Page 1035 - 5G Basics - Core Network Aspects

Transport aspects 2

X.6 Dynamic time assignment (DTA)

DTA is used to dynamically set and update the sharing of the TDD frame between upstream and
downstream, by changing the number of downstream symbol periods (Mds) of the TDD frame during
showtime upon request by the DRA.
Support of DTA is optional for the FTU-O and mandatory for the FTU-R.

X.6.1 DTA-related primitives at the γO reference point
In addition to the DRA primitives specified in Table 8-3 of clause 8.1.1, the DTA-related DRA primitives at
the γO reference point are summarized in Table X.2. The physical implementation of these primitives is
vendor discretionary.

Table X.2 – DTA-related DRA primitives of the data flow at the γO reference point

Primitive name (parameters) Direction Description

DTA.request (Mds) DRA → FTU-O Requests the FTU-O to initiate a DTA update using the
provided Mds.

DTA.confirm (Mds, CNTLF) FTU-O → DRA Confirms to the DRA that the DTA update corresponding
to the DTA.request has been scheduled by the FTU-O. The
implementation of the change will be applied starting
from the first symbol of the TDD frame in which the
logical frame indicated by CNTLF starts (i.e., the logical
frame at which DTAFDC will be decremented to zero
during the countdown). See clause X.6.6.

If the FTU-O receives a DTA.request primitive, the FTU-O shall initiate the DTA update as specified in
clause X.6.2 at the earliest opportunity. Once the update is scheduled, the FTU-O shall send the
DTA.confirm primitive to the DRA at the earliest opportunity before the update takes effect. The DRA shall
only send another DTA.request primitive after the time instant associated with the logical frame count
indicated in the DTA.confirm primitive.
The DRA shall coordinate sending the DTA.request primitive with the link state request as described in
clause T.3.
X.6.2 The DTA procedure

The DRA indicates the request for a DTA update to the FTU-O via the DRA primitive DTA.request
(See clause X.6.1). Upon such an indication, the FTU-O initiates the DTA update by sending the 'DTA update'
RMC command (see clause X.6.11) to the FTU-R. This command synchronizes the update of the Mds
parameter at the FTU-O and FTU-R as specified in clause X.6.6. The details of updating Mds, the
requirements, and the impact on the TDD frame parameters is described in clauses X.6.3 and X.6.4.
NOTE – The DRA makes the decision to initiate the DTA updates. See Annex T for higher-layer control aspects of the
DTA.

X.6.3 Valid values of Mds for DTA
With DTA enabled per a specific line, the FTU shall support the ranges of values of Mds as a function of MF
according to Table X.3 (rather than those in Table 10-13):

Table X.3 – Mds values to support as a function of MF

MF Mds values supported
36 from 5 to 30

23 from 5 to 17

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