Interoperability Between GSM and WCDMA(GBSS14.0_04)

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GSM BSS

GBSS14.0

Interoperability Between GSM andWCDMA Feature Parameter Description

Issue 04

Date 2013-04-12

HUAWEI TECHNOLOGIES CO., LTD.


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Copyright Huawei Technologies Co., Ltd. 2013. All rights reserved.

No part of this document may be reproduced or transmitted in any form or by any means without prior writtenconsent of Huawei Technologies Co., Ltd. Trademarks and Permissions

and other Huawei trademarks are trademarks 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 thecustomer. 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 representationsof any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in thepreparation of this document to ensure accuracy of the contents, but all statements, information, andrecommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd. Address: Huawei Industrial Base

Bantian, LonggangShenzhen 518129People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

Issue 04 (2013-04-12) Huawei Proprietary and ConfidentialCopyright Huawei Technologies Co., Ltd.

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Contents

1 Introduction........ ............................................................................................................................11.1 Scope....... ...........................................................................................................................................................1

1.2 Intended Aud ience..............................................................................................................................................2

1.3 Change Histo ry...................................................................................................................................................2

2 Overview........ .................................................................................................................................5

3 Iur-g Interface Between GSM and WCDMA...........................................................................6

4 Measurement of Neighboring WCDMA Cells........................................................................7

5 GSM/W CDMA Inter-RAT Cell Reselection............................................................................95.1 Cell Resel ection from WCDMA to GSM.........................................................................................................10

5.1.1 Cell Res election from WCDMA to GSM for MSs in Idle Mode............................................................10

5.1.2 WCDM A-to-GSM NACC.......................................................................................................................10

5.2 Cell Reselecti on from GSM to WCDMA.........................................................................................................11

5.2.1 Cell Res election Based on Cell Ranking.................................................................................................11

5.2.2 Optimiz ed GSM-to-WCDMA Cell Reselection in Packet Transfer Mode.............................................12

5.2.3 Fast WCDMA Reselection at 2G CS Call Release.................................................................................13

5.2.4 NC2 bet ween GSM and WCDMA..........................................................................................................15

5.2.5 Forced NC2 Between GSM and WCDMA.............................................................................. ...............20

5.3 BSC supp orting Blind Search...........................................................................................................................21

6 GSM/W CDMA Inter-RAT CS Handover...............................................................................236.1 CS Handover from WCDMA to GSM.............................................................................................................24

6.2 CS Handover from GSM to WCDMA.............................................................................................................24

6.2.1 Overview.................................................................................................................................................24

6.3 Se rvice-Based CS Handover from GSM to WCDMA.....................................................................................25

6.3.1 Over view.................................................................................................................................................25

6.3.2 Proc edure.................................................................................................................................................25

6.4 Load-Bas ed CS Handover from GSM to WCDMA.........................................................................................26

6.4 .1 Overview.................................................................................................................................................26

6.4.2 Procedure.................................................................................................................................................26

7 GSM/WCDMA Inter-RAT PS Handover................................................................................287.1 WCDMA-to-GSM PS Handover......................................................................................................................29

7.1.1 Overview.................................................................................................................................................29

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description Contents


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7.1.2 Procedure.................................................................................................................................................29

7.2 GSM-to-WCDMA PS Handover......................................................................................................................31

7.2.1 Overview.................................................................................................................................................31

7.2.2 Procedure.................................................................................................................................................33

8 Related Features...........................................................................................................................36

9 Impact on the Network...............................................................................................................409.1 GSM/WCDM A Interoperability.......................................................................................................................40

9.1.1 Impact o n System Capacity.....................................................................................................................40

9.1.2 Impact o n Network Performance.............................................................................................................40

9.2 GSM/WCDM A Service Based Handover........................................................................................................40



9.3 GSM/WC DMA Load Based Handover............................................................................................................409.3.1 Impact o n System Capacity.....................................................................................................................41


9.4 2G/3G Cell R eselection Based on MS State....................................................................................................41



9.5 BSC supporti ng Blind Search...........................................................................................................................41

9.5.1 Impa ct on System Capacity.....................................................................................................................41

9.5 .2 Impact on Network Performance.............................................................................................................41

9.6 Fast WCDMA Reselection at 2G CS Call Release..........................................................................................41



10 Engineering Guidelines...........................................................................................................4310.1 When to Use Interoperability Between GSM and WCDMA.........................................................................43

10.1.1 GS M/WCDMA Interoperability............................................................................................................43

10.1.2 GSM/ WCDMA Service Based Handover.............................................................................................43

10.1.3 GSM/ WCDMA Load Based Handover.................................................................................................43

10.1.4 2G /3G Cell Reselection Based on MS State.........................................................................................44

10.1.5 BSC su pporting Blind Search................................................................................................................4410.1.6 Fast W CDMA Reselection at 2G CS Call Release...............................................................................44

10.2 Informat ion to Be Collected...........................................................................................................................44

10.2.1 GSM/ WCDMA Interoperability............................................................................................................44

10.2.2 GSM/ WCDMA Service Based Handover.............................................................................................44

10.2.3 GS M/WCDMA Load Based Handover.................................................................................................44

10.2.4 2G/3G Cell Reselection Based on MS State.........................................................................................44

10.2.5 BSC su pporting Blind Search................................................................................................................45

10.2.6 Fas t WCDMA Reselection at 2G CS Call Release...............................................................................45

10.3 N etwork Planning...........................................................................................................................................45

10.3.1 GSM/WCDMA Interoperability............................................................................................................45



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10.3.2 GSM/WCDMA Service Based Handover.............................................................................................45

10.3.3 GSM/WCDMA Load Based Handover.................................................................................................46

10.3.4 2G/3G Cell Reselection Based on MS State.........................................................................................46

10.3.5 BSC supporting Blind Search................................................................................................................46

10.3.6 Fast WCDMA Reselection at 2G CS Call Release...............................................................................47

10.4 Overall Deployment Procedure......................................................................................................................47

10.5 Deploying GSM/WCDMA Interoperability...................................................................................................47

10.6 Deploying 2G/3G Cell Reselection Based on MS State.................................................................................47

10.7 Deploying GSM/WCDMA Service Based Handover....................................................................................47

10.8 Deploying GSM/WCDMA Load Based Handover........................................................................................47

10.9 Deploying Fast WCDMA Reselection at 2G CS Call Release......................................................................48

10.10 Deploying BSC supporting Blind Search.....................................................................................................48

10.11 Performance Optimization............................................................................................................................48

10.11.1 GSM/WCDMA Interoperability and 2G/3G Cell Reselection Based on MS State............................4810.11.2 GSM/WCDMA Service Based Handover and GSM/WCDMA Load Based Handover.....................48

10.11.3 Fast WCDMA Reselection at 2G CS Call Release.............................................................................49

10.11.4 BSC supporting Blind Search..............................................................................................................49

10.12 Troubleshooting............................................................................................................................................49

11 Parameters...................................................................................................................................50

12 Counters....................................................................................................................................134

13 Glossary.....................................................................................................................................152

14 Reference Documents.............................................................................................................153



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1 Introduction1.1 Scope

This document describes the Interoperability Between GSM and WCDMA feature, includingits technical description, feature dependencies, network impact, and engineering guidelines. Thetechnical description includes measurement of neighboring WCDMA cells, GSM/WCDMAinter-RAT cell reselection, and GSM/WCDMA inter-RAT CS/PS handover.

