The concept of block acknowledgment is defined in IEEE 802.11e and was introduced in HT (802.11N).
When a unicast frame is transmitted wirelessly, it necessitates acknowledgments.
Failure to receive an acknowledgment prompts the retransmission of the same frame with the retry bit enabled.
Frames with CRC errors may be disregarded.
The implementation of block acknowledgment allows a single acknowledgment to cover a block of MPDUs, enabling multiple MPDUs to be acknowledged with a single block acknowledgment frame.
This frame comprises a 64*16-bit bitmap.
The 16 bits denote the fragment numbers of the MPDUs to be acknowledged, with each bit representing the success or failure of the corresponding MPDU.
This method enhances efficiency by consolidating multiple MPDU acknowledgments into a single acknowledgment.
Flow:
Add block ack request {ADDBA request} is sent to AP which AP will ack first then send the response with ADDBA response which is acked by the client followed by data transfer.
Once the data transfer is over, the connection will be torn down.
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