WLC Transmit Power

[subhojithalder198]

HI Expert,

I want to control the WLC transmit power to centain distance, asume AP is supporting 20m, can we restrict the signal to 10m

What I mean to say in Aruba we can restrict the signal with the help of ":Transmit power" vlaue manipulation

How to do it on Cisco

Share the command/docuemnt for wlc.

Br/Subhojit

[Scott Fella]

You can achieve that in many vendors equipemnt.  On the WLC, you can confiugre each radio of a given AP to a specific TA Power level if you want.  On the GUI, click on the Wirless tab, then on the left side, click on the radio, either 802.11an or 802.11bgn.  When you find the AP you want to tweak, you click on the blue triangle all the way on the right side.  Click configure and set your power level.

[subhojithalder198]

Hi,

Thanks for the suggestion.

As per your direction, I have checked in TX Power Level, Presently it is set to 1 & 1-8 value is avaiable.

Pls suggest whether 1 is lowest menas it will cover Lowest distance or reverse.

br/Subhojit

[Amjad Abdullah]

Hi,

No. Tx 1 is the highest. 8 is the lowest in your scenario.

from config guide:

'''snip'''

The transmit power level is assigned an integer value instead of a value in mW or dBm. The integer corresponds to a power level that varies depending on the regulatory domain in which the access points are deployed. The number of available power levels varies based on the access point model. However, power level 1 is always the maximum power level allowed per country code setting, with each successive power level representing 50% of the previous power level. For example, 1 = maximum power level in a particular regulatory domain, 2 = 50% power, 3 = 25% power, 4 = 12.5% power, and so on.

'''snip'''

source: http://goo.gl/7cc3On

HTH

Amjad

[subhojithalder198]

Hi,

THanks for the same.

Assume when I set 1: if it cover 30m radius, If we set 2: it seems then it will cover approx 15m due to 50% emission.

Br/Subhojit

[Scott Fella]

It's never like that.... Even with all the other vendors, cutting the power from 100% to 50% doesn't mean it's the same for the coverage. TX power and data rates play a factor in how large your cell size will be and this is for any wireless installation, Cisco, Aruba, Meraki, etc. How you determine the cell size is to have a site survey performed or use a tool to determine what your RSSI/SNR is at a given location.

[subhojithalder198]

Hi,

I am fully agreeing on Site-Survey part for fine-tuning the parameter

What I mean to say that , If I set the value to 2, distnace covered with Value 2 should be less than if the vlaue is 1 ( depending on cell size fully agreeing on that part also)

We need to test the distance covered after changing the value with site-survey tool help for actual measurement.

Pls configm

Br/Subhojit

[Scott Fella]

Again you have to look at TX power and data rates. If you cut the TX power in half from 100mW to 50mW then the coverage is less. If you have 50mW with all the data rates and and AP at 100mW with many of the lower data rates disable, then the 5mW would cover more area. So you really need to look at both the TX and data rates. The data rates is important especially in high density deployments.

[Amjad Abdullah]

Hi,

That's not correct.

The power is proportional to the square of the distance.

In ideal situations, doubling the transmit power will make the distance 4 times longer. Decreasing the power to the half will make the distance 25% of the previous distance.

That's all depends on your RF environment though in real life.

Regards,

Amjad

[subhojithalder198]

Hi,

Sorry for the same

So theoritically, if value 1 support 40m, value 2 will support 10m

correct ?

Br/Subhojit

[Amjad Abdullah]

I think that's "theoretically" right. :)

[Sandeep Choudhary]

Just to add...

Here is the doc for static change in trnsmit power on each AP:

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-0/configuration/guide/c70/c70rrm.html#wp1099018

Regards

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