The Interoperability Between GSM and WCDMA feature involves the following features:

l GBFD-114301 GSM/WCDMA Interoperabilityl GBFD-114321 GSM/WCDMA Service Based Handover l GBFD-114322 GSM/WCDMA Load Based Handover l GBFD-114323 2G/3G Cell Reselection Based on MS Statel GBFD-114325 Fast WCDMA Reselection at 2G CS Call Releasel GBFD-511101 Load Based Handover Enhancement on Iur-gl GBFD-511102 NACC Procedure Optimization Based on Iur-gl GBFD-511103 GSM and WCDMA Load Balancing Based on Iur-gl GBFD-511104 GSM and WCDMA Traffic Steering Based on Iur-gl GBFD-119502 PS Handover l

GBFD-116201 Network-Controlled Cell Reselection (NC2)l GBFD-511110 BSC supporting Blind Search

The following features are described in this document:

l GBFD-114301 GSM/WCDMA Interoperabilityl GBFD-114321 GSM/WCDMA Service Based Handover l GBFD-114322 GSM/WCDMA Load Based Handover l GBFD-114323 2G/3G Cell Reselection Based on MS Statel GBFD-114325 Fast WCDMA Reselection at 2G CS Call Releasel GBFD-119502 PS Handover l GBFD-116201 Network-Controlled Cell Reselection (NC2)

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l GBFD-511110 BSC supporting Blind Search

The following features are described in the Common Radio Resource Management Feature Parameter Description :

l GBFD-511101 Load Based Handover Enhancement on Iur-gl GBFD-511103 GSM and WCDMA Load Balancing Based on Iur-gl GBFD-511104 GSM an d WCDMA Traffic Steering Based on Iur-g

The following features are described in the NACC Feature Parameter Description :

l GBFD-511102 NACC Procedure Optimization Based on Iur-g

1.2 Intended AudienceThis document is intended for:

l Personnel who need to understand the Interoperability Between GSM and WCDMA featurel Personnel who work with Huawei GSM products

1.3 Change HistoryThis section provides information about the changes in different document versions.

There are two types of changes, which are defined as follows:

l Feature change: refers to a change in the Interoperability Between GSM and WCDMAfeature of a specific product version.

l Editorial change: refers to a change in wording or the addition of information that was notdescribed in the earlier version.

Document Issues

The document issues are as follows:

l 04 (2013-04-12)l 03 (2012-12-31)l 02 (2012-08-30)

l 01 (2012-04-28)l Draft A (2012-02-15)

04 (2013-04-12)

This is the fourth release of GBSS14.0. Compared with issue 03 (2012-12-31) of GBSS14.0,issue 04 (2013-04-12) of GBSS14.0 incorporates the changes described in the following table

ChangeType

Change Description ParameterChange

Featurechange

Added section 5.2.2 Optimized GSM-to-WCDMA CellReselection in Packet Transfer Mode

None



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ChangeType


Editorialchange

Added descriptions about the mutually exclusive featuresand impacted features of GBFD-511110 BSC supportingBlind Search. For details, see chapter 8 Related Features .

None

03 (2012-12-31)This is the third release of GBSS14.0. Compared with issue 02 (2012-08-30) of GBSS14.0, issue03(2012-12-31) of GBSS14.0 incorporates the changes described in the following table

ChangeType


Featurechange

Added the following chapter:

Chapter 5.2.5 Forced NC2 Between GSM and WCDMA

Added thefollowing

parameter:

GSMTOFDDFORCENC2

Editorialchange

None None

02 (2012-08-30)This is the second release of GBSS14.0.

Compared with issue 01 (2012-04-28) of GBSS14.0, issue 02 (2012-08-30) of GBSS14.0incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change None None

Editorial change Deleted the descriptions of cell reselection based on cell

priority and added therelevant descriptions to the Interoperability BetweenGSM and LTE Feature

Parameter Description .

None

01 (2012-04-28)This is the first release of GBSS14.0.

Compared with issue draft A (2012-02-15) of GBSS14.0, issue 01 (2012-04-28) of GBSS14.0has no change.



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Draft A (2012-02-15)

This is a draft.

Compared with issue 01 (2011-03-31) of GBSS13.0, draft A (2012-02-15) of GBSS14.0

incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change Added the GBFD-511110BSC supporting BlindSearch feature.

Optimized theGBFD-114325 FastWCDMA Reselection at2G CS Call Release

Added the following parameter:

INPUT3GARFCNEN

INTERRATCELLRESELOPT- EN

Editorial change Added the followingchapters:l Chapter 8 Related

Featuresl Chapter 9 Impact on

the Network l Chapter 10

EngineeringGuidelines

None



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2 OverviewWCDMA and GSM will coexist for a long time. Therefore, Huawei GSM BSS provides GSM/WCDMA interoperability, which allows inter-RAT handovers and inter-RAT cell reselections

between GSM and WCDMA.

GSM/WCDMA interoperability supports smooth evolution from GSM to WCDMA, whichhelps reduce operators' capital expenditure (CAPEX). This feature provides operators with bothWCDMA and GSM networks complete support for a seamless coverage from GSM to WCDMA.For example, with the cell reselection or handover function, operators can keep providingservices for a dual-mode MS that moves away from the WCDMA coverage, thereby improvinguser experience.

In areas covered by both GSM and WCDMA networks, Interoperability between GSM andWCDMA balances traffic loads between two networks. For example, when the traffic load in a

GSM cell is too high, Interoperability between GSM and WCDMA can hand over some calls inthe GSM cell to a WCDMA cell.

Interoperability between GSM and WCDMA also allows operators to set different service access policies in areas covered by both GSM and WCDMA networks. For example, GSM is preferentially selected for handling CS services and WCDMA for PS services.

NOTE

All MSs mentioned in this document are multi-mode MSs that support both GSM and WCDMA.

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 2 Overview


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3 Iur-g Interface Between GSM and WCDMALoad information exchange is a prerequisite for the Interoperability Between GSM andWCDMA feature. Load information exchange consists of the following types:

l Load information exchange through the core network (CN): Load information, which iscarried in the information elements (IEs) in the signaling for handovers, is exchanged

between the GSM BSC over the A interface and the WCDMA RNC over the Iu interface.In this situation, load information exchanges irregularly. Therefore, unnecessary handover attempts may occur.

l Load information exchange through the Iur-g interface: Load information is exchanged between the GSM BSC and the WCDMA RNC through the Iur-g interface instead of theCN. Through the Iur-g interface, the GSM BSC and WCDMA RNC can exchange loadinformation with each other by performing information exchange and commonmeasurement. This simplifies the GSM/WCDMA interoperability procedure, shortens thehandove r delay, and increases the handover success rate.

