Page 945 - 5G Basics - Core Network Aspects

Transport aspects 2

handshake reset. The probe sequence modulating sync symbols shall be continued from the previous stage
with no interruption.

At the first symbol of the stage, the VCE updates the precoder and the downstream transmit PSD in all
active and joining lines using the channel estimation results obtained during the VECTOR 2 stage. The
transmit PSD after the update will be PRMPSDds. The O-P-PRM-UPDATE 1 signal shall use all subcarriers
from the SUPPORTEDCARRIERSds set.

NOTE – The PRMPSDds might be different from V2PSDds (e.g., the PSD might be higher at some subcarrier frequencies
while lower at other subcarrier frequencies).
The FTU-O shall start transmission of the O-P-PRM-UPDATE 1 signal upon completion of transmission of the
O-P-SYNCHRO 4 signal. From the start of the first downstream logical frame of the O-P-PRM-UPDATE 1
signal, the SOC shall send O-IDLE and continue sending O-IDLE during at least ten superframes followed by
an O-SNR message defined in Table 12-31. The O-SNR message shall be sent in the RQ mode.
After the FTU-R acknowledges by the R-SNR message defined in Table 12-33, the FTU-O shall send O-IDLE
for a time period from 3 to 15 superframes, followed by transmission of the O-P-SYNCHRO 4-1 signal. The
O-P-SYNCHRO 4-1 signal transmission shall start from the symbol with index 0 of the first downstream
logical frame of a superframe and is determined by the VCE.

12.3.3.3.8.2 O-P-PRM-UPDATE 2
During transmission of the O-P-PRM-UPDATE 2 signal, the FTU-O further optimizes its transmit PSD and
communicates to the FTU-R the updated downstream and upstream PSD and other relevant parameters
obtained during the PARAMETER UPDATE stage.

After transmission of O-P-SYNCHRO 4-1 signal is complete, FTU-O shall start transmission of the
O-P-PRM-UPDATE 2 signal from the symbol with index 0 of the following logical frame. The O-P-PRM-
UPDATE 2 signal shall differ from O-P-PRM-UPDATE 1 signal only by:
– the SOC shall use normal bit mapping with SOC tone repetition rate pds indicated in R-SNR
message;
– the SOC quadrant scrambler shall be back in reset mode;

– transmission shall use the MEDLEYds subcarriers.
After starting transmission of O-P-PRM-UPDATE 2 signal, the FTU-O shall first transmit O-IDLE for at least
three superframes, followed by O-PRM message, as defined in Table 12-35. Upon reception of the R-PRM
message defined in Table 12-37, the FTU-O shall continue transmitting O-IDLE for at least three
superframes. The FTU-O completes this stage by sending the O-P-SYNCHRO 5 signal. The O-PRM message
shall be sent using the RQ mode (see clause 12.2.2.2).
The actual duration of the O-P-PRM-UPDATE 2 signal is determined by the VCE. The O-P-SYNCHRO 5
transmission shall start at the symbol with index 0 of the first downstream logical frame of a superframe.
After transmission of the O-P-SYNCHRO 5 signal, the FTU-R shall transition to the channel analysis and
exchange phase.

12.3.3.3.8.3 R-P-PRM-UPDATE 1
During transmission of the R-P-PRM-UPDATE 1 signal, the FTU-R communicates to the FTU-O the
downstream SNR report.
The R-P-PRM-UPDATE 1 signal shall have the same structure as the R-P-CHANNEL-DISCOVERY 1 signal and
shall consist of upstream sync symbols and initialization symbols. The SOC shall be in its active state and use
normal bit mapping with SOC tone repetition rate p communicated in the O-VECTOR-FEEDBACK message.
The SOC quadrant scrambler shall be in free running mode. The scrambler shall be initialized at the first
SOC symbol of R-P-PRM-UPDATE 1 signal with the value communicated during the ITU-T G.994.1
handshake. The transmit PSD shall be equal to CDPSDus (obtained during the CHANNEL DISCOVERY 2
stage). The R-P-PRM-UPDATE 1 signal shall use all subcarriers from the SUPPORTEDCARRIERSus set. The
probe sequence modulating sync symbols shall be continued from the previous stage with no interruption.

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