CS Fallback Feature Parameter Description(ERAN2.0_01)

eRAN

CS Fallback Feature Parameter Description Issue 01

Date 2010-07-30

Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

Copyright © Huawei Technologies Co., Ltd. 2010. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd. Trademarks and Permissions

and other Huawei trademarks are the property of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders. Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied. The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute the warranty of any kind, express or implied.

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Email: [email protected]

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eRAN CS Fallback Feature Parameter Description Contents

Issue 01 (2010-07-30) Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

i

Contents

1 Introduction.................................................................................................................................1-1 1.1 Scope.............................................................................................................................................................1-1 1.2 Intended Audience.........................................................................................................................................1-1 1.3 Change History..............................................................................................................................................1-1

2 Overview of CSFB......................................................................................................................2-1 2.1 Architecture for CSFB to UTRAN/GERAN .................................................................................................2-2 2.2 Architecture for CSFB to CDMA2000 1xRTT..............................................................................................2-3 T

3 CSFB of Voice Services .............................................................................................................3-1 3.1 Overview.......................................................................................................................................................3-1 3.2 Triggering Phase at CSFB.............................................................................................................................3-2 3.3 Measurement Phase at CSFB ........................................................................................................................3-3

3.3.1 Measurement Configuration ................................................................................................................3-3 3.3.2 Setup of Measurement Gaps ................................................................................................................3-3 3.3.3 Measurement Reporting.......................................................................................................................3-3

3.4 Decision Phase at CSFB................................................................................................................................3-4 3.5 Execution Phase at CSFB..............................................................................................................................3-4

3.5.1 CSFB Method Selection.......................................................................................................................3-4 3.5.2 Retry and Penalty.................................................................................................................................3-5

3.6 Signaling Procedures of Typical CSFB.........................................................................................................3-5 3.6.1 Normal CSFB Procedures....................................................................................................................3-5 3.6.2 RRC Connection Re-Establishment After a Handover Failure ............................................................3-9

4 Engineering Guidelines............................................................................................................4-1 4.1 Network Selection for CSFB.........................................................................................................................4-1 4.2 Setting of Blind Handover Priorities for CSFB.............................................................................................4-1 4.3 Setting of Handover Parameters for CSFB ...................................................................................................4-2

5 Parameters ...................................................................................................................................5-1

6 Counters .......................................................................................................................................6-1

7 Glossary .......................................................................................................................................7-1 7.1 Terms.............................................................................................................................................................7-1 7.2 Acronyms and Abbreviations ........................................................................................................................7-1

1 Introduction eRAN

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ii Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

Issue 01 (2010-07-30)

8 Reference Documents ...............................................................................................................8-1

eRAN CS Fallback 1 Introduction


1-1

1 Introduction

1.1 Scope This document describes the Circuit Switched Fallback (CSFB) feature with its main focus on

procedures. It also provides engineering guidelines for setting the d to this feature.

1.2 Intend This document is intended for:

Personnel who need to understand CSFB o work with Huawei products

1.3 Changeis

Ther ined as follows:

Feature change: refers to the change in the CSFB feature of a specific product version. orial change: refers to the change in wording or the addition of the information that

ersion.

Document Issues The document issues are as follows:

01 (2010-07-30)

01 (2010-07-30) Compared with draft (2010-05-20), issue 01 (2010-07-30) incorporates the changes described i ab

the voice service fallbackessential parameters relate

ed Audience

Personnel wh

History Th section provides information on the changes in different document versions.

e are two types of changes, which are def

Editwas not described in the earlier v

Draft (2010-05-20)

n the following t le.

Change Type Change Description Parameter Change

Feature change None. None.

1 Introduction eRAN

CS Fallback

1-2 Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

Issue 01 (2010-07-30)

Change Type Change Description Parameter Change

Editorial change The mapping relationship between this document and features is added.

The description of voice and SMS services is added. For details, see chapter 2 "Overview of CSFB."

A figure is added to show the CSFB procedure of a voice service. For details, see Figure 3-1.

The reference documents are updated. For details, see chapter 8 "Reference Documents."

None.

Draft (2010-05-20) This is the draft.

eRAN CS Fallback 2 Overview of CSFB


2-1

2 Overview of CSFB

In the initial phase of Evolved Packet System (EPS) network deployment, operators owning mature 2G or 3G networks may adopt the following policy based on their Long Term

gacy

S)

, and ology (VoLGA). Based on the analysis of

technological maturity, industry chain, and deployment costs, CSFB can be used as an interim

, and [3] respectively.

r

ing

isited Mobile ge must be d Short

ord,

tions provide CSFB of voice and SMS services (in either a mobile-originated case or a mobile-terminated case) to a 2G or 3G network. The target

network.