Figure 3-1 shows the position of the Iur-g interface on a network.

Figure 3-1 Position of the Iur-g interface on a network

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 3 Iur-g Interface Between GSM and WCDMA


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4 Measurement of Neig hb oring WCDMACel ls

To support cell resele ction and handover from GSM to WCDMA, the BSS sends the neighboringWCDMA cell list and parameters for cell reselection and handover through system information(SI) to MSs. MSs the n measure neighboring WCDMA cells based on the received information.SI consists of SI2quater and Measurement Information. SI2quate r is sent on the BCCH, andMeasurement Inform ation is sent on the SACCH. The Send2QuterFlag parameter specifieswhether to send SI2quater.

MSs in GSM cells m easure both the signal level of neighboring GSM cells and the signal qualityof neighboring WCDMA cells. The BSS controls the neighborin g cell measurement to avoidunnecessary measurements and reduce the power con sumption of MSs. MSs in idle mode or

packet transfer mode can perform inter-RAT cell reselection. MSs in dedicated mode can perform inter-RAT handover. Operators can set different measurement parameters for MSsoperating in different modes.

When an MS is in idle mode, it determines whether to measure information about neighboringWCDMA cells based on the value of QI and the receive level of the serving cell. The conditionsfor triggering measurement depend on the value of QI .

l If QI is set to a value within the range of 0 to 6, the measurement is triggered when thereceive level of the serving cell is lower than QI .

l If QI is set to a value within the range of 8 to 14, the measurem ent is triggered w hen thereceive level of the serving cell is higher than QI .

l If QI is set to 7, MSs always measure neighboring WCDMA cell information.l If QI is set to 15, MSs do not measure neighboring WCDMA cell information.

Normally, MSs in packet transfer mode determine whether to measure the information aboutneighboring WCDMA cells according to the value of QI and the receive level of the servingcell. If any of the following conditions are met, MSs in packet transfer mode determine whether to measure neighboring WCDMA cell information based on the value of QP and the receivelevel of the serving cell.

l The GSM cell has a PBCCH, and QP is broadcast on the PBCCH.l The serving GSM cell does not have a PBCCH but QP is broadcast on the BCCH. In

addition, MSs have received the Packet Cell Change Order message or the Packet

Measurement Order message that carries the GPRS cell reselection parameters of one or more WCDMA cells.

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 4 Measurement of Neighboring WCDMA Cells


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The conditions for triggering measurement depend on the value of QP .

l If QP is set to a value within the range of 0 to 6, the measurement is triggered when thereceive level of the serving cell is lower than the value of QP .

l If QP is set to a value within the range of 8 to 14, the measurement is triggered when thereceive level of the serving cell is higher than the value of QP .

l If QP is set to 7, MSs always measure neighboring WCDMA cell information.l If QP is set to 15, MSs do not measure neighboring WCDMA cell information.

When an MS is in dedicated mode, it determines whether to measure the information aboutneighboring WCDMA cells based on QSEARCHC and the receive level of the serving cell. Theconditions for triggering the measurement depend on the value of QSEARCHC .

l If QSEARCHC is set to a value within the range of 0 to 6, the measurement is triggeredwhen the receive level of the serving cell is lower than QSEARCHC .

l If QSEARCHC is set to a value within the range of 8 to 14, the measurement is triggered

when the receive level of the serving cell is higher than QSEARCHC .l If QSEARCHC is set to 7, MSs always measure neighboring WCDMA cell information.l If QSEARCHC is set to 15, MSs do not measure neighboring WCDMA cell information.

QSEARCHC is contained in the Measurement Information message. After entering dedicatedmode, MSs attempt to obtain QSEARCHC from the Measurement Information messagetransmitted on the SACCH. Before QSEARCHC is obtained, MSs use the value of QCI that istransmitted on the BCCH as the value of QSEARCHC .

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 4 Measurement of Neighboring WCDMA Cells


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5 GSM/WCDMA Inter-RAT Cell ReselectionGSM/WCDMA inter-RAT cell reselection includes WCDMA-to-GSM cell reselection andGSM-to-WCDMA cell reselection. Cell reselection is mainly performed by MSs.

For MSs in idle mode, GSM/WCDMA interoperability involves only GSM/WCDMA inter-RATcell reselection. A dual-mode or multi-mode MS camping on a GSM cell measures theinformation about neighboring WCDMA cells, and then decides whether to reselect theWCDMA cell based on cell reselection parameters.

For MSs in packet transfer mode, cell reselection modes include network-controlled mode 0(NC0), network-controlled mode 1 (NC1), and network-controlled mode 2 (NC2). MSs canreselect a WCDMA cell for PS services. NC0 cell reselection and NC1 cell reselection are

performed by MSs without the intervention of the BSS. In NC2 cell reselection, the BSS sendssignaling to steer MSs towards desired camping cells.

The INTERRATCELLRESELEN parameter specifies whether to enable GSM/WCDMA inter-RAT cell reselection. When INTERRATC ELLRESELEN is set to NO( No) , the BSS does notsend the neighbor ing WCDMA cell list and the p arameters related to GSM/WCDMA inter-RATcell reselection. In this case, MSs in a GSM cell cannot reselect a WCDMA cell.

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 5 GSM/WCDMA Inter-RAT Cell Reselection


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5.1 Cell Reselection from WCDMA to GSMCell reselection from WCDMA to GSM involves the cell reselection for MSs in idle and packettransfer modes. In addition, cell reselection for MSs in packet transfer mode is WCDMA-to-GSM NACC or enhanced WCDMA-to-GSM NACC.

5.1.1 Cell Reselection from WCDMA to GSM for MSs in Idle ModeWhen an MS moves to the GSM coverage area and reselects a GSM cell, the MS initiates alocation update to the GSM network if the location area is changed. The GSM network handlesthe location update regardless of whether the MS is from a WCDMA cell.

In the BSS, the cell reselection procedure from WCDMA to GSM is the same as that betweenGSM cells. Therefore, this procedure is not described in this document.

5.1.2 WCDMA-to-GSM NACCThe WCDMA-to-GSM NACC procedure is specified in 3GPP specifications. The GSM-to-WCDMA NACC procedure, however, is not.

Figure 5-1 shows the WCDMA-to-GSM NACC procedure.

Figure 5-1 WCDMA-to-GSM NACC procedure

After the RNC determines that an MS should reselect a GSM cell, it sends a Cell Change Order From UTRAN message to the MS. If the WCDMA-to-GSM NACC procedure is applied, theCell Change Order From UTRAN message carries the IE "Geran System Information" thatcontains the SI1, SI3, and SI13 of the target GSM cell.

