very interesting.
  • by pubjames (468013) on Friday November 04, 2005 @12:22PM (#13951298)
    It is still in early development...

    I have a technology that's ten times better than this one, although it is in very early stages of development...

    No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

    • >>No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

      "At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS....."

      Was the demo mention in the summary fictional?

      • Was the demo mention in the summary fictional?

        Pretty much, yes. In their demo, the alleged transmitter was up on an 850' tower. Reporters had to take it on faith that the signals reported by the recievers were really coming from that transmitter and that there wasn't a bank of car batteries and a 100W linear amp up there.

        Until someone from outside the company can hook meters up to the transmitter and verify that it is really the source of the signal and that it's really using as little power as they claim
    • If you had RTFA, and g-d forbid, a couple of the links, you'd know that they gave a working demo. They will also be giving another "broader" demo next week. This is also backed by a Stanford prof who is taking a big risk here.
    • by pscottdv (676889) on Friday November 04, 2005 @12:40PM (#13951455)
      "No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo."

      You don't know much about raising venture capital, do you?
    • They have an effing demo. Did you RTFA?
    • No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

      Unless they are looking for more funding because, apparantly, they don't yet have a genuine working prototype and have run out of money.

      -Adam
  • Two things (Score:5, Insightful)

    by aztektum (170569) on Friday November 04, 2005 @12:22PM (#13951302)
    There are two primary stumbling blocks before it will take over WiMax:

    1) It actually does what the article says

    2) It isn't bound up the ass by patents and doesn't require hefty fees to implement.
    • "but this technology could allow anyone to set up as an ISP."

      I'm sure there are some heavily-moneyed parties who would rather not see things de-centralize. This is part of a larger losing picture for the whole computer/networking technology arena. We've become everyone's beating boy, and so far everyone has succeeded in doing this. If only our industry had a fraction of the clout of the NRA. If only the Founding Fathers had understood the concept of end-to-end networking. Oh well. We'll probably figure out
  • relay network (Score:5, Interesting)

    by TheSHAD0W (258774) on Friday November 04, 2005 @12:22PM (#13951310) Homepage
    There had been some discussion here in the past about using cell phones as network relays as well as end-points to increase range and reach, but one of the conclusions was that having cell phones constantly retransmitting data would run down the batteries too quickly. This technology might change the equation, making it possible to have an ad-hoc networking system shuttling data between portable devices rather than needing a lot of infrastructure.
    • ad-hoc networking system shuttling data between portable devices rather than needing a lot of infrastructure.

      Won't somebody please think of the propagation time!

  • This tech may be better but given all the installed pre-wimax stuff and strong industry support I doubt that anybody will just scrap WiMax and restart all over... Betamax/VHS anyone ? [wikipedia.org]
  • by EriktheGreen (660160) on Friday November 04, 2005 @12:25PM (#13951333) Journal
    The poster of this article assumes that the technically superior solution will rise to the top. In fact, the administratively superior solution will... this means that if companies spend millions of dollars preparing a standard and products for market, they won't switch to something else automatically even if it's obviously better.

    The reality of the situation is that if the new solution is exactly what it's sold to be (unlikely) then it probably will eventually break into the market, but even if it's made into a useable product immediately its use will be overshadowed by the well advertised and enthusiastically sold solution that the vendors are pushing instead. Vendors really don't care what's superior unless they're picking technologies from a menu and they have no interest in any of them (positive or negative). Vendors care about money, and if they've already spent some on one technology, they won't switch unless it's obvious that another technology will immediately dominate the market (VERY, VERY rarely does this happen).

    Take off the rose colored glasses, people. Technically superior solutions MAY eventually win out over poorer ones if all else is equal, but all else NEVER is equal.

    Plus, it's unlikely that this "breakthrough" is anything but some ambitious people trying to sell something inferior as if it's the solution to All Our Problems (tm).

    Erik

  • by Hoi Polloi (522990) on Friday November 04, 2005 @12:27PM (#13951355) Journal
    This would probably one of the few Florida-based start-ups that didn't involve spam or real estate fraud. Maybe it is a breakthough in spam transmission!
    • Hey, I'm a Floridian you insensitive clod! You forgot trailer park developments in coastal hurricane zones, sketchy interstate-side strip clubs that take out every billboard for miles in either direction, and the Tampa Bay Devil Rays!
    • Well, they are starting in a swamp...
    • just like:
      Texas = Fraud
      Telecom = Fraud

      Why do you think the bushies control these states? They're corrupt as hell, but unlike the rest of the corrupt south, these two states have money.

