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RAN

Handover Parameter DescriptionIssue 01

Date 2009-03-30

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Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service. Forany assistance, please contact our local office or company headquarters.

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

Bantian, Longgang

Shenzhen 518129

People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

Copyright Huawei Technologies Co., Ltd. 2009. All rights reserved.No part of this document may be reproduced or transmitted in any form or by any means without priorwritten consent 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 respectiveholders.

NoticeThe 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 the warranty of any kind, express or implied.
http://www.huawei.com/http://www.huawei.com/mailto:[email protected]:[email protected]:[email protected]://www.huawei.com/

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iii

About This Document

AuthorPrepared by Hu Lianfang, Wang Yiyun Date 2008-10-20

Edited by Wang Deyang Date 2008-12-09

Reviewed by - Date -

Translated by Tong Aruna Date 2008-12-09

Tested by Tang Min Date 2009-01-10

Approved by Duan Zhongyi Date 2009-03-30

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v

Content

1 Change History ........................................................................................................................... 1-1

2 Handover Introduction ............................................................................................................. 2-1

3 Handover Overview .................................................................................................................. 3-1 3.1 Handover Types ............................................................. ................................................................. ............... 3-1 3.2 Intra-Frequency Handover ...................... ................................................................. ..................................... 3-2

3.3 Inter-Frequency Handover ...................... ................................................................. ..................................... 3-3

3.4 Inter-RAT Handover (3G to 2G) ........................ ................................................................. .......................... 3-4

3.4.1 Inter-RAT Handover Introduction ........................................................................................................ 3-4

3.4.2 Rules for Enabling 3G-to-2G Handover ............................................................................... ............... 3-5

4 Intra-Frequency Handover Algorithms ................................................................................. 4-1 4.1 Intra-Frequency Handover Procedure ................................................................................. .......................... 4-1

4.2 Intra-Frequency Handover Measurement ................................................................................................ ...... 4-1

4.2.1 Intra-Frequency Handover Measurement Quantities ............................................................ ............... 4-2

4.2.2 Intra-Frequency Handover Measurement Events ....................................................... .......................... 4-2

4.2.3 Intra-Frequency Handover Neighboring Cell Combination Algorithm ..................... .......................... 4-9

4.3 Intra-Frequency Handover Decision and Execution ........................................................... ........................ 4-10

4.3.1 Decision and Execution ................. ................................................................. ................................... 4-10

4.3.2 Rate Reduction After an SHO Failure ............................................................. ................................... 4-12

4.4 Intra-Frequency Handover of HSDPA .................................... ............................................................... ..... 4-15

4.4.1 Decision and Execution of Intra-Frequency Handover ......................................................... ............. 4-15

4.4.2 F-DPCH Handover Protection ........................................................................ ................................... 4-16

4.5 Intra-Frequency Handover of HSUPA .................................... ............................................................... ..... 4-17 4.5.1 Decision and Execution of Intra-Frequency Handover ......................................................... ............. 4-17

4.5.2 Handover Between E-DCHs of 10 ms TTI and 2 ms TTI ................................................................ .. 4-20

4.6 Signaling Procedures for Intra-Frequency Handover .................................................................................. 4-20

4.6.1 Intra-NodeB Intra-Frequency Soft Handover Signaling Procedure ................................................... 4-20

4.6.2 Intra-RNC Inter-NodeB Intra-Frequency Soft Handover Signaling Procedure ................................. 4-22

4.6.3 Inter-RNC Intra-Frequency Soft Handover Signaling Procedure ...................................................... 4-24

4.6.4 Intra-RNC Inter-NodeB Intra-Frequency Hard Handover Signaling Procedure ................................ 4-26

4.6.5 Inter-RNC Intra-Frequency Hard Handover Signaling Procedure ..................................................... 4-27

5 Inter-Frequency Handover Algorithms ................................................................................. 5-1

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5.1 Inter-Frequency Handover Procedure ................ ................................................................. .......................... 5-1

5.1.1 Coverage- or QoS-based Inter-Frequency and Inter-RAT Handover Procedure .................................. 5-1

5.1.2 Load-based Inter-Frequency Handover Procedure ................................................................ ............... 5-3

5.1.3 Speed-based Inter-Frequency Handover Procedure .............................................................. ............... 5-3

