Wireless Access


Determining cell edges - ACDP question

Hi community,


I have found this sample question about determining the cell edges:acdp4.PNG



I understand to use the 5 GHz band since the signals at this frequency have more attenuation, so options a and b are not the answer. Also I understand the risks related to high transmit power, so option c seems not to be the answer as well. But I doubt in the wireless deployment the 5 GHz band will be configured to the minimum transmit power, among other reasons because it should be 6 dB higher than the 2.4 GHz band, then, option d seems incorrect as well. Any suggestion?






Contributor II

Re: Determining cell edges - ACDP question

Hi Julián,


I wonder if there is an implicit (but not entirely clear) idea of minimum and maximum transmit power being the min and max for the design rather than the transmit min and max for the AP model.


5GHz is important, not because of attenuation or design theory, because 802.11ac only operates in 5GHz and the question calls out that it is a 802.11ac upgrade.


What is not totally clear is the intended reason for defining the cell edge. Let's say (going with the theory that it means min and max design TX power) you set a range of TX power in your AirMatch (or ARM) profile. Knowing the minimum power cell edge is important as this is the sweet spot for clients to operate. Clients may operate outside of this cell but ideally they would then associate to a better cell on a neighbouring AP. Knowing the maximum power cell edge is important so you can check you don't design in unintended co-channel interference.


With all that said, as long as I'm correct in guessing that the inference of transmit power is min and max designed power (ARM/AirMatch profile), then testing for worst case of the smallest cell is in my opinion the best way to go about the survey. Understanding the footprint of the AP when it's set to it's lowest transmit power (as per the design) will help ensure there are no coverage gaps when the AP plan is implemented.


I highly recommend the Official ACDP Study Guide. It suggests in the section about steps during an Active Survey to Provision radio minimum transmit power for the deployment.


:) Good luck with the study!


Re: Determining cell edges - ACDP question

Hi Matt,


Very nice and correct explanation, many thanks!




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