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Orbi using MU-MIMO in backhaul?

Discussion in 'NETGEAR AC / AX Wireless' started by sfx2000, Aug 14, 2018.

  1. sfx2000

    sfx2000 Part of the Furniture

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    I'm thinking a lot of folks might be using MU, and not realizing it - many of the Mesh/Multiple Point platforms are supporting it between nodes, not out to the client STA's, but between them.

    Orbi is a good example with one base and 2 or more satellites - I've seen the wireless PCAP's that suggest MU is in play, since I have a neighbor with an 3-node Orbi system in place.

    This is captured from the Root/Primary/Base Orbi - see MU is there...

    orbi_backhaul_160_1.png

    It's only on the backhaul 5GHz link, but it's there, at least in the captures - one can see the VHT NDP Announcement going out on Broadcast vs. being addressed to a specific STA - that's a sounding request for beamforming, and broadcast is a tell...

    Makes sense actually - for certain traffic in a multiple point system like Orbi, it can help on the backhaul.

    FWIW - saw hints in that same PCAP that suggests for the Orbi Backhaul - it may support 160MHz in the future - both 160 and 80+80, might be something in the driver code, but it's there - disabled at present (because DFS? - this was in the US)

    orbi_backhaul_160.png
     
    Jim Salter likes this.
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  3. thiggins

    thiggins Mr. Easy Staff Member

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    Do chipsets even support MU-MIMO for more than 2x2?

    And isn't 160 MHz more useful for getting more bandwidth for 1x1/2x2 STAs?
     
  4. avtella

    avtella Very Senior Member

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    I thought the single Satellite and router connect with 4 STAs making MU pointless for backhaul, unless maybe the router connects to multiple satellites using 2x2 mode with MU.
     
  5. Internet Man

    Internet Man Senior Member

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    There are satellites (RBS20, RBW30, RBS40) and routers (RBR20, RBR40, CBR40) with two-stream backhaul.

    They all use a QCA9886 which supports MU-MIMO.
     
    Jim Salter and avtella like this.
  6. thiggins

    thiggins Mr. Easy Staff Member

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    You're right. I forgot about those.
     
  7. sfx2000

    sfx2000 Part of the Furniture

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    MU is implied, but cannot be confirmed without having a MU capable client and being part of the active MU group - which with Orbi could be a challenge, as one would have to "fake" being a satellite unit, as it was indicated only on the backhaul.

    2*2:2 - nothing says that it cannot be done, but I didn't see any indication of MU capability on the Client links, only on the backhaul link.

    160MHz (or 80+80) - probably an artifact of the driver - doesn't mean it's active or supported* - and again, this was on the backhaul link - the client visible side was more like Wave 1 - 80MHz links, 2*2:2 SU only.

    (* because of DFS - should note however that both the client link and backhaul link indicate DFS channel capability)

    For 2.4GHz - the default seems to be VHT mode, with 20/40 support (in the UI, according to screenshots and user guide info would be the "up to 400Mbps" mode.

    It was interesting to look at - there's more to an Orbi system than meets the eye - only complaint I have is that the 2.4GHz automatic channel selection could be better (it has a bad habit of picking less than desirable channels - e.g. 2/4/8 - that could be because of weighting of certain channels in the ACS algo, but also means that it will add to the interference issues between adjacent WLAN, and that will cut both ways)
     
    Jim Salter likes this.
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