This document describes optional features LOFD-001033 CS Fallback to UTRAN, ck to CDMA2000

Evolution/System Architecture Evolution (LTE/SAE) deployment plans: Use the leCircuit Switched (CS) voice solutions to provide voice services, and use the LTE/SAE network to provide Packet Switched (PS) services, including IP Multimedia Subsystem (IMdata services. This policy protects the CS investments of the operators.

From the technological perspective, three solutions are available for voice service provisioning in LTE networks: Single Radio Voice Call Continuity (SRVCC), CSFBVoice over LTE via Generic Access Techn

solution for CS service access before mature commercial use of IMS, to better utilize the existing CS networks. For details about CSFB, SRVCC, and VoLGA, see reference documents [1], [2]

When UEs under LTE coverage attempt to process CS services, CSFB enables switching of the UEs back to CS networks. In this way, the CS domain is reused to provide CS services fousers in the EPS.

CSFB is essentially a session setup procedure. That is, UEs fall back to the CS networks before CS voice sessions are set up. The UEs are always located in the CS networks durthe voice sessions. The CSFB feature is applicable in scenarios where the LTE network overlaps a 2G or 3G CS network. When such an LTE network is deployed, all VSwitching Centers (VMSCs) that serve overlapping areas with the LTE coveraupgraded to support the functions such as combined TA/LA update, paging, anMessage Service (SMS) on the SGs interface, which is similar to the Gs interface. In a wCSFB features simple network architecture, with the IMS system not required.

Huawei CSFB solu

network may be the Universal Terrestrial Radio Access Network (UTRAN), GSM EDGERadio Access Network (GERAN), or CDMA2000 1x Radio Transmission Technology (1xRTT)

LOFD-001034 CS Fallback to GERAN, and LOFD-001035 CS Fallba1xRTT.

2 Overview of CSFB eRAN

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2.1 Architecture for CSFB to UTRAN/GERAN

1 To implement CSFB to UTRAN or GERAN, an SGs interface is introduced between the Mobility Management Entity (MME) and the Mobile Switching Center (MSC). Figure 2-shows the architecture for CSFB to UTRAN/GERAN.

Figure 2-1 Architecture for CSFB to UTRAN/GERAN

es from Evolved

Voice Service

um (NAS) fies the MME of the call. Under the instruction from the MME, the

E-UTRAN performs CSFB to UTRAN/GERAN. Then, the UE makes the voice call in the target UTRAN/GERAN.

e

he target

SMS Service TRAN

S message that carries the SMS. The MME sends the SMS to the MSC for processing. When an SMS towards the UE arrives, the MSC sends the SMS to the MME, and E-UTRAN pages the UE. Then, the MME sends the UE an NAS message that carries the SMS.

The subsequent sections describe the CSFB of voice and SMS servicUTRAN (E-UTRAN) to UTRAN/GERAN.

The prerequisite for the CSFB to UTRAN/GERAN is that the UE is attached to E-UTRAN and also UTRAN/GERAN that covers the same area as E-UTRAN.

When the UE initiates a voice call, the UE sends the MME a Non Access Stratmessage, which noti

When a voice call towards the UE arrives, the MSC informs the MME of the call arrival. ThMME pages the UE in E-UTRAN. After the UE responds to the paging, E-UTRAN performs CSFB to UTRAN/GERAN. Then, the UE receives the voice call in tUTRAN/GERAN.

The prerequisite for the CSFB to UTRAN/GERAN is that the UE is attached to E-Uand also UTRAN/GERAN that covers the same area as E-UTRAN.

When the UE initiates an SMS service, the UE sends the MME an NA

eRAN CS Fallback 2 Overview of CSFB


2-3

During the SMS session, E-UTRAN transmits the SMS transparently. Thadoes not process the SMS. This document describes the CSFB of voice se

t is, E-UTRAN rvices only. For

2.2 ArchiteFigure 2-2 shows the architecture for CSFB to CDMA2000 1x Radio Transmission

of the S102 interface between the MME and the Circuit Switched Fallback Interworking Solution Function for 3GPP2 1xCS

the 1xCS IWS to

details about the CSFB of SMS services, see reference document [1].

cture for CSFB to CDMA2000 1xRTT

Technology (1xRTT), which is implemented on the basis

(1xCS IWS). The S102 interface provides a tunnel between the MME and relay 3GPP2 1xCS signaling messages.

