Catalyst 9120 cannot reach 23 dBm transmit power

[alexandersatria_Zlf]

Hi Community,
I have C9120 access point.

But i have a issue that my Access point C9120AXI-F cannot reach 23 dBm.
it's only reach to 17/18 dbm.
i make the coverage really bad and not me the expectation.
I have set it to maximum PoE+ and power transmit,
But it's still stay at 17/18 dbm.
Base on datasheet, it should be reach 23 dbm

Is there any idea why is that happen ?

Thx 

[Arshad Safrulla]

what is the country configured? what channel the AP is on? 

Did you check with local regulatory what is the maximum power eirp allowed for that channel?

Also did you consider the antenna gain? data sheet shows the below

Flexible radio (either on 2.4 GHz or on 5 GHz)

●  2.4 GHz, peak gain 4 dBi, internal antenna, omnidirectional in azimuth

●  5 GHz, peak gain 5 dBi, internal antenna, omnidirectional in azimuth

Dedicated 5-GHz radio

●  5 GHz, peak gain 5 dBi, internal antenna, omnidirectional in azimuth

EIRP = (Output power-Cable loss+Antenna Gain)

[Karsten Iwen]

23dBm is the max for this AP, but that does not mean that it is available in your regulatory domain.

There is an Excel-sheet (that I don't find at the moment) that lists the max power per AP and domain. I would expect that it's not allowed to transmit with more power in your country.

[Rich R]

Go to the "Cisco Regulatory Domain White Paper" at https://www.cisco.com/c/dam/en/us/products/collateral/wireless/access-points/sales-tool-c96-744090.pdf (linked on the AP data sheet at https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9120ax-series-access-points/datasheet-c78-742115.html) and inside that pdf you will find a link to the power channel data for each AP on page 6.

The 9120i data is at https://www.cisco.com/c/dam/en/us/td/docs/wireless/access_point/channels/reference/9120i-pwr-chn.xlsx

C9120AXI-F is only approved for Indonesia so assuming it's Indonesia then you look at the -F tables for each radio and see the power per channel per antenna configuration showing the max transmit power with effective total power (including antenna gain).  I think the original poster is probably forgetting the antenna gain.  I didn't go through it in detail but I think total power is mostly max 22 dBm and in many cases less.

As the others have pointed out that max 23 dBm is the highest for any channel in any country which the AP is capable of but that does not mean you will achieve that in your regulatory domain or on the channel you're using.  You have to check those detailed tables.

Also there have been a few bugs with power levels so you're best advised to make sure you're on an up to date IOS-XE to make sure you have all those known bug fixes.

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/214749-tac-recommended-ios-xe-builds-for-wirele.html

Actually you didn't bother to mention what WLC or software version you were using so if it's AireOS then look at https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-tac-recommended-aireos.html