Wireless Access

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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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Colocation of Wi-Fi APs and 5G

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  • 1.  Colocation of Wi-Fi APs and 5G

    Posted 10 days ago

    Hi all,

    We are investigating how close we could deploy Wi-Fi and 5G transmitters (3.7-3.8GHz).
    Both technologies use different frequency bands but we are concerned about out-of-band interference when co-locating both outdoor transmitters (e.g., on the same lightpole covering a parking area).

    Do you happen to have detailed information on input/output RF filter characteristics of Aruba outdoor APs (e.g., 560 series) and antenna patterns for non-Wi-Fi frequency bands?
    I'm also interested in any other relevant feedback.

    Thanks in advance.
    Best regards,

    Matthias



    ------------------------------
    Matthias WELLENS
    5G / Wi-Fi Engineer
    ZF Group
    Düsseldorf
    GERMANY
    ------------------------------


  • 2.  RE: Colocation of Wi-Fi APs and 5G

    Posted 10 days ago
    Good point Matthias. It is often ignored that radios operating on different bands can still interfere as a result of OOB emissions.
    However, the combination of dedicated filtering in the Aruba products and the fact that the 5G transmitter is operating quite far from the Wi-Fi bands, should be sufficient to ensure there's no interference.
    What's the anticipated distance between the radios, transmit power from the 5G radios, and antenna gain in the direction of the AP?

    ------------------------------
    Onno Harms
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  • 3.  RE: Colocation of Wi-Fi APs and 5G

    Posted 9 days ago
    Hi Onno,

    Thanks for the quick response.
    Anticipated distance could be very close, i.e., right on top of each other on the same lightpole. Something like 30cm?
    The planning of the outdoor Wi-Fi deployment is further ahead compared to the 5G side such that we do not have the details available, yet. I guess something like 40dBm transmit power for 5G but do not have antenna characteristics, yet. That's the reason why I was looking for details on the input filtering on the Wi-Fi APs to do some rough calculations if there is the risk of OOB interference.
    Do you happen to have an estimate for the max. Rx power at 3.7-3.8 GHz that the APs will manage to filter out without any desens?

    Best regards,
    Matthias

    ------------------------------
    Matthias WELLENS
    5G / Wi-Fi Engineer
    ZF Group
    Düsseldorf
    GERMANY
    ------------------------------



  • 4.  RE: Colocation of Wi-Fi APs and 5G

    Posted 9 days ago
    Matthias,

    The design requirements for our APs specify that receiver performance should be "unaffected" (no more than 3dB degradation) in the presence of an OOB interfering signal with power level of up to -10dBm (in a 1 MHz channel). I do not have any actual test data, but am confident that we far exceed that target on our APs for signals that far away from our band edges.
    Free-space pathloss at 30cm and 3.5GHz is about 30dB. Antenna coupling and dramatically reduced gain for the Wi-Fi antennas at these frequencies will add some further attenuation. 40dBm would translate to 33dBm/MHz assuming a narrow 5MHz channel, and less for wider channels.
    All in all, the interfering signal strength could be somewhat above the level we use as the design target, but that assumes the AP is within the beam of the 5G radio antenna, which seems unlikely.
    This should be fine.

    ------------------------------
    Onno Harms
    ------------------------------



  • 5.  RE: Colocation of Wi-Fi APs and 5G

    Posted 8 days ago

    Hi Onno,

     

    Thanks for the numbers and confirmation that we'll be fine.

    I also agree that the beams of both antennas will obviously not point to each other because both will target the same user areas below.

     

    Thanks,
    Matthias

     

    ---

    Mit freundlichen Grüßen/Kind regards
    Dr.-Ing. Matthias WELLENS

    Expert 5G Wireless Network Technology
    IT WIO IP Network Technology (FIII52)

    ZF Group

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