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First Public White-Space Network Is Alive 97

Posted by timothy
from the ubiquity-keeps-getting-bigger dept.
An anonymous reader writes "The first public white space network officially launched on Wednesday in Claudville, Virginia. It uses sensing technology from Spectrum Bridge with software and Web cams supplied by Microsoft and PCs from by Dell. The project was funded the TDF Foundation. White space networks use unlicensed television spectrum and have been called 'WiFi on steroids.' They offer more bandwidth, over larger areas, than does WiFi. IT companies duked it out with broadcasters for years to get white spaces approved by the FCC. They finally got the FCC's nod in November, 2008."
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First Public White-Space Network Is Alive

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  • What channel is Hulu on? v.v

    • Re: (Score:3, Interesting)

      In other news, the residents of Claudville VA are no longer able to watch distant stations in Roanoke due to these internet devices broadcasting over the channels.

      The FCC Chairman's comment - "You're not supposed to see out of market stations anyway." One of the local viewers replied, "Now I only get 5 stations from Salem NC, where I used to get 10 from both Salem and Roanoke. They took away my channels."

  • by t0qer (230538) on Wednesday October 21, 2009 @06:33PM (#29829703) Homepage Journal

    have been called 'WiFi on steroids.' They offer more bandwidth, over larger areas, than does WiFi.

    Someone correct me if I'm mistaken, but doesn't lower frequency (30mhz to 300mhz) mean less bandwidth? I could see bonding several channels at once to achieve a higher bandwidth, but doesn't this mostly offer greater range?

    • by spottedkangaroo (451692) * on Wednesday October 21, 2009 @06:42PM (#29829775) Homepage
      It really doesn't matter what frequency when you're talking bandwidth. When you're talking size of the antenna or signal loss the wavelength might matter, but not for bandwidth. The reason you get more bandwidth here is because the spectrum is wider. The ISM spectrum is very very narrow and low power channels all bunched up around 2.4Ghz. With the new white spaces, they can use tons more and much louder. But, yes, they need longer antennas.

      As far as the range? You can make a microwave signal go light years and a HAM signal go a few feet (although, there will be some distortion for transmitting a signal over a distance shorter than the wavelength). The range is more of a function of signal power.

      • by BitZtream (692029)

        (although, there will be some distortion for transmitting a signal over a distance shorter than the wavelength)

        Citation or clarification needed.

        This is only true if the receiving antenna is basically wrapped around the transmitting antenna. From a practical perspective it doesn't happen, you'd just connect the wires directly and avoid the time domain issues you are referring to.

        • A HAM radio signal is really large. I was working with 80m radios, so the wavelength is literally 80m long.

          I noticed huge deadspots in the room where there was almost no radio signal and other spots where it was distorted evilly.

          This is called "nearfield" distortion. Generally speaking, receivers need to be at least one wavelength away to work reliably. Also, Tx antennae need to be at least one wavelength off the ground, or it changes the impedance of the whole array.

          You can read about this on t

      • by slifox (605302) * on Wednesday October 21, 2009 @08:28PM (#29830641)
        I think the OP was referring to data transfer bandwidth (the throughput, or data rate), rather than the traditional electronics use of "bandwidth" (referring to the width of the transmitted signal in the frequency spectrum; though "channel width" is a more exact term).

        Of course higher carrier frequencies don't have a higher bandwidth, because bandwidth is a property of the whole system, including the data signal and modulation method. You can make the bandwidth as big or small as your system's constraints allow (e.g. one constraint might be to keep most of your transmitted power inside the allocated bandwidth).

        If your data signal is modulated in the exact same manner regardless of the carrier, varying the frequency of the carrier will not affect the transmitted signal's bandwidth. The carrier frequency imposes the upper limit on the data signal's frequency, and thus a higher carrier frequency will theoretically allow for a high data rate.

