ExposedTerminal

From Cmcl

9.11 No Acknowledgment (No Ack) The usage of No Ack is determined by the policy at the QoS STA. When No Ack policy is used, there is no MAC-level recovery, and the reliability of this traffic is reduced, relative to the reliability of traffic with other acknowledgment policies, due to the increased probability of lost frames from interference, collisions, or timevarying channel parameters. A protective mechanism (such as transmitting using HCCA, RTS/CTS, or the mechanism described in 9.13) should be used to reduce the probability of other STAs transmitting during the TXOP

Bits in QoS Control field Meaning Bit 5 Bit 6 0 0 Normal Ack.

1 0 No Ack

0 1 No explicit acknowledgment.

1 1 Block Ack

jigsaw

To DS From DS Address 1 Address 2 Address 3 Address 4
 0      0      DA        SA       BSSID      N/A
 0      1      DA       BSSID      SA        N/A
 1      0     BSSID      SA        DA        N/A
 1      1      RA        TA        DA        SA