It’s the minimum time between the start of adjacent MPDUs within an A-MPDU.
The following shows the MPDU start spacing between two adjacent A-MPDU subframes.
When the spacing is shorter than the Minimum MPDU Start Spacing, one or more MPDU delimiters will be added as padding to extend the spacing. The following example shows padding with one MPDU delimiter. As a result, the length of the A-MPDU is extended by 4 octets.
