Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
• The addition of a Cyclic Reduncancy Check (CRC) to every fragment of packet or packet when burst is set
as unencripted.
• The Packet ACK Protocol (PAP) for sequence control and selective acknowledgement of packets
(CLPDUs).
5.2 BURST HEADER
There are two types of burst header, one with data and other one without data.
5.2.1 Burst header with data
The Burst Header is the LLC Delimiter which precedes every burst. It has the following fields:
- Preamble – 32 bits. Always set to 0xBDADC3.
- TMI – 4 bits. Tonemap ID. Tonemap used in the data encoding. TMI 0 is reserved for HURTO mapping.
- Version – 3 bits. Set to 0.
- Transmission Port – 7 bits. Local Port of the intended receiver of the Burst.
- APL – 14 bits. Aggregated Payload Length. Length of the payload in 32-bit words of the current burst,
including RS FEC redundancy. The APL will be defined by the RS FEC redundancy used and the length of
the data included in the burst.
- FEC payload – 6 bits. RS Fordward Error Correction codeword payload length in 32-bit words. The RS
FEC codeword payload allowed values are indicated in Table 2. The FEC Redundancy + FEC payload has
to be less or equal to 63 words.
- FEC Redundancy – 2 bits. RS Fordward Error Correction codeword redundancy length:
o 0: 8 redundancy bytes (2 words)
o 1: 12 redundancy bytes (3 words)
o 2: 16 redundancy bytes (4 words)
o 3: 20 redundancy bytes (5 words)
- BPS –14 bits. Bits Per Symbol for the current burst. It depends on the encoding used for the current
transmission. Possible values range from 24 to 14592. The BPS calculation (See Equation 17) includes the
RS redundancy and excludes the 4D-TCM. With the BPS and APL values nodes that are not the destination
of the burst, but that may be the destination of subsequent bursts in the same frame, may calculate the burst
duration in symbols in order to know when the next burst header or token is going to be placed.
- HURTO – 1 bit. It shall be set to 1 when the burst is transmitted in HURTO mode.
- Dummy Hdr– 1 bit. It shall be set to 1 if the burst is not carrying data symbols.
Submission page 148 UPA-OPERA