Reason for DELBA with initiator = recipient

Rolf Schmidt

Hi,

I have noticed that Android device using WiLink chipset is terminating once and then Block Ack Session for downlink data stream (AP -> WiLink8 device) by transmitting a DELBA with initiator = recipient. What could be the reason that WiLink8 is terminating reception of aggregated frames? Could it be that re-ordering buffer has run full? Would that be a hint that something is not running smoothly on host side of the Android device using WiLink8 Note: Android device has told in ADDBA Response to AP that buffer size is 32 (see packet 13264 of attached airtrace)

Btw, why is transmitting WL8 DELBA a second time (see below) although first DELBA has been alreadyWL18 acked by AP?

Capture 2-2017-01-13T11.33.52.154_DELBA_Issue.zip

over 7 years ago

0 Rolf Schmidt over 7 years ago

Intellectual 310 points

Hi,
I would like to add one more observation: first time Android device (WL8) is responding to ADDBA request of AP with buffer size of 32. After the DELBA the Android device is then responding to subsequent ADDBA request of AP with buffer size of 8, i.e. AP is then only aggregating max 8 packets of size 1538 byte.

0 Rolf Schmidt over 7 years ago in reply to Rolf Schmidt

Intellectual 310 points

Hi,
one more interesting fact: in config file ht.rx_ba_win_size = 0x20 (=32) is set. Why is later on reduced)

0 Rolf Schmidt over 7 years ago in reply to Rolf Schmidt

Intellectual 310 points

Hi,
when Android (WL8) device is connecting to AP it's saying in the HT Capability Info of the Assoc Req that maximum Rx A-MPDU size is 16383 Byte. AP is transmitting in our case all MPDUs with size 1538 Byte. This means that WL8 can receive only 10 Packets of size 1538 Byte in one A-MPDU which is 15380 Byte. The AP however is aggregating up to 12 packets of size 1538 Byte (see packet 13473 ff in attached airtrace). Could this be the reason why WL8 is deleting BlkAck session and reducing BlockAck buffer size to 8?

0 Vihang Parmar over 7 years ago in reply to Rolf Schmidt

TI__Mastermind 29250 points

Hi Rolf,

Your query has been assigned to a relevant expert. We will get back to you soon.

Best regards,
Vihang

0 S over 7 years ago in reply to Vihang Parmar

TI__Mastermind 35795 points

Hi , Yes, WiLink8 will send DELBA in case it receives A-MPDU greater than 16k. It will also reduce buffer size to 8 when it sees a violation .
Saurabh

Wi-Fi

Wi-Fi forum

Reason for DELBA with initiator = recipient