392 Configuring Auto-RF
NN47250-500 (Version 03.01)

Initial channel and power assignment

The following process is used to assign the channel and power to an AP radio when it is first enabled:
• If Auto-RF is disabled for both channel and power assignment, the radio uses the channel and power settings in the
radio profile that manages the radio. After this, the channel and power do not change unless you change the settings
in the radio profile, or enable Auto-RF.
• If Auto-RF is enabled for channel and power assignment, the radio performs an RF scan and reports the results to
the WSS that is managing the AP the radio is on. The scan results include third-party access points. Based on the
scan results, WSS Software sets the channel and power on the radio. WSS Software always selects channel and
power settings that are valid for the country of operation.
●Initial channel assignment—WSS Software selects a channel at random from the set of valid
channels for the radio type and country code. After this, each subsequent time the radio or Auto-RF
is restarted, a different channel is selected to ensure even distribution among the channels.
During radio operation, WSS Software periodically reevaluates the channel and changes it if needed.
(See “Channel tuning” on page 393.)
●Initial power assignment—The AP sets a radio’s initial power level to the maximum value allowed
for the country code (regulatory domain). In a deployment with few APs, the radio remains at
maximum power. Otherwise, the radio reduces power until the power is just enough to reach the
AP’s nearest neighbor that is on the same channel.

How channels are selected

When a radio first comes up, if Auto-RF for channels is enabled, the initial channel selected will follow a uniform distri-
bution of channels that spans the list of channels, rather than selecting the next sequential channel number.
For example, the range of valid channels for 802.11a radios in the US is as follows:
40, 44, 48, 52, 56, 60, 64, and 68
On each WSS, the first channel chosen will be random. Assuming that channel 60 is the first channel selected, the order
of the channel selections will be as follows:
After these initial 8 channel selections are chosen, the pattern will repeat itself.
Order:25836147
Channel: 40 44 48 52 56 60 64 68