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Regarding Channel Selection of 2.4GHz and 5Ghz band.

Hello Team, 


Thanks for replying on my questions. 


Team i have little bit confusion regarding Channel of 2.4ghz band and 5ghz band. as i know there are 11 channel in 2.4ghz band and 24 channel in 5ghz band, i wanted to know who they select in our production , i thing you are getting my query. 


Selection of channel how happens ?


Re: Regarding Channel Selection of 2.4GHz and 5Ghz band.


You may have a look on the Cisco's white paper which talk about their Dynamic Channel Assignment (DCA).
VIP Advocate

Re: Regarding Channel Selection of 2.4GHz and 5Ghz band.

Important to note, only channels 1,6,11 on 2.4 GHz are not overlapping other channels and compatible with newer Bluetooth versions. On 5 GHz none of the selectable channels is overlapping. So in 2.4 GHz that leaves you with three usable channels (in some regions theoretically 4, but that is most of the times a bad design and will cause issues with Bluetooth).

Re: Regarding Channel Selection of 2.4GHz and 5Ghz band.

Actually I wanted to know that how dynamically happens automatically selection of channels . There are 14 channel in 2.4ghz right , how they select automatically

Re: Regarding Channel Selection of 2.4GHz and 5Ghz band.

Different brand have their algorithm and patented technology deal with radio resource management.


That's why you pay a lot for WLC rather than a Linksys.


If you talking about the exact logic that how does Cisco's WLC perform DCA, I think there is no public document would describe it.


But I believe you may have a general idea from the RRM White Paper.



1. Same Channel Contention—other AP's/clients on the same channel - also known as Co-Channel
interference or CCI

2 Foreign Channel - Rogue—Other non RF Group AP's operating on or overlapping with the AP's served

3 Noise—Non-Wi-Fi sources of interference such as Bluetooth, analog video, or cordless phones - see
CleanAir for useful information on using CleanAir to detect noise sources

4 Channel Load—through the use of industry standard QBSS measurements - these metrics are gathered
from the Phy layer - very similar to CAC load measurements.

5 DCA Sensitivity—A sensitivity threshold selectable by the user that applies hysteresis to the evaluation
on channel changes


The impact of each of these factors is combined to form a single RSSI based metric known as the Cost Metric
(CM). The CM then represents complex SNIR of a specific channel and is used to evaluate the throughput
potential of one channel over another. The goal is to be able to select the best channel - for a given AP/Radio
while minimizing interference


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