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Re: Movies, household network and 54g limits... (maybe...)



On Fri, Jan 11, 2008 at 10:03:41AM -0800, johnny wrote:
> The graphs say it is clearly not bandwith fault. Reading around:
> "                                                    It is well known
> that the medium access control (MAC) layer is the main bottleneck for
> the IEEE 802.11 wireless LANs."
 
In particular, the hidden transmitter problem really bites 802.11b/g.
If computer A , Computer B, and access point P can "see" each other,
things work better.  If A and B can see P, but not each other, problems
arise.  A starts transmitting.  B doesn't see A, and also starts
transmitting.  P gets junk because there are overlapping transmissions.
Neither A nor B see the collision, and have to wait for a timeout before
retrying.  This is a large window, because B could start transmitting
any time during A's packet.

This is also a problem when A can see B, and they start transmitting at
the "same" time, but these occurrences are less frequent since the
window is much smaller.

-- 
Rob

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