      Don't get me started on Telecom.
      • or swampy, whichever you prefer but I wouldnt be surprised if we got some legitimate startups out here.

        My girlfriend and I moved from LA and now we're seeing new california license plates out here every week as well as recent transplants from colorado and oregon. Theres alot of opportunity out here because it isn't built up yet and realestate prices are cheap.

        The thing is you know these people moved here and aren't realestate speculators because they wouldnt move their car cross country, they would just fly
  • by hurfy (735314)
    Either cut down the mast or file this under: Too good to be true......
  • Usually different modulation schemes are used tailored to the needs of he environment.
    For example... your cable modem will most likely use QAM (Quadrature Amplitude
    Modulation) because it doesn't have to expect a lot of interference on the
    media. Your digital satellite feed and 802.16 Wimax use QPSK (Quadrature Phase Shift Keying)
    because noise does not nearly affect carrier phase as much as the amplitude. None of
    the modulation schemes today transmit information on the basis of a single cycle. A QPSK
    transmitte
    • More likely however, even though there is still a lot we could squeeze out of 1MHz of spectrum: it is hype but hey... surprise me...

      Is this true? I thought modern modulation/coding/etc. schemes were already close to the Shannon limit. Barring some serious MIMO trickery I doubt this company can do what they claim they do.
  • by Resident Netizen (769536) on Friday November 04, 2005 @12:38PM (#13951441)
    Cool! So we get these little transmitter-thingies that are super-efficient and then implant them and run them off of our own bio-electrical energy... then we just all plug in to each other!

    I want a pony!
  • The real truth is (Score:5, Informative)

    by zappepcs (820751) on Friday November 04, 2005 @12:42PM (#13951487) Journal
    That xMax technology is patented etc. It uses a low power signal to orchestrate the use of very low power signals in what is 'normally' the noise bands adjacent to the desired signal. That is to say, it uses multiple frequencies, but at such low power it only looks like noise. It is both clever and capable. The real trouble is that it

    1 - is owned by a single vendor,
    2 - has yet to be approved by the FCC,
    3 - still needs to pass more testing stages before anyone will dare use it.

    Even though it is a sound technology, it does something that other tech has not been allowed to do: use adjacent spectrum that is not licensed to the operator. There are significant hurdles to this technology being used.
  • WTF does a watt have to do with bandwidth? This has got to be one of the stupidest things Slashdot has posted in a while.
  • by DSP_Geek (532090) on Friday November 04, 2005 @12:48PM (#13951536)
    The transmitter just happened to be atop an 850 foot mast so the reporter had to take the power and antenna descriptions on trust? Come on. They could've put KABC up there and no-one would be the wiser. I won't believe a word of it until they actually show actual hardware transmitting actual bits. Until then it's a press release.
  • by Rorschach1 (174480) on Friday November 04, 2005 @01:02PM (#13951641) Homepage
    Your assignment for today is to read up on the Shannon-Hartley theorem [wikipedia.org]. Then ponder the sort of signal-to-noise ratio required to do what they're saying. I'm just not seeing it happen. And the explanation of changing the frequency of individual cycles - that doesn't make any sense to me. That's just FM, not a novel modulation technique.

    Also, consider the black-box demo - so typical of snake oil these days. If it was an actual, novel system, you'd probably have a custom board with a pile of FPGAs and such in there. No amount of staring at it would tell you anything significant about how it works. On the other hand, if it's a commercial WiFi board with 'Netgear' plastered all over it, it's going to be pretty obvious. So what are they hiding?

  • From the marketing blurb: "by combining advanced technologies"... aha! I knew it! I can return to the future now, Looks like I found my ship!!
  • by TheSync (5291) on Friday November 04, 2005 @01:10PM (#13951704) Journal
    20050008087 [tinyurl.com] Tri-state integer cycle modulation

    The invention disclosed in this application uses a method of modulation named Tri-State Integer Cycle Modulation (TICM) wherein a carrier signal, comprised of a continuum of sine waves is modulated such that spectrum utilization is minimal. A modulation event is imposed upon the carrier signal by modifying the carrier frequency at precisely the zero crossing point or the zero degree angle. The method of imposing the modulation event is by increasing the frequency of the carrier for one or an integer number of wavelets then lowering the frequency of the carrier for one or the same integer number of wavelets then returning to the carrier frequency to derive the modulation event. The main carrier frequency is only modulated beginning at the zero degree phase angle and ending at the 360-degree phase angle.