Before performing WCDMA-to-GSM NACC, the RNC obtains the SI of the target GSM cell

through the RAN Information Management (RIM) procedure. The RIM procedure consists of SI request and SI update procedures.



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l SI request procedure: This procedure is initiated by the source RNC, requesting the SI aboutthe target GSM cell.

l SI update procedure: This procedure is initiated by the target BSC, instructing the sourceRNC to update the SI about the target GSM cell.

After receiving the Cell Change Order From UTRAN message, the MS leaves the WCDMA celland reselects the GSM cell. After the cell reselection is complete, the MS use s the SI abou t thetarget GSM cell in the initial packet access procedure. In this manner, the period of packet servicedisruption is shortened.

During the WCDMA-to-GSM NACC procedure, the RIM procedure must be supported on theGb interface. To support the RIM procedure, the BSC must be configured with the RIMSUP

parameter for the NSE to indicate whether the RIM procedure is supported.

5.2 Cell Reselection from GSM to WCDMACell reselection from GSM to WCDMA includes cell reselection for MSs in idle and packettransfer modes. Cell reselection for MSs in idle mode refers to cell reselection based on cellranking. Fast 3G Reselection at 2G CS Call Rel ease and NC2 between GSM and WCDMA areoptimized cell reselection solutions, which ca n accelerate cell reselection.

5.2.1 Cell Reselection Based on Cell Ranking MSs in a GSM cell obtain the neighboring WCDMA cell list and cell reselection parametersfrom SI2quater, and then measure neighboring WCDMA cells according to the list and

parameters. The mechanism for NC0 or NC1 cell reselection from GSM to WCDMA for MSsin idle mode is the same as that for MSs in packet transfer mode. In the GSM network, cell

reselection from GSM to WCDMA is controlled by QI , FDDQOFF , and FDDQMIN .QI is the start level for measuring neighboring WCDMA cells. In the NC0 or NC1 cell reselectionfor MSs in idle or packet transfer mode, MSs start to search for ne igh boring WCD MA cellswhen the level of the serving cell is lower than the value of QI (when QI is set to a value withinthe range of 0 to 6) or higher than the value of QI (when QI is set to a value within the range of 8 to 14). When QI is set to 7, MSs always search for neighboring WCDMA cells.

Ec/No and Received Signal Code Power (RSCP) of the Common Pilot Channel (CPICH) arecommonly used during neighboring WCDMA cell measurement. An MS starts GSM-to-WCDMA cell reselections if the following conditions are met and last for more than five seconds:

l CPICH RSCP > RLA_C + FDDQOFF l CPICH Ec/No FDDQMIN - FDDQMINOFFSET l CPICH RSCP FDD_RSCP_threshold

NOTE

In WCDMA, Ec/No is the ratio of energy per modulating bit to the noise spectral density. It is equivalentto C/I in GSM.

Where,

l RLA_C is the average receive level. In a GSM-to-WCDMA cell reselection, the RSCP of the neighboring WCDMA cell must meet the following requirements: RSCP > Average receive level of the serving cell + FDDQOFF RSCP > Receive level of each neighboring GSM cell + FDDQOFF



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l FDDQOFF is the receive level difference between the candidate WCDMA cell and theserving GSM cell. This parameter is a key factor for controlling the GSM-to-WCDMA cellreselection. The greater the value of FDDQOFF is, the more difficult it is for the GSM-to-WCDMA cell reselection condition to be met, and more MSs will camp on the GSMcell.

l FDDQMIN is the minimum Ec/No threshold for GSM-to-WCDMA cell reselection. Thegreater the value of FDD Q MIN is, the more difficult it is to meet the cell reselectioncondition. FDDQMINOFFSET is offset of the minimum Ec/No threshold for GSM-to-WCDMA cell reselection. An MS determines the minimum receive level of a candidateWCDMA cell for cell reselection based on FDDQMIN and FDDQMINOFFSET . Thatis, FDDQMIN and FDDQMINOFFSET do not determine the cell reselection from GSMto WCDMA directly but guarantee the signal quality of the candidate WCDMA cell.

l FDD_RSCP_threshold is calculated as follows: If FDD_RSCPmin is broadcast in the serving cell, then FDD_RSCP_threshold =

FDDRSCPMIN - min((P_MAX - 21 dBm), 3 dB).

If FDD_RSCPmin is not broadcast in the serving cell and Qrxlevmin andPcompensation can be obtained in the serving cell, then FDD_RSCP_threshold =Qrxlevmin + Pcompensation + 10 dB.

If FDD_RSCPmin is not broadcast in the serving cell and Qrxlevmin andPcompensation cannot be obtained in the serving cell, then FDD_RSCP_threshold =-102dBm (the de fault value o f FDD_RSCPmin).

Where, P_MAX is the maximum RF output power of an MS in a WCDMA cell. Qrxlevmin is the minimum required RX level in a WCDMA cell. Pcompensation is max(UE_TXPWR_MAX_RACH P_MAX, 0).

UE_TXPWR_MAX_RACH is the maximum TX power level an MS may use whenaccessing a W CDMA cell on RACH. FDDRSCPMIN is used to calculate the FDD_RSCP_threshold of the target cell for a

GSM-to-WCDMA cell reselection.

If multiple WCDMA cells meet the cell reselection conditions, the MS selects the cell with thehighest RSCP as the target cell.

The GSM-to-WCDMA cell reselection cannot be triggered within five seconds after theWCDMA-to-GSM cell reselection. In case of a cell reselection occurring within the previous15 seconds, FDDQOFF is increased by 5 dB.

If both the conditions for the GSM-to-WCDMA cell reselection and those for the GSM-to-GSM

cell reselection are met, the MS selects a WCDMA cell as the target cell.

5.2.2 Optimized GSM-to-WCDMA Cell Reselection in PacketTransfer Mode

This section describes the GBFD-114323 2G/3G Cell Reselection Based on MS State feature.

This feature is designed to optimize cell reselection from GSM to WCDMA. It enables dual-mode MSs in idle mode and in packet transfer mode to adopt different reselection policies toaccess the 3G networ k as require d.

An MS in idle mode searches for neighboring FDD cells based on the value of the Qsearch_I

information element (IE) con tained in system infor mation (SI). The value of Qsearch_I isspecified by the QI parameter.



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An MS in packet transfer mode searches for neighboring FDD cells based on the value of theQsearch_P IE contained in the PACKET MEASUREMENT ORDER message. If an MS doesnot obtain the Qsearch_P IE, the MS searches for neighboring FDD cells based on the value of the Qsearch_I IE. The value of Qsearch_P is specified by the QP parameter. When QP is set to15 , MSs in packet transfer mode are not allowed to reselect to an neighboring FDD cell.

5.2.3 Fast WCDMA Reselection at 2G CS Call ReleaseThis section describes the GBFD-114325 Fast WCDMA Reselection at 2G CS Call Releasefeature .