Figure 2-2 Architecture for CSFB to CDMA2000 1xRTT

Voice Service

00 1xRTT network.

e MME of the call arrival. The MME sends a paging message through E-UTRAN to the UE. If the UE accepts the call, the UE sends an NAS message to the MME. Under the instruction from the MME, E-UTRAN performs CSFB to CDMA2000 1xRTT. (In this case, if there is any S1-U

The subsequent sections describe the CSFB of voice and SMS services from E-UTRAN to CDMA2000 1xRTT.

The prerequisite for the CSFB to CDMA2000 1xRTT is that the UE is attached to E-UTRAN and registers on the CS domain of the CDMA20

When the UE initiates a voice call, the UE sends the MME an NAS message, which notifies the MME of the call. Under the instruction from the MME, E-UTRAN performs CSFB to CDMA2000 1xRTT. (In this case, if there is any S1-U connection dedicated to the UE, the MME releases all the S1-U connections dedicated to the UE.) Then, the UE makes the voice call in the target CDMA2000 1xRTT network.

When a voice call towards the UE arrives, the CDMA2000 1xRTT network informs th

2 Overview of CSFB eRAN

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connection dedicated to the UE, the MME releases all the S1-U connections dedicated to the UE.) Then, the UE receives the voice call in the target CDMA2000 1xRTT network.

SMS Service

E sends the SMS to the 1xCS IWS for processing.

ries

During the SMS session, E-UTRAN transmits the SMS transparently. That is, E-UTRAN does not process the SMS. This document describes the CSFB of voice services only. For details about the CSFB of SMS services, see reference document [1].

The prerequisite for the CSFB to CDMA2000 1xRTT is that the UE is attached to E-UTRANand registers on the CS domain of the CDMA2000 1xRTT network.

When the UE initiates an SMS service, the UE sends E-UTRAN a Radio Resource Control (RRC) message that carries the SMS, and E-UTRAN forwards the message to the MME. Then, the MMWhen an SMS towards the UE arrives, the 1xCS IWS sends the SMS to the MME and the MME forwards the SMS to E-UTRAN. E-UTRAN sends the UE an RRC message that carthe SMS.

eRAN CS Fallback 3 CSFB of Voice Services


3-1

3 CSFB of Voice Services

3.1 Overviice session, it sends an

Extended Service Request (CS Fallback Indicator) to the MME. Based on this request es fallback of the voice service to

the target network through handover. For details about handover, see the Mobility meter Description.

dure of a voice service.

e service

ew When a UE is attached to the CS domain and cannot initiate an IMS vo

indication, the MME will perform CSFB. The CSFB enabl

Management in Connected Mode Feature Para

Figure 3-1 shows the CSFB proce

Figure 3-1 CSFB procedure of a voic

3 CSFB of Voice Services eRAN

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The

ter-RAT system, it performs a blind handover without delivering figuration to the UE. Otherwise, the eNodeB delivers the

ce ind handovers, however, have an impact on the

s rate.

the inter-RAT measurement configuration, and the UE performs

s.

ended

ties of the target network. If the target network supports PS handovers, the eNodeB performs a PS handover to the target network. Otherwise, the eNodeB suspends the PS services in the source cell.

edure of voice services and the typical signaling

3.2 TriggerodeB an

-A eNodCSF

Afte

lind handover, a list of candidate cells is generated on the basis of the blind

e r

If the eNodeB is configured to manage measurement-based handovers (that is, if the BlindHoSwitch parameter is set to OFF), it sends the UE the measurement configuration, according to which the UE performs measurements on the specified

CSFB of a voice service consists of the following phases:

Triggering phase The eNodeB receives a CS Fallback Indicator from the MME. If the eNodeB supports blind handovers to an inthe measurement conmeasurement configuration to the UE. Compared with measurement-based handovers, blind handovers can reduce the access delay. Therefore, blind handovers take precedenover measurement-based handovers. Blhandover succesMeasurement phase The eNodeB delivers inter-RAT measurements accordingly. Decision phase The eNodeB checks the measurement results and generates a list of candidate cellExecution phase The eNodeB executes CSFB to enable the UE to initiate the voice call in the target cell. The ongoing PS services of the UE might be handed over to the target cell or suspin the source cell. The action to take depends on the PS handover and PS service capabili

This chapter describes the CSFB procprocedures.

ing Phase at CSFB After a UE initiates a voice service in an E-UTRAN cell, the MME sends the eNS1 P Request message that contains a CS Fallback Indicator. This message indicates to the

eB that the UE should be moved to the target network. The target networks to which B is applicable are indicated through the CSFBHoSwitch parameter.

r receiving the S1-AP Request message, the eNodeB proceeds as follows:

If the eNodeB is configured to provide blind handovers (that is, if the BlindHoSwitchparameter is set to ON), it does not deliver the measurement configuration to the UE. Instead, the eNodeB performs a blind handover. During the bhandover priorities, which are determined by both the RAT-specific priorities and the cell-specific priorities. Of these candidate cells, cells in a system with a higher blind handover priority take precedence over cells in a system with a lower priority. In addition, cells in one system are ranked in descending order of their blind handover priorities. The RAT-specific priorities used in blind handovers for CSFB are defined through thInterRatHighestPri, InterRatSecondPri, and InterRatLowestPri parameters. Fodetails, see section 4.1 "Network Selection for CSFB."



