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Xbox 360's Jamming Wireless Signals?

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  • by beheaderaswp (549877) * on Monday December 17, 2007 @01:02PM (#21726470)
    Oh like we didn't know this was going to happen.

    I don't know what other IT guys thought when we found out the Xbox was using 2.4 Ghz for it's controllers, but I laughed out loud!

    2.4 Ghz is one of the most badly managed spectrum for consumers. You have phone systems that take out access points, access points that take out phone systems, and no idea at all which of those systems will interact badly with another.

    And you can't fix it either! Access points use a static channelization for their transmission, and controllers/phones use spread spectrum. Why is that bad??

    It's bad because 2.4 Ghz is radio, carrying digital info, which due to the nature of the produced sign wave results in a signal distortion more commonly known as "bleed over". Without the ability to separate the signals by a large frequency, digital over analog bleeds all over the place. Additionally, spread spectrum ensures the signal will at some point transmit across the whole spectrum.

    Add to that the fact that these antenna aren't tuned all that well....

    Oh well 2.4 Ghz is a mess. No one likes to talk about it... and companies are still making equipment for 2.4 Ghz.

    Caveat Emptor.
  • Didn't notice (Score:4, Informative)

    by Bryansix (761547) on Monday December 17, 2007 @01:06PM (#21726514) Homepage
    Just a little anicdotal evidence but I have a 360 in the same room at my PC which is on wireless and two access points in that room as well. They all work fine at the same time.
  • by evanbd (210358) on Monday December 17, 2007 @01:09PM (#21726540)

    It's bad because 2.4 Ghz is radio, carrying digital info, which due to the nature of the produced sign wave results in a signal distortion more commonly known as "bleed over". Without the ability to separate the signals by a large frequency, digital over analog bleeds all over the place.

    The hell? There is nothing magic about digital data that means you can't bandwidth-limit the outgoing transmission. There are plenty of digital radio protocols that use a very well defined slice of bandwidth, without any more bleed over than traditional AM or FM radio analog broadcasts. Just because the signal represents digital data doesn't mean you have to use square waves or something.

    I suppose we should all be thankful that radio engineers are better educated than the average Slashdot poster...

    (Of course, it's entirely possible there's something broken about the XBOX radio. It's also entirely possible it's just a spread-spectrum transmitter doing exactly what it's supposed to do in a largely unregulated piece of spectrum.)

  • by phantomcircuit (938963) on Monday December 17, 2007 @01:09PM (#21726542) Homepage
    WiFi refreshes so often that most people dont notice the significant proformance drop

    their internet connection is almost always the real choke point anyways.
  • by PJ1216 (1063738) * on Monday December 17, 2007 @01:23PM (#21726758)
    A small college is experience problems with their new wireless network equipment in the presence of a few xbox's. however, apparently all over the rest of the country, in huge universities with thousands of xbox 360s... there's no problem whatsoever. the only bit that doesn't fit with this is that they said the IT staff had issues using their bluetooth headsets. now, the only comment i can make on this is that i think they have cheap bluetooth headsets. they said the 360 makes the signal even when its not turned on... just plugged in. i have both a ps3 & 360 virtually one on top of the other (a shelf plus a few inches of space in between) and the ps3's bluetooth controllers work just as fine as they did before i got the 360. so, all in all, i think this is a load of bull. the 360 has been out for way too long for this to not have been noticed. i think something else is screwing with their headsets & wireless network. or maybe its just the wireless network thats screwing with the headsets and they're looking for a scapegoat.
  • by coolGuyZak (844482) on Monday December 17, 2007 @01:24PM (#21726780)
    The PS3 uses the bluetooth protocol to transmit data, which was designed to share 2.4 GHz with WiFi. MS, as usual, has reinvented the wheel, poorly.
  • by beheaderaswp (549877) * on Monday December 17, 2007 @01:29PM (#21726870)
    "I suppose we should all be thankful that radio engineers are better educated than the average Slashdot poster..."

    Rather, I'd hope "radio engineers" would take notes from the Slashdot posters. This way Slashdot posters, who have to trouble shoot wireless systems going down for no apparent reason, don't have to argue with "radio engineers" over a problem that is reproducible.

    Also, you might want to ask why this "IT Director" (me) appears to know more about this problem than you do?

    At any rate I've seen the sign wave off a couple of these wireless transmitters and it doesn't look clean to me.