        Practically, however, the data signal is almost always much smaller than the carrier signal, and the transmitted frequency is subject to many other important factors such as noise, signal propagation through the environment, etc... In the case of 2.4GHz vs. 800MHz carrier frequencies, there is no practical gain in potential data rate.

        This is all based on my limited understanding of communication theory. Please correct me and/or provide further details if possible!
        • by kaiser423 (828989)
          You are correct.

          But here's why most people associate higher frequencies with higher bandwidths: typically RF devices scale as percentages.

          You're dipole that covers 10% bandwidth at 2.4Ghz is going to cover up to 200MHz of spectrum. You're dipole at 300MHz is only going to cover 30MHz. You can shove more data through 200MHz than you can 30MHz. Now, of course, you have to get that amount allocated, but the lower frequencies are packed, so the FCC typically gives out bigger chunks as you go higher in f
          • Rather than guessing you could just google "width of TV channel".

            The answer is 6 megahertz. That's how much room these TV Band Devices (TVBD) will have for communicating over the internet. That's approximately 40 Mbit/s using 16VSB with a theoretical max of 96 Mbit/s if you strip all error correction.

            • by Methlin (604355)

              Rather than guessing you could just google "width of TV channel".

              The answer is 6 megahertz. That's how much room these TV Band Devices (TVBD) will have for communicating over the internet. That's approximately 40 Mbit/s using 16VSB with a theoretical max of 96 Mbit/s if you strip all error correction.

              16VSB would be 4 bits/symbol @ 6Msymbols/sec = 24Mbit without error correction (25.85 if you stay with ATSC's symbol rate of 6.46Msymbols/s). The wikipedia article on 16VSB is correct about bits/symbol then fails to get the math right about being "twice the data capacity of 8VSB" which is 3 bits/symbol.

      • by evilviper (135110) on Wednesday October 21, 2009 @10:18PM (#29831247) Journal

        As far as the range? You can make a microwave signal go light years and a HAM signal go a few feet (although, there will be some distortion for transmitting a signal over a distance shorter than the wavelength). The range is more of a function of signal power.

        You're horribly wrong.

        Distance has everything to do with frequency. You aren't going to have shortwave/ham radio skipping around the world with a 2.4GHz transmitter no matter how much power you put into it. Similarly, there's a reason WiFi is popular at 2.4Ghz but the higher 5Ghz band used with the now-forgotten 802.11a standard has been vastly less utilized.

        Frequency determines how well a signal will disperse around obstacles, and therefore, whether it will work AT ALL if you don't have 100% line-of-sight between transmitter and receiver.

        • by MacAnkka (1172589)
          question: In eath atmospehere, different wavelengths travel different distances because some wavelengths get absorbedby oxygen in the air or water vapor, some travel over the horizon because they use reflect of the ionospehere, etc... But what about in a total vaccuum? Do different radio waves travel the same distance in a vaccuum?
          • by evilviper (135110)

            Do different radio waves travel the same distance in a vaccuum?

            Not entirely... Higher frequencies will disperse less, so they can be broadcast in a much more narrow cone (see: high-gain antenna), so that a much stronger signal will arrive at the (much smaller) destination. Compare flashlight versus, eg., a laser, to see the difference.

            OTOH, like on earth, lower frequencies will disperse around an obstacle, rather than being stopped entirely, so if there's any solid objects in the vacuum, the same princip

        • by drinkypoo (153816)

          OT, you just made me snicker at Microsoft. On the Xbox 360 they backed HD-DVD and 802.11a. Fail, fail.

        • I'm horribly wrong out of context, but perfectly correct if you think about it.

          "They perform EME (earth-moon-earth) using microwave radios with regularity." (see below)

          Frequencies have a lot to do with obstacles and path-loss, line of site, moving through water (or other mediums), but not distance.

          • by evilviper (135110)

            Frequencies have a lot to do with obstacles and path-loss, line of site, moving through water (or other mediums), but not distance.

