3.1 802.11 MAC Header
• Frame Control (Frame Control field)
• Duration/ID
• Address (address field)
• Sequence Control (Sequence Control field)
3.1.1 Frame Control (frame control field)
• Protocol Version: usually 0;
• Type (type field) and Subtype (subtype field): jointly indicate the type of the frame;
• To DS: indicate that the frame is a frame sent by the BSS to the DS;
• From DS : Indicates that the frame is sent by DS to BSS;
• More Frag: Indicates the long frame is fragmented, whether there are other frames;
• Retry (retransmission field): used for frame retransmission, receiving STA uses this field to eliminate retransmission frames;
• Pwr Mgt (energy management field): 1: STA is in power_save mode; 0: in active mode;
• More Data (more data field): 1: at least one more data frame is required Sent to STA;
• Protected Frame: 1: The frame body part contains the data processed by the key set; otherwise: 0;
• Order (Sequence Number field): 1: The long frame segment transmission adopts the strict numbering method; otherwise: 0.
3.1.2 Duration/ID
Indicates how long the frame and its acknowledgment frame will occupy the channel; for frames whose frame control field subtype is: Power Save-Poll, this field indicates the STA's connection identity (AID, Association Identification).
3.1.3 Address (address field)
Address (address domain): source address (SA), destination address (DA), transmitting station address (TA), receiving station address (RA), SA and DA are essential, the latter two are only useful for cross-BSS communication, The destination address can be a unicast address (Unicast address), a multicast address (Multicast address), or a broadcast address (Broadcast address).
3.1.4 Sequence Control
Sequence Control (Sequence Control Field): It consists of a 12-bit sequence number (Sequence Number) representing MSDU (MAC Server Data Unit) or MMSDU (MAC Management Server Data Unit) and a 4-bit fragment representing the number of each fragment of MSDU and MMSDU Fragment Number.