    But you know... I'm no "radio engineer". My license only reads "Technician".
  • Re:Read TFNOTBOED (Score:4, Informative)

    by operagost (62405) on Monday December 17, 2007 @01:36PM (#21726996) Homepage Journal
    Are you thick? These are very old regulations, and they have nothing to do with any one party. You could have at least looked up the regs first instead of proving to everyone that you don't know what you're talking about. Class B from memory:
    • The device must not create any harmful interference,
    • The device must accept any interference that may cause undesired operation.
  • by mikej (84735) on Monday December 17, 2007 @01:38PM (#21727024) Homepage
    Seriously. Come on.
  • Re:xbox wireless (Score:4, Informative)

    by CastrTroy (595695) on Monday December 17, 2007 @01:39PM (#21727054) Homepage
    For the record, my Wii seems to have problems with the wireless. If I leave the WiiConnect24 on, after a couple days the wireless router stops responding, and it doesn't kick back on until I turn off the WiiConnect24 , even after I reboot the router.
  • by Anonymous Coward on Monday December 17, 2007 @01:59PM (#21727382)
    A radio technician license doesn't make you an expert. That's quite clear from your post.

    Try being a Technology Director, with a radio license, and an EE from an excellent engineering school, plus 20 years experience in digital communications. I can personally tell you that it still doesn't make one an expert.

    However, I can tell you you're way off base in your post. The whole point is that 2.4 GHz (not Ghz, BTW) is that it isn't managed! It's up to everyone to pretty much fend for themselves!

    Good grief. No wonder it's a "mess" when people like you start talking about "sign" waves.
  • by coolGuyZak (844482) on Monday December 17, 2007 @02:05PM (#21727464)
    • The PS3 bluetooth implementation may be spotty, but that doesn't change the crux of the argument:
      1. Bluetooth is designed to play nicely with WiFi
      2. The PS3 uses the bluetooth standard, so it plays nicely with WiFi.
      3. MS designed a proprietary protocol, which happens to break WiFi.
      4. MS could have used Bluetooth as well, thus averting this problem.
      5. Thus, MS reinvented the wheel, poorly. (At least, given this metric)
      6. This is not out of the ordinary. MS has quite a history of breaking [microsoft.com] things [microsoft.com].
    • Your comments about the battery have no context in this conversation. I'm not discussing the pros & cons of a PS3, merely the technologies used in various controllers.
    • Your comments concerning WiFi interfering with other devices is likewise irrelevant. Again, I wasn't discussing the console, but the controller.
  • by TheThiefMaster (992038) on Monday December 17, 2007 @02:13PM (#21727602)
    I'd have thought that if the Wii was messing up a laptop's WiFi connection, it would also have been messing up its OWN WiFi connection. Coupled with the fact that it uses an international standard (bluetooth) for its wireless controllers, which is used by millions of other devices without problem, it seems unlikely that it's messing up WiFi signals.

    The 360, on the other hand, doesn't have WiFi, and has wireless controllers that use a proprietary (I think) wireless system, on the same frequency spectrum as WiFi. There's every chance that it interferes.
  • by Shakrai (717556) * on Monday December 17, 2007 @02:15PM (#21727620) Journal

    I have been using channel 14 for 3 years with virtually no disconnects

    Minor detail that you can't legally use that channel in the United States (or Canada?). Granted, the odds of getting caught are next to nothing, but I don't think this is a viable "fix" for anybody in the business world.....

  • by Shakrai (717556) * on Monday December 17, 2007 @02:25PM (#21727800) Journal

    Bluetooth is designed to play nicely with WiFi

    Bluetooth doesn't "play nicely" with WiFi. Bluetooth (from 1.2 onwards) was designed to remove channels that are being used from it's hopping sequence. But until it detects that those channels are in use (which may take quite awhile if your wifi network doesn't have a lot of traffic) you are still going to have interference issues. WiFi will usually "win", in that if either of the devices is going to be affected by the interference it's much more likely to be the bluetooth one.

  • by ajlitt (19055) on Monday December 17, 2007 @02:27PM (#21727832)
    Fine, then. How would viewing a plot of a sine wave tell you anything useful? Wouldn't you rather look at the frequency domain to see how well your equipment is staying within its part of the spectrum? Are you sure you know what you're looking at? You may want to save the HAM and IT rank-pulling for the users in HR.
  • by Shakrai (717556) * on Monday December 17, 2007 @02:30PM (#21727858) Journal

    Devices that use spread spectrum do not cause interference

    "Devices that use spread spectrum do not cause interference with each other"

    There, fixed that for you.

    Seriously, anybody that has ever tried to use an analog 2.4Ghz cordless phone near a busy wi-fi network knows that they do cause interference. Hell, I can even tell when my wi-fi has a burst of activity if I'm using my bluetooth headset.... and bluetooth is supposed to avoid channels that are in use.

  • by evanbd (210358) on Monday December 17, 2007 @02:43PM (#21728040)

    I'm not saying that there isn't a problem. The article reads more like an advertisement in spots, but they do give a modest amount of technical info -- enough that I'm willing to believe the problem is real. It appears that the spread-spectrum controller is interfering with the WiFi signal. That's not overly surprising, but it has absolutely *nothing* to do with the fact that the data is digital. It has everything to do with the fact that these two devices are using each other's bandwidth and not handling the interference well, which is unsurprising given the relatively unregulated nature of the 2.4GHz band. The intereference could just as easily be caused by an analog source as a digital one.