    20050007447 [tinyurl.com] Modulation compression method for the radio frequency transmission of high speed data

    20040196910 [tinyurl.com] Integer cycle frequency hopping modulation for the radio frequency transmission of high speed data
  • Black Box (Score:3, Funny)

    by GungaDan (195739) on Friday November 04, 2005 @01:16PM (#13951746) Homepage
    "At this stage, with patents pending, the technology behind this is very much under wraps, and was literally present at the demonstration in a 'black box.'"

    Wait... I've heard this one before. Recently. $10 says there's a midget with a chess set inside that box.

    • $10 says there's a midget with a chess set inside that box.

      Q: What's the chess set for?

      A: To keep the midget from getting board.

  • by FrankDrebin (238464) on Friday November 04, 2005 @01:19PM (#13951777) Homepage

    By comparison, GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz per Watt.

    In a world where CDMA EV-DO with Turbo Coding [wikipedia.org] comes within 1-2dB of the Shannon Limit [wikipedia.org], xG claims their system is 1000x (60dB) better. Perhaps they are modulating the tachyon-neutrino field? Ensign, Crusher... evasive maneuvers!

  • Zuh? (Score:3, Funny)

    by Hershmire (41460) on Friday November 04, 2005 @01:23PM (#13951808) Homepage
    If everyone is an ISP, who will be the subscribers?
  • "At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS, but had to take the 50mW base station - and its omnidirectional antenna - on trust, since it was at the top of an 850ft mast. The demonstration will be repeated for the US press next week.
    Before any of this happens, more demonstrations are needed, to show the system is robust against interference and multipath, and can operate in an area more crowded than 18 mile
  • by Anonymous Coward
    Joe Bobier is behind this technology, and it's not his first time of trumping up "new" ideas.

    His last venture was to "revolutionize" wireless networks by "inventing" Wireless to home users. He did this in Parkersburg WV using Wirefire Internet Service. It worked moderately well, though line of sight transmissions caused a problem, since the system required bulky exterior antennas, and trees blocked signal nearly universally. He claimed to have invented the system, even though the equipment was actually off
  • is xG VMSK (Score:3, Informative)

    by TheSync (5291) on Friday November 04, 2005 @01:35PM (#13951896) Journal
    I thought it sounded like Very Minimal Shift Keying (VMSK), then I saw this at VMSK.org [vmsk.org]:

    "XG technologies goes on the air with their method in November from an 800 foot tower..."

    More info on VMSK here [uni-lj.si] and here [qualcomm.com]. The first paper states "no ultra narrowband modulation method, which includes VMSK and VPSK, can have substantially greater efficiency than conventional methods, such as QAM, in transmission in the same frequency band".
  • Whats the catch? (Score:2, Interesting)

    by petantik f00l (926671)
    My lecturers teach me one thing. Whenever something new comes out that seems to be so fantastic as to be miraculous ask one question

    Whats the catch?

    I'm doing engineering and i'm alway wary about such claims

    where else/how much have they tested it?
    How much does weather affect its operation?
    How much will it cost?

    Of course. i'm not saying that they are lying, they have achieved an engineering marvel that can only change things for the better. can you imagine how useful this would be in the develop
  • I know this was posted under "hardware.slashdot.org" - But I propose a new section for this item

    How about "vaporware.slashdot.org"?
  • IAARE (Score:5, Informative)

    by elgatozorbas (783538) on Friday November 04, 2005 @01:51PM (#13952009)
    I am a radio engineer...
    well, not professionally but I know what it is about.

    Digital transmission works as follows: you select a certain waveform out of a set and transmit it. At the receiver you try to figure out which one it was. Unfortunately the reception is distorted because of noise you pick up, such that the distinction is not perfect (e.g. in case you can reliably tell 8 possible waveforms apart three bits will be conveyed each time you do this). Using more power will lead to a better distinction and therefore higher bit rate. Using a larger (RF) band width allows you to send more waveforms per second hence also increasing the number of bits transferred (this is simplified somewhat).

    Shannon left us a nice formula to calculate the capacity aka maximum possible throughput EVER, but first you need to calculate the signal and noise power you receive.

    1) If we assume the waves travel in free space, the received signal power will be dependent on
    - transmit power
    - transmit antenna gain (dish is more focused than dipole etc.)
    - free space loss (FSL, i.e. field strength getting weaker far from the source because the energy is spread out in all directions)
    - receive antenna gain
    This is an optimistic assumption because their setup takes place in suburban territory!

