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2 Transport aspects
2) Reduce the PSD to achieve SNRM ≤ L2.1_MAXSNRM within the constraint PSD reduction L2_PSDR
≤ L2_PSDR_max.
Within the above constraints, for downstream, the FTU-O and VCE shall jointly select the values in the L2.1-
Entry-Request eoc command so as to optimize in the priority specified:
1) While keeping same PSD as in L0, the FTU-O determines via a vendor discretionary method
– the set of L2.1 subcarriers
– the proposed bit loading table
– the number of RMC symbols per superframe (N)
2) Reduce the PSD to achieve SNRM ≤ L2.1_MAXSNRM within the constraint PSD reduction L2_PSDR
≤ L2_PSDR_max.
Within the above constraints, for downstream, the FTU-R shall select the bit loading table and the framing
parameters values in the L2.1-Entry-Confirm eoc response so as to minimize the bit loading.
NOTE 2 – The above policy allows a vendor discretionary compromise between robustness and power saving.
13.4.1.3 Operation during L2.1
At the entry into an L2.1 link state, FTUs apply the RMC transmission schedule and transmission parameters
and framing parameters determined during the L2.1 entry procedure, as defined in clause 13.4.1.2.1.
During an L2.1 link state, the RMC schedule and transmission/framing parameters of the FTUs may be
updated using appropriate OLR procedure.
13.4.1.3.1 L2.1 operation policy
The method used by the transceivers to select the updated values of RMC transmission schedule,
transmission and framing parameters described in this clause is vendor discretionary. However, the
selected values shall meet all of the following constraints.
For the settings of L2.1 upstream RMC transmission schedule and transmission parameters:
• L2.1_ETR ≥ L2.1_ETR_min_eoc;
• L2.1_NDR ≤ L2.1_NDR_max;
• L2.1_Exit_ETR ≥ L2.1_Exit_ETR_min;
For the settings of L2.1 downstream RMC transmission schedule and transmission parameters:
• L2.1_ETR ≥ L2.1_ETR_min_eoc;
• L2.1_NDR ≤ L2.1_NDR_max;
• L2.1_Exit_ETR ≥ L2.1_Exit_ETR_min;
• bi values shall be not greater than the bi values proposed in the L2.1-Entry-Request eoc command,
unless they are modified through a following TIGA procedure;
• BDR ≥ L2.1_BDR_min.
For both the upstream and downstream transmission parameters:
• DTU size restriction:
NDTU + Q × RFEC ≤ (N-1) × BDR,
where N is the number of active TDD frames per superframe in L2.1 (see clause 13.4.1.1).
NOTE – This requirement on the L2.1 framing parameters implies the one-way latency without retransmission in the
L2.1 link state does not exceed the duration of 1 superframe (TSF).
• Impulse noise protection:
• at least against a combined threat of worst-case REIN impulses as described by the
retransmission control parameters INP_min_rein and iat_rein_flag and of worst-case SHINE
impulses as described by the retransmission control parameter INP_min_shine, and
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