Page 940 - 5G Basics - Core Network Aspects

2 Transport aspects

DISCOVERY 2 signal with its element indices aligned such that they are the same as they would have been if
the probe sequence communicated in O-SIGNATURE message were actually used in O-P-CHANNEL-
DISCOVERY 1 signal.
NOTE – This is to ensure that the probe sequence of a joining line has proper phase alignment with the probe
sequences of the other lines in the vectored group.

The FTU-O shall start transmission of the O-P-CHANNEL-DISCOVERY 2 signal right upon completion of
transmission of the O-P-SYNCHRO 1 signal, starting from the symbol with index zero of the following
downstream logical frame. From the start of the first superframe of the O-CHANNEL DISCOVERY 2 stage,
the SOC shall transmit O-IDLE until the FTU-O receives the R-MSG 1 message. The FTU-O shall acknowledge
R-MSG1 by sending an O-UPDATE message, as defined in Table 12-26. The O-UPDATE message shall be sent
in RQ mode (see clause 12.2.2.2). The FTU-R acknowledges O-UPDATE message by sending R-UPDATE
message. Reception of R-UPDATE message completes the message exchange of O-CHANNEL DISCOVERY 2
stage.

The O-P-CHANNEL-DISCOVERY 2 signal shall be followed by the O-P-SYNCHRO 2 signal, which determines
the actual duration of the CHANNEL DISCOVERY 2 stage. The start time of O-P-SYNCHRO 2 transmission
shall be at the symbol with index 0 of the first downstream logical frame of a superframe and is determined
by the VCE. Transmission of O-P-SYNCHRO 2 signal may terminate transmission of O-IDLE prior to
completion of all SOC symbol repetitions (RS).
12.3.3.3.5.2 R-P-CHANNEL-DISCOVERY 2

During transmission of the R-P-CHANNEL-DISCOVERY 2 signal, the FTU-R communicates to the FTU-O all
necessary information to update the downstream PSD.

The R-P-CHANNEL DISCOVERY 2 signal shall consist of upstream sync symbols and initialization symbols.
Sync symbols shall be transmitted at each upstream sync symbol position. SOC symbols shall be transmitted
at the first sus upstream symbol positions; all other initialization symbols shall be quiet. The value of sus is
defined in field 19 of O-SIGNATURE message. The sync symbols shall be generated and modulated by probe
sequences as described in clause 10.2.2.1. The SOC shall be in its active state. The SOC quadrant scrambler
shall be in reset mode. The probe sequence modulating sync symbols shall be continued from the previous
stage with no interruption.
The R-P-CHANNEL DISCOVERY 2 signal shall use all subcarriers from the SUPPORTEDCARRIERSus set. SOC
symbols shall use robust bit mapping (see clause 10.2.2.2.1). The transmit PSD shall be equal to
STARTPSDus.
The FTU-R shall start transmission of the R-P-CHANNEL-DISCOVERY 2 signal after reception of the
O-P-SYNCHRO 1 signal, starting from the symbol with index 0 of the first upstream logical frame following
completion of O-P-SYNCHRO 1 signal. From the start of the first superframe of the R-CHANNEL DISCOVERY
2 stage, the FTU-R shall transmit R-IDLE for a period of five superframes, followed by the R-MSG 1 message,
as defined in Table 12-25. The R-MSG 1 message shall be sent in auto-repeat mode (see clause 12.2.2.1).
The transmission of R-MSG 1 message shall be terminated upon reception of O-UPDATE message.
The FTU-R shall acknowledge the O-UPDATE message by sending R-UPDATE message, as defined in
Table 12-27. The R-UPDATE message shall be sent in auto-repeat mode. The transmission of the R-UPDATE
message shall be acknowledged by the O-P-SYNCHRO 2 signal that determines the actual duration of the
CHANNEL DISCOVERY 2 stage. Upon reception of the O-P-SYNCHRO 2 signal, FTU-R shall transition to the
R-VECTOR 1.1 stage starting from the symbol with index zero of the upstream logical frame that follows the
last symbol of the O-P-SYNCHRO 2 signal.
12.3.3.3.5.3 O-P-SYNCHRO 2

The O-P-SYNCHRO 2 signal provides an exact time marker for transition from the CHANNEL DISCOVERY 2
stage to the R-VECTOR 1.1 stage. The O-P-SYNCHRO 2 signal shall have the same format, start time and
duration as the O-P-SYNCHRO 1 signal. During transmission of the O-P-SYNCHRO 2 signal, the SOC is
inactive.

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