Overview

When an MS terminates a call in the GSM network, it camps on the cell in which the call isreleased and then starts neighboring cell measurement. When a neighboring WCDMA cell meetsthe requirements for cell reselection, the MS reselects the WCDMA cell. The WCDMA cell

reselection is initiated after the MS receives the SI and performs the related calculation.When the feature Fast WCDMA Reselection at 2G CS Call Release is activated, the BSS selectsthe best neighboring WCDMA cell based on the measurement information after the MS in aGSM cell terminates a CS call. Then, the BSS sends the MS the cell information through theChannel Release message, instructing the MS to camp on that WCDMA cell. With this feature,an MS can ca mp on a W CDMA cell without performing cell reselection decisions, acceleratingcell reselection. This feature allows the MS to camp on the WCDMA cell for a longer period.In addition, the number of location area updates is reduced, and the paging success rate isincreased, increasing the revenue of operators in the WCDMA network.

NOTE

The WCDMA network in this document refers to the UTRAN FDD. FDD stands for frequency divisionduplex (FDD).

Procedure

After an MS in a GSM cell releases a CS call, the BSC sends the MS a Channel Release messagethat carries the IE "Cell selection indicator after release of all TCH and SDCCH". This IE carriesthe neighboring WCDMA cell information, facilitating the MS to reselect a WCDMA cell. Thisfeature needs the support of both the network and the MS.

Figure 5-2 shows the cell reselection procedure for an MS-terminated call.



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Figure 5-2 Procedure for fast WCDMA reselection at 2G CS call release

1. After receiving a Release Complete message from the MS, the MSC sends a Clear Commandmessage to the BSC, instructing the BSC to release the occupied resources on the A and Uminterfaces.

2. The BSC sends a Channel Release message to the MS, instructing the MS to release the TCHor SDCCH on the Um interface. The Channel Release message may carry the IE "Cell selectionindicator after release of all TCH and SDCCH", which contains the information about the targetneighboring WCDMA cell.

The MS in the serving GSM cell measures neighboring cells.

If... Then...

The information about neighboringWCDMA cells is carried in a measurementreport (MR)

The BSC carries the information (includingFDD-ARFCN and FDD_CELL_INFORMA-TION) about the best neighboring WCDMAcell in the Channel Release message,instructing the MS to reselect thatneighboring WCDMA cell.

No neighboring WCDMA cell information iscarried in an MR or the value of CELLSELECTAFTERCALLREL is NO(No)

The BSC does not carry the IE "Cell selectionindicator after release of all TCH andSDCCH" in the Channel Release message.

3. After receiving the Channel Release message, the MS releases the main signaling link. Then,the MS sends a DISC frame to the BTS, instructing the BTS to release the TCH or SDCCH.

4. After receiving an Unnumbered Acknowledgement message, the MS switches to idle modeand initiates cell reselection based on the IE "Cell selection indicator after release of all TCH

and SDCCH".



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If... Then...

The Channel Release message contains the IE"Cell selection indicator after release of allTCH and SDCCH"

The MS attempts to camp on the cell indicatedin the Channel Release message.

The Channel Release message does notcontain the IE "Cell selection indicator after release of all TCH and SDCCH"

The MS attempts to camp on the cell wherethe TCH or SDCCH is already released.

5. If step 4 fails, th e MS performs a n ormal cell reselection procedure to camp on any appropriatecells.

5.2.4 NC2 between GSM and WCDMAThis section describes the GBFD-116201 NC 2 betw een GSM and WCDMA feature .

NC2 cell reselecti on c an be performed for inter-RAT cell reselection only when an MS is in packet transfer mode.

NC2 cell reselection between GSM an d WCDMA refers to th e network-controll ed ce llreselection from GSM to WCDMA triggered by a BSC.

NC2 cell reselection is activated after the NCO parameter is set to NC2(NC2) .

In NC2 cell reselection mode, an MS generally determines whether to measure neighboringWCDMA cells based on the value of QI and the receive level of the serving cell. If any of thefollowing conditions are met, the MS determines whether to measure neig hboring WCDMAcells based on the value of QP and the receive level of the se rvin g cell:

l The serving GSM cell has a PBCC H, a nd QP is broadcast on the PBCCH.l The serving GSM cell does not have a PBCCH but QP is broadcast on the BCCH. In

addition, MSs have received the Packet Cell C hange Order message or the PacketMeasurement Order message that carries the GPRS cell reselection parameters of one or more WCDMA cells.

In NC2 cell reselection mode, an MS performs inter-RAT neighboring WCDMA cellmeasurements based on QP , FDDFREQCNUM , FDDCELLOFF , and FDDCELLTHREDand sends MRs.

l QP is the threshold for an MS in PS mode to search for WCDMA cells. If the level of theserving GSM cell is lower than the value of QP (when QP is within the range of 0 to 6) or higher than the value of QP (when QP is within the range of 8 to 14), the MS starts to searchfor WCDMA cells.

l FDDFREQCNUM is the number of WCDMA cells that should be contained in the bestcell list, which is carried in the MR from an MS.

l FDDCELLOFF is the receive level offset for WCDMA cells. During the ranking of measured neighboring cells, the value of this parameter is added to the receive level of measured WCDMA cells.

l FDDCELLTHRED is the threshold for reporting a WCDMA cell. The MS reports onlythe cells whose RSCP is greater than this threshold.

Figure 5-3 shows the procedure for NC2 cell reselection between GSM and WCDMA.



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Figure 5-3 Procedure for NC2 cell reselection between GSM and WCDMA

1. An MS in the GPRS Mobility Management (GMM) Ready state periodically sends PacketMeasurement Report messages or Packet Enhanced Measurement Report messages to theBSC. These MRs contain the RSCP of neighboring WCDMA cells.

2. After receiving a packet MR, the BSC processes the measurement results. Then, the BSCdetermines whether to perform a cell reselection.

3. If the BSC determines to initiate a cell reselection, it sends the Packet Cell Change Order message to the MS to instruct the MS to reselect the specified target WCDMA cell. Targetcell reselection is based on the NC2 cell reselection algorithm.

4. If a cell reselection fails, the MS sends the Packet Cell Change Failure message to the BSC.After receiving this message, the BSC subtracts PENALTYRXLEV from the receive levelof the target cell. If the receive level of the target cell is less than PENALTYRXLEV , theBSC sets the receive level of the target cell to 0.

The NC2 cell reselection algorithms include the service-based NC2 cell reselectionalgorithm, quality-based NC2 cell reselection algorithm, and load-based NC2 cellreselection algorithm.

Service-Based NC2 Cell Reselection AlgorithmThe service-based NC2 cell reselection is activated when TrafficReselAllow is set to PERMIT(Permit) .

