Hello,
I have an ASUS TUF AX6000 with OpenWRT installed and would like to perform some tests with OFDMA. From what I can gather it seems like UL OFDMA is not supported (https://github.com/openwrt/mt76/issues/870), but I don't see anything regarding DL OFDMA being disabled. Are there some settings I could tweak to increase my chances of seeing DL OFDMA (or even UL OFDMA if possible) on this router?
Thank you!
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Enable muru_debug and observe muru_stats (or something similar). It will show you how often OFDMA is used. You might need to start concurrent downloads on many AX devices supporting OFDMA to see any usage.
That's useful to know, thank you!
I set /sys/kernel/debug/ieee80211/phy1/mt76/muru_debug to 1 and observed /sys/kernel/debug/ieee80211/phy1/mt76/muru_stats. It seems like with only two devices running iperf DL OFDMA does not occur, instead preferring MU-MIMO. With three devices I did however see a decent amount of DL OFDMA PDDUs.
I unfortunately only have three AX devices right now (I am using one to capture the packets). Is there a way I could disable MU-MIMO or make it less likely?
You have to overfill 5MHz sub-band (something like super-suppressing nearby 20MHz non-stop transfer both ways can flip it)
You could try to disable AX beamforming capabilities in hostapd-$if.conf, but I'm not sure if that would disable MU-MIMO. Reference: https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf
You could hack the driver to disable it. For sure MU-MIMO upload is disabled for some (all?) chipsets, so probably download can be as well.
In my case it helps when I put the devices next to each other and next to the AP. I think OFDMA is preferred with high SNR, but still MU-MIMO happens.