Page 679 - 5G Basics - Core Network Aspects

Transport aspects 2

errored DTUs can be successfully recovered by the retransmission function resulting in no errors at higher
layers, regardless of the number of errors within the DMT symbol periods.

3.2.16 linear precoding: The precoder mode of operation where each Zi' output is a linear combination of
the Zi inputs, with coefficients controlled by the vectoring control entity (VCE) (see Figure 10-16).

3.2.17 logical frame: A set of symbol positions assigned to the same transmission direction, starting with
(and including) a robust management channel (RMC) symbol position and ending on the last symbol
position just before the next RMC symbol position.
3.2.18 management data packet: A set of bits generated by the FTU management entity to be
transmitted to the management entity of the peer FTU.
NOTE – Management data packets are retrieved by the TPS-TC from the FTU management entity via the
TPS-TC_MGMT interface, transmitted transparently over the line and retrieved by the peer TPS-TC, which passes them
to the peer FTU management entity.
3.2.19 MEDLEY set: A subset of the SUPPORTEDCARRIERS set determined during the initialization to
contain the subcarriers to be used for transmission. For each subcarrier in the MEDLEY set, a bi and a gi
value will be assigned and exchanged during the initialization. The MEDLEY set is denoted MEDLEYds and
MEDLEYus, respectively, for the downstream and upstream directions. BLACKOUT subcarriers are not part
of the MEDLEY set.

3.2.20 MOD: The modulo function is defined as
 x 
xMOD y  x  y  floor   

 y  .

3.2.21 net data rate (NDR): The data transfer unit (DTU) payload rate (DPR) minus the embedded
operation channel (eoc) data rate.

3.2.22 pilot symbol: A symbol that is constructed by setting the precoder inputs (Zi) equal to 0 for all non-
pilot subcarriers (see PMD functional reference model, Figure 10-1).
3.2.23 pilot symbol position: A symbol position within each superframe, which is reserved on request of
the FTU-R, for transmission of a pilot symbol only if no robust management channel (RMC) symbol is
available for transmission at that symbol position. Within a logical frame, a pilot symbol position has the
same index as the RMC symbol position.

3.2.24 PILOT TONE set: A subset of the SUPPORTEDCARRIERS set determined by the FTU-R receiver
during the initialization to be allocated for transmission of pilot tones in the downstream direction.
Selected pilot tone subcarriers are transmitted using special modulation. Pilot tone subcarriers are part of
the MEDLEY set.

3.2.25 quiet symbol: A symbol that is constructed by setting the modulator input (Zi' at the FTU-O and Zi
at the FTU-R) equal to zero for all subcarriers (see PMD functional reference model, Figure 10-1).
Transmission of a quiet symbol results in zero transmit power at the U-interface.

3.2.26 reference point: A set of interfaces between any two related functional blocks through which
information flows from one block to the other. A reference point comprises one or more logical
(non-physical) information-transfer interfaces, and one or more physical signal-transfer interfaces.
3.2.27 repetitive electrical impulse noise (REIN): A type of electrical noise encountered on subscriber
lines. It is evident as a continuous and periodic stream of short impulse noise events. Individual REIN
impulses commonly have duration less than 1 millisecond. REIN is generally coupled from electrical power
cable when appliances draw power from the AC electrical power network.
3.2.28 RMC frame: An object originated by the physical media specific – transmission coverage (PMS-TC)
sub-layer that contains management and control information to be communicated through the RMC,
protected by a Reed-Solomon forward error correction (FEC) code. An RMC frame is multiplexed with
DTU(s) and mapped into a data frame by the PMS-TC sub-layer.

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