PSDU and PPDU Formats
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PSDU and PPDU Formats

• PLCP Service Data Unit
  • The PLCP Service Data Unit (PSDU) is a view of the MPDU from the
  • Physical layer.
  • The MAC layer refers to the frame as the MPDU, while the Physical layer refers to this same frame as the PSDU.
  • The only difference is from which layer of the OSI model you are looking at the
  • frame.
• PLCP Protocol Data Unit
  • When the PLCP receives the PSDU, it then prepares the PSDU to be
  • transmitted and creates the PLCP Protocol Data Unit (PPDU).
  • The PLCP adds a preamble and PHY header to the PSDU.
  • The preamble is used for synchronization between transmitting and receiving 802.11 radios.
  • When the PPDU is created, the PMD sublayer takes the PPDU and modulates
  • the data bits and begins transmitting.

Figuree 18.13 802.11n PPDU formats

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Reference:
Coleman, David D.,Westcott, David A. CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-106 Wiley.