[OpenWrt-Devel] ath9k: fix dynack in IBSS mode

Koen Vandeputte koen.vandeputte at ncentric.com
Fri Aug 16 05:48:49 EDT 2019

>> Hi Joe,
>>> Lorenzo,  I deployed an ath9k auto distance solution in April that is
>>> working for the AREDN community http://www.arednmesh.org .
>>> https://github.com/aredn/aredn_ar71xx/blob/develop/patches/712-auto-distance-settings.patch
>>> Summary of solution:
>>> * no dependency on wpa_supplicant
>>> * initial ack_to is set to max,  to not enter late ack conditions
>>> * User level trigger to flip distance setting to static and back to
>>> auto when new 802.11 adhoc neighbor joins. (we archive and chart SNR
>>> values for neighbors and natural to hook in this trigger).
>> Have you initialized the ackto to the max value to remove wpa_supplicant
>> dependency or because the system is not able to trigger the 'late ack'?
>> I did not get why you need to flip the algo off/on when new 802.11 adhoc
>> neighbor joins
>> Regards,
>> Lorenzo
> initialized the ackto to max:
> A) avoidance of late-ack state
> B) not require wpa_supplicant  -- not in use by our community today
> C) Suspect some conditions, e.g. low SNR Neighbors, do not trigger
> "late ack" (consistent, with observation of low SNR Neighbors sticking
> at max ack_to with my changes )
> flip the algo off/on when new neighbor joins:
> Intended technique to reset ack_to to max.  If ack_to is set to 20km
> and then a new adhoc neighbor joins at 30km, this would be a late ack
> state, and unable to detect.    My early testing results showed the
> algo off/on would restart the ack_to to max and start the process over
> with the new neighbor.   I trust I got it right?
> There are 10s to 100s of users testing this bleeding edge change from
> nightly builds, and so far, I've not found a failure case.
> Although, the findings are showing the cases where static setting has
> better throughput.
> Joe AE6XE



It's been a while regarding the above.

I can confirm the issue that if the algorithm misses the late ack's due 
to low initial snr, the initial ack_to is too low to recover afterwards.

Do you think it would be useful to start at high ack_to and let it 
estimate/drop afterwards?


I've got my 24km link back if required to do some additional testing.



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