3-3

system. The measurement configuratioinformation for only the RATs and freq

n sent to the UE contains the configuration uencies that are supported by the UE.

3.3 Measu3.3.1 Measu uration

B to 2G or 3G networks is the same as that for ture

3.3.2 Setup t Gaps for CSFB is the same as that of measurement gaps for

3.3.3 MeasuCSFB is triggered by event B1, which is reported in event-triggered periodic reporting mode.

ty is higher than a specified threshold t ines the entering and leaving conditions

B1 as follows:

wher

It is

AN,

f the

e Power (RSCP) threshold for CSFB to UTRAN, Ec/No B

S

n about the ,

frequency-specific offset for the frequency of the neighboring cell, hysteresis, reporting interval, maximum number of cells contained in one report, and number of periodic reports)

rement Phase at CSFB rement ConfigThe measurement configuration for CSFinter-RAT handovers. For details, see the Mobility Management in Connected Mode FeaParameter Description.

of MeasuremenThe setup of measurement gaps inter-RAT handovers. For details, see the Mobility Management in Connected Mode Feature Parameter Description.

rement Reporting

The triggering of event B1 indicates that the signal qualiin a least one neighboring cell. 3GPP TS 36.331 defof event

Entering condition: Mn + Ofn – Hys > Thresh Leaving condition: Mn + Ofn + Hys < Thresh

e:

Mn is the measurement result of the neighboring cell. Ofn is the frequency-specific offset for the frequency of the neighboring cell.contained in the associated measurement object Information Element (IE) in the measurement configuration. Hys is the hysteresis for event B1. The hysteresis values for CSFB to UTRAN, GERand CDMA2000 are included in the delivered measurement configuration. Thresh is the threshold for event B1. The values of Thresh are set on the basis omeasurement quantities of each RAT. The Received Signal Codthreshold for CSFB to UTRAN, threshold for CSFB to GERAN, and threshold for CSFto CDMA2000 1xRTT are specified through the CsfbHoUtranB1ThdRSCP, CsfbHoUtranB1ThdECN0, CsfbHoGeranB1Thd, and CsfbHoCDMAB1ThdPparameters respectively.

When the triggering condition of event B1 is met, the UE reports the informatiocells that meet the condition. The time-to-trigger for event B1 related to CSFB to UTRANGERAN, or CDMA2000 1xRTT is specified through the CsfbHoUtranTimeToTrig, CsfbHoGeranTimeToTrig, or CsfbHoCDMATimeToTrig parameter respectively.

The parameters related to periodic reporting of event B1 for CSFB (that is, the


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riodic reporting of event B1 for inter-RAT handovers. For ent in Connected Mode Feature Parameter Description.

3.4 Decisio, the eNodeB checks the measurement result reported by the UE.

Based on the result, the eNodeB determines whether CSFB is to be initiated and, if so, determines the target cell of the CSFB. The target cell is selected from a list of candidate cells,

fter the eNodeB receives the event B1 report. The target

3.5 Executi3.5.1 CSFB M

le to CSFB to UTRAN, GERAN, and C T and d e method sel pplicable methods are set t Switch r.

Table 3-1 CSFB methods es

are the same as those related to pedetails, see the Mobility Managem

n Phase at CSFB In the decision phase at CSFB

which is generated by the eNodeB acell is the best cell in the list.

on Phase at CSFB ethod Selection

Table 3-1 lists the methods that are applicabDMA2000 1xRT

hrough the HoAlgescribes th paramete

ection rules. The a

and selection rul

Target System Method Selection Rule

UTRAN PS handover od to use is selected from the list Redirection

The methin the Method column in descending order of priority, as determined by the support of both the UTRAN and the UE for the method.

GERAN

der ut

ssisted e

(CCO/NACC) Redirection

od to use is selected from the list in the Method column in descending order of priority, as determined by the support of both the GERAN and the UE for the

PS handover Cell Change Orwith or withoNetwork ACell Chang

The meth

method.

