[New Feature - 5.10.0] MU-MIMO Support

Products ePMP
1

Affected platforms: ePMP 4500C 8x8, ePMP 4500 8x8 and ePMP 4600 4x4 (ROW/FCC)
Affected versions: 5.10.0 and newer

The 5.10 software release introduces MU-MIMO (Multi-User Multiple Input Multiple Output) support for 5GHz and 6GHz multi-chain Access Points (APs), including ePMP 4500C 8x8, ePMP 4500 8x8, and ePMP 4600 4x4 (ROW/FCC).

  • Simultaneous Downlink Transmission: Enables concurrent data transmission to multiple Subscriber Modules (SMs), improving sector efficiency.
  • Configurable via Web Interface: MU-MIMO is disabled by default and can be enabled through the AP’s web UI.

1600×491 129 KB

  • Real-Time Monitoring: MU-MIMO traffic is highlighted in green on the throughput chart.

1600×620 181 KB

  • Sector Capacity Enhancement: MU-MIMO increases the total capacity of a sector by enabling simultaneous data transmission to multiple SMs that can form a MU-MIMO group.
  • SM Grouping Based on Azimuth: For MU-MIMO grouping, the AP determines the azimuth of each SM relative to its sector antenna.
  • SMs can form a MU-MIMO group if their angular separation meets specific criteria as follows:
    615×446 26 KB

ePMP4500 8x8 Sector

F (MHz) Min1 (°) Max1 (°) Min2 (°) Max2 (°)
4900 6.7 39.2 59.9 EOS
5000 6.6 38.2 58.0 EOS
5100 6.5 37.3 56.2 EOS
5200 6.3 36.5 54.6 EOS
5300 6.2 35.7 53.1 EOS
5400 6.1 35.0 51.7 EOS
5500 6.0 34.2 50.4 EOS
5600 5.9 33.5 49.2 EOS
5700 5.8 32.9 48.1 EOS
5800 5.7 32.2 47.0 EOS
5900 5.6 31.6 45.9 EOS
6000 5.5 31.0 45.0 EOS
6100 5.4 30.5 44.0 EOS

ePMP4600 4x4 Sector

F (MHz) Min1 (°) Max1 (°) Min2 (°) Max2 (°)
5900 10.4 32.9 65.0 EOS
6000 10.3 32.3 63.0 EOS
6100 10.1 31.7 61.2 EOS
6200 9.9 31.2 59.6 EOS
6300 9.8 30.6 58.0 EOS
6400 9.6 30.1 56.6 EOS
6500 9.5 29.6 55.3 EOS
6600 9.3 29.1 54.1 EOS
6700 9.2 28.6 52.9 EOS
6800 9.0 28.1 51.8 EOS
6900 8.9 27.7 50.8 EOS
7000 8.8 27.3 49.8 EOS
7100 8.7 26.9 48.8 EOS
  • Beamforming Limitation: SMs with MU-MIMO enabled do not benefit from beamforming when receiving MU-MIMO traffic.
  • MU-MIMO is not supported in Split Sector Mode.
  • Performance optimization is pending for Flexible TDD ratio configurations.
  • UI does not yet indicate groupable SMs.
4 Likes
2

So does MU-MIMO take effect anytime there are SMs that can be grouped and are asking for data, or only if the AP needs the extra capacity?

Meaning is the SM azimuth the only thing that determines MU-MIMO vs SU-MIMO traffic or is there some other criteria the AP uses to decide if to do MU or SU-MIMO?

3

Yes, MU is used anytime when the traffic flows come to groupable SMs even the AP doesn’t reach the SU capacity limit.
Thanks

4

Is MU-MIMO only enabled for downlink or is it also used for uplink? If it is not currently used on uplink will it be supported in the future?

5

MU is available for Downlink only in 5.10 release.
Uplink MU may be implemented in the future.

Thanks

6

So does that mean SMs still benefit from beam forming gain on UL or was beam forming only in the DL direction?

7

Beamforming is only on downlink. Beamforming gains are only applicable to SU-MIMO… when MU-MIMO is triggered, beamforming gains are negated. So there’s a trade off… SU-MIMO/beamforming allows higher individual SM top line downlink tput vs MU-MIMO which allows potentially higher AP aggregate tput.

3 Likes
8

So what happens if I turn on MU-MIMO but none of my SMs are groupable or they group rarely? When the AP is talking to an SM that cannot be grouped will it just do normal beamforming and get the benefits of beamforming gain?

9

Yes, it will work in Single User mode and will be leveraging the benefit of SU Beamforming.

Thanks.

10

Can MU-MIMO be disabled on an SM, where I need beamforming to work because the RSSI is lower from the AP as compared to other SMs on that AP?

2 Likes
11

Not today, but we are considering that option for the future releases.

Thank you.

1 Like
12

We’ve got some users (SMs) that need the beamforming to get a good usable signal. We probably shouldn’t have SMs on the system with signals that weak, but we do. Without beamforming, I’m not sure that they’ll be ‘usable’.

1 Like
13

I completely understand. We will try to bring that feature sooner rather than later.

Thank you.

2 Likes
14

Unfortunately this RC candidate is not working well for us. The APs I am testing on have lost more than half their individual capacity on link tests and real world throughput. The issue does not appear immediately after upgrading but over time the capacity tanks. A reboot seems to restore the capacity but again it does not last. We have made a ticket with support but we are forced to downgrade to stable firmware. Hopefully the next RC will offer the fix.

1 Like
15

Hi Greg,

Did you have a chance to grab the Tech Support File before rebooting the AP?

Thank you.

16

Yes, got one before and one after reboot for theAP and 3 CPEs as well as screen shots of link tests before and after for 5 or 6 CPEs. Hopefully it will help. Everything has been submitted in our ticket.

1 Like
17

I’m wondering what AP type is this? I’m wondering if it’s maybe a MU-Mimo issue? On our 4500L (without MU-Mimo) it’s still seeing ~400 Mbit aggregates and this is 3.5 days on 5.10.0-RC33 with 80Mhz/40Mhz asymmetric bandwidth.

Screenshot_20250312_230105_Chrome
Screenshot_20250312_230105_Chrome652×1019 101 KB

1 Like
18

Hi guys, this function only work in Downlink/Uplink Ratio “Manual” and not yet in “Flexible”?
Sorry, i don´t understand this note in the limitations.
Thanks!

19

The MU-MIMO performance is not optimised for Flexible TDD ratio yet.

Thank you.

1 Like
20

So UL MU-MIMO is not currently planned? I remember multiple videos on the ePMP 4k platform and DL and UL MU-MIMO and beamforming were mentioned as a selling point. I mean it is even an option on the official Cambium Capacity Planner tool.

Please don’t pull a Ubiquiti and market a feature as a selling point and then not follow through and pretend that feature was not marketed.

1 Like