Page 1200 - 5G Basics - Core Network Aspects

2 Transport aspects

Table 19-2 – OPU3 tributary slot OH allocation

MFAS bits TSOH 2.5G MFAS bits TSOH MFAS bits TSOH

5 6 7 8 TS 4 5 6 7 8 1.25G TS 4 5 6 7 8 1.25G TS
0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 17
0 0 0 1 2 0 0 0 0 1 2 1 0 0 0 1 18
0 0 1 0 3 0 0 0 1 0 3 1 0 0 1 0 19
0 0 1 1 4 0 0 0 1 1 4 1 0 0 1 1 20
0 1 0 0 5 0 0 1 0 0 5 1 0 1 0 0 21
0 1 0 1 6 0 0 1 0 1 6 1 0 1 0 1 22
0 1 1 0 7 0 0 1 1 0 7 1 0 1 1 0 23

0 1 1 1 8 0 0 1 1 1 8 1 0 1 1 1 24
1 0 0 0 9 0 1 0 0 0 9 1 1 0 0 0 25
1 0 0 1 10 0 1 0 0 1 10 1 1 0 0 1 26
1 0 1 0 11 0 1 0 1 0 11 1 1 0 1 0 27
1 0 1 1 12 0 1 0 1 1 12 1 1 0 1 1 28
1 1 0 0 13 0 1 1 0 0 13 1 1 1 0 0 29
1 1 0 1 14 0 1 1 0 1 14 1 1 1 0 1 30
1 1 1 0 15 0 1 1 1 0 15 1 1 1 1 0 31
1 1 1 1 16 0 1 1 1 1 16 1 1 1 1 1 32

19.1.3 OPU1 tributary slot allocation
Figure 19-3 presents the OPU1 1.25G tributary slot allocation. An OPU1 is divided into two 1.25G tributary
slots numbered 1 to 2.
– An OPU1 1.25G tributary slot occupies 50% of the OPU1 payload area. It is a structure with 1904
columns by 8 (2  4) rows (see Figure 19-3) plus a tributary slot overhead (TSOH). The two OPU1
1.25G TSs are byte interleaved in the OPU1 payload area and the two OPU1 TSOHs are frame
interleaved in the OPU1 overhead area.
The tributary slot overhead (TSOH) of OPU1 tributary slots is located in column 16 plus column 15, rows 1,
2 and 3 of the OPU1 frame.
The TSOH for a 1.25G tributary slot is available once every 2 frames. A 2-frame multiframe structure is used
for this assignment. This multiframe structure is locked to bit 8 of the MFAS byte as shown in Table 19-3
and Figure 19-3.

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