CDMA2000 1xRTT Redirection If the CDMA2000 1xRTT network and the port redirection, redirection is

applied.UE sup

The preceding CSFB methods are described as follows:

PS handover is applicable to PS services. In a PS handover, the services are handed over from the PS domain of the source system to the PS domain of the target system, to ensure continuous service provision. For details about PS handover, see the Mobility Management in Connected Mode Feature Parameter Description.

CCO/NACC is specific to the GSM cases. During the CCO/NACC, the UE is ordered to switch to the GERAN idle mode, and consequently it can try to access the GSM network.



3-5

The procedure is simple but causes a long delay. For details about CCO/NACC, see the Mobility Management in Connected Mode Feature Parameter Description. Redirection is a process i n which the eNodeB selects the highest ranked frequency based

n of frequency priorities and sends the information to the UEs through ion. It occurs when the resources for UEs in an overloaded E-UTRAN

e

3.5.2 Retry a

E to the cell where a e-induced admission failure has occurred. The UE is not allowed to retry CSFB to

this reduce the risk of call drops caused by CSFB failures.

on the configuratiosystem informatcell are released. For details about redirection, see the Idle Mode Management FeaturParameter Description.

nd Penalty If CSFB fails, the eNodeB tries the next best cell among the candidate cells. If the CSFB successively fails when the eNodeB tried all the candidate cells, the eNodeB waits for the next set of event-triggered periodic reports and if necessary performs the next cycle of retries.

During retries, a penalty is applied to the CSFB of the Unon-resourcthis cell for a specified number of times. After the retry prohibition, the UE can retry CSFB to

cell, but the number of retries is restricted. This can increase the success rate of CSFB and

For the description about the non-resource-induced admission failurConnected Mode Feature Parameter Description.

e, see the Mobility Management in

3.6 Signaling Procedures of Typical CSFB g procedures of voice call fallback to a 2G or 3G network.

The signaling procedure varies depending on the CSFB method. For details about the

3.6.1 Norma

PS Handover Procedure for CSFB to UTRAN/GERAN Figure 3-2 shows the signaling procedure of PS handover for CSFB to UTRAN or GERAN.

This section describes the signalin

signaling procedures, see reference document [1].

l CSFB Procedures


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Figure 3-2 Signaling procedure of PS handover

CCO/NACC Procedure for CSFB to GERAN Figure 3-3 shows the signaling procedure of CCO/NACC for CSFB to GERAN.



3-7

Figure 3-3 Signaling procedure of CCO/NACC

Redirection Procedure for CSFB to UTRAN/GERAN Figure 3-4 shows the signaling procedure of redirection for CSFB to UTRAN or GERAN.


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Figure 3-4 Signaling procedure of redirection to UTRAN or GERAN

Redirection Procedure for CSFB to CDMA2000 1xRTT Figure 3-5 shows the signaling procedure of redirection for CSFB to CDMA2000 1xRTT.



3-9

Figure 3-5 Signaling procedure of redirection to CDMA2000 1xRTT

3.6.2 RRC Connection Re-Establishment After a Handover Failure After handover-based CSFB fails, the UE performs a cell selection procedure and then performs a procedure of RRC connection re-establishment towards the selected cell.

The RRC connection re-establishment procedure performed after a handover-based CSFB failure is the same as that performed after an intra-frequency handover failure. For details, see the Mobility Management in Connected Mode Feature Parameter Description.

eRAN CS Fallback 4 Engineering Guidelines


4-1

4 Engineering Guidelines

This chapter provides engineering guidelines for the configuration of CSFB.

4.1 NetwoxRTT network.

The CSFB methods applicable to each target network are set through the HoAlgSwitch parameter. For example, the support of UTRAN for PS handovers can be specified through

N, GERAN, and Selection."

4.2 Setting of Blind Handover Priorities for CSFB lay;

ties are defined for each Public Land Mobile Network (PLMN). By default, the RATs are ranked as follows: UTRAN, GERAN, and CDMA2000, in descending order of

setting the priorities.

ators' policies, and the erage quality.

rk Selection for CSFB The target network of CSFB can be the UTRAN, GERAN, or CDMA2000 1The coverage of the target network must overlap that of E-UTRAN. The target networks to which CSFB is applicable are set through the CSFBHoSwitch parameter.

The BlindHoSwitch parameter is used to select whether blind handover or measurement-based handover should take place. If this parameter is set to ON, blind handover is selected. If this parameter is set to OFF, measurement-based handover is selected.

this parameter. For the methods applicable to the eNodeB for CSFB to UTRACDMA2000 1xRTT and the selection rules, see section 3.5.1 "CSFB Method

Compared with measurement-based handovers, blind handovers can reduce the access detherefore, blind handovers take precedence over measurement-based handovers. Blind handovers, however, have an impact on the handover success rate.

