I know there are only 3 non-overlapping channels in the b specification, but find it hard to find out the "dangers" of having overlapping channels. At my university, some of the buildings required more than 3 channels, therefore we had to overlap some of the Access Points(ie. we use channel 1 in the basement of the libary and channel 2 on the 4th floor).
Is this degrading my network without me knowing it? If so, how? I haven't had any complaints from the student body.
My understanding is that if you're saturating the channels, you'll see some signal degradation. For bursty purposes, you may see little or nothing. The inteference issues are sorted out at the physical layer, so only UDP-based applications that won't retransmit missing packets (streaming audio and video, for instance) would have any real problems.
Everything else, however, should be fine. 802.11b devices send out beacons and other signals all the time, but they're not sending a full stream of 11 Mbps of data across their allotted channels.
Also, weaker signals at the edges of channels probably won't cause you any problems either.
I'm not sure why the buildings would require more than three channels. All overlapping regions should be served by no three adjoining areas that would share channels.
The channels are 1, 7, and 11, by the way. If you had a region of 1 and 7 overlapping and serving one floor, the floor above and below could both be on channel 11 if you couldn't "see" those channels (or see them with any strength) from the mid-point. The client devices should pick the strongest channels, so even overlaps with weak signals won't cause problems.
Thanks Glenn, your response is pretty much the findings that we are experiencing.
I thought the non-overlapping channels were 1, 6, & 11 rather than 1, 7, & 11???
The reason we were using more than 3 channels is because the library needed a whole bunch of access points to cover a relatively small area. We figured the book shelving, etc.. caused the signal to degrade quickly. I will need to take another look at things and will probably be able to work it out to only use those 3 channels.