Cisco Cisco Aironet 1140 Access Point 디자인 가이드

Starting with Wireless LAN Controller version 5.2, the default configuration of RRM’s dynamic channel 
assignment algorithm will exclude these UNII-2 Extended channels from the list of automatically 
selected channels. This frequency sub-band can be re-enabled by means of the following configuration 
parameter found in the ‘802.11a -> RRM -> DCA -> DCA Channel List’ configuration on the 
controller. However, before re-enabling this frequency sub-band, ensure that the client base supports 
UNII-2 Extended channels.

The maximum throughput of 802.11n can only be realized when 40MHz channels are utilized. In this 
mode, two traditional and contiguous 20MHz channels are bonded together to create a double-wide 
channel which essentially doubles performance. As a result of the expansive amount of spectrum in the 
5GHz frequency band, 40MHz channels are recommended for operation in this band. There are two 
mechanisms by which this 40MHz operation is configured on the controller, either by using RRM to 
automatically assign channels, or statically configuring Access Point radios into a specific 40Mhz 
channel.

RRM (Radio Resource Management) can be utilized to automatically select 40MHz channels amongst 
802.11n capable Access Points. The configuration for this capability can be accessed under the 
‘802.11a/n -> RRM -> ‘Dynamic Channel Assignment’ configuration page. Change the ‘Channel 
Width’ configuration from ‘20MHz’ to ‘40MHz’ and click Apply.