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Hi All,

how many times will a STA try to send a frame before discarding it? Obviously if it does not receive an ACK after a certain number of attempts the frame must be dropped. Is this actually defined by the standard and can it be changed within an AP (I don't remember seeing an option on an AP for this).

Dave

From IEEE doc.: IEEE 802.11-07/0636r2

In clause 9.2.5.3 "Recovery procedures and retransmission limits":

?¡é?€?¡é "STAs shall maintain a SRC and a LRC for each MSDU, A-MSDU or MMPDU awaiting transmission."

?¡é?€?¡é "If the RTS transmission fails, the SRC for the MSDU, A-MSDU or MMPDU and the SSRC are incremented. This process shall continue until the number of attempts to transmit that MSDU, A-MSDU or MMPDU reaches dot11ShortRetryLimit."

?¡é?€?¡é "The SRC for an MPDU of type Data or MMPDU and the SSRC shall be incremented every time transmission of a MAC frame of length less than or equal to dot11RTSThreshold fails for that MPDU of type Data or MMPDU. This SRC and the SSRC shall be reset when a MAC frame of length less than or equal to dot11RTSThreshold succeeds for that MPDU of type Data or MMPDU."

?¡é?€?¡é "Retries for failed transmission attempts shall continue until the SRC for the MPDU of type Data or MMPDU is equal to dot11ShortRetryLimit or until the LRC for the MPDU of type Data or MMPDU is equal to dot11LongRetryLimit. When either of these limits is reached, retry attempts shall cease, and the MPDU of type Data (and any MSDU or A-MSDU of which it is a part) or MMPDU shall be discarded."

I dunno what the retry values are, without checking I have a feeling it's 4 for short retry and 7 for long retry.

That's great thanks.

Dave