FHSS frame
The frequency hopping data frame( FHSS) consists of the Physical Layer Convergence Protocol( PLCP) preamble, the actual PLCP header and the user data.
The preamble is used for signal detection and comprises 80 bits, followed by the 16-bit Start Frame Delimiter( SFD) data field for synchronization. The header starts with the 12 bit long PLCP Packet Header (PLW) in which the length of the data packet is entered, followed by the 4 bit long PLCP- PDU Signalling Field (PSF) data field for the identification of the transmission speeds.
The header is completed by the 16-bit data field for the cyclic block check(CRC). The length of the user data field, the payload, is variable.