MU-MIMO won't disable on AC86U

[cplay]

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.

It's neither based on testing.

If i disable mu-mimo both 2.4 and 5ghz backhaul still show the M flag.

However, if I disable explicit beamforming on both bands as well as leaving MIMO disabled then M flag disappears.

M flag is tied to explicit beamforming not mu mimo which means lots of studies people have done on this forum based on that M flag are put into question.

 

[doczenith1]

@cplay I did some MU-MIMO testing a while back that may be of interest to you. My initial test found no increase in throughput when using MU-MIMO. My second round of testing found the opposite (post #45). Seems like it's hit or miss depending on your particular environment.

https://www.snbforums.com/threads/is-anyone-using-mu-mimo.40553/

 

[RMerlin]

It's neither based on testing.

If i disable mu-mimo both 2.4 and 5ghz backhaul still show the M flag.

However, if I disable explicit beamforming on both bands as well as leaving MIMO disabled then M flag disappears.

M flag is tied to explicit beamforming not mu mimo which means lots of studies people have done on this forum based on that M flag are put into question.

Concretely, what this flag indicates (according to Broadcom's SDK) is whether a STA is a MU_BEAMFORMER or a MU_BEAMFORMEE. In either cases, the M flag will be shown on the webui.

This is separate from the capability of being a SU_BEAMFORMER or an SU_BEAMFORMEE.

 

[Grisu]

very interesting article about beamforming: https://www.arubanetworks.com/pdf/technology/whitepapers/wp_Designed_Speed_802.11n.pdf
BTW beamformee is the client.

 

[cplay]

Concretely, what this flag indicates (according to Broadcom's SDK) is whether a STA is a MU_BEAMFORMER or a MU_BEAMFORMEE. In either cases, the M flag will be shown on the webui.

This is separate from the capability of being a SU_BEAMFORMER or an SU_BEAMFORMEE.

Understood

@cplay I did some MU-MIMO testing a while back that may be of interest to you. My initial test found no increase in throughput when using MU-MIMO. My second round of testing found the opposite (post #45). Seems like it's hit or miss depending on your particular environment.

https://www.snbforums.com/threads/is-anyone-using-mu-mimo.40553/

That's explicitly what I was questioning.

I read your very interesting studies but you denoted MU-MIMO support based on the M flag:

"On the System Log>Wireless Log page both of my phones show an "M" flag and per the legend M=MU Beamforming."

However, from my testing when MIMO is disabled devices still show M flag. M flag ONLY disappears when you turn explicit beamforming off.

Therefore, M flag is not related to MIMO but instead Explicit beamforming.

That was what I was so suprised about.

 

[cplay]

very interesting article about Beamforming: https://www.arubanetworks.com/pdf/technology/whitepapers/wp_Designed_Speed_802.11n.pdf
BTW beamformee is the client.

Informative.

 

[cplay]

Concretely, what this flag indicates (according to Broadcom's SDK) is whether a STA is a MU_BEAMFORMER or a MU_BEAMFORMEE. In either cases, the M flag will be shown on the webui.

This is separate from the capability of being a SU_BEAMFORMER or an SU_BEAMFORMEE.

It's the MU_Beamformer that is confusing.

The M flag stays between both wireless backhauls with MIMO disabled - The M flag ONLY disappears if you disable explicit beamforming on both bands.