What you NEED to know about TX Power and 802.11a (5GHz) on a Cisco LWAPP AP

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
Thu Oct 29 10:37:02 2009: afa0: Radio AIR-RM1252A, Base Address 001d.70dd.afa0, BBlock version 0.00, Software version 2.00.22
Thu Oct 29 10:37:02 2009: afa0: Serial number: XXXXXXXXXXXXXXX
Thu Oct 29 10:37:02 2009: afa0: Number of supported simultaneous BSSID on Dot11Radio0: 16
Thu Oct 29 10:37:02 2009: afa0: Carrier Set: Americas (OFDM) (US) (-A)
Thu Oct 29 10:37:02 2009: afa0: Uniform Spreading Required: YesThu Oct 29 10:37:02 2009: afa0: Configured Frequency: 5180 MHz  Channel 36  40Mhz, extended above (Power 1)
Thu Oct 29 10:37:02 2009: afa0: Allowed Frequencies: 5180(36) 5200(40) 5220(44) 5240(48) *5260(52) *5280(56) *5300(60) *5320(64) *5500(100) *5520(104) *5540(108) *5560(112) *5580(116) *5660(132) *5680(136) *5700(140) 5745(149) 576
5(153) 5785(157) 5805(161) 5825(165)

Thu Oct 29 10:37:02 2009: afa0: * = May only be selected by Dynamic Frequency Selection (DFS)Thu Oct 29 10:37:02 2009: afa0: Listen Frequencies: 5180(36) 5200(40) 5220(44) 5240(48) 5260(52) 5280(56) 5300(60)5320(64) 5500(100) 5520(104) 5540(108) 5560(112) 5580(116) 5660(132) 5680(136) 5700(140) 5745(149) 5765(153) 5785(1
57) 5805(161) 5825(165)

Thu Oct 29 10:37:02 2009: afa0: Beacon Flags: 0; Beacons are enabled; Probes are enabled
Thu Oct 29 10:37:02 2009: afa0: Configured Power: 14 dBm
Thu Oct 29 10:37:02 2009: afa0: Active power levels by rate
Thu Oct 29 10:37:02 2009: afa0:      6.0 to 54.0  , 14  dBm
Thu Oct 29 10:37:02 2009: afa0:      m0. to m15.-4, 11  dBm, changed due to regulatory maximum
Thu Oct 29 10:37:02 2009: afa0:   OffChnl Power: 14, Rate 6.0
Thu Oct 29 10:37:02 2009: afa0: Allowed Power Levels:  -1 2 5 8 11 14
Thu Oct 29 10:37:02 2009: afa0: Allowed Client Power Levels: 2 5 8 11 14
Thu Oct 29 10:37:02 2009: afa0: Receive Antennas : right left middle
Thu Oct 29 10:37:02 2009: afa0: Transmit Antennas : right left, ofdm single
Thu Oct 29 10:37:02 2009: afa0: Antenna: external, Gain: Allowed 11, Reported 11, In Use 11

UNII-2/3 POWER LEVEL - Controller Power Level 1

(Cisco Controller) >
Thu Oct 29 10:34:21 2009: afa0:
Thu Oct 29 10:34:21 2009: afa0: !
Thu Oct 29 10:34:21 2009: afa0: interface Dot11Radio0
Thu Oct 29 10:34:21 2009: afa0: Radio AIR-RM1252A, Base Address 001d.70dd.afa0, BBlock version 0.00, Software versin 2.00.22
Thu Oct 29 10:34:21 2009: afa0: Serial number: XXXXXXXXXXXXXXX
Thu Oct 29 10:34:21 2009: afa0: Number of supported simultaneous BSSID on Dot11Radio0: 16
Thu Oct 29 10:34:21 2009: afa0: Carrier Set: Americas (OFDM) (US) (-A)
Thu Oct 29 10:34:21 2009: afa0: Uniform Spreading Required: YesThu Oct 29 10:34:21 2009: afa0: Configured Frequency: 5745 MHz  Channel 149  40Mhz, extended above (Power 1)
Thu Oct 29 10:34:21 2009: afa0: Allowed Frequencies: 5180(36) 5200(40) 5220(44) 5240(48) *5260(52) *5280(56) *5300(60) *5320(64) *5500(100) *5520(104) *5540(108) *5560(112) *5580(116) *5660(132) *5680(136) *5700(140) 5745(149) 576
5(153) 5785(157) 5805(161) 5825(165)

Thu Oct 29 10:34:21 2009: afa0: * = May only be selected by Dynamic Frequency Selection (DFS)Thu Oct 29 10:34:21 2009: afa0: Listen Frequencies: 5180(36) 5200(40) 5220(44) 5240(48) 5260(52) 5280(56) 5300(60)5320(64) 5500(100) 5520(104) 5540(108) 5560(112) 5580(116) 5660(132) 5680(136) 5700(140) 5745(149) 5765(153) 5785(157) 5805(161) 5825(165) 

Thu Oct 29 10:34:21 2009: afa0: Beacon Flags: 0; Beacons are enabled; Probes are enabled
Thu Oct 29 10:34:21 2009: afa0: Configured Power: 20 dBm
Thu Oct 29 10:34:21 2009: afa0: Active power levels by rate
Thu Oct 29 10:34:21 2009: afa0:      6.0 to m15.-4, 17  dBm, changed due to regulatory maximum
Thu Oct 29 10:34:21 2009: afa0:   OffChnl Power: 14, Rate 6.0
Thu Oct 29 10:34:21 2009: afa0: Allowed Power Levels:  -1 2 5 8 11 14 17 20
Thu Oct 29 10:34:21 2009: afa0: Allowed Client Power Levels: 2 5 8 11 14 17 20
Thu Oct 29 10:34:21 2009: afa0: Receive Antennas : right left middle
Thu Oct 29 10:34:21 2009: afa0: Transmit Antennas : right left, ofdm single
Thu Oct 29 10:34:21 2009: afa0: Antenna: external, Gain: Allowed 11, Reported 11, In Use 11