Dynamic GBR Admission Control

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 21.2 Benefits 21.3 Additional Information 3

2 Feature Operation 52.1 Network Requirements 52.2 Feature Operation Sequence Diagram 5

3 Parameters 73.1 Introduced Parameters 73.2 Affected Parameters 7

4 Network Impact 94.1 Capacity 9

5 Associated Features and Affected Functions 115.1 Prerequisite Features 115.2 Affected Features 115.3 Related Features 115.4 Affected System Functions 11

6 Performance 136.1 KPIs 136.2 Counters 136.3 Events 13

7 O&M Information 15

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Introduction

1 Introduction

This document describes the Dynamic GBR Admission Control feature and itsmain benefits and impacts in the LTE RAN.

Dynamic GBR admission control is performed by monitoring the use of certainsystem resources, referred to as monitored system resources (MSR), andallowing the setting up of new guaranteed bit rate (GBR) bearers only if theMSR usage by GBR bearers does not exceed a configured threshold. Thesemonitored system resources are scheduler-handled resources and includehardware and software resources as well as license limited resources onboth cell and RBS level. The MSRs include resources such as the usage ofphysical resource blocks (PRB), scheduling elements (SE), control channelelements (CCE) and baseband capacity. The use of the MSRs is measuredduring a measurement period after which a filtered value for the MSR usageis calculated. This filtered MSR usage value is updated after each newmeasurement period.

The MSRs considered are the following:

UL GBR PRB utilization per cell

UL GBR PRB utilization per RBS

DL GBR PRB utilization per cell

DL GBR PRB utilization per RBS

UL GBR SE utilization per cell

UL GBR SE utilization per RBS

DL GBR SE utilization per cell

DL GBR SE utilization per RBS

GBR CCE utilization

UL GBR Baseband Capacity utilization per RBS

DL GBR Baseband Capacity utilization per RBS

Upon a GBR bearer setup the utilization of each MSR will be checked againsta configured threshold (shown in Figure 1) and is only allowed if the resourceusage does not exceed the threshold.

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Dynamic GBR Admission Control

L0000273A

Block new non-privileged accessesAllow incoming mobilityAllow high-privileged access

Allow all GBR requests

Max capacity

GBRload

GBR AdmissionThreshold

Figure 1 GBR Admission Threshold

The GBR load on the dynamic MSRs is not considered for handover andprivileged access. Privileged access is described in more detail in AdmissionControl.

1.1 Basic CharacteristicsThis section describes the basic characteristics of the feature.

Feature Identity

TDD: FAJ 221 1748, Dynamic GBR Admission Control

Replaces: N/A

Dependencies

This feature requires the following RAN features to be active:

This feature has no prerequisite features.

This feature affects the following RAN features:

This feature affects no other features.

1.2 BenefitsThis section describes the benefits of this feature.

The main purpose of Dynamic GBR Admission control is to prevent GBRbearers from starving out non-GBR, or best effort, traffic as well as ensuring

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Introduction

that the Quality of Service(QoS) is maintained for GBR bearers in the system.By enabling the dynamic GBR admission control feature, a headroom will bereserved for non-GBR bearers. Furthermore, using a dynamic method ofmeasuring the use of resources by GBR bearers allows for more efficient use ofresources as well as avoiding unnecessary rejections.The Dynamic GBR Admission control feature may also serve as to provide atool to control the ratio between GBR and non-GBR traffic in the network.

Enabling the Dynamic GBR Admission Control feature will also enable tuning ofthe GBR cost per QCI (QoS Class Identifier) in the basic GBR admission controlfunction. This will in turn enable the basic admission control function to makeadmit or reject decisions with higher precision by considering service-specificprotocol overhead and activity factor.

1.3 Additional InformationMore information about this feature and related topics can be found in thefollowing documentation:

3GPP TS 23.203

3GPP TS 36.413

3GPP TS 36.211

License Management

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Feature Operation

2 Feature Operation

This section describes the Dynamic GBR Admission Control feature in moredetail, including network configuration requirements and operation flows.

The GBR threshold is common for all MSRs and controlled, for the downlink anduplink, by the parameters dlNonGbrRatio and ulNonGbrRatio introducedin Admission Control. The threshold is given as a ratio and can be expressed as1 - dlNonGbrRatio for the downlink and 1 - ulNonGbrRatio for the uplink.

2.1 Network RequirementsThe following must be fulfilled at feature activation:

This feature has no prerequisite network configuration requirements.

2.2 Feature Operation Sequence DiagramFigure 2 is a flow diagram showing how the Dynamic GBR Admission Controlfeature handles bearer requests.

