MU-MIMO won't disable on AC86U

[cplay]

I have 2 x ac86u and 1 x ac68u in aimesh mode with a AC86U at the main router.

Everything works great (have followed common advice on these forums for settings and installs etc).

However, although I have disabled MU-MIMO in professional settings, the two AC86U's via wireless backhaul are still connecting via MU-MIMO and illustrating the M = MU Beamforming flag in wireless system log:

975 / 1053 Mbps
-62 dBm
20:47:11
4 (ac)
_STMAU_

Could anyone shed light on why the wireless backhaul of the two ac86us are still connecting via MU-MIMO/M = MU Beamforming even though MU-MIMO is disabled on both bands in professional settings.

Noticed that @RMerlin , @L&LD , @OzarkEdge , and @Val D appear to have covered professional settings so your advice would be greatly appreciated and anyone else who also has experience/answer to the question.

Hope you are all well and COVID-19 unaffected.

Cheers,

Cplay

Here's a photo of the flag still remaining even though mimo is disabled:

 

[cplay]

Nearly forgot you @thiggins .

Anyone have any idea's why this issue is occurring and/or whether it is simply impossible to turn off MU-MIMO between AiMesh Router and Node?

 

[OzarkEdge]

I have 2 x ac86u and 1 x ac68u in aimesh mode with a AC86U at the main router.

Everything works great (have followed common advice on these forums for settings and installs etc).

However, although I have disabled MU-MIMO in professional settings, the two AC86U's via wireless backhaul are still connecting via MU-MIMO and illustrating the M = MU Beamforming flag in wireless system log:

975 / 1053 Mbps
-62 dBm
20:47:11
4 (ac)
_STMAU_

Could anyone shed light on why the wireless backhaul of the two ac86us are still connecting via MU-MIMO/M = MU Beamforming even though MU-MIMO is disabled on both bands in professional settings.

Noticed that @RMerlin , @L&LD , @OzarkEdge , and @Val D appear to have covered professional settings so your advice would be greatly appreciated and anyone else who also has experience/answer to the question.

Hope you are all well and COVID-19 unaffected.

Cheers,

Cplay

I don't know what _STMAU_ means.

When I once disabled MU-MIMO, the backhaul rates dropped. I did not make note of the MUBF flag in the Wireless Log. I assume MUBF means Multi-User Beam Forming.

I always keep MU-MIMO enabled and now some client MACs in the Log list MUBF No and some list Yes... my 2.4 backhaul is No and my 5.0 backhaul is Yes.

OE

 

[cplay]

I don't know what _STMAU_ means.

When I once disabled MU-MIMO, the backhaul rates dropped. I did not make note of the MUBF flag in the Wireless Log. I assume MUBF means Multi-User Beam Forming.

I always keep MU-MIMO enabled and now some client MACs in the Log list MUBF No and some list Yes... my 2.4 backhaul is No and my 5.0 backhaul is Yes.

OE

It's only the M that is important in the wireless log with MU-MIMO as that corresponds to the flag M = MU Beamforming.

Could you quickly disable MU-MIMO on your 5GHZ band and check whether your 5ghz wireless backhaul still displays the M flag with MIMO disabled?

Cheers for your help!

Cplay

 

[cplay]

I don't know what _STMAU_ means.

When I once disabled MU-MIMO, the backhaul rates dropped. I did not make note of the MUBF flag in the Wireless Log. I assume MUBF means Multi-User Beam Forming.

I always keep MU-MIMO enabled and now some client MACs in the Log list MUBF No and some list Yes... my 2.4 backhaul is No and my 5.0 backhaul is Yes.

OE

I've also added photo to thread so you can see what i am referring to in wireless log.

 

[OzarkEdge]

I've also added photo to thread so you can see what i am referring to in wireless log.

My 86U Wireless Log does not look like your pic(?).

Also, why would you want to disable MUBF for the wireless backhaul? Can't two AiMesh nodes work that out for themselves?

OE

 

[KevTech]

I always thought that MU-MIMO stood for multi-user, multiple input, multiple output.

Beamforming focuses a wireless signal towards a specific receiving device instead of having the signal spread in all directions.

So if the log is showing beamforming I would think you want that.

 

[cplay]

My 86U Wireless Log does not look like your pic(?).

Also, why would you want to disable MUBF for the wireless backhaul? Can't two AiMesh nodes work that out for themselves?

OE

Because I'm testing speed with and without. however from the sounds of it, it is not turning off properly.

That's why i was wondering if you could check your wireless logs and flags (M for MU beamforming) with mimo enabled and disabled so I can ascertain whether its just me with the problem or not.

If you get the same results as me it looks like its hard coded that MIMO will always be enabled for wireless backhaul independant of you setting it to enable/disable in wireless.

This is the image of my wireless log, is it different to yours?

 

[cplay]

I always thought that MU-MIMO stood for multi-user, multiple input, multiple output.

Beamforming focuses a wireless signal towards a specific receiving device instead of having the signal spread in all directions.

