A-MPDU transmission in net80211 on FreeBSD 8

[Alexander Egorenkov]

Hi,

i'm implementing a device driver for a 802.11n NIC under FreeBSD 8
und experimented with A-MPDU transmission. I looked into net80211 code
and there is some code which implements this feature but it worked not very
well for me.
I noticed e.g. that sequence numbers are not assigned to A-MPDU frames
and found this comment in file ieee80211_output.c :


/*
         * Check if A-MPDU tx aggregation is setup or if we
         * should try to enable it.  The sta must be associated
         * with HT and A-MPDU enabled for use.  When the policy
         * routine decides we should enable A-MPDU we issue an
         * ADDBA request and wait for a reply.  The frame being
         * encapsulated will go out w/o using A-MPDU, or possibly
         * it might be collected by the driver and held/retransmit.
         * The default ic_ampdu_enable routine handles staggering
         * ADDBA requests in case the receiver NAK's us or we are
         * otherwise unable to establish a BA stream.
 */

Can somebody elaborate this description to me please.

Thanks.

ALex.