QoS-Aware Scheduler

USER DESCRIPTION

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Copyright

Ericsson AB 2011. All rights reserved. No part of this document may bereproduced in any form without the written permission of the copyright owner.

Disclaimer

The contents of this document are subject to revision without notice due tocontinued progress in methodology, design and manufacturing. Ericsson shallhave no liability for any error or damage of any kind resulting from the useof this document.

Trademark List

All trademarks mentioned herein are the property of their respective owners.These are shown in the document Trademark Information.

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Contents

Contents

1 Introduction 11.1 Basic Characteristics 11.2 Dependencies 11.3 Benefits 11.4 Configuration Aspects 11.5 Further Information 2

2 Feature Operation 32.1 Network Requirements 32.2 High Level Flow 32.3 QoS-Aware Scheduler Process Steps 3

3 Parameters 53.1 Introduced Parameters 53.2 Affected Parameters 5

4 Network Impact 7

5 Associated Features and Affected Functions 95.1 Prerequisite Features 95.2 Affected Features 95.3 Related Features 95.4 Affected System Functions 9

6 Performance 116.1 KPI 116.2 Counters 116.3 Events 11

7 O&M Information 13

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QoS-Aware Scheduler

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Introduction

1 Introduction

This document describes the QoS-Aware Scheduler feature.

The information in this document reflects the feature at the time of its release.

The feature overview section provides basic information about the feature'sidentity, benefits and dependencies. More detail is given in the followingsections.

1.1 Basic CharacteristicsFeature identity:

FAJ 221 0984, QoS-Aware Scheduler

Replaces: N/A

1.2 DependenciesThis feature has no prerequisite features.

This feature affects no other features.

1.3 BenefitsThe QoS-Aware Scheduler feature allows configuration of the scheduler on aQCI basis. This can be used to configure absolute priority scheduling for DataRadio Bearers (DRBs) in regard to air interface resources.

1.4 Configuration AspectsAbsolute priority for DRBs must be applied conservatively. It is recommendedfor use for prioritization of QCI1 [Voice over Internet Protocol (VoIP)] and QCI5(IMS signalling) only. It is not recommended to be used for non-GuaranteedBit Rate (GBR) traffic unless it corresponds to infrequent and low-intensitytraffic similar to signalling.

Since the scheduling in uplink is performed per LCG, see Section 2 on page3, it is not recommended to mix QCIs with and without absolute priority in thesame LCG.

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1.5 Further InformationFurther information about related topics can be found in the followingdocumentation:

Quality of Service

Scheduler

Admission Control

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Feature Operation

2 Feature Operation

This section describes the QoS-Aware Scheduler feature in more detail,including network configuration requirements and operation flows.

2.1 Network RequirementsThe following network configuration prerequisites must be fulfilled at featureactivation:

The QoS-Aware Scheduler feature license must be present.

2.2 High Level FlowThe high level flow for scheduling is described in Scheduler, which also appliesfor QoS-aware scheduling except that now also differentiated priorities of DRBsare considered when absolute priority scheduling is enabled for a Quality ofService Class Indicator (QCI).

2.3 QoS-Aware Scheduler Process StepsThis section describes the main process steps for the QoS-Aware Schedulerfeature flow.

2.3.1 Configuration

Configuration of the QoS-Aware Scheduler feature is done in the following way.

First, QCIs are assigned priorities using the QciProfilePredefined.priority parameter. The default values for theQciProfilePredefined.priority parameter are according to 3GPP23.203.

Absolute priority is enabled on a QCI basis by means of QciProfilePredefined.absPrioOverride.

For QCIs with the QciProfilePredefined.absPrioOverride parameterset to NO_OVERRIDE, Downlink (DL scheduling) maps the DRB to a defaultpriority level lower (less important) than any other DRB priority.For QCIs with the QciProfilePredefined.absPrioOverride parameterset to HI_PRIO_OVERRIDE, Downlink (DL) scheduling considers theQciProfilePredefined.priority parameter of the DRB as given bythe QCI.

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In uplink, scheduling considers LCGs and this affects the way theparameters QciProfilePredefined.absPrioOverride andQciProfilePredefined.priority are handled by the scheduler.QCIs are grouped into Logical Channel Groups (LCGs) by assigning theQciProfilePredefined.logicalChannelGroupRef parameter to pointto a certain instance of LogicalChannelGroup. More information on therelation between QCI and LCGs, can be found in Quality of Service.

In a LCG where the QCI with the most important priority have theQciProfilePredefined.absPrioOverride parameter set toNO_OVERRIDE, Uplink (UL scheduling) maps the LCG to a default prioritylevel lower (less important) than any DRB priority.In a LCG where the QCI with the most important priority have theQciProfilePredefined.absPrioOverrideparameter set toHI_PRIO_OVERRIDE, Uplink (UL scheduling) maps the LCG to theQciProfilePredefined.priority parameter of the same QCI.