The BSC may find the IE "Service UTRAN CCO" in multiple DL-UNITDATA PDUs,CREATE-BSS-PFC PDUs, or PS-HANDOVER-REQUEST PDUs sent from the SGSN. TheBSS considers that the last received IE "Service UTRAN CCO" is of the highest priority. The

IE "Service UTRAN CCO" carries Service UTRAN CCO Value part , which indicates the mostsuitable RAT for the current service.



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Table 5-1 lists the values of Service UTRAN CCO Value part and their meanings.

Table 5-1 Values of Service UTRAN CCO Value part and their meanings

Coding Bits Meaning

000 Network initiated cell change order toUTRAN or PS handover to UTRAN

procedure should be performed


procedure should not be performed


procedure should not be performed

111 If received, should be interpreted as noinformation available (bits 4-5 valid)

Other values If received, should be interpreted as noinformation available

If the value of Service UTRAN CCO Value part is 000 , the MS triggers a service-based cellreselection and selects the neighboring WCDMA cell with the highest receive level.

If no neighboring WCDMA cell is available, the MS proceeds to perform a quality-based, load-

based, or coverage-based NC2 cell reselection.

Quality-Based NC2 Cell Reselection AlgorithmThe quality-based NC2 cell reselection is activated when URGENTRESELALLOW is set toPERMIT(Permit) .

When the conditions for triggering a service-based NC2 cell reselection are not met, the BSCdetermines whether to initiate a cell reselection based on the receive quality of the radio link onthe Um interface. The MRs or Bit Error Rate (BER) indicates the receive quality on the radiolink and the number of times bad radio link quality occurs.

In a receive quality measurement period, if the MS receive quality deterioration ratio is greater than the CELLRXQUALWORSENRATIOTHRSH parameter, a quality-based NC2 cellreselection is initiated.

l MS receive quality deterioration ratio = Times of bad radio link quality/Number of radiolink quality MRs

In quality-based NC2 cell reselection, the cell with the highest priority is selected as the targetcell from candidate GSM cells. The priority of a cell is determined by its receive level andcharacteristics information such as cell type, and support for EDGE. In quality-based NC2 cellreselection, the candidate WCDMA cell with the highest receive level is selected as the targetcell. If NC2LoadResel is set to Support(Support) , the cell characteristics information alsoincludes the load of the candidate GSM cells under the same BSC.

In quality-based NC2 cell reselection, a candidate cell must meet the following conditions:



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l Receive level of the neighboring GSM candidate cell > Max(Receive level of the servingcell, MINACCRXLEV ) + RESELHYST .

l Measured RSCP of the neighboring WCDMA cell > FDDRSCPQUALTHRSH .l When NC2LoadResel is set to Support(Support) , the neighboring GSM candidate cells

under the same BSC are not congested.l When Service UTRAN CCO Value part is set to 010 or 001 , none of the neighboring

WCDMA cells is selected as the target cell.

Then, the highest level candidate cell within the highest priority cells is selected as the targetcell. If a neighbori ng WCDMA cell is selected, an NC2 cell reselection from GSM to WCDMAis triggered.

Load-Based NC2 Cell Reselection AlgorithmThe load-based NC2 cell reselection algorithm is activated when LOADRESELALLOW is setto PERMIT(Permit) .

When neither the conditions for initiating a service-based NC2 cell reselection nor the conditionsfor initiating a quality-based NC2 cell reselection are met, a load-based NC2 cell reselection isinitiated to balance the load among the cells in the network. In load-based NC2 cell reselection,some MSs in cells with heavy load are reselected to cells with light load. In addition, the MSsin neighboring cells should not be reselected to these heavily-loaded cells.

Figure 5-4 shows a load-based NC2 cell reselection.

Figure 5-4 Load-based NC2 cell reselection

When the serving cell is overloaded and the receive level in this cell is lower than LOADRESELMAXRXLEV , load-based NC2 cell reselection is triggered.

l If the channel multiplexing rate of a cell is higher than LOADRESELSTARTTHRSH , thecell load is heavy. Then, the load-based NC2 cell reselection should be enabled.

l In a load-based NC2 cell reselection, only the MS whose signal level is lower than LOADRESELMAXRXLEV can be reselected to a neighboring cell.

In load-based NC2 cell reselection, the cell with the highest priority is selected as the target cellfrom the candidate GSM cells. The priority of a cell is determined by its receive level and



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characteristics information such as cell type, and support for EDGE. Alternatively, the candidateWCDMA cell with the highest receive level is selected as the target cell. If NC2LoadResel isset to Support(Support) , the characteristics information about a cell also includes the load of GSM candidate cells under the same BSC.

In load-based NC2 cell reselection, a candidate cell must meet the following conditions:

l Receive level of the neighboring GSM cell > Max(Receive level of the serving cell, MINACCRXLEV ) + RESELHYST .

l Measured RSCP of the neighboring WCDMA cell > FDDRSCPQUALTHRSH .l When NC2LoadResel is set to Support(Support) , the neighboring GSM candidate cells

under the same BSC are not congested.l When Service UTRAN CCO Value part is set to 010 or 001 , none of the neighboring

WCDMA cells can be selected as th e candidate cell.

Then, the highest l evel candidate cell within t he highest priority cells is selected as the target

cell. If a neighboring WCDMA cell is selected, an NC2 cell reselection from GSM to WCDMAis triggered.

Coverage-Based NC2 Cell Reselection Algorithm

Coverage-based NC2 cell reselection is activated when NORMALRESELALLOW is set toPERMIT(Permit) .

When none of the conditions for initiating a service-based, quality-based, a nd load-based N C2cell reselection are met and the P/N criterion for initiating a coverage-based NC2 cell reselectionis met, a coverage-based NC2 cell reselection is initiated.

The P/N criterion for initiating a coverage-based NC2 cell reselection is as follows: In the periodspecified by RESELWATCHPERIOD , the nu mber of times that the receive level of the servingcell is lower than the value of MINACCRX LEV reaches the v alue of

RESELWORSENLEVTH RSH .

In coverage-based NC2 cell reselection, the cell with the highest priority is selected as the targetcell from the candidate GSM cells. The priority of a cell is determined by its receive level andcharacteristics information such as cell type, and support for EDGE. Or, the candidate WCDMAcell with the highest receive level is selected as the target cell. If NC2LoadResel is set to Support(Support) , the characteristics information about a cell also includes the load of the GSMcandidate cells under the same BSC.

In coverage-based NC2 cell reselection, a candidate cell must meet the following conditions:

l Receive level of the neighboring GSM candidate cell > Max(Receive level of the servingcell, MINACCRXLEV ) + RESELHYST .

l Measured RSCP of the neighboring WCDMA candidate cell >FDDRSCPQUALTHRSH .

l When NC2LoadResel is set to Support(Support) , the neighboring GSM candidate cellunder the same BSC are not congested.

l When Service UTRAN CCO Value part is set to 010 or 001 , none of the neighboringWCDMA cells can be selected as th e candidate cell.