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Dynamic GBR Admission Control

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Reject Admit

E-RAB request

Yes

Yes

No

No

No

Yes

Yes

Resourcesavailable?

E-RAB isGBR?

Is Privilegedaccess?

No

Cause ismobility?

Figure 2 Flow Diagram for the Dynamic GBR Admission Control Feature

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Parameters

3 Parameters

This section describes parameters introduced by the Dynamic GBR AdmissionControl feature and parameters affected by activating the feature.

3.1 Introduced ParametersThis feature introduces no new parameters.

3.2 Affected ParametersTable 1 Affected Parameters for the Admission Control feature

Parameter Description

dlNonGbrRatio Sets the downlink threshold for the Dynamic GBR AdmissionControl feature.

ulNonGbrRatio Sets the uplink threshold for the Dynamic GBR Admission Controlfeature.

qciAcTuning Tuning factor per QCI for the basic admission control function.Needs the Dynamic GBR Admission Control feature to beactivated to take effect.

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Network Impact

4 Network Impact

This section describes how the Dynamic GBR Admission Control featureimpacts the network functions and capabilities.

4.1 CapacityThis section provides information on the impact of the feature on networkcapacity.

Dynamic GBR Admission Control limits the amount of resources used by GBRbearers, this helps ensure that the quality of service is fulfilled for GBR bearerswithin the system but may come at a cost of accordingly reduced GBR capacity.As the feature also provides a headroom for non-GBR bearers, the non-GBRcapacity will be improved for scenarios with a high load from GBR bearers.

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Associated Features and Affected Functions

5 Associated Features and AffectedFunctions

This section describes how the Dynamic GBR Admission Control feature affectsother features and functions.

5.1 Prerequisite FeaturesThis feature has no prerequisite features.

5.2 Affected FeaturesThis feature affects no other feature.

5.3 Related FeaturesTable 2 lists features that are related to the Dynamic GBR Admission Controlfeature.

Table 2 Related FeaturesFeature Description

Differentiated Admission Control Activating the Differentiated Admission Control feature allows forsome high priority GBR bearer setup requests to be accepted inspite of MSR usage being above the selected threshold whenpreemption has been performed.

5.4 Affected System FunctionsTable 3 lists functions affected by the Dynamic GBR Admission Control feature.

Table 3 Affected System FunctionsFunction Description

Admission Control If the Dynamic GBR Admission Control feature is activated, the parameterqciAcTuning will be able to configure GBR cost per QCI. Activating theDynamic GBR Admission control function will also affect the functionality ofthe parameters dlNonGbrRatio and ulNonGbrRatio. The basic admissioncontrol function also introduces privileged access which allows some GBRbearer setup requests to be accepted in spite of resource shortage.

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Performance

6 Performance

This section describes performance indicators, counters, and events associatedwith the Dynamic GBR Admission Control feature.

6.1 KPIsTable 4 lists the main Key Performance Indicators (KPIs) associated with theDynamic GBR Admission Control feature.

Table 4 KPIsKPI Description

Accessibility The ability of a service to be obtained, within specified tolerances and othergiven conditions, when requested by the end user.

Retainability The probability that a service, once obtained, continues to be providedunder given conditions for a given time duration.

6.2 CountersThis feature has no directly associated counters.

More information about counters can be found in Managed Object Model RBS.

6.3 EventsTable 5 lists the events associated with the Dynamic GBR Admission Controlfeature.

Table 5 EventsEvent Event Parameter DescriptionINTERNAL_PROC_INITIAL_CTXT_SETUP

EVENT_ARRAY_ERAB_SETUP_RESULT

This feature returns lack ofresources at reject due to GBRoverload.

INTERNAL_PROC_ERAB_SETUP

EVENT_ARRAY_ERAB_SETUP_RESULT

This feature returns lack ofresources at reject due to GBRoverload.

More information about events can be found in PM Event List.

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O&M Information

7 O&M Information

This section provides Operation and Maintenance (O&M) information for theDynamic GBR Admission Control feature.

Activating the Dynamic GBR Admission Control feature requires that thecorresponding license is installed. More information on handling licenses canbe found in License Management.

Adjusting the GBR thresholds is done with the parameters dlNonGbrRatioand ulNonGbrRatio as described in Feature Operation.

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toc1 Introduction1.1 Basic CharacteristicsDependencies1.2 Benefits1.3 Additional Information

2 Feature Operation2.1 Network Requirements2.2 Feature Operation Sequence Diagram

3 Parameters3.1 Introduced Parameters3.2 Affected Parameters

4 Network Impact4.1 Capacity

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

6 Performance 6.1 KPIs6.2 Counters6.3 Events

7 O&M Information