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New Phased-Array AP Boosts 802.11b Range

Posted by timothy on from the bring-it-on-quickly dept.

ttul writes "Vivato, a well-funded wireless startup, today came out of stealth mode to announce its "WiFi" switch product, a super high performance 802.11b access point that uses an array of hundreds of antennas to provide wide-area coverage to standard 802.11b clients. See stories at Wired, and The New York Times. Vivato's new AP completely changes the economics of WiFi especially for providers such as FatPort and WayPort, who now have the technology to deliver 11Mbps to your laptop even if you're miles from a location -- it's the Jetson's, folks!"

10 of 203 comments (clear)

  1. Repost ? by Merkins · · Score: 2, Informative

    Umm, didn't this already get posted today ??
    Timothy, do you not not read Slashdot ?

    --

    Learn to Improvise
  2. Phased Array Antennas by Spooge+Demon · · Score: 2, Informative

    The tech is a phased array antenna, there was a good article about using it with 802.11 (notice there is no b) in the IEEE spectrum [ieee.org] a while ago.

    Consider it a sort of software antenna, you have a series of antenna that you can bias towards a particular direction. You then listen for incoming signals and use a processor to calculate environmental multipath (RF signals bouncing off buildings, etc.) and then fire off your signal so that the main signal and multipath reflections arrive at the reciever at the same time. Instant gain.

    I'm skeptical on the reported max range but they should get a good amount. If you're sitting in the middle of a parabolic dish and so is your target, sure I expect that kind of increase in range, but in the real world...

    1. Re:Phased Array Antennas by dtg · · Score: 2, Informative
      I'm skeptical on the reported max range but they should get a good amount. If you're sitting in the middle of a parabolic dish and so is your target, sure I expect that kind of increase in range, but in the real world...

      This doesn't make any sense. The purpose of a phased array is to provide gain in a given direction. Generally, this kind of technique isn't used as a feed for a parabolic dish because it's a whole hell of a lot cheaper to turn the dish than to build a phased array.

      As for users, higher gain at the receiver will help even if they're using the same antenna as always.

    2. Re:Phased Array Antennas by calidoscope · · Score: 2, Informative
      From what the articles said, I'd reckon that the antenna should be good for about 20 dB gain over a dipole. Figure that with the inverse square law, you'd be getting 10 dB in range (a factor of 10). 4 miles in free space sounds like a reasonable figure IF the laptop on the other end is in a reasonably quiet area.

      The big advantage of this system is to be able to generate multiple beams - something that is a bit difficult to do with parabolic reflector antennas.

      --
      A Shadeless room is a brighter room.
  3. Why...... by jwilcox154 · · Score: 5, Informative

    use a Phased-Array AP to Boost the 802.11b Range, when you can use a Pringles Can as the Wi-Fi Antenna to Boost the Range? ;)

  4. Re:Is this a good thing? by Merkins · · Score: 5, Informative

    Did you read the articles ?

    The actual output of this thing is on 30mw. It just increases range by locking on to it's clients and adjusting itself to aim more directly at them. because of this, it will actually cause less general interferance than a standard garden variety AP

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    Learn to Improvise
  5. Re:9 Hours by cscx · · Score: 3, Informative

    How right you are.

    Here and here, only a few hours apart.

  6. Re:Question.... by mindstrm · · Score: 2, Informative

    No, it's all about power.

    Yes, there can be interference.. but it's also about power. As long as one signal is significantly stronger than another, it should prevail...
    This is also why there are multiple channels... so you can try to avoid overlap.

    You can't extend the range of 802.11b to miles.... not omnidirectional anyway... you can in a certain direction, yes.... but the higher the gain, the narrower the 'beam'.

    In the case of your neighbor, chances are his AP will be what his cards will see, and yours is what your cards will see, because the signal of the local ap will be significantly stronger.

  7. Re:Actually... by div_2n · · Score: 3, Informative

    The FCC limitations for the 2.4 band is 1 watt (30dBm) for Point-to-Multipoint. For point to point you can get away with a lot more.

    None of that matters though because obtaining true line of sight past 20 miles without more than a 20 percent impedence on the Fresnal Zone is a battle I don't want to fight.

  8. This is an active phased array... by Newer+Guy · · Score: 5, Informative

    It works much like the active radar antennas that do not move. Here in Santa Monica we have a large phased array of hundreds of fixed antennas aimed at the horizon that are sequentially pulsed on and off to get the familiar 'rotating' pattern of a single rotating radar dish. This design is much more robust then a rotating array as there are no mechanical rotating parts at all...everything is switched by PIN diodes. Military jets also use a variation of this for secure communications. In the jets' wings are switched inductor antennas that are used in a fast frequency hopping scheme over a 50 mhz range. The transmissions can be anywhere within a 50 mhz frequency segment at any given fraction of a second. If the frequency synthesizer at all locations are moving to the same frequency at exactly the same time, the transmisison will sound completely continuous.
    They use PIN diodes to change the taps on an inductor to resonate the antenna over the (wide) frequency range. This way, they can use smaller, lighter, narrower bandwith antennas and rapidly tune them to the exact frequency in use at any given moment.

    All in all, a very slick technology and another example of a civilian use of military technology.