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5508 WLC Tx Power Control(TPC)- High Density Deployment

We have a multi-floor office building with a high denisty wireless deployment.  Each floor is close to 25,000 sq feet with 6 to 7 3602i AP's per floor.  There is about 1 AP per 3500 sq foot.  This is mainly for Data only, but we do some voice and will do more in the future.  My question is around the Transmit power configuration on the 5508.  RRM is setting the power levels on these access points to 5 and 6 on most all of these.  I have seen where certian client devices are not getting adequate throughput, and the RSSI is around -72 for some of these.  Would it be recommended to manually adjust the power levels on each AP, or globally set the TPC minimum power level assignment to something other than the default which is currently -10 dBm?  I typically do not modify the global TPC setting on our WLC's for indoor office envionrments, but was curious what the experts on here think as far as best practices concerning this.  Thank you.

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Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

I would set the minimum TX power to 8 or 11 and see if that helps.... The one reason AP's can lower their TX power is because they are line of sight, for example, in the hallways.  Depending on your coverage, the TX power should be tweaked. The data rates is another thing to tweak, which can also shrink your cell size so that clients roam to close access points.

Thanks,

Scott

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-Scott
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17 REPLIES
Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

I would set the minimum TX power to 8 or 11 and see if that helps.... The one reason AP's can lower their TX power is because they are line of sight, for example, in the hallways.  Depending on your coverage, the TX power should be tweaked. The data rates is another thing to tweak, which can also shrink your cell size so that clients roam to close access points.

Thanks,

Scott

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-Scott
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Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

You can also set the maximum TX power to maybe 17, which would be 50mW and that will also help make sure one AP isn't trying to cover everything.

Thanks,

Scott

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-Scott
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New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Thanks Scott.  I appreciate your quick response.  So just that I am clear, you would adjust the minimum power level assignment from -10 to 8 or 11, and the also set the maximum from 30 to something like 17?  You are referring to the settings I have in screenshot below, correct?  Thanks again.

TPC.JPG

Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

Yes... those settings... you need to disable the band though, so you will have to take a down time, but not that long.

Thanks,

Scott

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-Scott
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New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

I had actually planned on creating an RF Profile with these settings, and then applying that profile to a specific AP Group.  Do I still have to disable the bands donig it that way?

Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

No, but when you move the AP's to that group, the AP's will reboot.

Thanks,

Scott

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New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Guys... could you explain, what is the purpose to have a negative power value here? (-10?)

Hall of Fame Super Silver

Re: 5508 WLC Tx Power Control(TPC)- High Density Deployment

It's just in case you have a really high gain antenna. But I look at it as a default min to reduce the TX power to the lowest possible. Just like the max... That is outdoor power.

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-Scott
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New Member

Re: 5508 WLC Tx Power Control(TPC)- High Density Deployment

Mhm... so the point is...

0 dBm = 1 mW

-10 dBm = 0.1 mW

Thanks!

New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Since I am not adjusting TPC globally on the WLC, and making this change under an RF profile, when I apply the RF profile to the AP Group, will it automatically adjust at that moment?  The access points are already in this AP Group.

New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

It will start adjustments, but probably take several cycles to fully adjust.  The TPC algorythm runs every ten  minutes.  You can force it manually, but I would just let it work, after after a couple hours check the power levels, client coverage, and see if you need to make further changes to the settings.

Hall of Fame Super Silver

Re: 5508 WLC Tx Power Control(TPC)- High Density Deployment

Takes about 30-40 minutes but DCA will have to adjust also. Typically I have DCA set at 24 hours. You can restart DCA from the CLI:

config advanced 802.11a channel global restart

config advanced 802.11b channel global restart

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-Scott
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New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Thanks.  I have DCA set for 24 hours as well.

New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Is there a recommended minimum power level assignment under TPC for the A/N Band?

Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

I would set that the same.... now it varies depending on how dense or sparse your environment it.  Take a look at what RRM is setting your channels and if you think that the 5ghz is lacking in your environment, you will then know what your min should be.  I tend to set the max still at 17 or 14 just to see if aps on the 5ghz is consistent or close after RRM settles down.

Thanks,

Scott

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-Scott
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New Member

5508 WLC Tx Power Control(TPC)- High Density Deployment

Hi Scott,

I have another question. For example I have AP2602i and I set Max Tx power to 17dBm.

Do I need to think about internal antennas when configuring Max Tx power?

To be more clear, AP 2602i has 4 internal antennas:

• 2.4 GHz, Gain 4 dBi, internal omnidirectional, horizontal beamwidth 360°

• 5 GHz, Gain 4 dBi, internal omnidirectional, horizontal beamwidth 360°

So now we have : 17dBm + 4dBi = 21dBm?

Hall of Fame Super Silver

5508 WLC Tx Power Control(TPC)- High Density Deployment

You always do, but remember that this process has been the same as in the past with older equipment.  For example... voice, Cisco suggest 50mW at one time then 25mW.... this doesn't include the antenna's.  So it depends if you want to look at it a just the radio TX power or if you also want to calculate it with antennas to get your total EIRP.  If we survey, then I know what values I can play with, when I come into a project that we haven't surveyed, I have to look at the AP neighbor info, clients RSSI and SNR and from that, I can utilize RF Groups or multiple RF Groups to achieve the cell sizes I need.

So for your question... I do take the antenna into account, especially since we use high gain antennas in some installs.

Thanks,

Scott

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-Scott
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