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Cisco 1131AG - Using just 1 channel? Advice.

I did a topic search first and didn't find anything specific to my question, so I am starting this new topic.

We have a 9-story building and have deployed 6 Cisco 1131AG Access points on every other floor (1,3,5,7,9) and let them bleed through to cover the even floors.

The AP's are Lightweight and controlled by a 4400-series controller.

We're having various issues with coverage disappearing at times and coming back, and I believe it is crosstalk between AP's and the channels.

I had been reading about a new 'trend' of setting AP's to one channel instead of the 1,6,11 method.

I need to know if this is something you think we could try and make it work without any major issues?

I was thinking of making the 1st floor all channel 1, the 3rd floor all channel 6, the 5th floor all channel 11, 7th floor channel 1 and the 9th floor channel 6 - or if I am going to do something like that, should I make it 1st floor CH1, 3rd floor CH11, 5th floor CH1, 7th floor CH11, 9th floor CH1 ?

What is the school of thinking on this?

Thanks for any and all input.

If I am missing information to help you help me, please advise.


- Mike

Everyone's tags (2)

Re: Cisco 1131AG - Using just 1 channel? Advice.


     I'm not sure what your referring to as a trend, the only scenario's I am aware of where you set an entire floor to a single channel in is a DAS (Distributed Antenna System) deployment, but a DAS deployment varies greatly from a traditional wireless deployment in a number of ways. The idea behind the Innerwireless DAS environment is that there is a single AP that goes to many antennas, the end result is a much larger coverage area all on one channel (potenially and entire floor) but again it's typically drive by a single AP so there really isn't co-channel interference (this is a 1-to-Many configuration). In terms of the Mobileaccess DAS solution there's is designed similar to the Innerwireless DAS although you have the ability to also do a 1-to-1 AP distribution, which means you can either do the 1-to-Many or 1-to-1.

     In both of these cases there is a much higher level RF calculations and calibration done, so that there are stricter more controlled cells so that there is minimal interference and crosstalk. The DAS system design has pros and cons like any design and there are other things to consider when going that route aswell as other best practices that should be implemented.

     That information in mind I haven't seen or heard of anyone taking a traditional wireless network design, disabling the RRM and setting all the access points to a single channel, with that being said if the power level were set accordingly and spacing was correct it might be possible to limit the amount of interference from AP to AP, but it's not something I'd reccomend in the environment you describe.

     As for the issue your having when you say converage disappears then comes back have you looked at the logs to see if there are coverage holes being generated? interference alarms? Load alarms? What is the transmit power threshold set at? Do you have WCS? What code version?

There are a number of things that could be happening..

Hope this helps... Please rate useful posts



New Member

Re: Cisco 1131AG - Using just 1 channel? Advice.

Good information. I had been reading all over the web - no official places - that this was a solution. I am not the 'wifi guy' here at work so I would have to get that information you asked for. Thanks again!

Re: Cisco 1131AG - Using just 1 channel? Advice.


Are you doing just data, no voice right? Normally you dont want to do the floor bleed through design becuase of "hidden node" and coverage related issue.Your design should have access points on the floors your clients will be on. Keep in mind your access point power. If your aps ate on "1" this means 100 mW on the 2.4 GHz side. Your typical clients like Intel only tansmit at 25 - 30 mW. In this example your client can hear the AP but your AP cant hear your client reliable. Make sense?

Also, you want to use channels 1,6,11 and have 20 dB difference between same channels. Example if you have 2 aps on channel 1. One is at -80 and the other is -60. You are ok ... If you have one at -60 and the other at -65 you will have interference.

Keep in mind, wireless is half duplex. Just like a switch that is in half duplex only 1 device can talk at a time. if you have 2 aps on the same channel your "chatter" errors and retires increase.

make sense?

__________________________________________________________________________________________ "Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin ___________________________________________________________