Extreme Networks Altitude 4700 Series Product Reference Manual page 177

Channel Width
Channel Selection
Power Level
Altitude 4700 Series Access Point Product Reference Guide
Select the Channel Width (MHz) from the drop-down
menu. The AP radio can support 20 and 40 MHz channel
widths. 20 MHz is the default setting for the 2.4 GHz radio.
20/40 MHz operation (the default setting for the 5 GHz
radio) allows the Access Point to receive packets from
clients using 20 MHz of bandwidth while transmitting a
packet using 40 MHz bandwidth. This mode is supported
for 11n users on both the 2.4 and 5 GHz radios. If an 11n
user selects two channels (a Primary and Secondary
channel), the system is configured for dynamic 20/40
operation.
When 20/40 is selected, clients can take advantage of
"wider channels." 802.11n clients experience improved
throughput using 40 MHz while legacy clients (either
802.11a or 802.11b/g depending on the radio selected)
can still be serviced without interruption using 20 MHz.
Define a value as needed depending on the channel used.
This field is not available when B and G is selected as the
802.11 b/g/n mode.
The following channel selection options exist:
User Selected—This is the default setting. If 20/40 MHz is
selected as the Channel Width (supporting 11n), the
Secondary Channel drop-down menu becomes enabled.
The user must define the primary channel first. Then,
depending on the primary channel defined, the secondary
channel list is filled with channels making the combination
of primary and secondary channels valid. The actual
channels available depend on regulatory domain
requirements.
Automatic—When the Access Point is booted, the Access
Point scans non-overlapping channels listening for
beacons from other Access Points. After the channels are
scanned, it will select the channel with the fewest Access
Points. In the case of multiple Access Points on the same
channel, it will select the channel with the lowest average
power level.
The Random option is available for use with the 802.11a/n
radio. To comply with Dynamic Frequency Selection (DFS)
requirements in the European Union, the 802.11a/n radio
uses a randomly selected channel each time the Access
Point is powered on.
Use the drop-down menu to defines the transmit power of
the 802.11a/n or 802.11b/g/n antenna(s). The values are
expressed in dBm and mW.
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