(Mobility_Express) >config 802.11a txPower ap AP-name 8

Transmit Power—1 to 8.
This is a logarithmic scale of the transmit power, that is the transmission energy used by the AP, with 1 being the highest, 2 being half of it, 3 being 1/4th, and so on.

TPC Parameters
TPC sets the transmit power of each AP to maximize the coverage and minimize co-channel interference. TPC adjusts the Tx power up or down to meet the required coverage level indicated by the TPC Threshold.
In order to configure RRM to do the TPC calculations, you need to set the txPower assignment to global with the command config {802.11a | 802.11b} txPower global auto.
For ex:
(Mobility_Express) >config 802.11a txPower global auto
 
 You can also trigger RRM to take effect once with the command config {802.11a | 802.11b} txPower global once.
For ex:
(Mobility_Express) >config 802.11a txPower global once
You can also specify the maximum and minimum power levels that can be assigned to the AP with the command config {802.11a | 802.11b} txPower global {max | min} txpower.
For ex:
(Mobility_Express) >config 802.11a txPower global max 10
The range of values that can be configured for maximum and minimum power are between 30 dBM to -10 dBM. The default values are 30dBM for max power and -10 dBM for minimum power. If you configure a maximum transmit power, RRM does not allow any access point to exceed this transmit power. For example, if you configure a maximum transmit power of 11 dBm, then no access point would transmit above 11 dBm, unless the access point is configured manually.
You can also set the power level of an AP manually with the command config 802.11a txPower ap ap_name power_level.
For ex:
(Mobility_Express) >config 802.11a txPower ap AP00A3.8EFA.DC16 8 ----- Here this AP has been assigned a value of 13 dbm