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Access network design for branch, remote, outdoor and campus locations with Aruba access points, and mobility controllers.
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Minimum recommended RSSI

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  • 1.  Minimum recommended RSSI

    Posted Sep 17, 2021 09:50 PM
    Hello
    I was reading the Aruba WIFI 6  Network deployment VRD and i found something interesting
    Before the RSSI was fine up to -67dBm  but now the recommended value is -55 dBm
    That s a big difference i think, in number of APs! and more if you got walls or some gypsum walls or i dont know other materials, between APs.


    Anyways -67 dBm as the limit is not good anymore for the new 802.11ax APs?
    Im asking because im kind of outdated right now for some reasons, but i want to get updated again.
    that just took me a bit by a surprise.

    Any comment is welcome as i would like to know more
    Thanks

    Carlos


  • 2.  RE: Minimum recommended RSSI

    Posted Sep 18, 2021 03:36 AM
    "An Enterprise Network that needs to support realtime voice and video applications".  This is a suggestion if you have phones that need to support realtime video and voice for devices that need to roam throughout the enterprise.  Your actual mileage may vary depending on your environment, what applications you are running and the results of a survey.  Again, these are just recommendations.

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    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.
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  • 3.  RE: Minimum recommended RSSI

    Posted Sep 18, 2021 09:19 AM
    Hello Joseph
    Even if they are just "only" recommendations i try to fallow them and thats why  i read the VRDs, fallowing the recommendations.  They has been always good for me, because whenever i do a deployments noone ever complain about lack of performance or things like that and if they do, is not related to the wifi itseft, i have to prove that but thats another history.
    anyways Josepth my question is: it have always been recommended -55 dBm for that scenario or is just NOW in 802.11ax?   is just that i don't remember that -55 dBm before at least back on the 802.11n VRD,  not sure int he 802.11ac?

    Also if its for the communications in a warehose for Pdts between the database and the pdt the -67 dBm would be still be good for 802.11ax?  at least it has worked in the past fine for the deployment i have done with 802.11n and 802.11ac aps.

    Thanks!


  • 4.  RE: Minimum recommended RSSI
    Best Answer

    Posted Sep 18, 2021 03:30 PM
    It is good to hear that you have followed the VRDs and got good performance. The document states that the -57 number is to reliably provide MCS11 in a 40mhz environment on HE (802.1ax).  It is very specific.

    A warehouse is not considered a high density environment so this recommendation does not apply.

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    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.
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  • 5.  RE: Minimum recommended RSSI

    Posted Sep 18, 2021 05:22 PM
    Thanks for the reply Joseph!

    Carlos


  • 6.  RE: Minimum recommended RSSI

    Posted 30 days ago
    Question -- how do these recommendations change when you get into an 80mhz environment?

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    Cathy Fasano
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  • 7.  RE: Minimum recommended RSSI

    Posted 29 days ago
    I my designs i would recommend mostly always -62dBm RSSI  5Ghz@30mW tx-power for standard office deployments. The reason for stronger RSSI is a better modulation rate, 802.11ax introduce modulation rate of 1024-QAM which need a higher signal strength.

    @Cathyf  When double the channel width you loose 3dBm RSSI. So when you have 60dBm@20Mhz it will be 63dBm@40Mhz and 66dBm@80Mhz, and so on... Always plan your channel width and avoiding co-channel interference.

      ​​

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    Marcel Koedijk | MVP Guru 2021 | ACEP | ACMP | ACCP | ACDP | Ekahau ECSE | Not an HPE Employee | Opinions are my own
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  • 8.  RE: Minimum recommended RSSI

    Posted 29 days ago
    @Cathy f  An 80mhz environment with high density is not recommended. ​

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    Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.
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  • 9.  RE: Minimum recommended RSSI

    Posted 29 days ago
    I think the math should be for -60dBm@20MHz => -57dBm@40MHz / -54dBm@80MHz at the receive side?

    In fact, it is not the signal strength that is relevant for the MCS rate, but the signal-to-noise ratio. And if you add more radios in a high-density environment the background noise level is expected to go up as well, so it may be really challenging to design a proper high-density environment the denser it gets.

    Seeking advice from a professional with experience in these types of designs is generally a very good investment in the long run, as it can avoid/reduce potential issues and improve the performance/cost balance.

    Note that most standard offices are not (ultra) high-density. Taking more details into account is probably needed to tell if using 80MHz, AP density, AP power settings is a good idea; a professional can assist.

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    Herman Robers
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    If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
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  • 10.  RE: Minimum recommended RSSI

    Posted 28 days ago
    Some good info about channel width and RSSI here.

    In office environments keep your channel width small, always 2,4GHz@20Mhz and 5GHz@20Mhz or 5GHz@40Mhz max. when you can without have any co-channel interference. Co-channel interference is one of your biggest enemies in WiFi.

    And agree with you Herman, Signal-Noise Ratio (SNR) is more important than the RSSI self.



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    Marcel Koedijk | MVP Guru 2021 | ACEP | ACMP | ACCP | ACDP | Ekahau ECSE | Not an HPE Employee | Opionions are my own
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