Then, the highest level candidate cell within the highest priority cells is selected as the target

cell. If a neighbori ng WCDMA cell i s selected, an NC2 cell reselection from GSM to WCDMAis triggered.



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5.2.5 Forced NC2 Between GSM and WCDMA

Overview

To enable the forced network-controlled GSM-to-WCDMA cell reselection function, setGSMTOFDDFORCENC2 to SUPPORT(Support) when NCO is set to NC0(NC0) or NC1(NC1) . The BSC sends a Packet Measurement Order message to MSs in packet transfer mode.This messages contains NC2 and inter-RAT measurement parameters. Based on these

parameters, the MSs measure neighboring WCDMA cells and periodically send packet MRs tothe BSC. To support this function, the BSC must be configured with a database of IMEI segmentsfor MSs that do not support the forced network-controlled GSM-to-WCDMA cell reselectionfunction. The database consists of one or more IMEI segments. ImeiMin and ImeiMax specifystart IMEI and end IMEI in an IMEI segment, respectively.

Forced NC2 Procedure

Figure 5-5 shows the forced network-controlled GSM/WCDMA cell reselection procedure.

Figure 5-5 Forced network-controlled cell reselection procedure

1. Setting the NC2 mode

The BSC is configured with a database of IMEI segments for MSs that do not support theforced network-controlled GSM-to-WCDMA cell reselection function.

Once the forced network-controlled GSM-to-WCDMA cell reselection function is enabled,the BSC sends an IMEI query message to MSs in packet transfer mode to check whether



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these MSs support this function. If these MSs support this function, the BSC sends a PacketMeasurement Order message to these MSs. The Packet Measurement Order messagecontains NC2 and the inter-RAT measurement control parameters,including PsBestFddCellNum , PsFddCellRptOff , PsFddCellRptThd ,PsFddRptThr2Ecno , and PsFddRptThr2Rscp .

2. NC2 decision

Using the MRs sent by the MS, the BSC makes the GSM/WCDMA NC2 decision andselects a target neighboring WCDMA cell that meets the following condition:

Measured RSCP of the neighboring WCDMA cell > FDDRSCPQUALTHRSH

The BSC checks the PS service duration for the MS. If the service duration is greater thanthe value of FddReselTimeThd and the MS is still in packet transfer mode, the BSCinstructs the MS to reselect a WCDMA cell.

5.3 BSC supporting Blind SearchThis section describes the GBFD-511110 BSC supporting Blind Search feature.

Generally, WCDMA/TD-SCDMA frequencies and scrambling codes need to be configured for GSM-to- WCDMA/TD-SCDMA cell reselection. Based on the configured information, MSssearch for appropriate neighboring WCDMA/TD-SCDMA cells to camp on.

This feature allows the BSC to configure only WCDMA/TD-SCDMA frequencies for GSM-toWCDMA/TD-SCDMA cell reselection. Based on configured WCDMA/TD-SCDMAfrequencies, MSs can automatically search for appropriate neighboring WCDMA/TD-SCDMAcells to camp on. Currently, few frequencies are used by a WCDMA/TD-SCDMA network.Therefore, using this feature can greatly simplify configurations for GSM-to- WCDMA/TD-SCDMA cell reselection.

The procedure for implementing this feature is as follows:

1. The BSC selects frequencies. If frequencies have been configured for a cell, use thefrequencies configured for the cell. If frequencies have not been configured for the cell,use the frequencies configured for the BSC.

2. The BSC checks whether the cell is configured with a neighboring WCDMA/TD-SCDMAcell.

l If the neighboring WCDMA/TD-SCDMA cell has been configured, the BSC sends an MSthe SI2Quater carrying frequencies and scrambling codes used by the neighboringWCDMA/TD-SCDMA cell.

l If the neighboring WCDMA/TD-SCDMA cell has not been configured, the BSC sends theMS the SI2Quater carrying frequencies configured by running the BSC6900 MMLcommand SET GCELL3GARFCN or SET G3GARFCN .

NOTE

The WCDMA/TD-SCDMA frequencies configured by running the BSC6900 MML command SETGCELL3GARFCN are preferentially used. The detailed explanation is as follows:l If WCDMA/TD-SCDMA frequencies have been configured by running the BSC6900 MML command

SET GCELL3GARFCN , the BSC sends the infor mation about the configured frequencies to the MSregardless of whether WCDMA/TD-SCDMA frequencies are configured by running the BSC6900MML command SET G3GARFCN .

l If WCDMA/TD-SCDMA frequencies have not been configured by running the BSC6900 MML

command SET GCELL3GARFCN , the BSC sends the WCDMA/TD-SCDMA frequenciesconfigured by running the BSC6900 MML command SET G3GARFCN to the MS.



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6 GSM/WCDMA Inter-RAT CS HandoverGSM/WCDMA interoperability for MSs in dedicated mode involves GSM-to-WCDMAhandover and WCDMA-to-GSM handover. Handovers are implemented by MSs and the BSS.

GSM/WCDMA inter-RAT handovers include emergency handovers, better cell handovers,load-based inter-RAT handovers, and service-based inter-RAT handovers.

Emergency handover is triggered when an ongoing call initiated by a multi-mode MS can nolonger be processed in its serving cell due to limited network coverage or other factors. For example, when an MS making a call in the GSM cell edge is about to move outside the cell, anemergency handover is triggered to avoid call drops. For details, see the Handover Feature

Parameter Description.

Better cell handover is triggered when the signal quality of a neighboring cell is better than thatof the serving cell. Better cell handovers help improve service quality and user experience. For example, when the signal quality of a WCDMA cell is better than that of the serving GSM cell,MSs in the serving cell can be handed over to the WCDMA cell to achieve higher voice quality.For details, see the Handover Feature Parameter Description.

Load-based inter-RAT handover is triggered when the traffic load on the serving cell is too high.For a WCDMA-to-GSM load-based handover, if the traffic load on the target GSM cell is alsohigh, the target cell rejects the handover to avoid ping-pong handovers.

Service-based handover allows an operator to use the MSC to choose a network for MSs. If theMSC indicates that a service-based handover should be performed on a call in a GSM cell, theBSS hands over the call to a WCDMA cell. If the MSC indicates that a call should not be handedover to a WCDMA call, the BSS does not hand over the call to a WCDMA cell when a handover

is needed during the call.

GSM BSSInteroperability Between GSM and WCDMA FeatureParameter Description 6 GSM/WCDMA Inter-RAT CS Handover


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6.1 CS Handover from WCDMA to GSMMSs in dedicated mode can be handed over from a WCDMA cell to a GSM cell. The handover decision and handover procedure are controlled by the RNC. The BSS considers the handover from WCDMA to GSM as a general inter-BSC handover.

The handover from WCDMA to GSM is supported when INTERRATINBSCHOEN is set toYES(Yes) .