            Sure they do. Note that NASA, as you said, uses the highest frequencies they practically can. Distance has a lot to do with it.

      • Re: (Score:3, Informative)

        by mwilliamson (672411)

        Uh, no. Range is not a function of signal power. It more is a function of the overall signal/noise ratio and the sensitivity of the receiver. This includes noise introduced in the transmitter, natural/other noise, and noise introduced in the receiver. An antenna system with gain can both concentrate and attenuate signals, depending on the directivity and where its pointed.

        BTW, I got over 1400 miles out of a little 0.3 watt ham signal, but thats no where near as impressive as Earth still being able to r

        • Uh, no. Range is not a function of signal power.
          Range is a measurement of how far you can go before path loss (note: many people think path loss is inverse square, this is only true in free space, there are a few situations where it is better and a load where it is much worse) reduces the signal to a level where the SNR is too bad to receive it. Crank up the transmit power and you increase the recieved signal power and hence improve the SNR at any given distance.

          An antenna system with gain can both concentr

        • Uh, no. Range is not a function of signal power. It more is a function of the overall signal/noise ratio and the sensitivity of the receiver. This includes noise introduced in the transmitter, natural/other noise, and noise introduced in the receiver. An antenna system with gain can both concentrate and attenuate signals, depending on the directivity and where its pointed.

          BTW, I got over 1400 miles out of a little 0.3 watt ham signal, but thats no where near as impressive as Earth still being able to receive signals from Voyager 1 and 2 nearly 10 billion miles away. That's impressive.

          -Michael

          This post is horribly misleading. If range wasn't a function of signal power, why on earth don't we have handsets which operate with microwatt transmit power instead of (typically) something on the order of a tenth of a watt?

          Range is certainly a function of transmit power. If you have line of sight between the transmitter and receiver, every factor of 4 increase in transmit power (6 dB) doubles your range. It should be pointed out that often times we don't have line of sight for cellular, even when the

      • by niko9 (315647) on Wednesday October 21, 2009 @11:52PM (#29831707)

        You can make a microwave signal go light years and a HAM signal go a few feet

        Just for clarification, ham radio operators operate in the microwave region as well. They perform EME (earth-moon-earth) using microwave radios with regularity.

        Some info here: http://www.dxzone.com/catalog/Operating_Modes/EME/ [dxzone.com]

      • by stonefoz (901011)
        When TV started it grabbed a large chunk of the sweat spot between realistic antenna size and signal that'll pass through trees, walls, over small hills. Two low of a freq and the antenna has to match, low freq big antenna, high freq and doesn't pass through anything. So for a realistic link across either rural nothing and trees, or urban towers and noise, tv hold's about half of all desirable frequencies. While I wait to see how this range will be managed, anything is better than handing over half the real
        • >>>Analog TV did nothing to try and reduce space occupied...nothing but waste.

          This statement couldn't be more wrong. Why do you think analog television is interlaced rather than progressive scan? Answer: The engineers made that decision to save space and reduce the channel size from 12 to 6 megahertz. Why do you think they overlaid the color image with a nominal resolution of only 160x486? Again, to save space. Analog did "nothing" to reduce space is not an accurate representation of the work

          • by stonefoz (901011)
            Color was added after the signal spacing was established, nothing was changed but color. Interlacing makes the receiver requirements cheaper. Vertical scan was already driven at over 1MHz. High power is required to move the vertical scan, high power + fast = expensive. . How many other 1930 technologies are still one the air? AM radio occupies a spectrum that's inhibitory difficult for any other use, and TV is left as the only other wagon wheel left running. There was great work done, but conservation was n
        • >>>Each TV channel occupies 10mHz...space 640mBPS

          Also your numbers are wrong. 10 millihertz? 640 millibits/s? I'm going to assume you mean 10 Megahertz which is still not correct. Each channel spacing is 6 or 8 MHz, and the maximum theoretical bandwidth on these channels is 96 and 128 Megabits/s respectively, although a more realistic speed with 16VSB or COFDM plus error correction is only 40-60 Mbps - nowhere near 640.

