To understand the Block ACK Request frame – kindly refer here — <Block ACK Request Frame>.

Block Ack Frame

The Block Ack frame is shown below

• The Duration ID is set to the time required to transmit one ACK frame + a SIFS duration
• The RA field incorporates the address of the recipient station which request the block Ack
• The TA field incorporates the address of the Station transmitting the Block Ack frame
• The Block Ack control is similar to the the Block Ack Request Control field and is shown below

• The Block Ack Policy sub-field, the Multi-TID/compressed Bitmap encoding and the TID_INFO field are similar to the BAR control field and are provided below for reference

• The compressed bitmap and multi-TID encoding is provided below

• The TID_INFO contains the TID for which the Block ack was requested. The BA information field contains the starting sequence number of the block ack and the block ack bitmap. It is shown below

Note: If Compressed bitmap is selected – the Block Ack Bitmap is of 8 octets (bytes)

• In the case of the block ack session supporting Multi-TID aggregation – the Block Ack information field is as shown below

Regulatory requirements in 802.11