The RAT-specific priorities used in blind handovers for CSFB are specified through the InterRatHighestPri, InterRatSecondPri, and InterRatLowestPri parameters. A set of RAT-specific priori

priority. A maximum of four sets of RAT-specific priorities can be defined for each eNodeB. An operator can check the PLMNs that are already configured on the eNodeB, before

The blind handover priorities of RATs should be set according to operblind handover priorities of cells should be set on the basis of cell cov

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4.3 Setting

eeds to be set properly, to ensure that inter-RAT

er

FB to UTRAN, Ec/No threshold for CSFB to UTRAN, threshold h

, and CsfbHoCDMATimeToTrig parameters respectively. The setting of the time-to-trigger can reduce the number of incorrect handover decisions and the number of ping-pong handovers. An excessively long time-to-trigger, however, causes a long delay in CSFB, thereby affecting the user experience. It is recommended that these parameters retain their default values.

of Handover Parameters for CSFB According to the analysis of simulation results and the handover-related experience, the optimization of the eNodeB parameter settings related to handovers for CSFB can improve the handover performance. Examples of Key Performance Indicators (KPIs) related to handover performance are handover success rate, call drop rate, and ping-pong handover rate.

The threshold for event B1 related to CSFB nhandovers are triggered in time. A higher threshold results in a lower probability of triggering event B1, thereby affecting the user experience. A lower threshold results in a higher probability of triggering event B1, but it also causes a higher probability of incorrect handovdecisions and risk of ping-pong handovers.

The RSCP threshold for CSfor CSFB to GERAN, and threshold for CSFB to CDMA2000 1xRTT are specified througthe CsfbHoUtranB1ThdRSCP, CsfbHoUtranB1ThdECN0, CsfbHoGeranB1Thd, and CsfbHoCDMAB1ThdPS parameters respectively. It is recommended that these parametersretain their default values.

The time-to-trigger for event B1 related to CSFB to UTRAN, GERAN, and CDMA2000 1xRTT are specified through the CsfbHoUtranTimeToTrig, CsfbHoGeranTimeToTrig

eRAN CS Fallback 5 Parameters


5-1

5 Parameters

This chapter describes all the parameters presented in this document.

tion of each parameter, see Table 5-1. For the default value, value ranges, and M of each Table 5-2.

T r

For the descripML commands parameter, see

able 5-1 Paramete description (1)

MO Parameter ID Description

ENODEBALGOSWITCH

CSFBHoSwitch . If the switch is

to the GERAN is allowed. CS FALLBACK CDMA2000 1XRTT switch: This parameter is

CS FALLBACK UTRAN switch: This parameter is used to control whether to perform CS Fallback to the UTRANenabled, CS Fallback to the UTRAN is allowed. CS FALLBACK GERAN switch: This parameter is used to control whether to perform CS Fallback to the GERAN. If the switch is enabled, CS Fallback

used to control whether to perform CS Fallback to the CDMA2000 1XRTT. If the switch is enabled, CS Fallback to the CDMA2000 1XRTT is allowed.

ENODEBALGO BlindHoSwitch Blind handover switch: Indicates the switch that is used to enable

inter-frequency SWITCH and disable the blind handover algorithm. When this switch is set to

ON, the blind handover is allowed in CS fallback, load balancing, and inter-RAT load balancing.

CSFBBLINDHOCFG

InterRatHighestPri Indicates the high-priority system to be considered in blind handovers for CS fallback. It is UTRAN by default.

CSFBBLINDHOCFG

InterRatSecondPri m to be considered in blind handovers for CS fallback. It is GERAN by default. If this Indicates the medium-priority syste

parameter is set to null, the system with the medium blind handover priority is not specified. In this case, only the blind handovers to the high-priority system are applicable.

CSFBBLINDHOCFG

InterRatLowestPri ered in blind handovers for CS fallback. It is CDMA2000 by default. If this parameter is set to null, the system with the low blind handover priority is not specified. In this case, only the blind handovers to the high- and medium-priority systems are applicable.

Indicates the low-priority system to be consid

5 Parameters eRAN

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CSFALLBACKHO

CsfbHoUtranTimeToTrig

Indicates the time-to-trigger for event B1 that is used in CS fallback to UTRAN. When CS fallback to UTRAN is applicable, this parameter is set for UEs and used in the evaluation of whether to trigger event B1. When detecting that the signal quality in at least one UTRAN cell meets the entering condition, the UE does not send a measurement report to the eNodeB immediately. Instead, the UE sends a report only when the signal quality continuously meets the entering condition during the time-to-trigger. This parameter helps decrease the number of occasionally triggered event reports, the average number of handovers, and the number of wrong handovers, and thus helps prevent unnecessary handovers. For details, see 3GPP TS 36.331.