  • by jjoelc (1589361) on Wednesday October 21, 2009 @06:34PM (#29829707)
    while I am personally glad this finally went through... I can vouch for the potential issues this can cause with existing broadcasts. ATSC is so sensitive to multi-path as it is... (and other forms of interference to boot, but I digress) Throwing out a bunch of unlicensed transmitters, borrowing the space between TV stations is a very scary proposition.
    • by drinkypoo (153816)

      What's scary to me is how important broadcast TV is to so many. Internet access is far more useful than TV, not to mention, you can watch TV on it. As far as I'm concerned it makes more sense to use every bit of spectrum currently allocated for television to provide ubiquitous wireless internet access.

      • by jjoelc (1589361)
        If they can figure out a way to implement something like the Emergency Alert System [Wikipedia] on the internet, you might be able to convince me (And a lot of other people) {they are currently working on updating the EAS system, including an IP protocol... the trouble is that IP is by design a fault tolerant protocol, and Emergency alerts are by nature NOT [they HAVE to get through, is what I mean]) There are some very specific requirements for EAS and they are having a lot of fun talking about the future
        • by drinkypoo (153816)

          If they can figure out a way to implement something like the Emergency Alert System [Wikipedia] on the internet, you might be able to convince me

          I would suspect that it should be possible to railroad connections using packet inspection and mangling and railroad people off to a page, video stream, audio stream, Autocad document, or whatever. It would be a fairly brutal thing to do, but it would be functionally equivalent to BEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEP and a blue screen on your TV. Of course, the repercussions are significantly more severe. On the other hand, the EAS already doesn't help me if I am one of the many who have given up on broadca

      • I'm not buying it. Wireless internet is already using ten times as much bandwidth as broadcast television, and it still can't provide the same level of service.

        Also, speaking frankly, my local television sucks which is why I watch distant signals from Baltimore and Richmond (about 60 miles in opposite directions). If the TV Band/whitespace Devices block my access to these cities due to transmitting directly over the stations, then I'm going to track down the gadgets and politely ask the owner to turn them

    • by sosume (680416)

      It seems to work well .. but wait I suddenly have a splitting headache, be right back ...

  • by segedunum (883035) on Wednesday October 21, 2009 @06:43PM (#29829789)
    Interested parties (whose businesses rely and will expand with cheap or free bandwidth) are angling to use it as a means to get around current mobile operators, and it can't come a moment too soon in many ways as far as I'm concerned. However, I can only see this being a recipe for disaster given the state of many wireless devices and all their broken firmware updates today if it's accurate:

    Devices must both consult an FCC-mandated database to determine which channels are available for use at a given location, and must also monitor the spectrum locally once every minute to confirm that no legacy wireless microphones, video assist devices or other emitters are present.

  • Webcams? (Score:2, Interesting)

    by d0rp (888607)
    I'm confused... what do they need webcams for in this project? I actually read the article and it didn't mention what they were for either.
  • Seems rather pathetically low power to me.

    I can't see them getting too much range out of that, not to mention that lower freqs = bigger antennas.

    But more BW is always nice.
    • Those frequencies are largely unaffected by foliage and the walls of buildings, unlike the microwave frequencies used by WiFi. They also propagate over the horizon somewhat.

    • by Tiger4 (840741)
      Low power, and small antennas is probably a good thing here. Small antennas will have poor efficiency, low power will mean short range. Combined it means the footprint for a given transmitter will be small. More can be put into a given community without undue interference. If anyone wants to put a 5 foot TV aerial on their laptop or Blackberry, they have way more need for this spectrum than the average Joe or Jane.
      • by mirix (1649853)
        Right, I agree.
        The part I don't understand is, why are they spinning it as "long range" & "a wifi killer" then?
    • by CompMD (522020)

      The average wifi card in your laptop has a 30mW transmitter, seems rather pathetically low power to me.