    We can assume both the antenna gains are 0dB, being small and probably not perfectly matched.
    The FSL is equal to: R^2*4pi^2/lambda^2 (R=distance, lambda=wavelength)
    At 900 MHz lambda=0.33m, R=18 miles=29e3 m.
    FSL= 3e11(in 'power') or 115dB.
    The transmit power was 50mW, i.e.17dBm, the total received power will be 17-115=-98 dBm. The thermic background noise is equal to -173dBm/Hz (best case, due to ambient temparature - this is a bit optimistic too because other wireless devices are transmitting there too).

    2) The channel capacity is given by Shannon as C=B*log2(1+S/N), where C=capacity (bits/sec), B=bandwidth (physical, in Hz), S=signal power (-98dBm), N=noise power (-173dBm/Hz*B).
    You can now play with the bandwidth to influence the capacity. To a certain extent an increased bandwidth will increase the capacity but after a while you are just catching more noise while the signal will be spread out in frequency, so this saturates.
    For these numbers the (theoretical) maximum capacity would be about 4.5e7 bits/sec or 45MB/sec. But even to achieve the 3.7Mb mentioned you already need a bandwidth of 700kHz (rough estimate, I made a plot in matlab).
    At that point you transmit 3.7Mb/(50mW)/(0.7Mhz)=100Mb/s/W/MHz, so their figure of 7.4 MB/2/W/MHz is not impossible. However it will be difficult to achieve. We have made some assumptions (especially about the loss in the urban envorinment), and their bit rate only has a 'margin' of a factor 12 (45 to 3.7). There you have it.
  • Brings to mind VMSK (Score:3, Informative)

    by w9ofa (68126) on Friday November 04, 2005 @02:30PM (#13952295) Homepage
    Phil Karn debunked the claims about VMSK here:
    http://www.ka9q.net/vmsk/ [ka9q.net]

    I AM a radio engineer, and I am extremely dubious about some of the claims in the article/website/etc. The thin line on the spectrum analyzer looks alot more like a sine wave than a system that "modifies each cycle of the sine wave". Others have pointed out that this is another way of stating the essence of phase/frequency modulation, a very old modulation technique.

    On the xG website there is a press release that has some tortured details:
    http://www.xgtechnology.com/newsitem.asp?id=21 [xgtechnology.com]

    "xG's Flash Signal technology, which utilizes single-cycle waveforms to transmit information at a minimum effective rate of 1 MB/s for each megahertz of spectrum"

    Well, to me, you take away the "megas" and you get 1 bit/sec/Hz for the spectral efficiency .. .the same as BPSK.

    The only important technical point I can find in the article is this one:

    "Moreover, because the receiver -- the design of which is xG's most-guarded intellectual property -- includes a passive wavelet path filter that acknowledges only single-cycle waveforms, all other RF signals are ignored."

    My guess is that he has an antenna/feedline scheme that cancels signals that cross correlate with a 1 cycle delayed version of themselves. Most likely, he does this by using two antennas and a bit more coax (at a particular design frequency) on one antenna to cancel any signals that are coherent with themselves for some integration time. This is not a particularly new or cleaver idea, but I suppose you could use it with the modulation scheme to increase the SNR of the signal (assuming of course that most signals are not like yours).

    Also, if this is the case, then the geometry of the antenna array relative to the transmitter will be important, because at the wavelength used (900 Mhz) the configuration of the antennas will yeild different phases depending on how they are aligned relative to the transmitter. I take further proof of this in the zdnet article which describes the signal as degrading when the antenna is pointed away from the transmitter. (near the end)

    ZDNet UK saw that the bitstream vanished when the receiving antenna was moved out of alignment with the distant transmitter

    http://news.zdnet.co.uk/communications/wireless/0, 39020348,39235645,00.htm [zdnet.co.uk]

    This scheme will yield better performance, that is.. until everyone is using it. If there are many signals that are not coherent with themselves over the integration time of the circuit, then the supposed advantages in terms of interference rejection will disappear.

    In summary, if everything is as I have guessed, this technology is about the same as using a better antenna for a regular wifi system ... it will get better performance, but at the cost of requiring knowledege of where the base station is located relative to the mobile unit. Also, if the technology is what I have guessed, it will be easily copied if the market finds it to have great value, of which I am dubious. I could be wrong about all of this, but it would be interesting to see more technical information rather than a few plots and a dog-and-pony show. Appeals to authority fail to be very convincing when you are talking about claims in a field with well-known laws limiting performance.

I don't have any use for bodyguards, but I do have a specific use for two highly trained certified public accountants. -- Elvis Presley

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