6.2 CS Handover from GSM to WCDMA

6.2.1 OverviewHandover from GSM to WCD MA is supporte d when INTERRATOUTBSCHOEN is set toYES(Yes) .

The BSS determines whether to initiate an inter-RAT handover from GSM to WCDMA. The process is as follows:

1. An MS in dedicated mode obtains the neighboring WCDMA cell list and other informationfrom measurem ent informati on.

2. The MS reports the measurement result to the BSS through an MR.

3. After receiving the measurement r esult, the BSS determines whether to initiate a handover based on the measurement result and the handover algorithm.

Inter-RAT handover from GSM to WCDMA can be classified into emergency handover and better 3G cell handover. The algorithm for emergency handover from GSM to WCDMA is thesame as that for general emergency handover. For details, see the Handover Feature Parameter

Description.

In the GSM network, the HOOPTSEL parameter specifies whether a GSM cell or a WCDMAcell is preferentially selected as the target cell.

l If HOOPTSEL is set to Pre_2G_Cell(Preference for 2G cell) , the BSC preferentiallyselects a GSM cell as the target cell.

l If HOOPTSEL is set to Pre_3G_Cell(Preference for 3G cell) , the BSC preferentiallyselects a WCDMA cell as the target cell.

l If HOOPTSEL is set to Pre_2G_CellThres(Preference 2G cell by thresh) , the BSCdetermines the target cell according to the receive level of the neighboring GSM cells andthe value of HOPRETH2G . If the receive level of all neighbori ng GSM cells is lower than

HOPRETH2G , the BSC selects a WCDMA cell as the target cell.

Better 3G cell handover can be performed only when both INTERRATOUTBSCHOEN and BET3GHOEN are set to YES(Yes) . As the measurement result of a WCDMA cell can bereported in the format of RSCP or Ec/No, the methods for handover decision differ accordingly.

l When the value of FDDREP is RSCP(RSCP) , the better 3G cell handover is triggered if during HOSTAT3G , the following condition is met for the period specified by

HODURT3G :

CPICH RSCP > HORSCPTH3G



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l When the value of FDDREP is EcN0(Ec/N0) , the better 3G cell handover is triggered if the following condition is met for the period specified by HODURT3G within

HOSTAT3G :

CPICH Ec/No > HOECNOTH3G

6.3 Service-Based CS Hando ver from GS M to WCDMAThis section describes the GBFD-114321 GSM/WCDMA Service Based Handover feature.

6.3.1 OverviewOperators can provide more diversified services when GSM and WCDMA coexist in a mixednetwork. Services of different types can be carried o n different networks to optimize theutilization of resources. For example, voice services and low-rate data services are carried onthe GSM network, and high-rate data services are carried on the WCDMA network to allowhigh peak throughput.

6.3.2 ProcedureIf INTERRATOUTBSCHOEN is set to YES(Yes) , the BSC applies different handover algorithms for MSs to be handed over from a GSM cell to a WCDMA cell according to thesetting of InterRatServiceLoadHoSwitch .

l If InterRatServiceLoadHoSwitch is set to CnService-based(CN Service-based) , the BSC processes handovers according to the service handover attributes of the core network (CN)as follows: If the service handover indicator of the CN is Handover to UTRAN or cdma2000

should be performed , the MS should be handed over to a WCDMA cell. In this case,the BSC selects a WCDMA cell from the neighboring cell list as the target cell andstarts the handover from GSM to WCDMA.

If the service handover indicator of the CN is Handover to UTRAN or cdma2000should not be performed , a GSM cell should be preferentially selected as the servingcell. In this case, the BSC does not start the handover from GSM to WCDMA. If ahandover is required during the call, a GSM cell is preferentially selected as the targetcell.

If the service handover indicator of the CN is Handover to UTRAN or cdma2000shall n ot be performed , the MS mu st not be handed over to a WCDMA cell. In thiscase, the BSC will not hand over the MS to a WCDMA cell, and selects only a GSMcell as the target cell if a handover is required.

l If InterRatServiceLoadHoSwitch is set to Service-based(Service-based) , the BSCremoves the WCDMA candidate cell whose uplink/downlink traffic is in the minor congestion level. If the MS is performing a CS service, the MS accesses the current GSMcell.

l If InterRatServiceLoadHoSwitch is set to Load-based(Load-based) and the value of theIE "Service Handover" in the ASSIGNMENT REQUEST message sent from the CN ishandover to UTRAN or cdma2000 should be performed , the BSC selects a neighboringWCDMA cell whose uplink and downlink loads meet the following condition fromWCDMA candidate cells:

G2GLoadAdjustCoeff x Load of the current GSM serving cell 10 x Load of the neighboringWCDMA cell 10 x G2G3GLdBlcDeltaThrd 1000



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If multiple neighboring WCDMA cells meet the preceding condition, the BSC starts the directedretry to the WCDMA cell with the highest receive quality. If no neighboring WCDMA cell meetsthe preceding condition, the BSC selects a GSM cell as the target cell.

NOTE

If there is no WCDMA candidate cell, or the directed retry to the WCDMA cell fails, the BSC starts thereassignment procedure to a GSM cell.

l When InterRatServiceLoadHoSwitch is set to Dynamic-based(Dynamic Ser vice/Load -based) :

If the current cel l has a normal load, the servic e-based WCDMA-to-GSM handover algorithm is appl ied.

If the current cell has a high load, the load-based WCDMA-to-GSM handover algorithmis applied.

6.4 Load-Based CS Handover fr om GSM to WCDMAThis section describes the GBFD-114322 GSM/WCDMA Load Based Handover feature .

6.4.1 OverviewIn a mixed network where GSM and WCDMA coexist, MSs in connected mode can be handedover between GSM and WCDMA to balance the overall network load and enlarge systemcapacity.

If the GSM cell that the MS camps on is congested, the BSC redirects the MS to the WCDMAnetwork according t o the load of the WCDMA net wor k.

6.4.2 ProcedureIf both INTERRATOUTBSCHOEN and OutSysLoadHoEn are set to YES(Yes) , the followingconditions must be met to trigger the handover between GSM and WCDMA for MSs inconnected mode:

l The flow control level of the current system is smaller than or equal to SYSFLOWLEV .l The load on the serving cell is greater than or equal to TRIGTHRES .l The Service Handover attribute of the service is not handover to UTRAN or cdma2000

shall not be performed .

A candidate WCDMA cell must meet the following conditions:

l G2GLoadAdjustCoeff x Load of the current GSM serving cell 10 x Load of theneighboring WCDMA cell 10 x G2G3GLdBlcDeltaThrd 1000

l For a WCDMA FDD cell, the following conditions must be met if FDDREP is set to RSCP(RSCP) : InterRATLoadHoRSCPStart InterRATLoadHoRSCPBandWidth < CPICH RSCP IntRATLoadHORSCPThr l

For a WCDMA FD D cell, the following conditions m ust be met if FDDREP is set to EcN0(Ec/N0) :



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