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Date: Thu, 29 Nov 2007 15:14:52 -0500
From: "Lewis G Rosenthal" <os2-wireless_users@2rosenthals.com>
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Subject: [OS2Wireless] Xbox 802.11b/g (2.4GHz) interference (was: Re:
 [OS2Wireless] First large-scale 802.11n wireless LAN...)

On 11/29/07 05:27 am, Ed Durrant thus wrote :
> Will Honea wrote:
>> ** Reply to message from "Lewis G Rosenthal"
>> <os2-wireless_users@2rosenthals.com> on Wed, 28 Nov 2007 21:23:39 -0500
>>
>>
>>> I don't see how there can be "alternatives" to other people jamming 
>>> noise in the 2.4GHz spectrum, Leon...
>>
>> Lew, there are some interesting frequency-hopping techniques that 
>> work well in
>> such an environment, although my math says that with the limited 
>> number of
>> channels (11) for target center frequencies even the most elaborate
>> spread-spectrum techniques become saturated fairly quickly. The 
>> problem with
>> any of it is that most of us don't have military type capability 
>> needed to
>> deploy the really good ones (and the black helicopters would just 
>> create more
>> problems if we tried <g>).
>>
>> Hey, I'm going to bounce emails for a day or two while I get the 
>> hosting and
>> domain crap straight, so don't cut me off the list, please.
>>
No problem, Will...
> Also while "N" is not a certified standard - it could be said that it 
> is the problem not the X-Boxes !
>
> By all accounts the Draft N used by some companies use several 
> frequencies at the same time and that can't be fair in what is a busy 
> spectrum anyway !
>
Okay, it looks like I should have started a different thread for my 
comments concerning the Xbox interference. I've corrected that, above.

To recount, and to quote from the article at hand:

    One novel problem has been the disruptive interference in the 2.4GHz
    band caused by Microsoft Xbox game consoles. Barber and his team
    noticed a strange pattern of interference: a strong signal jumping
    around all the channels on that band. The team gradually narrowed
    the interference down to a few areas in some dorms, and by a process
    of elimination focused on game consoles.

    To confirm it, Barber brought in his own Xbox from home, plugged it
    in, and found the same “very strong, crazy interference” pattern
    showing up on the radio-frequency analyzer. “It was even worse with
    multiple Xboxes in a given location,” he says. So far MSC hasn’t
    come up with a solution. But it was found that shielding the Xboxes
    with the antistatic bags used to protect electronic equipment from
    electrostatic discharge during assembly and shipping led to a
    noticeable drop in interference. It’s probably not a long-term
    solution because “that’s not good for the heat [level],” Barber says.

This is not specific to 802.11n, but rather a concern for b and g clients.

Leon, your point about using subchannels is moot when discussing client 
connections to an AP. Between carrier grade AP's, yes, but I've never 
seen a client with the ability to use subchannels (and that's not part 
of the 802.11b or g specs, AFAIK).

The solution is for Microsoft to fix their broken boxes.

-- 
Lewis
------------------------------------------------------------
Lewis G Rosenthal, CNA, CLP, CLE
Rosenthal & Rosenthal, LLC
Accountants / Network Consultants
  New York / Northern Virginia           www.2rosenthals.com
eComStation Consultants                  www.ecomstation.com
Novell Users Int'l       www.novell.com/openenterpriseserver
Need a managed Wi-Fi hotspot?               www.hautspot.com
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