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Occasional Contributor I

Aruba site survey, power transmit

Hi I am going to do a site survey with an Arubas 215 with internal antenna, I would like to know the range of power transmit values and what is recommended

Guru Elite

Re: Aruba site survey, power transmit

Please see here:  http://community.arubanetworks.com/t5/Validated-Reference-Design/Indoor-802-11n-Site-Survey-and-Planning/ta-p/155136

 

It is the same principles for 802.11ac



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba site survey, power transmit

Hi so if I want to set the 2.4 ghz to 50% of the power I cannot see what the lowest to highest setting is on the AP

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Declan Liddy
Professional Services Consultant
Logicalis, Inc.

M: 412-304-1506

Declan.Liddy@us.logicalis.com
285 Kappa Drive, Suite 120
Pittsburgh, PA 15238

www.us.logicalis.com
Guru Elite

Re: Aruba site survey, power transmit

12 db  as minimum and maximum is a safe number to start out your survey.  

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba site survey, power transmit

Hi this is my first time using Aruba Access points for a survey so I usually use a lower value for 2.4 ghz than 5ghz.

Cisco, Extreme etc has specific values for the power settings is there a chart for the Aruba, is 24 the most

so the min and max settings should be the same

Declan Liddy
Professional Services Consultant
Logicalis, Inc.

M: 412-304-1506

Declan.Liddy@us.logicalis.com
285 Kappa Drive, Suite 120
Pittsburgh, PA 15238

www.us.logicalis.com
Guru Elite

Re: Aruba site survey, power transmit

The survey transmit power depends on your kind of deployment.  The survey guide at the link will give you a clue.  " In general, the transmit power of the AP should be set to match that of the least-capable device in the network".

 

Please read the VRD and if you have any further questions, please come back with them.  The VRD is very detailed and I would just end up copying and pasting answers from it here.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba site survey, power transmit

The link you give me does not specify the power limits of the AP. The weakest device has nothing to do with it. I will be performing the survey with Airmagnet with a -65 dBm. So the power setting on the AP only determines the distance the signal will be sent from the AP, environment depending. SO all I am asking is what the range is for this setting, so I can make adjustments as needed when doing the survey.

Declan Liddy
Professional Services Consultant
Logicalis, Inc.

M: 412-304-1506

Declan.Liddy@us.logicalis.com
285 Kappa Drive, Suite 120
Pittsburgh, PA 15238

www.us.logicalis.com
Guru Elite

Re: Aruba site survey, power transmit

So, from how I understand it, using a -65 cutoff in Airmagnet has nothing to do with the transmit power of the AP.  It only determines after you have done the survey where you can get a -65 signal.  You will also have to compare the receive sensitivity of the adapter in airmagnet to the weakest devices you have so that you get a true picture of how those devices will see those access points.

 

In addition, you always set the access points to a fixed transmit power (the same max and min), that you have even results.

 

Quite frankly, I don't recommend it, but I just draw 50 foot square boxes and put an access point in each box.  Site surveys are very time consuming...

 

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I

Re: Aruba site survey, power transmit

Hi I have a question, not to be rude have you performed a wireless site survey.

So the transmit power from the AP is how strong the signal will be, thus goes further

So when I do a survey, with other vendors AP's I can adjust the transmit power, if say I am in a
Warehouse. When I use Airmagnet it is already determined what the coverage is going to be, but in a warehouse
I don't need the density that I would in a conference room so I can have two different power setting for each location.

I don't draw boxes to do a survey, if you are not sure about this can we have someone else involved that does.

Thanks

Re: Aruba site survey, power transmit

Armagh1, condescension not withstanding, CJoseph is 100% absolutely correct. To add, because he won't, has probably done more surveys and active installs in hundreds of Fortune 500 companies around the world, and is one of our company's leading SEs in terms of best practices.

 

We (Aruba) recommends you set the AP power at the power the least capable/least powerful device you expect coverage with when doing a survey. If all of your clients are 100mW clients, then set that as the modeled adapter in AirMagnet, then you can set the AP power at 20dB and do your survey. If your least capable device is an Intermec CK61G HHT, with a transmit power of 20mW, then set the AP to 13dB power ouput, set the modeled adapter in AirMagnet to that type of device, and do your survey. 

 

As I'm sure you know, coverage models and capacity models are two different things to plan for, but the coverage model still has a baseline of minimum coverage and that is what we are discussing here when setting the AP power to match the client type. We also recommend to set min and max at the same value such that the AP power is constant and won't change. Having a fixed power ouput of the AP(s) being surveyed with is a requirement for the survey to be valid. If one is at 12 and one is at 15, unless accounted for in the model, the survey will be invalid.

 

It is NOT good practice to rasie power of the AP *just* to get a bigger coverage model unless you are accounting for the clients that will be connecting to the AP, or the minimum SNR at the client is lowered. While higher output of the AP will give bigger coverage model, the client 'reach back' is the same (as clients will not raise power nor will the APs become MORE sensitive at higher AP power ouput, the client xmit and AP rx is a fixed link budget).

 

Best practice is to set the coverage threshold based on the client types to be used and the applications required (generally -65 for voice, -75 for basic data), identify all areas on the floor plans that require coverage at or above that threshold, and design accordingly. The environment (propagation and fade margin models) will take care of itself such that in an open warehouse you should get better propagation and fade margin than what you would find indoors. If you just raise the AP power up to get a bigger coverage area, the clients may not likely be at or above the threshold due to the longer distance and lower client power ouput to reach back and will fall below requirement at the edge of coverage.

 

That is the best practices put forth in said documents CJoseph refers to. If you need the max power ouput for the APs you will be modeling, they are and always have been on the data sheets. Power range is anywhere between 0dB and max. Our user guides are not behind a paywal or login and can be read for details on the how-to or the granularity of the power range (0.1dB for newer code, 1-3dB on older code depending on version). 

 

Jerrod Howard
Sr. Technical Marketing Engineer
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