Back in the day I was messing around with MadWifi and, if I remember properly, after a packet was transmitted if the sender did not receive an ACK in SIFS time after the completion of the transmission, the sender would attempt a retransmission using the same or lower rate (multi rate retransmissions) without going into the backoff/contention phase.

I spent some time going through the 802.11-2012 protocol trying to find relevant information without any luck. Is anyone familiar with that concept? Does this happen in newer drivers like ath5k and ath9k? Is this what the protocol implies?

Any pointers/suggestions are greatly appreciated.



So, madwifi/freebsd had a TXOP burst mode where even best-effort traffic had a TXOP burst if it wasn't otherwise busy. So, it could do a retry without DIFS+CW, like any other 802.11 burst inside a TXOP.

ath9k doesn't do that by default, but freebsd still does. It's easy to do; mac80211 just needs to grow the "aggressive mode" burst things so the best effort queue gets a TXOP window if nothing else is active.




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