MAC HSDPA PDU (MAC-hs)

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There are two different types of MAC HSDPA PDU format depending upon the upper layer configuration.

  • MAC-hs
  • MAC-ehs

In this tutorial only MAC-hs is covered.

MAC-hs

In this case the MAC HSDPA PDU is consists of

  • MAC-hs header
  • One or more MAC-hs SDU

NOTE: A maximum of one HSDPA PDU is transmitted in on TTIMAC-hs PDU Format

Header Elements

  • VF (Version Flag): 1 bit

VF field is there to provide extension capabilities.
This should be set to zero for now

  • Queue ID (Queue Identifier): 3 bits

    • The Queue ID field provides identification of the reordering queue in the receiver.

  • TSN (Transmission Sequence Number): 6 bits or 9 bits

    • The TSN field provides an identifier for the transmission sequence number on the HS-DSCH. The TSN field is used for reordering purposes to support in-sequence delivery to higher layers.
    NOTE: Only for TDD 1.28 Mcps configuration TSN can have a value of 6 bits of 9 bits otherwise it is always 6 bits

  • SID (Size Index Identifier): 3 bits

    • The SID field identifies the size of a set of consecutive MAC-d PDUs. The MAC-d PDU size for a given SID is configured by higher layers and is independent for each Queue ID.

  • N (Number of MAC PDU): 7 bits

    • The number of consecutive MAC-d PDUs with equal size is identified with the N field.
    NOTE
    FDD mode, the maximum number of PDUs transmitted in a single TTI shall be assumed to be 70.
    1.28 Mcps TDD mode, the maximum number of PDUs transmitted in a single TTI shall be assumed to be 45.
    3.84 Mcps TDD mode, the maximum number of PDUs transmitted in a single TTI shall be assumed to be 318
    7.68 Mcps TDD mode, the maximum number of PDUs transmitted in a single TTI shall be assumed to be 636.

  • F (Flag): 1bit

    • The F field is a flag indicating if more fields are present in the MAC-hs header or not.

    • If the F field is set to “0” the F field is followed by an additional set of SID, N and F fields.
    • If the F field is set to “1” the F field is followed by a MAC-d PDU.

    NOTE: The maximum number of MAC-hs header extensions, i.e. number of fields F set to “0”, in a single TTI shall be assumed to be 7.

    Example in decoding

    MAC-hs PDU

    0a 00 18 10 41 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03

    In Bits

    0000 101000 000 0000001 1 000 – – –

    MAC-hs Header

    • VF: 0
    • Queue ID: 000
    • TSN: 000110
    • SID: 000
    • N: 0000001
    • F: 1

    Reference

    Medium Access Control (MAC) protocol specification:
    http://www.3gpp.org/ftp/Specs/archive/25_series/25.321/

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