Wireless Access

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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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SNR not affected by Noise

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  • 1.  SNR not affected by Noise

    Posted Mar 21, 2019 01:22 PM
      |   view attached

    Hi,


    We are using IAP-225 in our company. We were trying to determine what is a good indicator for showing the quality of network. Since the signal strength is not a good indicator, we thought SNR would give a better picture of the network.

    However, in our testing, the results did not show any change in SNR when noise was introduced. We used Waveform generator tool to generate noise on WAP operating frequency. Our results showed the following.

    • AP’s Noise level measurements do respond to us adding interferer on the channel
    • Client reported SNR does not change from adding an interferer on the channel
    • Client negotiated PHY rate does change from adding an interferer on the channel
    • How the AP calculates RSSI seems to be incorrect. It assumes the client’s noise floor is a static -95 dBm and the value of how it calculates SNR is unclear, as it doesn’t seem to change by adding noise to the channel.


    Steps to Reproduce:

     

    • Measure the noise floor.
    • Associate a client to the network and note the SNR and tx-rate specific to it.
    • Generate noise using Waveform generator tool.
    • Check the noise floor. Also, check the SNR and tx-rate reported by WAP for the same client.

    The logs are attached below.

     

    Can you please explain me why the SNR stays constant with noise being introduced?

    Attachment(s)

    pdf
    Captures.pdf   1.50 MB 1 version


  • 2.  RE: SNR not affected by Noise

    EMPLOYEE
    Posted Mar 21, 2019 08:35 PM
    Please open a technical support (TAC) case.


  • 3.  RE: SNR not affected by Noise

    EMPLOYEE
    Posted Mar 22, 2019 01:39 AM
    A quick but unverified answer in your case is that noise is only collected and displayed once every 60 seconds from an access point. If you did not wait for 60 seconds before inspecting the value, that could be your issue. If you did wait, you should open a TAC case, because it could be a bug.


  • 4.  RE: SNR not affected by Noise

    EMPLOYEE
    Posted Mar 22, 2019 01:40 AM
    A quick but unverified answer in your case is that noise is only collected and displayed once every 60 seconds from an access point. If you did not wait for 60 seconds before inspecting the value, that could be your issue. If you did wait, you should open a TAC case, because it could be a bug.


  • 5.  RE: SNR not affected by Noise

    Posted Mar 22, 2019 03:25 PM

    Thank you for your answer.

    Yes. I waited for more than 60 seconds. Further, only after the noise floor change, I looked for a new SNR. 

     

    I will open a TAC case and report the issue.

     

    Thanks,

    Shiva