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Microsoft Wireless Networking

Researchers Test WiFi Access From Moving Vehicles 155

Posted by CmdrTaco
from the catch-me-if-you-can dept.
Julie188 writes "Researchers from Microsoft and the University of Massachusetts have been working on a technology that would let mobile phones and other 3G devices automatically switch to public WiFi even while the device is traveling in a vehicle. The technology is dubbed Wiffler and earlier this year its creators took it for a test drive with some interesting results. Although the researchers determined that a reliable public WiFi hotspot would be available to their test vehicles only 11% of the time, the Wiffler protocol was able to offload almost 50% of the data from 3G to WiFi."
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Researchers Test WiFi Access From Moving Vehicles

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  • by TrisexualPuppy (976893) on Wednesday October 13, 2010 @09:16AM (#33882280)
    The multipath and doppler effects SUCK. This is why Wimax doesn't work well in vehicles and why the Mobile Wimax variant is more popular in such realms.

    But once you have the physical layer taken care of, you can play cool little tricks like data queuing for WAPs to save cost. Locational awareness is also feasible to anticipate whether there will be a hotspot in a quarter of a mile or to go ahead with the transfer now.
  • Re:not gonna work (Score:2, Interesting)

    by Anonymous Coward on Wednesday October 13, 2010 @09:25AM (#33882372)

    There really needs to be a standard way for an access point to say "I have no wireless authentication, but I am not open" when advertising itself, to allow devices to respond appropriately.

  • Re:Yo moron (Score:3, Interesting)

    by tepples (727027) <tepples AT gmail DOT com> on Wednesday October 13, 2010 @09:27AM (#33882398) Homepage Journal

    Just because it doesn't work on your iFruit doesn't mean that it won't work with something that was designed for this purpose.

    But how would a city bus line offering Wi-Fi negotiate carriage with every AP on its routes?

  • Re:not gonna work (Score:4, Interesting)

    by choongiri (840652) on Wednesday October 13, 2010 @09:41AM (#33882526) Homepage Journal
    Right, so you make the technology smart. It connects to the unsecured wireless network, attempts to make outgoing connections, and if the outgoing connection fails (or is redirected to a login page), switches to another network. You could quite easily test the connection in the background before attempting to pass application data to it.
  • Already been done (Score:2, Interesting)

    by BodeNGE (1664379) on Wednesday October 13, 2010 @10:05AM (#33882748)
    It's already been done in 2007 by Nokia and Siemens, and is part of the 3GPP standard. 3GPP TR 23.806 (for voice, but works for data too). Repeat after me all you Americans: International standards are better than propriatary ones.
  • Re:Yo moron (Score:4, Interesting)

    by Grismar (840501) on Wednesday October 13, 2010 @10:14AM (#33882852)
    I certainly hope so, because that will help overturn the rules that imply same for hotels. It simply doesn't make sense; if it has to be regulated, it could just as easily be changed to "a hotel has to register as an ISP if it provides network access to others than their guests". It's besides the point though, as far as TFA is concerned. However, trains already provide Wi-Fi as we speak and buses may just as well - and they'll have a harder time convincing the powers that be that they're not serving the public. It will be nigh impossible to restrict access to people inside the bus, unless you feel like changing the passkey for the connection every you hop onto a bus.
  • Re:Yo moron (Score:4, Interesting)

    by hedwards (940851) on Wednesday October 13, 2010 @10:20AM (#33882952)
    The transit system around here was working on that for a while. What they did was set up a low power access point in the middle of the bus, and hooked that up to a cellular card. The effect was that you were using WiFi, but since you were in the same reference frame, you didn't have to deal with any of the random interruptions you would otherwise have to deal with.

    The main problem would be in tunnels and plain old congestion.
  • 802.11p (Score:2, Interesting)

    by SirMasterboy (872152) on Wednesday October 13, 2010 @10:27AM (#33883014) Homepage
    Isn't this idea kind of what the 802.11p amendment that was published last summer was for?
  • by Anonymous Coward on Wednesday October 13, 2010 @01:00PM (#33884966)

    The multipath and doppler effects SUCK. This is why Wimax doesn't work well in vehicles and why the Mobile Wimax variant is more popular in such realms.

    The doppler problem is by far the more important one. WiFi is based on an OFDM modulation that takes advantage of the mathematical orthogonality of zillions (technical term) of low bitrate channels with respect to a given Fourier transform window. When the source or receiver is moving, the frequencies shift in a way that destroys their orthogonality with respect to that window and causes crosstalk between the channels. It doesn't just degrade performance, it pretty much obliterates it.

"Out of register space (ugh)" -- vi

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