CSFALLBACKHO

CsfbHoGeranTimeToTrig

Indicates the time-to-trigger for event B1 that is used in CS fallback to GERAN. When CS fallback to GERAN is applicable, this parameter is set for UEs and used in the evaluation of whether to trigger event B1. When detecting that the signal quality in at least one GERAN cell meets the entering condition, the UE does not send a measurement report to the eNodeB immediately. Instead, the UE sends a report only when the signal quality continuously meets the entering condition during the time-to-trigger. This parameter helps decrease the number of occasionally triggered event reports, the average number of handovers, and the number of wrong handovers, and thus helps prevent unnecessary handovers. For details, see 3GPP TS 36.331.

CSFALLBACKHO

CsfbHoCDMATimeToTrig

Indicates the time-to-trigger for event B1 that is used in CS fallback to CDMA2000. When CS fallback to CDMA2000 is applicable, this parameter is set for UEs and used in the evaluation of whether to trigger event B1. When detecting that the signal quality in at least one CDMA2000 cell meets the entering condition, the UE does not send a measurement report to the eNodeB immediately. Instead, the UE sends a report only when the signal quality continuously meets the entering condition during the time-to-trigger. This parameter helps decrease the number of occasionally triggered event reports, the average number of handovers, and the number of wrong handovers, and thus helps prevent unnecessary handovers. For details, see 3GPP TS 36.331.

CSFALLBACKHO

CsfbHoUtranB1ThdRSCP

Indicates the RSCP threshold for event B1 that is used in CS fallback to UTRAN. When CS fallback to UTRAN is applicable, this parameter is set for UEs and used in the evaluation of whether to trigger event B1. This parameter indicates the RSCP requirement for the UTRAN cells to be included in the measurement report. A UE sends a measurement report related to event B1 to the eNodeB when the RSCP in at least one UTRAN cell exceeds this threshold and other triggering conditions are met. For details, see 3GPP TS 36.331.



5-3


CSFALLBACKHO

CsfbHoUtranB1ThdECN0

Indicates the Ec/No threshold for event B1 that is used in CS fallback to UTRAN. When CS fallback to UTRAN is applicable, this parameter is set for UEs and used in the evaluation of whether to trigger event B1. This parameter indicates the Ec/No requirement for the UTRAN cells to be included in the measurement report. A UE sends a measurement report related to event B1 to the eNodeB when the Ec/No in at least one UTRAN cell exceeds this threshold and other triggering conditions are met. For a cell with large signal fading variance, set this parameter to a large value to avoid unnecessary handovers. For a cell with small signal fading variance, set this parameter to a small value to ensure that the handover is performed in time. Actual value = GUI value x 0.5. For details, see 3GPP TS 36.331.

CSFALLBACKHO

CsfbHoGeranB1Thd Indicates the RSSI threshold for event B1 that is used in CS fallback to GERAN. A UE sends a measurement report related to event B1 to the eNodeB when the RSSI in at least one GERAN cell exceeds this threshold and other triggering conditions are met. For details, see 3GPP TS 36.331.

CSFALLBACKHO

CsfbHoCDMAB1ThdPS

Indicates the pilot strength threshold for event B1 that is used in CS fallback to CDMA2000. A UE sends a measurement report related to event B1 to the eNodeB when the pilot strength in at least one CDMA2000 cell exceeds this threshold and other triggering conditions are met. Actual value = GUI value x 0.5. For details, see 3GPP TS 36.331.

Table 5-2 Parameter description (2)