So if the log is showing beamforming I would think you want that.

If you check my latest reply (and photos) to OE you can see the M flag corresponds to MU Beamforming which is apparently MU-MIMO beamforming from the MU-MIMO threads on SNB.

The point is it shouldn't be saying that because I've disabled MU-MIMO in wireless professional settings which is why I started the thread.

If it is saying that then you either cant disable MU-MIMO wireless backhaul in AI or the M flag represents explicit beamforming not MU-MIMO Beamforming.

 

[OzarkEdge]

This is the image of my wireless log, is it different to yours?

Yes, my 86U 3.0.0.4.384_81352 Wireless Log is one scrolling text field with a formatted text report in it.

Is MU-MIMO the same as Beam Forming? This must be confirmed first before you can interpret setting cause and affect.

OE

 

[cplay]

Yes, my 86U 3.0.0.4.384_81352 Wireless Log is one scrolling text field with a formatted text report in it.

Is MU-MIMO the same as Beam Forming? This must be confirmed first before you can interpret setting cause and affect.

OE

They are not the same.

MU-MIMO is dependant on Explicit Beamforming in order for it to work.

If you go into wireless settings/professional on Merlin and try to disable explicit beamforming it ALSO disables MU-MIMO as MU-MIMO can't function without explicit beamforming enabled on ac86u. Try it for yourself on your Merlin main router - it wont allow you to disable explicit beamforming without it disabling MU-MIMO also (also gives error message).

Explicit Beamforming can work independantly from MU-MIMO - so you can disable MU-MIMO and still use explicit beamforming.

Just tested disabling explicit beamforming on both bands in addition to MU-MIMO being disabled and it appears the M = MU Beamforming flag actually relates to Explicit beamforming.

Disable explicit beamforming and the M flag in wireless log for wireless backhaul dissapears.

 

[OzarkEdge]

Disable explicit beamforming and the M flag in wireless log for wireless backhaul dissapears.

Did the backhaul Rx/Tx RSSI numbers also drop?

OE

 

[cplay]

Did the backhaul Rx/Tx RSSI numbers also drop?

OE

So, when i disable MU-MIMO numbers were the same if not better than when enabled.

However, when i disabled explicit beamforming maximum tx rate for 2.4ghz increased from 260 to 312, however rx rate was always 1 and device kept disconnecting.

On 5ghz band, tx rate stayed the same however rx rate literally halved with explicit beamforming disabled.

So the next question is this;

Apart from manually searching if a device is MU-MIMO supported then how do i tell if a device is MU-MIMO capable?

Obviously my finding indicate the M = MU Beamforming flag in WirelessLog relates to explicit beamforming not MU-MIMO.

This means lots of the threads I've seen on MU-MIMO (the test mu-mimo impact on throughput) are quite flawed as people were denoting their device as MU-MIMO capable if it showed the M flag in wireless log, which we know now is not related to MU-MIMO compatibility.

 

[cplay]

Did the backhaul Rx/Tx RSSI numbers also drop?

OE

Just did another test with explicit beamforming on and Mu-MIMO off,

RX and TX rates are constantly higher with MU-MIMO off.

Constant connect of -60 on 5ghz backhaul.

 

[cplay]

Did the backhaul Rx/Tx RSSI numbers also drop?

OE

What are your test results with MU-MIMO on and off?

And what are your test results with MU-MIMO off and Explicit Beamforming off?

Also, do you have universal beamforming on or off - I've noticed more random behaviour with devices and link speed when on so I have universal beamforming set to off.

 

[Grisu]

Are there any 2.4GHz clients able to run MU-MiMo at all?

 

[OzarkEdge]

What are your test results with MU-MIMO on and off?

And what are your test results with MU-MIMO off and Explicit Beamforming off?

Also, do you have universal beamforming on or off - I've noticed more random behaviour with devices and link speed when on so I have universal beamforming set to off.

I can't play with my network right now... sorry!

I only disable Airtime Fairness. My clients seem ok with other default settings.

I have disabled Universal Beamforming on a 68U at another site to keep a 2010 Dell Latitude E6410 laptop Intel 6300 adapter connecting at full link speed.

OE

 

[KevTech]

Only things I disable are Airtime Fairness and Roaming assistant as this is the defaults for those two setting in Merlin firmware.

Basically I match the professional setting in stock to what Merlin does.

 

[cplay]

Are there any 2.4GHz clients able to run MU-MiMo at all?

that’s the issue, the wireless log with m flag only shows you are using explicit beam forming not mu MIMO.

It means lots of studies and tests I’ve seen on here based on the m flag indicating mu MIMO is working are flawed.

I can say objectively 2.4ghz wireless backhaul connects via explicit beam forming but can’t say MIMO works or not on 2.4.

 

[RMerlin]

We can't tell for sure if the flag reports that MU-MIMO is in use, or simply that the client reports being capable of using it. Only Broadcom would know the answer to that question.

So if you disabled it and the flag still shows, it's highly likely that it simply mentions the client's capability, not its actual usage.