      100mW in VHF with the proper antenna has much better range than a wifi card at the same power with a proper antenna. For comparison, police walkie-talkies have transmit powers between 1W and 5W usually, and they can cover huge areas.

  • by MrKaos (858439) on Wednesday October 21, 2009 @07:01PM (#29829957) Journal
    The people at the CSIRO [youtube.com] wasn't it?

    enjoy :-)

  • Why Claudville? (Score:4, Interesting)

    by molo (94384) on Wednesday October 21, 2009 @07:09PM (#29830001) Journal

    Why Claudville? According to the Wikipedia page, there are around 20,000 people in the entire county. And according to the FCC DTV maps, they can only expect to receive two (!) TV stations, both from the Winston-Salem, North Carolina area. See here: (enter Claudville, VA) http://www.fcc.gov/mb/engineering/maps/ [fcc.gov]

    That is perhaps why they are testing it there. Its not hard to avoid active TV channels if there are only two.. and they are on adjacent RF channels (31 and 32).

    -molo

    • Re: (Score:3, Insightful)

      by Obfuscant (592200)
      And according to the FCC DTV maps, they can only expect to receive two (!) TV stations,

      You didn't read the "maps" correctly. They are expected to get two STRONG signals, and 6 weak ones. The weak ones are on UHF 19, 29, 51, 33 and 14.

      If the "white space" devices in that area are as capable of reading the maps as you are, those people WILL only get two stations instead of the 8 they might, especially those people who have invested money in good outside antennas so they CAN get the other weak signals.

      But

      • Re: (Score:1, Insightful)

        by Anonymous Coward
        If they have an outside antenna, it's going to be highly directional.
        • by profplump (309017)

          Because outdoor antennas are necessarily high gain?

          • In my experiance outdoor antennas are usually a lot larger with a lot more elements than set top ones and presumablly this means they are higher gain.

        • >>>If they have an outside antenna, it's going to be highly directional.

          (1) No. My CM 4228 is directional but not "highly" directional, since it still gets signals from the rear and side. (2) Directionality doesn't matter if the TV Band/whitespace Device User is standing between me and whatever station I'm trying to watch.

          "Well honey I wanted to watch the Yankees game on channel 19, but unfortunately our neighbor is using his iPod on the same channel."

    • Re: (Score:3, Funny)

      by plover (150551) *

      Why Claudville?

      I'm not from Virginia, you insensitive Claud!

    • by suso (153703) *

      Because Claudville sounds like Baudville. *shrugs*

  • by Cajun Hell (725246) on Wednesday October 21, 2009 @07:24PM (#29830109) Homepage Journal
    Please, think of the example this is setting for the children. Congress should immediately hold hearings about Wifi cheaters.
  • by owlnation (858981) on Wednesday October 21, 2009 @08:41PM (#29830735)
    "First Public White-Space Network Is Alive"

    I think you mean "live". If it's "alive" we have some real problems ahead of us.
  • White space network, eh? I wonder if the security architect implemented true network segregation?
  • So this white space is "unlicensed"? Completely? What, if any restrictions are there on usage of it? Is it at all possible in the foreseeable future that there will be consumer-level devices for this type of frequency? Like routers and other networking equipment, or is this really more for just companies to provide service? Also, what kind of range can you expect on this band at 'normal' power levels?
    • (1) No it's licensed to TV broadcast.

      (2) TV Band/whitespace Device users are expected to turn-off their gadgets if they interfere with licensed stations (WABC, WCBS, WFOX, et cetera). However if they refuse there's no real punishment.

      (3) Yes TV Band Devices are expected to be used by average people, so expect iPods and other gadgets to soon be transmitting over channels 2 through 51.

      (4) Range is probably 1-2 miles same as today's cellphones but with enough power to drown-out television reception of stat

  • What? An entire network protocol written in Whitespace? That must have been hard as hell!

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