There are 3 MPDU frame, control MPDU, data MPDU, management MPDU, in 802.11 MAC protocol. They both consists of MPDU header, MPDU body(except control MPDU) and MPDU tail(FCS). Control MPDU is rather shorter than data MPDU and management MPDU as it has no frame payload and usually it’s unicast and un-encrypted. Control MPDU is commonly consumed in hardware and not reported to host. Mangement MPDU is used to manage and maintain wireless connection. Data MPDU is used to carry transmission data in MPDU body.
MPDU header contains frame control field, duration, address1/2/3/(4), sequence control field, qos control field and htc field.
Each mpdu type contains different MPDU header length. All MPDU need check FCS at the end of receiving MPDU to avoid transmission error.