5.2 Inter-Frequency Handover Measurement ................................................................................................ ...... 5-5

5.2.1 Inter-Frequency Handover Measurement Switches .............................................................. ............... 5-5

5.2.2 Inter-Frequency Handover Measurement Report Modes ..................................................................... 5-6

5.2.3 Inter-Frequency Handover Measurement Quantity ............................................................... ............... 5-6

5.2.4 Inter-Frequency Handover Measurement Events ................................................................................. 5-7

5.2.5 Inter-Frequency Handover Neighboring Cell Combination Algorithm .............................................. 5-10

5.2.6 Inter-Frequency Handover Compressed Mode ............................................... ................................... 5-10

5.3 Inter-Frequency Handover Decision and Execution............................ ........................................................ 5-12

5.3.1 Coverage- and QoS-based Inter-Frequency Handover Decision and Execution ................................ 5-12

5.3.2 Load-based Inter-Frequency Handover Decision and Execution ....................................................... 5-14 5.3.3 Speed-based Inter-Frequency Handover Decision and Execution ..................................... ................ 5-15

5.3.4 Blind Handover Decision and Execution Based on Event 1F .......................................................... .. 5-16

5.3.5 Inter-Frequency Anti-Ping-Pong Algorithm ............................................................... ........................ 5-16

5.3.6 Inter-Frequency Handover Retry ... ................................................................. ................................... 5-17

5.4 Inter-Frequency Handover of HSDPA .......................... ................................................................. ............. 5-17

5.5 Inter-Frequency Handover of HSUPA .......................... ................................................................. ............. 5-19

5.6 Signaling Procedures for Inter-Frequency Handover .................................................................................. 5-22

5.6.1 Inter-Frequency Handover Within One RNC ............................................................. ........................ 5-22

5.6.2 Inter-Frequency Handover Between RNCs ................................................................ ........................ 5-24

6 Inter-RAT Handover Algorithms ............................................................................................ 6-1 6.1 3G-to-2G Handover Procedure .......................... ................................................................. .......................... 6-1

6.1.1 Coverage-based 3G-to-2G Handover Procedure ........................................................ .......................... 6-1

6.1.2 Load-based 3G-to-2G Handover Procedure ............................................................... .......................... 6-2

6.1.3 Service-based 3G-to-2G Handover Procedure ........................................................... .......................... 6-3

6.1.4 Speed-based 3G-to-2G Handover Procedure ................................................................................ ....... 6-3

6.2 3G-to-2G Handover Measurement ................................................................................................................ 6-3

6.2.1 3G-to-2G Handover Measurement Switches ............................. .......................................................... 6-4

6.2.2 3G-to-2G Handover Measurement Report Modes ..................................................... .......................... 6-4 6.2.3 3G-to-2G Handover Measurement Quantity ........................................................................................ 6-4

6.2.4 3G-to-2G Handover Measurement Events ................................................................. .......................... 6-5

6.2.5 3G-to-2G Handover Neighboring Cell Combination Algorithms ........................................................ 6-8

6.2.6 3G-to-2G Handover Compressed Mode ... ................................................................. .......................... 6-8

6.2.7 BSIC Verification Requirements for 2G Cells ........................................................... .......................... 6-8

6.3 3G-to-2G Handover Decision and Execution ........................................................... ..................................... 6-8

6.3.1 Coverage and QoS-based UMTS-to-GSM Handover Decision and Execution ................................... 6-8

6.3.2 Load- and Service-based 3G-to-2G Handover Decision and Execution .............................................. 6-9

6.3.3 3G-to-2G Handover Retry ............. ................................................................. ................................... 6-10

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6.3.4 3G-to-2G Multimedia Fallback .......................................................................................................... 6-11

6.3.5 3G-to-2G Handover in the PS Domain with NACC .......................................................................... 6-13

6.4 Inter-RAT Handover of HSDPA ............................................................................................................. ..... 6-13

6.5 Inter-RAT Handover of HSUPA ............................................................................................................. ..... 6-14

6.6 2G-to-3G Handover............................................ ................................................................. ........................ 6-14

6.7 Interoperability Between Inter-RAT Handover and Inter-Frequency Handover ......................................... 6-15

6.8 Signaling Procedures for Inter-RAT Handover ........................ ................................................................. .. 6-15

