Co-Channel Contention (CCC) explained with simple drawings

3/1/2016

I came across some documentation I have made and I was explaining how Co-Channel Contention can have a bad impact on airtime using simple drawing.
I thought I might as well share these diagrams with you! I have included the PDF and Microsoft Visio version so you guys can change the colours if you would like.

ccc_explained_with_diagrams.pdf
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ccc_explained_with_diagrams.vsdx
File Size:	257 kb
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Enjoy!

François Vergès

4 Comments

Meindert

10/31/2016 12:03:26

Hi,

I was just wondering how you would explain (or rarther illustrate) the problem of overlapping 2.4 Ghz channels from the neighbors in the building and the effect on wifi performance.

Thanks

François link

11/7/2016 08:27:03

Hi there,

In a building where you have neighbor, you can have two type of interferences: CCI (Co-channel Interference) and ACI (Adjacent Channel Interference).

The first one is the one illustrated in this article (AP using the same channel as yours). The medium (frequency) will be shared and all the clients will content for the same airtime. This might introduce slower performance on your home Wi-Fi network especially when lower data rates are enabled (which is typically the case with consumer-grade AP).

The second one (ACI) means that there is neighbor AP using channels overlapping with the one used by your AP. This negative effect of ACI is much more important on a Wi-Fi network. This interference will, indeed, modified the signal received by the clients. The clients won't be able to decode the signal and, this will generate retries. Retries are bad in a Wi-Fi network since it significantly decrease the efficiency of the network.

Hopefully one day I have type to illustrate how this work.

Thank you!

François

Meindert

11/9/2016 04:49:10

Thanks François for the informative reply!

russell

1/12/2018 11:38:58

So, about ACI... is that merely a device communicating on channel 2 affecting me when I'm on channel 1?

Or is that a misconception?
Would I need to worry about ACI if my network's devices all use non-overlapping channels?

Co-Channel Contention (CCC) explained with simple drawings

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François Vergès

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