The interested reader can refer the first part of the series here — <802.11ac PLCP Frame Format – Part 1>
VHT Signal Fields – VHT-SIG A
The VHT-SIGA field provides information on the different parameters of the frame at the receiver to configure itself to decode the received 802.11ac frame. The VHT-SIGA field is provided below for reference
FIG Courtesy – 802.11 standard
The description of the different parameters for VHT-SIGA fields are provided below
FIG Courtesy – 802.11 standard