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UWB Wireless Access Could Be Here Soon

Posted by timothy on from the mommy-what-were-wires dept.

fluppy88 writes: "802.11b doesn't have anything on UWB. With a potential of 1000M bits/sec it blows the pants out of 802.11b and doesn't eat up the tightly controlled spectrum. This article on CNN gives an interesting introduction to UWB, another candidate in the future of wireless." It was mentioned here a while ago, but much more mired in controversy about whose idea it was. Now there are several companies which seem anxious to get products based on UWB to market -- if it's approved.

3 of 82 comments (clear)

  1. Gotta pick one or the other... by Robber+Baron · · Score: 4, Interesting

    For one thing, because UWB pulses don't actually use a traditional radio signal, called a carrier, UWB transmissions don't take up any of the radio spectrum. Spectrum is limited, and demand for it is growing fast. That's one reason for the FCC interest: UWB would allow a whole new class, and volume, of voice and data communications that, in effect, wouldn't take up any more "space" in the crowded radio spectrum.

    But there is concern that UWB transmissions, especially for UWB devices that will operate below about 2 GHz, will interfere with other broadcasts. These include the Global Positioning System (GPS), public safety nets, air traffic, marine navigation and communications, AM and FM radio, and television broadcasts, to name just a few.

    Where do they get these guys? First he says that it doesn't use any spectrum...then he says that anything below 2 GHz will interfere with existing Nav and Comm systems. Gotta be one or the other. Can't be both.
    (BTW pulse transmissions do take up spectrum, even if they don't have a carrier...)

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    You're using her as bait, Master!

  2. And not inly in the US. by mwillems · · Score: 3, Interesting

    ...and IF it is approved outside the US as well!

    This is not unimportant. Prices drop and rapid adoption increases when a standard is worldwide (like 802.11b on 2.4 GHz).

    The 5 GHz equivalent of 802.11b (.a) will be approved at the world radio freqeuency conference in 2003 (light speed for governments) - and I was already told by the British govt Radio Agency
    that the UK frequency will differ slightly from the US frequency. And that the 5 GHz standard wil be approved for commercial use (unlike the current 2.4 GHz standard).

    That's just for one country, the UK. Imagine when all others (Japan, Europe, etc) also get in on the act. Result: nothing moves.

    So, nice as all these new 'standards' are, I am afraid they will slow down wireless adoption.

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    BDOS ERR ON A:>
  3. OFDM? by Nova · · Score: 3, Interesting

    This UWB term I've never heard of, but I worked at a company that was developing 802.11a goods. This sounds like the same, as the article touts ~40-55mb/ps (I don't know what this 1000MB/ps shit is).

    I wasn't one of the engineers working on it (I was actually a high school co-op who worked on higher-level code in the same dept), so some of my facts may be off. 802.11a (or at least the variant we were working on) used a modulation scheme called OFDM. OFDM was "invented" in the 1960s if I remember, but the technology is finally catching up with the math to allow for mass production and the data precision required in the algorithm.

    OFDM would fit with the articles blurb about it being in the "noise" area. Basically, a baseband signal is multiplexed into multiple low-power subcarriers, which are aligned in such a way that the intersymbol/intercarrier interference (ISI/ICI) is minimized. Basically, this means orthangonally (at 90 deg angles), so that the peak distabution of one carrier occurs at the zero points of the carriers on either side of it. So it's a particulary advanced form of FDM. All that low power shit comes from this fact, and that the nature of noise is amplitude-related, not frequency related. Plus, data interleaving and error detection coding (described below) goes on during baseband processing I think. I forget the symbol length and all that in detail crap, but there is QAM coding and FFTs/IFFTs going on in the process. (I remember 64-QAM being a popular initial choice.) Error correction/detection might be left open in the specs (i.e. it could be this or that), but the one I was familiar using was reed-soloman (a convolutional encoding method used with CDroms) and/or turbocoding (a very advanced convolutional encoding method which gets pretty close to the limit imposed by the Shannon theorem).

    OFDM has been defined as packing the data as close as physics will allow, and it whoops 802.11b in both range and bandwidth. I think it will be both in the 2GHz and the 5.4GHz bands.

    Sounds exciting. The race is on.

    I have seen a good intro paper on OFDM before, but I lost the URL, here is a more indepth one on it: http://www.eng.jcu.edu.au/eric/thesis/Thesis.htm

    Sorry about the spelling, I'm not using a spell checker. :)