start frame delimiter (SFD)
The Start Frame Delimiter (SFD) is a data field in the header of a transmission frame.
The SFD data field follows the data field of the preamble and consists of a fixed bit sequence that serves as a start pattern and marks the beginning of the frame. To the receiver, the SFD data field serves as an indication of the beginning of the frame.
InEthernet frames according to IEEE 802.3, the Start Frame Delimiter is one octet long and has the bit combination 10101011. In WLANs according to 802. 11, the bit combination is 0000110010111101. In other protocols, the Start of Frame (SoF) data field takes the place of the Start Frame Delimiter.