MCS setting to MCIMX8QM-CPU (88Q9098)

[Shigehiro]

Suppose you enter the following command to AP and STA.

<AP>
./uaputl.exe txratecfg AA BB CC

<STA>
./mlanutl mlan0 txratecfg AA BB CC

MCS can be specified by the parameter "BB (number)".

After communicating to some extent, if you enter the following command to STA and check the MCS, it may differ from the specified value.

<MCS confirmation command>
iw mlan0 station dump

<MCS confirmation result>
tx bitrate: 13.0 MBit / s VHT-MCS 1 VHT-NSS 1
rx bitrate: 13.5 MBit / s VHT-MCS 0 40MHz VHT-NSS 1

If the bandwidth is 20MHz, it looks fixed.
If the bandwidth is 40MHz, the MCS value on the tx side may differ from the set value.

Isn't it possible to completely fix MCS?

[Alexis_A]

Hello @Shigehiro,

I have some questions about this:

Do you have enabled the re-association feature?

Is there any disconnection at some point when doing the tests?

BR,

Alexis Andalon

[Shigehiro]

Hello Alexis.

Thank you for your comment.

Is it something to set in "hostapd.conf"?

If so, it has not been set.

If there is a method or setting to try, please tell me concretely.

Best regards,

Shigehiro

[Alexis_A]

Hello @Shigehiro,

In this case I would suggest to check the following settings:

In the AP side (uaputl):

Ensure the 20/40 coexistance is enabled. Check sys_cfg_2040_coex command.

Check the 20/40 MHz band is enabled . Check the httxcfg and sys_cfg_11n commands.

In the STA side:

Check the 20/40 MHz band is enabled . Check the httxcfg and htcapinfo.

Look if the 40 MHz Intolerant bit is not enabled using the htcapinfo command.

BR,

Alexis Andalon

[Shigehiro]

Hello Alexis.

Thank you for your comment.

The result of the confirmation is as shown in the attached file (Confirmation result.txt).

Disclose the "hostapd.conf" you are using.

The following command is input to AP / STA.
(When specifying MCS0 at Band 40MHz)

<AP>
./mlanutl uap0 vhtcfg 2 3 0 0x33d179b0 0xffff 0xfffe

./uaputl.exe txratecfg 2 0 1

<STA>
./mlanutl mlan0 txratecfg 2 0 1

If there are any mistakes, it would be helpful if you could point them out.

Best regards,

Shigehiro

[Alexis_A]

Hello @Shigehiro,

From the configuration file shared there doesn't seem to be anything wrong. I'm trying to reproduce this issue but would be helpful if you could sent the log of your configuration process and where the MCS change and some sniffing captures of this.

Also, which kernel version are you using? If its an old one I would suggest to try with the newest one (If-5.15.5-1.0.0) and see if the issue is still present.

BR,

Alexis Andalon

[Shigehiro]

Hello Alexis.

Thank you for your comment.

I got the console output from AP and STA startup-connection-MCS setting-Ping confirmation.
The OS and kernel versions are as follows, but it is difficult to change them right away.

 root@imx8qmmek:/lib/firmware/nxp# cat /etc/issue
 NXP i.MX Release Distro 5.4-zeus \n \l
 root@imx8qmmek:/lib/firmware/nxp#
 root@imx8qmmek:/lib/firmware/nxp# uname -r
 5.4.70-2.3.0+g4f2631b022d8

Isn't the problem that MCS cannot be fixed in 11ac solved without using the latest kernel?

Best regards,

Shigehiro

[Alexis_A]

Hello @Shigehiro,

Seems this could be the reason, looks like the support for the 2.4GHz/40MHz band was included in the 5.10.72_2.2.0 but if you need to update the driver I would suggest to try with the latest one.

BR,

Alexis Andalon

[Shigehiro]

Hello Alexis.

Thank you for your response.

Due to business reasons, it is not possible to update the kernel immediately.
If I have a chance to update the kernel in the future, I will try it.

Best regards,

Shigehiro