Note that the rules above applies per DRB setup to each specific UE, meaningthat two UEs using the same LCG can have different priority in uplink (ULscheduling) if they have bearers from different QCIs configured.

2.3.2 QoS-Aware Scheduling

The process for scheduling is described in Scheduler, which also appliesfor QoS-aware scheduling except that now the priorities of DRBs are alsoconsidered in case they are assigned high-priority override.

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Parameters

3 Parameters

This section describes parameters introduced by the QoS-Aware Schedulerfeature, and parameters affected by activating the feature.

3.1 Introduced ParametersTable 1 describes the parameters introduced by the feature.

Table 1 Introduced ParametersParameter Description

absPrioOverride Indicates if the DRB mapped to the QCI are subject to absolutepriority override. This applies to both downlink and uplink.

3.2 Affected ParametersTable 2 describes the parameters affected by the feature.

Table 2 Affected ParametersParameter Description

priority QCI-related priority as defined in 3GPP TS 23.203This parameter can be configured. The default values are selectedin accordance with 3GPP TS 23.203 .

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Network Impact

4 Network Impact

There is no impact on the network resulting from the implementation of theQoS-Aware Scheduler feature.

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Associated Features and Affected Functions

5 Associated Features and AffectedFunctions

This section describes how the QoS-Aware Scheduler feature affects otherfeatures and functions.

5.1 Prerequisite FeaturesThere are no prerequisite features for this feature.

5.2 Affected FeaturesNo other features are affected by this feature.

5.3 Related FeaturesThere are no other features related to his feature.

5.4 Affected System FunctionsTable 2 describes the system functions affected by his feature.

Table 3 Affected ParametersParameter Description

Scheduler When there is no license available for the QoS-Aware Schedulerfeature, the system scheduler sets to Resource Fair (RF) asdefault.

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Performance

6 Performance

This section describes performance indicators, counters, and events associatedwith the QoS-Aware Scheduler feature.

6.1 KPIMore information on Key Performance Indicators (KPIs) can be found inKeyPerformance Indicators. The main KPIs associated with this feature are listedin Table 4:

Table 4 KPIs

DL latency per QCI Time it takes to schedule thefirst packet on the air interface,determined from the time it wasreceived in the RBS, on a QCI basis

6.2 CountersThis feature has no directly associated counters.

6.3 EventsThe important events associated with the QoS Aware Scheduler feature arelisted in Table 5.

Table 5 EventsEvent Event Parameter DescriptionINTERNAL_PER_UE_RB_TRAFFIC_REP

EVENT_PARAM_PER_DRB_DL_RLC_DELAY

Aggregated time for the DL delaymeasure in the RLC layer. Onesample per RLC(1) SDU(2) sent toMAC(3).The time for each sample is betweenreception of a packet (PDCP(4) SDU)until the packet is sent to the MAClayer entity for transmission on theair.

INTERNAL_PER_UE_RB_TRAFFIC_REP

EVENT_PARAM_PER_DRB_DL_RLC_DELAY_SAMPL

Number of samples to be used in DLMAC delay measure calculations

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Event Event Parameter DescriptionINTERNAL_PER_UE_RB_TRAFFIC_REP

EVENT_PARAM_PER_DRB_LAT_TIME_DL

Aggregated time samples for the DLlatency measure

The time is between reception of aPDCP SDU until the first successfultransmission of a MAC SDU havebeen transmitted.

INTERNAL_PER_UE_RB_TRAFFIC_REP

EVENT_PARAM_PER_DRB_LAT_SAMPL_DL

Number of samples to be used inDL latency measure calculations

(1) Radio Link Control(2) Service Data Unit(3) Media Access Control(4) Packet Data Convergence Protocol

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O&M Information

7 O&M Information

This section provides Operation and Maintenance (O&M) information for thefeature.

A license is needed to activate this feature so that the configuration of absolutepriority override takes effect.

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toc1 Introduction1.1 Basic Characteristics1.2 Dependencies1.3 Benefits1.4 Configuration Aspects1.5 Further Information

2 Feature Operation2.1 Network Requirements2.2 High Level Flow2.3 QoS-Aware Scheduler Process Steps2.3.1 Configuration2.3.2 QoS-Aware Scheduling

3 Parameters3.1 Introduced Parameters3.2 Affected Parameters

4 Network Impact5 Associated Features and Affected Functions5.1 Prerequisite Features5.2 Affected Features5.3 Related Features5.4 Affected System Functions

6 Performance 6.1 KPI6.2 Counters6.3 Events

7 O&M Information