Page 862 - 5G Basics - Core Network Aspects

2 Transport aspects

It is a 32-bit wrap-around counter. The counter shall be reset at power-on. The counters shall not be reset
with a link state transition and shall not be reset when read.

The upstream value shall be reported in the DPU-MIB as a near-end value.
The downstream value shall be reported in the DPU-MIB as a far-end value.
NOTE – DTUs that have been detected to be in error, and DTUs that exceed delay_max do not cross the  reference
point at the receiver side.
11.4.1.1.10 Signal-to-noise ratio margin parameter (SNRM)

The signal-to-noise ratio margin (SNRM) parameter is a parameter that reports the signal-to-noise ratio
margin (as defined in clause 9.8.3.2) for data symbols in the NOI in L0, and on data subcarriers for which bi
> 0 in the RMC symbols during the L2.1N, L2.1B and L2.2 link states.
NOTE – Estimation of the SNRM in the DOI by the receiver is not required.
The SNRM shall be measured by the receiver during the initialization. The measurement may be updated
autonomously and shall be updated on request during showtime (L0, L2.1N, L2.1B and L2.2). The SNRM
shall be sent to the far-end FTU during the initialization and shall be sent on request to the near-end ME at
any time. The near-end ME shall send the SNRM to the far-end ME on request during showtime (L0, L2.1N,
L2.1B and L2.2 link states).

The signal-to-noise ratio margin in the downstream direction shall be represented as a 10-bit two's
complement signed integer snrm, with the value of SNRMds defined as

SNRMds = snrm/10 dB.
This data format supports an SNRMds granularity of 0.1 dB and an SNRMds range from −50.9 to +50.9 dB,
corresponding to the set of valid values of snrm = −509 to 509.
A special value snrm = 510 indicates a value of SNRM = 51.0 dB or higher.

A special value snrm = –510 indicates a value of SNRM = –51.0 dB or lower.
A special value snrm = –512 indicates that the parameter is undetermined.

All other values are reserved by ITU-T.
The same definition and representation shall apply to the signal-to-noise ratio margin in the upstream
direction, SNRMus.
During the L0 link state, downstream and upstream SNRM values are reported by the FTU-O as SNRM in the
DPU-MIB. During the L2.1N, L2.1B or L2.2 link state, SNRM values of the last update in the L0 link state are
available in the DPU-MIB.

During the L2.1N or L2.1B link state, downstream and upstream SNRM values are reported by the FTU-O as
L2.1_SNRM in the DPU-MIB. During the L0 or L2.2 link state, SNRM values of the last update of L2.1_SNRM
in the L2.1N or L2.1B link state, are available in the DPU-MIB.

During the L2.2 link state, downstream and upstream SNRM values are reported by the FTU-O as
L2.2_SNRM in the DPU-MIB. During the L0, L2.1N or L2.1B link state, SNRM values of the last update in the
L2.2 link state are available in the DPU-MIB.
During the L3 link state (see Figure 12-1), the values of SNRM, L2.1_SNRM and L2.2_SNRM at the last
update are available in the DPU-MIB, until the FTU-O transitions to the O-INIT/HS state, at which time the
values may become "undetermined".

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