07-19-13 Expert Day

New Contributor

High Density AP environment and power settings



We currently have a 1000AP environment with 4 3200 controllers in a Master and Local x3 configuration. The AP's provide Wifi Services for restaurants including Clearpass Guest Captive portal. We have a quite dense AP setup per restaurant. We on average have 3 AP's per location though we have places with 5AP's.


The distance between AP's in some of these locations can be as low as 30 ft and on average around 40ft. Addiitonally we have some challanges with regard Interference due to equipment used in the kitchen enviroments. 


One of our current issues is with out payment devices. We have a higher than expected number incomplete transactions.  We have found that the roaming of the devices is somewhat sparodic and sometimes it seems to be effecting performance with devices hanging onto AP's right the other side of the restaurants. 

We currently have default RF profiles and ARM settings apart from a few sites where we have limited problamatic channels. 


We are looking for some general advice regarding such a high density setup with regard


- ARM min and Max power settings for such a environment

- Any other settings that may aid such an environment 


We additionally have access to the core device settings of the payment devices so we are able to change roaming parameters with regard when it looks to roam and the db value when it jumps to a new AP. 


However we want to have the best practices employed before we start this testing so any advice on this topic would be appreciated. 





Aruba Employee
Aruba Employee

Re: High Density AP environment and power settings

Aruba Employee

Re: High Density AP environment and power settings

Hello Dan,


The way you describe your environment, you are probably running all APs at max power. Meaning that ARM is not stepping in to lower power and most of your APs are sitting at an EIRP of 21.


If really all of your restaurants have a very similar RF design, I would feel comfortable lowering max-tx in your ARM profile to 18 or 15 dB and evaluate.


Otherwise, if you are unsure of this, you can use some of the other mechanisms we have such as max-tx-fail, station handoff assist or by cutting data rates.


Hope this was helpful.


ACE Engineer
New Contributor

Re: High Density AP environment and power settings

Thanks for both your comments.


I like the sound of the Mode Aware setting but i didnt put that we do run both B/G and A. The payment devices run on B but we also run Hand held tills on the A band. We also have band steering for Guest users towards A. The mode aware upon first read seems to be 2.4ghz only. 


It is right to assume that the 5ghz can run alongside a mode ware 2.4ghz environment and only the B/G aerials are converted to AMs?


I will also look into lowering ARM power limits as a beginning point before testing Mode aware and compare. Currently our Lab has 40ft apart AP's and the strength is too much for our payment devices to roam correctly.







Aruba Employee

Re: High Density AP environment and power settings

In a dense environment, there are a few things you can do to help the roaming and decrease the co-channel interference:

1. drop the Max-tx-EIRP under ARM profile, for b/g band, 9dbm, for A band, 12 to 15dbm.

2. increase "Cell Size Reduction" value under dot11a/dot11g radio profile, 15 to 20dbm is recommended.

3.For the stability of your B band payment system, you can cut the high rates of tx-rates of b/g band under SSID profile.


Be careful with mode aware, and check if the corner/edge of your restaurant has enough RF coverage after some AP is converted into AM.

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