The Power Settings parameters determines the minimum and maximum power values (in dBm) that can be assigned to 2.4 GHz and 5 GHz Smart RF managed radios. By default each 2.4 GHz and 5 GHz will be assigned a transmit power value between 4 - 17 dBm which can be configured by modifying the Minimum Power and Maximum Power parameters for each radio type.
As a general best practice recommendation it is not recommended that you increase the Maximum Power values for the 2.4 GHz or 5 GHz radios beyond the default 17 dBm value. The default value has been defined to provide a 3 dBm margin for the Neighbor Recovery and Coverage Hole Recovery features. If each radio in the system is operating at a maximum of 20 dBm, the Smart RF managed radios will be unable to increase their transmit power if a neighboring AP fails or a coverage hole is detected. You should only increase the Maximum Power values if the Neighbor Recovery and Coverage Hole Recovery features are disabled.