Page 1177 - 5G Basics - Core Network Aspects

Transport aspects 2

Under transient ppm offset conditions (e.g., AIS to normal signal), it is possible that Cn and Cm values
outside the range Cn,min to Cn,max and Cm,min to Cm,max may be generated and a GMP de-mapper should be
tolerant of such occurrences. Refer to Annex D for a general description of the GMP principles.
17.7.1 Mapping a sub-1.238 Gbit/s CBR client signal into OPU0

Table 17-4 specifies the clients defined by this Recommendation and their GMP mn and CnD parameter
values. Table 17-5 specifies the replacement signals for those clients.
The support for 1-bit timing information (C1) is client dependent. Clients for which the 8-bit timing
information in Cm with m=8 is sufficient will not deploy the ability to transport C1D and the JC4/5/6 value
will be fixed to all-0s.

The OPU0 payload for this mapping consists of 4  3808 bytes. The bytes in the OPU0 payload area are
numbered from 1 to 15232. The OPU0 payload byte numbering for GMP 1-byte (8-bit) blocks is illustrated
in Figure 17-11. In row 1 of the OPU0 frame the first byte will be labelled 1, the next byte will be labelled 2,
etc.
Groups of eight successive bits (not necessary being a byte) of the client signal are mapped into a byte of
the OPU0 payload area under control of the GMP data/stuff control mechanism. Each byte in the OPU0
payload area may either carry 8 client bits, or carry 8 stuff bits. The stuff bits are set to zero.

Figure 17-11  OPU0 frame structure for the mapping of a sub-1.238 Gbit/s client signal

Table 17-4 – m, n and CnD for sub-1.238G clients into OPU0

Nominal Bit rate
Client signal bit rate tolerance m n C nD
(kbit/s) (ppm)
Transcoded 1000BASE-X 15/16  100 8 8 No
(see clause 17.7.1.1) 1 250 000
STM-1 155 520 20 8 1 Yes
STM-4 622 080 20 8 1 Yes
FC-100 1 062 500 100 8 8 No
SBCON/ESCON 200 000 200 8 8 No
DVB-ASI 270 000 100 8 8 No
SDI 270 000 2.8 8 TBD TBD

1167