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DSSS data frame

Like the FHSSdata frame, Frequency Hopping Stread Spectrum ( FHSS), the DSSS data frame consists of a preamble, the header and the payload.

The preamble of the Physical Layer Convergence Protocol( PLCP) consists of a 128-bitdata field for synchronization, which is used for synchronized power control, signal detection and frequency adjustment, and the 16-bit data field for the start frame delimiter( SFD). The subsequent PLCP header has a 1 byte long signal field, which is used for the payloaddata rate and can be marked for 1 Mbit/s two phase shift keying(BPSK) or 2 Mbit/s quadrature phase shift ke ying( QPSK), followed by a 1 byte long service field for the service identifier.

The length field for the payload data and the cyclic block check(CRC) data field, which includes the signal, service, and length data fields, complete the header, which is followed by the variable data field for the payload.

Structure of the DSSS data frame

Structure of the DSSS data frame

The preamble and header are always transmitted at a data rate of 1 Mbit/s, regardless of the data rate of the payload data.

The DSSS data frame is transmitted by the station willing to transmit only after the SIFS waiting period. After the receiver has confirmed receipt with an acknowledgement( ACK), other stations can also use the medium.

Informations:
Englisch: DSSS data frame
Updated at: 03.01.2011
#Words: 211
Links: frame, frequency hopping spread spectrum (modulation) (FHSS), direct sequence spread spectrum (WLAN) (DSSS), data frame, header (HDR)
Translations: DE
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