Page 1242 - 5G Basics - Core Network Aspects

2 Transport aspects

Figure 20-8 – OPUCn 5G TS MSI coding – Payload type 22

1 2 3 4 5 6 7 8 5G TS
PSI[A.2 ]B Availability MSB
Tributary ort #p TS #A.B
PSI[A.2B+1 ] Occupation LSB

0 : Unavailable 00 0000 0000 0000 : Tributary port #1
1 : Available 00 0000 0000 0001 : Tributary port #2
00 0000 0000 0010 : Tributary port #3
0 : Unallocated 00 0000 0000 0011 : Tributary port #4
1 : Allocated
xx xxxx xxxx xxxx : Tributary port #10n
G.709-Y.1331(16)_F20-9
NOTE – A = 1... , = 1...20n B

Figure 20-9 – OPUCn MSI coding – Payload type 22

20.4.2 OPUCn payload structure identifier reserved overhead (RES)
216*n-1 (OPUCn) bytes are reserved in the OPUCn PSI for future international standardization. These bytes
are located in PSI[x.1] and PSI[x.42] to PSI[x.255] of the OPUCn overhead where x = 1…n and PSI[x.0], x=2
to n. These bytes are set to all-0s.

20.4.3 OPUCn multiplex justification overhead (JOH)

The generic mapping procedure (GMP) is used for the mapping of an ODUk into ODTUCn.ts. GMP uses
ODUk and OPUCn independent stuff and justification opportunity definitions (ODTUCn.ts). Stuff locations
within an ODTUCn.ts are determined by means of a formula which is specified in clause 20.4.3.1.

20.4.3.1 Generic mapping procedure (GMP)
The justification overhead (JOH) for the generic mapping procedure consists of two groups of three bytes of
justification control; JC1, JC2, JC3 and JC4, JC5, JC6. Refer to Figure 20-7.
The bits 3 to 8 of the JC1, JC2 and JC3 bytes consist of a 10-bit Cm field (bits C1, C2, .., C10), a 1-bit
increment indicator (II) field, a 1-bit decrement indicator (DI) field and a 6-bit CRC-6 field which contains an
error check code over the JC1, JC2 and JC3 bits 3 to 8 fields.
The bits 1 and 2 of the JC1, JC2, JC3 bytes and bits 2 to 8 of the JC4, JC5 and JC6 bytes consist of a 18-bit
CnD field (bits D1, D2, .., D18), a 9-bit CRC-9 field which contains an error check code over bits 2 to 8 in the

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