6.8.1 3G-to-2G Handover in CS Domain ................................................................. ................................... 6-16

6.8.2 3G-to-2G Handover in PS Domain ................................................................. ................................... 6-16

6.8.3 3G-to-2G Handover in Both CS Domain and PS Domain ................................................................. 6-18

6.8.4 2G-to-3G Handover in CS Domain ................................................................. ................................... 6-19

6.8.5 2G-to-3G Handover in PS Domain ................................................................. ................................... 6-20

7 HCS Handover Algorithms ...................................................................................................... 7-1 7.1 HCS Handover Overview ......................................................... ................................................................. .... 7-1

7.2 HCS Handover Phases ................. ................................................................. ................................................ 7-2

7.2.1 UE Speed Estimation ........................................................................... ................................................ 7-2

7.2.2 HCS Handover Execution .......................................................... .......................................................... 7-3

7.3 Signaling Procedure of HCS Handover ......................................................... ................................................ 7-4

7.4 Interoperability Between HCS Handover and Other Handovers ............................................................... .... 7-4

8 Handover Parameters ................................................................................................................ 8-1 8.1 Parameters Description ........................... ................................................................. ..................................... 8-1

8.2 Values and Ranges ......................................................... ................................................................. ............. 8-50

9 Reference Documents................................................................................................................ 9-1

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1-1

1 Change History The change history provides information on the changes in different document versions.

Document and Product Versions

Document Version RAN Version

01 (2009-03-30) 11.0

Draft (2009-03-10) 11.0

Draft (2009-01-15) 11.0

This document is based on the BSC6810 and 3900 series NodeBs.The available time of each feature is subject to the RAN product roadmap.

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

Feature change: refers to the change in the handover feature. Editorial change: refers to the change in the information that was inappropriately

described or the addition of the information that was not described in the earlier version.

01 (2009-03-30)This is the document for the first commercial release of RAN11.0.

Compared with draft (2009-03-10), this issue optimizes the description.

Draft (2009-03-10)This is the second draft of the document for RAN11.0.

Compared with draft (2009-01-15), draft (2009-03-10) optimizes the description.

Draft (2009-01-15)This is the initial draft of the document for RAN11.0.

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Compared with issue 02 (2008-07-30) of RAN10.0, draft (2009-01-15) incorporates thefollowing changes:

Change

Type

Change Description Parameter Change

Featurechange

None. The name of SIGNAL_HO_SWITCH is changed toHO_MC_SIGNAL_SWITCH .

The name of ACT_SET_QUAL_SWITCH ischanged toHO_INTER_FREQ_RPRT_2D2F_SWITCH .

The name of INTER_FREQ_HHO_SWITCH ischanged toHO_INTER_FREQ_HARD_HO_SWITCH .

The name ofHO_BEYOND_UE_CAP_ADD_TO_MC_SWITCH is changed toHO_MC_MEAS_BEYOND_UE_CAP_SWITCH .

The function CS Voiceover HSPA is added.

The added parameter is as follows: CSVoiceoverHSPASuppInd

Editorialchange

The Handover Parameter Description combines the contentsof the followingdocuments:

Intra-frequencyHandoverDescription

Inter-frequencyHandoverDescription

Inter-RAT HandoverDescription

HCS HandoverDescription

None.

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2-1

2 Handover IntroductionHandover is a basic function of the cellular mobile network. The purpose of handover is to

ensure that a UE in CELL_DCH state is served continuously when it moves.

Handover can be classified into the following types:

Intra-frequency handover Inter-frequency handover Inter-RAT handover

Intended AudienceThis document is intended for:

System operators who need a general understanding of handover. Personnel working on Huawei products or systems.

Impact Impact on system performance

Intra-frequency soft handover provides seamless connection services for moving UEs, but it uses more downlink code resources and transmission resources. In the network,resource utilization is determined by controlling the number of UEs involved in intra-frequency soft handover.

Inter-frequency handover and inter-RAT handover are implemented in compressed mode.When too many UEs stay at the cell edge, the downlink capacity and uplink coverage ofthe system may decrease. These two types of handover may introduce delay, thusimpacting on delay-sensitive services.

HCS handover improves the voice quality of fast-moving UEs, enhances system capacity,and reduces signaling load.

Impact on other features

None.

