Adjusting the Maximum Power level Assignment Value

Unanswered Question
May 2nd, 2012

I have a deployment of AIR-CAP35021 APs. They are in 2 buildings with multiple floors. They are installed in a row down the hallways. I want to increase the power levels by using the controller and not configuring the APs individually. I have set the TPC value to -50 but I still do not reach the outer walls of the floors in some areas. I need to know what to set the Max Power Level Assignment or Min Power Level Assignment to to get the APs to power up some more. If the MAX value is 30 and the default is 30 then how will it help to adjust that value?. Any help would be appreciated.

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Stephen Rodriguez Wed, 05/02/2012 - 07:09

IMHO, you should have a site survey done.  if you're not reaching the edge of the building, you may want to add AP to help cover vs, increasing the max transmit power.


evarner@digital... Wed, 05/02/2012 - 07:20

We did a site survey prior to the deployment and were showing -65 half way in to the rooms with a transmit power of 25mW . Now in some rooms we don't get but -89 at the outer walls.

Stephen Rodriguez Wed, 05/02/2012 - 07:28

what AP was the survey done with?  Also, take a look at what the current power levels of the AP are, it's possible that the AP are setting there power level low, as they can hear each other well.

Did you set both the max an minimum, or just the max?  25mW would be power level ~3, which would be 14dBm.


Num Of Supported Power Levels ............. 8

      Tx Power Level 1 .......................... 20 dBm

      Tx Power Level 2 .......................... 17 dBm

      Tx Power Level 3 .......................... 14 dBm

      Tx Power Level 4 .......................... 11 dBm

      Tx Power Level 5 .......................... 8 dBm

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

      Tx Power Level 7 .......................... 2 dBm

      Tx Power Level 8 .......................... -1 dBm

Make sure you are setting max and min values that fall in the above guidelines.

evarner@digital... Wed, 05/02/2012 - 07:40

We surveyed with 1252 APs which was the only 802.11n AP available when we did the survey.. I have not set any values on the Max and Min yet. The default Max is 30dBm which is greater than the max capabilities of the AP which is 20dBm. So I am wondering if I should set the min to 14 instead of 10.

Kayle Miller Wed, 05/02/2012 - 09:54

the default on most code revs is Max at 30 and the min is -10   (note the minus sign).. If your survey was done at 25 mw with a 1252, what type of antenna was on the 1252?? if it was a stick omni it may have a higher gain than the ap's your now using. That could also be coming into play here.

so initally I'd determine what the actual EIRP you were using during the survey and then figure out how to match that now.

if you aren't familiar with EIRP it's basically the radiated transmit power at the antenna output. So a quick example

If your ap is putting out 25mw or 14dBm and you are using a 6dBi antenna then your EIRP is 20dBm or 100mw

if your ap is putting out 25mw or 14dBm and you are using a 2.2dBi antenna then your EIRP is 16.2dBm or 50mw

I believe the 3502i's use a 2.2 dBi integrated antenna.

this can cause a drastic change in your coverage area.

but if all else fails change the TPC controls so that max power is either 20dBm or 30dBm and that the minimum has a value of either 14 or 17 (no minus sign).. 

30dBm = 1 watt

29dBm = 800mw

26dBm = 400mw

23dBm = 200mw

20dBm = 100mw       TXPower Level 1

17dBm = 50mw         TXPower Level 2

14dBm = 25mw         TXPower Level 3

11dBm = 12.5mw      TXPower Level 4


Hope this helps.


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