Environment- This article applies to Aruba OS 6.3 and above.
Answer- The temporal diversity feature of the Aruba WLAN system introduces a variable delay between retransmissions which helps to mitigate the effects of transient noises and increase the overall performance of the network by using the delays between retransmissions to transmit frames destined to other clients.
Temporal diversity (or software retries) is a Qualcomm Atheros QCA-based AP feature that the AP CPU can requeue a pkt if that had been sent without ACK/BlockAck by the client. Hardware retries is the basic radio chipset handled retrying mechanism.
All 11ac AP which is Broadcom-based does not have this support, so the knob is basically no effect on them.