    Also, unless you're really experienced at it, you can't tell a clean, bandwidth-limited signal by looking at it in the time domain -- you need a spectrum analyzer. (If you're really experienced, you'll do ok, but the spectrum analyzer is still important.) Furthermore, "spread spectrum" is not the same thing as "not clean" -- not in the slightest. From the perspective of the other device, though, they may produce similar results (undesired interference).

    The lesson here is not that the radio engineers are screwing up. (They might be, but there is no evidence presented to that effect.) Rather, it is that using multiple different transmission schemes in the same band without any coordination is likely to cause problems. And really, that's not exactly a surprising result. If you want someone to complain at, complain at the regulators for not providing more bandwidth with better negotiation protocols mandated.

  • by thestuckmud (955767) on Monday December 17, 2007 @03:01PM (#21728280)
    [Hit Submit instead of preview - here's the final version]

    You are right about 2.4 GHz devices interfering with each other. That's about it.

    First: Wi-Fi devices may be assigned "static channels", but these are not minimally wide frequency bands as you imply. In fact, the channels are 30Mhz wide and contain spread spectrum signals. Channel 1 overlaps channels 2 through 5 enough to cause interference.

    Second: Digital modulation techniques need not "bleed over" significantly past the bandwidth required to carry the information (i.e. potentially less than analog transmission of the same information). For example, psk31 is a digital mode with a bandwidth of about 31Hz.

    Third: Modulated signals are necessarily not sine waves. Especially signals designed to look like noise (n.b. Wi-Fi is meant to look like noise across 30MHz of spectrum). You will see changes in frequency or phase (I'm not certain which). If individual cycles of the 2.4GHz waveform you saw looked rough then you made a mistake sampling the signal. Visible distortion of a single wave so far out of bad it would not affect any 2.4GHz devices.

    BTW, my license says "Extra".
  • by Shakrai (717556) * on Monday December 17, 2007 @03:14PM (#21728504) Journal

    the choke point is the way the bandwidth slowly atrophies and then I have to reconnect every five minutes or so

    Try locking your access point to 802.11b-only mode and see what that does.

    I've noticed the exact same problem you describe with a lot of 802.11g chipsets (Intel Pro/Wireless being the worst offender in my experience). Watching the devices they seem to switch speed rates constantly up and down for no obvious reason. Every single time a rate change happens the network communications stop for at least a few seconds. Eventually they just stop communicating altogether until the client is reset.

    Once locked to 802.11b all of the devices remain connected at 11mbps. This should be a viable solution for you if you only need wi-fi to connect to the internet. 802.11b should provide at least 5.5mbps of usable bandwidth for TCP and upwards of 7mbps for UDP. If your internet connection is faster then that then I don't have a lot of sympathy for you, cuz mine isn't ;) If you need faster wireless (i.e: LAN file transfers) then you might need to look at finding different client cards or access points until you get a pair that communicates reliably.

    The other thing I've noticed is that some of the Intel Chipsets try to implement a proprietary power saving scheme that causes issues with a lot of APs. You can usually disable this feature, though the specifics of how to do so would depend on which OS and drivers you are using.

  • by Ephemeriis (315124) on Monday December 17, 2007 @03:56PM (#21729490)

    WiFi refreshes so often that most people dont notice the significant proformance drop

    their internet connection is almost always the real choke point anyways.
    I guess it really depends on what you're trying to do with your WLAN. Sure, if you're just using it to surf porn at home then I guess it doesn't matter much... But I support a few medical offices and I cringe every time someone mentions wireless. It's hard to get a good signal, it's even harder to keep a solid connection throughout the day. When you've got doctors roaming from one office to the next all day long, trying to pull up charts and test results, trying to dictate or pull up scans...the Internet connection is most certainly not the choke point. And just when you've finally got everything working the way it should someone in a near-by office will go and pick up a brand new 2.4 Ghz phone and throw it all off again.
  • by Radon360 (951529) on Monday December 17, 2007 @04:46PM (#21730508)

    True, provided that you can prove that a device covered under part 15 was indeed causing actual harmful interference, and not just transmitting as designed. Until amateur radio receives primary allocation status of its section of 2.4GHz, I doubt that any ham would be very successful at kicking a part 15 device off their local airwaves.

    Amateur radio has to comply with part 97, and the unlicensed devices have to comply with part 15, but the secondary allocation status for amateur radio (on 2.4GHz) puts the two almost on a level playing field as far as who has the "right" to be transmitting.

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