Channel usage

Reynolds, Alfred Alfred.Reynolds at
Thu Dec 6 14:04:23 EST 2001

Okay, I am going to take a long walk down a short jetty here, but doesn't
the use of DSSS within the wireless lan cards mean that this isn't a major
issue. The other base stations will raise the noise floor of the receiver
but given the low powers and high rate chipping rates I suspect that the
effects would be minimal. 

I would guess that when the IEEE designed the channels for 802.11 they did
the calculations to make sure that a 1 channel separation provided enough
attenuation on the base receiving frequency to remove any interference

> -----Original Message-----
> From: Bob Edwards [mailto:Robert.Edwards at]
> Sent: Thursday, December 06, 2001 1:51 PM
> To: wireless at
> Subject: Channel usage
> I want to put more than three access points into an area where there
> will be overlap in their coverage.
> At this time, I have three access points on channels 1, 6 and 11. As I
> understand it, channel 1 is at 2412MHz and the separation between
> channels is 5MHz. So the separation between channels 1 and 6 is 25MHz.
> Each 802.11DS signal needs 22MHz of radio frequency 
> bandwidth, so using
> channels 1, 6 and 11 means that the access points don't 
> overlap in their
> use of radio bandwidth, and therefore don't interfere with each other
> and so we get maximum channel utilisation.
> My question is this:
> If I use channels 1, 5, 9 and 13 in order to have four 
> distinct frequencies,
> I only have 20MHz of separation. As this is less than the 22MHz being
> utilised for 802.11DS, what sort of performance degradation 
> am I likely
> to experience?
> Anyone got a handle on this issue?
> Cheers,
> Bob Edwards.

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