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What you NEED to know about TX Power and 802.11a (5GHz) on a Cisco LWAPP AP
Friday, October 30, 2009 at 12:07AM 
Power, power power.... One of the MOST important design factors is selecting the proper radio TX power when designing any wireless network. You must consider your lowest common denominator and adjust your power equally between your client and AP for optimal design.
But did you know when you select different UNII channels in the 5 GHz band you are also changing the TX power of your AP on a Cisco WLC? When selecting power on a cisco ap in the WLC you are presented with the power levels 1,2,3,4,5 etc. Most folks are aware on the 2.4 GHz side power levels.
1 = 20 dBm / 100mW
2 = 17 dBm / 50mW
3 = 14 dBm / 25 mW
4 = 11 dBm / 12.5 mW
But did you know depending on the UNII band you select the power levels are different on the 802.11a 5GHz radio.
UNII 1 UNII 2 / 3
1 = 11 dBm / 12.5 mW 1 = 17 dBm / 50mW
2 = 8 dBm / 6.25 mW 2 = 14 dBm / 25 mW
3 = 5 dBm / 3 mW 3 = 11 dBm / 12.5 mW
4 = 2 dBm / 1.5 mW 4 = 8 dBm / 6.25 dBm
(Cisco Controller) >debug ap enable <Name of AP>
(Cisco Controller) >debug ap command "show controller do 1" <Name of AP>
Note:
"show controller do 0" is interface Dot11Radio0
"show comtroller do 1" interface Dot11Radio1
UNII-1 POWER LEVEL - Controller Power Level 1
(Cisco Controller) >
Thu Oct 29 10:37:02 2009: afa0:
Thu Oct 29 10:37:02 2009: afa0: !
Thu Oct 29 10:37:02 2009: afa0: interface Dot11Radio0