Variable 16/32 1 2 1 Preamble Start of frame Mode Reserved FCS delimiter (SFD) switch type Synchronization PHY header (PHR) header (SHR) (a) Normal PPDU format of MR-FSK PHY Variable 1 11 Variable Preamble Data Frame PHY whitening length payload Synchronization PSDU
header (SHR) Variable 16/32 1 2 Preamble Start of frame Mode Mode switch delimiter (SFD) switch parameter entry Synchronization PHY header (PHR) header (SHR) Variable 1 7 4 1 Preamble New mode New Checksum Parity FEC mode check Synchronization header (SHR) (b) Mode switch PPDU format of MR-FSK PHY Figure 3: General MAC frame format of IEEE 802.15.4e.
The confirm SFD block acquires the PSDU length and notifies the MAC layer of the PSDU obtained from the receiver.
Octets 1 variable Frame length Reserved Preamble SFD (7 bits) (1 bit) PSDU SHR PHR PHY payload
Each octet of PPDU is processed through the bit-to-symbol block sequentially, beginning with the Preamble field and ending with the last octet of the PSDU
The different MCSs and spreading factor determine different data rates of the PSDU
Remarks: It is specified in IEEE 802.15.4 that the Frame Length field in a PHY header (PHR) is 7 bits and specifies the total number of bytes in the PHY service data unit (PSDU
) (i.e., PHY payload), up to aMaxPHYPacketSize.
The Physical Service Data Unit (PSDU
) field contains a payload of 0 to 127 bytes length.
4 shows the frame format which consists of the OFDM Physical Layer Convergence Protocol (PLCP) preamble, PLCP header, PLCP Service Data Unit (PSDU
), tail bits, and pad bits.