MO Parameter ID

Default Value

GUI Value Range

Actual Value Range

Unit MML Command

ENODEBALGOSWITCH

CSFBHoSwitch

UTRAN_FALLBACK_SWTICH:off, GERAN_FALLBACK_SWTICH:off, CDMA_1XRTT_FALLBACK_SWTICH:off

UTRAN_FALLBACK_SWTICH, GERAN_FALLBACK_SWTICH, CDMA_1XRTT_FALLBACK_SWTICH

UTRAN_FALLBACK_SWTICH, GERAN_FALLBACK_SWTICH, CDMA_1XRTT_FALLBACK_SWTICH

None MOD ENODEBALGOSWITCH

ENODEBALGOSWITCH

BlindHoSwitch

OFF OFF, ON OFF, ON None MOD ENODEBALGOSWITCH

5 Parameters eRAN

CS Fallback


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MO Parameter ID

Default Value

GUI Value Range

Actual Value Range

Unit MML Command

CSFBBLINDHOCFG

InterRatHighestPri

UTRAN UTRAN, GERAN, CDMA2000

UTRAN, GERAN, CDMA2000

None MOD CSFBBLINDHOCFG

CSFBBLINDHOCFG

InterRatSecondPri

GERAN UTRAN, GERAN, CDMA2000, NULL

UTRAN, GERAN, CDMA2000, NULL


CSFBBLINDHOCFG

InterRatLowestPri

CDMA2000




CSFALLBACKHO

CsfbHoUtranTimeToTrig

40ms 0ms, 40ms, 64ms, 80ms, 100ms, 128ms, 160ms, 256ms, 320ms, 512ms, 480ms, 640ms, 1024ms, 1280ms, 2560ms, 5120ms

0ms, 40ms, 64ms, 80ms, 100ms, 128ms, 160ms, 256ms, 320ms, 512ms, 480ms, 640ms, 1024ms, 1280ms, 2560ms, 5120ms

ms MOD CSFALLBACKHO

CSFALLBACKHO

CsfbHoGeranTimeToTrig



ms MOD CSFALLBACKHO

CSFALLBACKHO

CsfbHoCDMATimeToTrig



ms MOD CSFALLBACKHO

CSFALLBACKHO

CsfbHoUtranB1ThdRSCP

-106 -120~-25 -120~-25 dBm MOD CSFALLBACKHO

CSFALLBACKHO

CsfbHoUtranB1ThdECN0

-13 -48~0 -24~0 0.5dB MOD CSFALLBACKHO

CSFALLBACKHO

CsfbHoGeranB1Thd

-103 -110~-48 -110~-48 dBm MOD CSFALLBACKHO



5-5

MO Parameter Default GUI Value Actual Value Unit MML ID Value Range Range Command

CSFALLBACKHO

CsfbHoCDMAB1ThdPS

-34 -63~0 -31.5~0 0.5dB MOD CSFALLBACKHO

eRAN CS Fallback 6 Counters


6-1

6 Counters

For details about the counters related to CSFB, see the eNodeB Performance Counter Reference.

eRAN CS Fallback 7 Glossary


7-1

7 Glossary

7.1 Terms

7.2 Acronym nd AWS llback Interworking Solution Function for 3GPP2 1xCS

r

2000

smission Technology

k

TRAN

N Network

ubsystem

ator

tion

y

ter

m

None.

s a bbreviations 1xCS I Circuit Switched Fa

3GPP Third Generation Partnership Project

CCO Cell Change Orde

CDMA1xRTT

CDMA2000 1x Radio Tran

CS Circuit Switched

CSFB Circuit Switched Fallbac

eNodeB E-UTRAN NodeB

EPS Evolved Packet System

E-U Evolved UTRAN

GERA GSM EDGE Radio Access

IE Information Element

IMS IP Multimedia S

KPI Key Performance Indic

LA Location Area

LTE Long Term Evolu

MME Mobility Management Entit

MO Managed Object

MSC Mobile Switching Cen

NACC Network Assisted Cell Change

NAS Non Access Stratu

7 Glossary eRAN

CS Fallback


Issue 01 (2010-07-30)

rk

ower

ervice

CC e Call Continuity

VMSC Visited Mobile Switching Center

VoLGA Voice over LTE via Generic Access Technology

PLMN Public Land Mobile Netwo

PS Packet Switched

RAT Radio Access Technology

RRC Radio Resource Control

RSCP Received Signal Code P

SAE System Architecture Evolution

SMS Short Message S

SRV Single Radio Voic

TA Tracking Area

UE User Equipment

UTRAN Universal Terrestrial Radio Access Network

eRAN CS Fallback 8 Reference Documents


8-1

8 Reference Documents

This chapter lists the reference documents related to CSFB:

[1] 3GPP TS 23.272, "Circuit Switched (CS) fallback in Evolved Packet System (EPS)"

(SRVCC); Stage 2"

tions

cription"

[7] Mobility Management in Connected Mode Feature Parameter Description

[8] Idle Mode Management Feature Parameter Description

[2] 3GPP TS 23.216, "Single Radio Voice Call Continuity

[3] VoLGA Forum Specifica

[4] 3GPP TS 36.300, "E-UTRAN Overall des

[5] eNodeB MO Reference

[6] eNodeB Performance Counter Reference

CS Fallback Feature Parameter Description(ERAN2.0_01)

Documents

Transcript of CS Fallback Feature Parameter Description(ERAN2.0_01)