Re: Is the data rate estimation for 5GHz channels overly pessimistic?

[Denis Kenzior <denkenz@gmail.com>]

Hi Simonas,

On 10/14/23 12:45, Simonas Kazlauskas wrote:
> Denis Kenzior wrote:
>> Hi James,
>>
>>>>
>>>>      RSSI                  -78 dBm
>>>>      AverageRSSI           -79 dBm
>>>>      RxMode                802.11ax
>>>>      RxMCS                 8
>>>>      TxMode                802.11ax
>>>>      TxMCS                 4
>>>>      TxBitrate             206400 Kbit/s
>>>>      RxBitrate             206500 Kbit/s
>>>
>>> This is probably because IWD doesn't take into account any of the newer 
>>> 802.11ax IEs when estimating the data rate. So its estimation is based on VHT 
>>> and not the newest EHT rates.
>>
>> We should support HE rates just fine.  Just look at the unit tests in 
>> test-band.c.  Probably need an iwmon log of the AP IEs and local capabilities 
>> to see why the estimate is lower than what happens in practice.
>>
>> What hardware is being used here?
> 
> Intel’s AX201 on the client side and Ubiquiti’s U6-Pro are the AP(s).
> 
> Thank you for pointing me at iwmon, I’ll fiddle with it :)

It may be we screwed something up with HE since hardware was still pretty rare 
when the feature was developed.  But we do treat RSSI values below -82 as almost 
unusable.  Perhaps this needs to be tweaked for newer hardware.

If you want to get your hands dirty, it should be fairly easy to modify 
unit/test-band.c to test what our estimate code does with your specific 
circumstances.

The local HE capabilities can be found via 'iw phy', looking at what iwd prints 
at start, or using iwmon.  Similarly, remote capabilities can be sniffed using 
iwmon and running an iwd scan or 'iw scan trigger'.

Me or James can walk you through all this if needed.

Regards,
-Denis