Power level on WLC

[Difan Zhao]

Hi experts,

I'm trying to support the wireless radio devices better. They recommend set the Tx power level to 3 instead of dynamic selection. I just want to understand what those power levels are... Is it industry standard or is it Cisco's standard? Is the number the lower the stronger the signal?

It looks like I can select power level only from 1 to 5. However under Wireless tab under 802.11b/g/n Radios, some AP's power levels are shown as 8. How many power levels can Cisco WLC support? Is the power level here the same as the power level in the TPC configuration?

Is there a power level to dBm or mW comparison table?

I am running WLC5508 7.2.110.0 code.

Thanks,

[Saravanan Lakshmanan · Accepted solution]

Static power levels showing 1 - 5 or 1 - 8 on AP is cisco's mappings to dBm. 1 is max while 5 or 8 is available least.

on 7.2, TPC configuration supports max upto 30dBm and this is for outdoor AP.

Power level 1 on indoor AP will be something like 3 or 4 for outdoor AP. Try below show command to verify the same.

Specifically for A radio, it varies vast by country domain requirement due to 802.11h.

Check the datasheet of each model AP.

check different Transmit power settings for Radio A & G on 3500, 1140, from datasheet.

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10981/data_sheet_c78-594630.html

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10092/datasheet_c78-502793.html

AP#show ap config 802.11b AP02

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Tx Power

      Num Of Supported Power Levels ............. 5

      Tx Power Level 1 .......................... 18 dBm

      Tx Power Level 2 .......................... 15 dBm

      Tx Power Level 3........................... 12 dBm

      Tx Power Level 4 .......................... 9 dBm

      Tx Power Level 5 .......................... 6 dBm

[Difan Zhao]

Thank you very much Saravanan. You have a very cool name btw.

So when I configure TPC, I only have options of 1-5. Even I only have AIR-CAP3502I-A-K9 in my network, which can support 8 power levels (as shown in the datasheet and with the show command you provided). However 1-5 here is the same as first 5 power settings shown on my AP correct? I mean, this 1-5 is not somehow matched to 1-8 of the AP power level, correct?

Thanks!

[Saravanan Lakshmanan]

However 1-5 here is the same as first 5 power settings shown on my AP correct?

Yes. see the Table.

I mean, this 1-5 is not somehow matched to 1-8 of the AP power level, correct?

Yes.

To configure RRM>> TPC from WLC, it is always recommeded to use dBm values instead of fixed 1 - 5. It it suppose to be 1 - 8, its a bug to me(for more info about this you might need to open a TAC case). If you set 1, it means max value on that specific model AP for that domain on that channel - check the table.

you may think having this value 1-5 on WLC is bad design. For RRM, Use dBm which is known instead of fixed values.

fixed value to dBm Table:

Power level 1 1 is "1", i.e. the highest power level supported in that channel/TPC/AP model/Modulation/Datarate.

power level 2 is "2", i.e. 3 dB less than above/highest power.

level 3 is "3", i.e. 3 dB less than the above/derived from power level 2.

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Power levels on datasheet is just to give you an general idea, check "channels and power" doc for the specific APs that you're interested in. Doc will be published for all new model APs soon.

http://www.cisco.com/en/US/docs/wireless/access_point/channels/lwapp/reference/guide/lwap_chp.pdf

http://www.cisco.com/en/US/docs/wireless/access_point/channels/ios/reference/guide/atonchp2.html

[pronko8901]

hi there

can you please share similar doc for the AIR-AP3802I-E-K9 and air-ap2802i -e-k9