Page 1000 - 5G Basics - Core Network Aspects

2 Transport aspects

If the FTU-R doesn't receive the L2-TRNS command within 50 ms after transmission of the L2.2-Entry-
Confirm eoc response has finished, it shall consider that the L2.1B  L2.2 transition has failed and continue
to operate in the L2.1B link state.
If the FTU-O receives no response to the L2.2-Entry-Request eoc command within the timeout specified in
Table 11-3, or upon reception of an L2.2-Entry-Reject eoc response, the L2.2 entry procedure shall be
considered as failed, and the FTU-O shall respond to the DRA over the γ-O interface (see Table 8-3) with a
LinkState.confirm (FAIL) primitive within the time shown in Table 12-1. If the L2.2 entry criteria are still met,
the DRA may send a new LinkState.request (L2.2) primitive to the FTU-O, upon which the FTU-O shall send
a new L2.2-Entry-Request eoc command to the FTU-R.
13.4.2.2.1 L2.2 entry policy

The method used by the transceivers to select the 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 the L2.2 upstream RMC transmission schedule and upstream transmission parameters in
the L2.2-Entry-Request eoc command:
• L2.2_ETR ≥ L2.2_ETR_min_eoc;
• L2.2_NDR ≤ L2.2_NDR_max;

• SNRM ≥ L2_TARSNRM.
For the settings of L2.2 downstream RMC transmission schedule and downstream transmission parameters
in the L2.2-Entry-Request eoc command:
• L2.2_ETR ≥ L2.2_ETR_min_eoc;
• L2.2_NDR ≤ L2.2_NDR_max;
• BDR ≥ L2.2_BDR_min.

For the settings of L2.2 downstream transmission parameters in the L2.2-Entry-Confirm eoc response:
• L2.2_ETR ≥ L2.2_ETR_min_eoc;

• L2.2_NDR ≤ L2.2_NDR_max;
• SNRM ≥ L2_TARSNRM;
• bi values shall be not greater than the bi values proposed in the L2.2-Entry-Request eoc command;

• BDR ≥ L2.2_BDR_min.
For both upstream and downstream transmission parameters:
• DTU size restriction:

(NDTU + Q × RFEC)×d= BDR,
where d is a integer equal to or bigger than 1.
NOTE – This requirement on the L2.2 framing parameters implies the one-way latency without retransmission in the
L2.2 link state does not exceed the duration of X superframes (X × 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
• within the latency bounds defined by the control parameter delay_max.
The control parameter delay_max during L2.2 shall be set to (2 × X) +1 superframes; the
configuration parameter DELAYMAX shall be ignored. This setting allows two retransmission
attempts.
• RFEC/NFEC ratio ≥ rnratio_min.

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