Page 1053 - 5G Basics - Core Network Aspects

Transport aspects 2

Annex Z

Cross-layer traffic monitoring functions and link state control
(This annex forms an integral part of this Recommendation.)

Z.0 Introduction
This annex describes coordination of the G.fast PHY-layer with higher layers in order to implement traffic
monitoring and to control link state transition to support low power operation. Transition between various
link states is driven by traffic demand variations evident in inlet queue arrival and occupancy. Also, external
influences, such as battery operation are taken into account.

This annex is beyond the scope of transceiver functionality and is optional for system implementations.

Z.1 Definition of Terms
This annex defines the following terms:

Z.1.1 data stream metric: The number of bytes in a data stream observed during a defined period.
Z.1.2 QoS queue: A logical queue associated with a particular traffic priority class.
Z.1.3 queue arrival metric: The number of bytes arriving at the inlet of a QoS queue in a defined period.

Z.1.4 queue fill metric: The number of bytes held in a QoS queue at the time of measurement.

Z.2 Abbreviations and acronyms
This annex uses the following abbreviations and acronyms:

DRRUSF DRR Upstream Function at the NT
LRCC-O LinkState Rate Configuration Control function at the DPU

QAD Queue Arrival metric in Downstream
QAU Queue Arrival metric in Upstream

QFD Queue Fill metric in Downstream
QFU Queue Fill metric in Upstream

QSI-US-QF Queue Status Indication UpStream with per queue QFU at the DPU
QSR-DS-QA Queue Status Report DownStream with per queue QAD at the DPU
QSR-DS-QF Queue Status Report DownStream with per queue QFD at the DPU

QSR-US-QA Queue Status Report UpStream with aggregate QAU for the data stream upstream at the
DPU

QSR-US-QF Queue Status Report UpStream with per queue QFU at the NT
TMF-O Traffic Monitor Function at the DPU

TMF-R Traffic Monitor Function at the NT
USSM UpStream Stream Monitor at the DPU

Z.3 Reference models

Reference models shown in clause 5.1 and in Figures Z.1 and Z.2 show how traffic monitoring and link state
control functions in L2+ (above the O and R reference points) relate to G.fast functions in the reference
models shown in Figures 5-2 and 5-3 of the main body of this Recommendation.

1043