Introduction : 802.11a and 802.11b/g use 20 MHz channels as defined in 2.4 GHz and 5 GHz bands. The draft 802.11n standard adds the 40 MHz channel offering, which approximately doubles throughput. Using 40 MHz channels is also called channel bonding because two channels are bonded and used as one. For example, on a 5 GHz band, 20 MHz channels that can be bonded into one 40 MHz channel are 36+, 40-, 44+, 48-, and so on. 36+ implies that channel 36 is bonded with channel 40, and 40- means that channel 40 is combined with channel 36 to form a 40 MHz channel.
Use of 40 MHz channels can be controlled from the High-Throughput SSID Profile. CLI commands and WebUI examples are provided here.
To configure 40 MHz channel use, issue these commands:
(Aruba-M3) (SSID Profile "default") #exit
(Aruba-M3) (config) #wlan ht-ssid-profile default
(Aruba-M3) (High-throughput SSID profile "default") # 40MHz-enable
To check if 40 MHz channel use is enabled, issue this command:
(Aruba-M3) #show wlan ht-ssid-profile default
High-throughput SSID profile "default"
---------------------------------------------------
Parameter Value
--------- -----
High throughput enable (SSID) Enabled
40 MHz channel usage Enabled
MPDU Aggregation Disabled
Max transmitted A-MPDU size 65535 bytes
Max received A-MPDU size 65535 bytes
Min MPDU start spacing 0 usec
Supported MCS set 0-15
Short guard interval in 40 MHz mode Enabled
Legacy stations Allowed
Allow weak encryption Disabled
WebUI Configuration
Navigate to Configuration > Wireless > AP Configuration > Wireless LAN and select the AP group to be modified. Click Virtual AP, SSID Profile, High-throughput SSID Profile, and click the 40 MHz channel usage checkbox as shown here.
Use of 40 MHz channels on 2.4 GHz band is a challenge because spectrum spread is limited and possible combinations are 1+, 5-, 7+, and 11-. This means that if 40 MHz channel is used in 2.4 GHz, it interferes with at least one other 2.4 GHz channel.
If using ARM, control the use of 40 MHz channels by disabling individual combinations in AP regulatory domain profile.
CLI Commands
(Aruba-M3) #configure t
Enter Configuration commands, one per line. End with CNTL/Z
(Aruba-M3) (config) #ap regulatory-domain-profile default
(Aruba-M3) (Regulatory Domain profile "default") #valid-11a-40mhz-channel-pair 36+
(Aruba-M3) (Regulatory Domain profile "default") #no valid-11a-40mhz-channel-pair 36+
(Aruba-M3) (Regulatory Domain profile "default") #valid-11g-40mhz-channel-pair 1+
(Aruba-M3) (Regulatory Domain profile "default") #no valid-11g-40mhz-channel-pair 1+
(Aruba-M3) (Regulatory Domain profile "default") #end
WebUI Configuration
Navigate to Configuration > Wireless > AP Configuration > Wireless LAN and select AP group to be modified. Click AP and Regulatory Domain profile as shown here.
