Page 678 - 5G Basics - Core Network Aspects

2 Transport aspects

3.2.5 data frame: An object originated by the physical media specific – transmission convergence (PMS-
TC) sub-layer that contains a set of data transfer unit (DTU) bytes and possibly a set of robust management
channel (RMC) bytes to be encoded and modulated onto a single symbol.
NOTE – The length of a data frame depends on whether or not it includes RMC bytes. The PMS-TC sub-layer sends a
data frame across the  reference point, for encoding and modulation onto a single data symbol by the PMD sub-
layer. If no DTU bytes and no RMC bytes are available for transmission at the PMS-TC sub-layer, no data frame is sent.
3.2.6 data packet: A set of bits of the bearer channel (e.g., an Ethernet packet) exchanged over the γ
reference point between the L2+ functional block and transport protocol specific – transmission
convergence (TPS-TC) sub-layer.
NOTE – Data packets are retrieved by the TPS-TC from the L2+ functional block, transmitted transparently over the
line and retrieved by the peer TPS-TC, which passes them to the peer L2+ functional block.

3.2.7 data symbol: A symbol that carries a data frame consisting of only data transfer unit (DTU) bytes
(normal data frame).

3.2.8 data transfer unit (DTU): A frame used to transfer data bits transparently between α reference
points of peer transceivers.

NOTE – Data is passed between peer transceivers by sets, each encapsulated into a single DTU. DTUs are exchanged
over the α reference point between the TPS-TC and PMS-TC sub-layers.
3.2.9 discontinuous operation: A functionality facilitating power savings by transmission of quiet or idle
symbols in place of data symbols when no user data is available or when transmission of data symbols is
not allowed.
3.2.10 DTU payload rate (DPR): The data rate corresponding to the data transfer unit (DTU) payload in
any one direction of transmission, assuming:
• L0 state with no discontinuous operation interval,
• data transmission on all data and robust management channel (RMC) symbol positions
(no idle/quiet symbols), and
• no retransmissions.

3.2.11 dummy DTU: A data transfer unit (DTU) marked as "dummy DTU" in the DTU header. The payload
of a DTU marked as "dummy DTU" in the DTU header contains no data packet or embedded operation
channel (eoc) packet or fraction thereof.
3.2.12 dynamic resource allocation (DRA): A functionality that determines the downstream and
upstream transmission opportunity for each time-division duplexing (TDD) frame based on the occupancy
of higher layer downstream and upstream quality of service (QoS) queues and within the bounds
configured by the operator through the DPU-MIB.
NOTE – As the QoS requirements (SLA, including best effort, as a QoS class) are served, the next target of the DRA
functionality is to minimize power consumption. DRA is performed during the showtime, seamlessly (causing no loss
of data or violation in the order of data).
3.2.13 idle symbol: A symbol that may be sent if no data frame is available for transmission. An idle
symbol is constructed by setting the precoder inputs (Zi) equal to 0 for all subcarriers (see PMD functional
reference model, Figure 10-1).
NOTE – If transmission of an idle symbol coincides with a data symbol being transmitted on another line in the
vectored group, the idle symbol consists of crosstalk pre-compensation signals only.
3.2.14 impulse noise protection against SHINE impulses (INP_SHINE): The number of consecutive DMT
symbol periods that are corrupted by SHINE as seen at the δ-reference point, for which 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.

3.2.15 impulse protection against repetitive electrical impulse noise (INP_REIN): The number of
consecutive DMT symbol periods that are corrupted by REIN, as seen at the -reference point, for which

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