Page 725 - 5G Basics - Core Network Aspects

Transport aspects 2

The valid DTU frame types are presented in Table 8-10. The DTU frame type is indicated by the first four
least significant bits of the DTU frame header. The length of the DTU frame header and maximum length of
the DTU frame payload depends on the DTU frame type. For all DTU frame types except idle DTU frame, the
length of the DTU frame header is extended to indicate longer DTU frame payloads.
The format of the DTU frame header is presented in Table 8-9 and Figure 8-7.

Table 8-9 – Format of the DTU frame header

Header byte number Format (Note 1)
1 (Note 2) [l3 l2 l1 l0 t3 t2 t1 t0]
2 (Note 2) [l11 l10 l9 l8 l7 l6 l5 l4]
NOTE 1 – The LSB of each byte is represented at the right side.
NOTE 2 – For an idle DTU frame, bits [l3 l2 l1 l0] shall be set to 0000, and the second byte shall not be present.

Figure 8-7 – Format of the DTU frame header

The valid DTU frame types and their coding are described in Table 8-10.

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