One can refer the first part of this blog here — <802.11g PLCP Frame Formats – Part 1>
ERP-OFDM format
The ERP-OFDM format is similar to the 802.11a OFDM PPDU format. The only change is that a signal extension field is added to the OFDM format of 802.11a as is done for all other 802.11g PPDU formats. Hence, the PHY RX_END indication is provided 6 microseconds after the end of the last symbol of the received frame.
The OFDM Frame format is shown below
FIG Courtesy: 802.11 standard
NOTE: in addition to the above – a signal extension field is present for ERP-OFDM frame format at the end of the frame
The Signal/Length/Service fields are the same as 802.11a OFDM Frame format and shall be discussed in the next article