Page 855 - 5G Basics - Core Network Aspects

Transport aspects 2

11.3.1.1 Near-end anomalies

• Forward error correction (fec): For further study. As such, this anomaly shall not occur.
• Uncorrected DTU (rtx-uc): An rtx-uc anomaly occurs at the receiver each time a DTU of the normal
DTU type (see clause 8.2.1.3) is not delivered to the alpha reference point by the receiving PMS-TC
because the DTU is received in error and has not been corrected by a retransmission within the
maximum delay;
• Retransmitted DTU (rtx-tx): An rtx-tx anomaly occurs at the transmitter each time a DTU of normal
type (see clause 8.2.1.3) is retransmitted. Multiple retransmissions of the same DTU are counted
as many times as the DTU has been retransmitted.
• Cyclic redundancy check (crc): The crc anomaly is defined by the detection of at least one rtx-uc
anomaly per 17ms time interval.
• Loss-of-power interruption (lpr_intrpt): Excluding reinitializations triggered by the ME-O (see
clause 12.1.2), this anomaly occurs when the time between the exit from the showtime of the
FTU-O and the first successful reception of an ITU-T G.994.1 message is less than 120 seconds and
at least one of the following conditions is met: a far-end loss-of-power (flpr) primitive (see
clause 11.3.3.2) is declared before the exit from showtime or the PLPR flag is set at the entry into
showtime (see clause 11.2.2.10).
This anomaly is only defined at the FTU-O.
• Host-Reinit interruption (hri_intrpt): Excluding reinitializations triggered by the ME-O (see
clause 12.1.2), this anomaly occurs when the PHRI flag is set at the entry into showtime (see
clause 11.2.2.10).

This anomaly is only defined at the FTU-O.
• Spontaneous interruption (spont_intrpt): Excluding reinitializations triggered by the ME-O (see
clause 12.1.2), this anomaly occurs when the time between the exit from showtime of the FTU-O
and the first successful reception of a ITU-T G.994.1 message is less than 120 seconds and neither
an lpr_intrpt nor an hri_intrpt occurs.
This anomaly is only defined at the FTU-O.

11.3.1.2 Far-end anomalies
No far-end anomalies are defined.

11.3.1.3 Near-end defects
• Loss of signal (los): A reference power shall be established by averaging the ITU-T G.9701 receive
power over the RMC symbol over a 0.1 s period and over a subset of subcarriers used for
showtime, and a threshold shall be set 6 dB below this level. An los shall occur when the level of
the ITU-T G.9701 receive power averaged over a 50 ms period and over the same subset of
subcarriers is lower than the threshold, and shall terminate when this level, measured in the same
way, is at or above the threshold. The subset of subcarriers is implementation dependent.
• Loss of margin (lom): This defect occurs when the signal-to-noise ratio margin (SNRM, see
clause 11.4.1.3) observed by the near-end receiver is below the minimum signal-to-noise ratio
margin (MINSNRM, see clause 12.3.4.2) for a bit-rate greater than or equal to ETR_min_eoc, and
an increase of SNRM is no longer possible within the far-end aggregate transmit power and
transmit PSD level constraints. This defect terminates when the SNRM is above the MINSNRM. The
SNRM measurement update rate shall be at least once every 0.5 second.
• Loss of RMC (lor): This defect occurs when the percentage of errored RMC messages within a
50 ms interval exceeds 50%. The lor defect terminates when this level is at or below the threshold.

11.3.1.4 Far-end defects
• Far-end loss of signal (los-fe): This defect occurs when a los detected at the far end is reported in
at least four of six consecutively received far-end los indicator reports (Table 9-8). A los-fe

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