Network Elements InvolvedTable 2-1 lists the Network Elements (NEs) involved in handover.

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2-2

Table 2-1 NEs involved in handover

HandoverType

UE NodeB RNC MSCServer

MGW SGSN GGSN HLR

Intra-frequencyhandover

Inter-frequencyhandover

Inter-RAThandover

HCS handover

NOTE: : not involved : involved

UE = User Equipment, RNC = Radio Network Controller, MSC Server = Mobile Service SwitchingCenter Server, MGW = Media Gateway, SGSN = Serving GPRS Support Node, GGSN = GatewayGPRS Support Node, HLR = Home Location Register

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3-1

3 Handover Overview3.1 Handover Types

Figure 3-1 shows the handovers supported by the Universal Mobile TelecommunicationsSystem (UMTS), which include intra-frequency handover, inter-frequency handover, andinter-RAT handover.

Figure 3-1 Handovers supported by the UMTS

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3-2

3.2 Intra-Frequency HandoverIntra-frequency handover is of the following two types:

Intra-frequency soft handover: means that multiple radio links are connected to the UE atthe same time. Intra-frequency hard handover: means that only one radio link is connected to the UE at

the same time.

Intra-Frequency Soft HandoverIntra-frequency soft handover is more commonly used than intra-frequency hard handover.The types of intra-frequency soft handover are as follows:

Intra-NodeB soft handover (also known as softer handover) Intra-RNC inter-NodeB soft handover Inter-RNC soft handover

Intra-frequency soft handover is characterized by the function that the UE can be connected tomultiple Universal Terrestrial Radio Access Network (UTRAN) access points at the sametime. Addition and/or release of radio links are controlled by the ACTIVE SET UPDATE

procedure.

Table 3-1 Differences between soft handover and softer handover

Item Softer Handover Soft Handover

Scenario When the UE is in the

overlapped coverage area ofmultiple neighboring cells of a NodeB with combined RLs

When the UE communicateswith multiple cells by settingup multiple channels over theUu interface

When the UE is in the overlapped

coverage area of two neighboring cellsof different NodeBs

When the UE communicates withdifferent cells by setting up multiplechannels over the Uu interface

Uplink signal Using maximum-ratiocombination

Using selection combination

Downlinksignal

Using maximum-ratiocombination

Using maximum-ratio combination

Resource use Occupying less Iub bandwidth Occupying more Iub bandwidth

The HO_INTRA_FREQ_SOFT_HO_SWITCH parameter is used to determine whether toenable both soft handover and softer handover. By default, this switch is set to ON , indicatingthat both soft handover and softer handover are enabled. After the RNC receives the event 1A,1B, 1C, or 1D report, it initiates the corresponding soft handover procedure for the UE. Forexample, the RNC can add or delete links.

The DivCtrlField parameter indicates whether maximum-ratio combination is enabled in theuplink during softer handover.

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3-3

Intra-Frequency Hard HandoverIntra-frequency hard handover refers to a handover where all the old radio links are released

before the new radio links are established. Compared with soft handover, intra-frequency hard

handover uses fewer resources.The scenarios of intra-frequency hard handover are as follows:

No Iur interface is present between RNCs. In this scenario, intra-frequency hardhandover instead of soft handover can be performed between two RNCs.

The Iur interface is congested between RNCs. In this scenario, also intra-frequency hardhandover instead of soft handover can be performed between two RNCs.

There is a high-speed Best Effort (BE) service.

Compared with soft handover, intra-frequency hard handover is used to save downlink bandwidth for a high-speed BE service.

The intra-frequency soft handover fails and intra-frequency hard handover is allowed.

When intra-frequency soft handover fails because of a congestion problem of the targetcell, the RNC tries an intra-frequency hard handover with a lower service bit rate.

The HO_INTRA_FREQ_HARD_HO_SWITCH parameter is used to determine whether toenable intra-frequency hard handover. By default, this switch is set to ON .

3.3 Inter-Frequency HandoverInter-frequency handover provides supplementary coverage for inter-frequency cells to shareload with each other and to ensure service continuity.

From the UE point of view, inter-frequency handover is the same as intra-frequency hardhandover, because for both cases, the old connection is released before a new connection isset up. For detailed information, see Intra-Frequency Hard Handover.

The types of inter-frequency handover are as follows:

Table 3-2 Types of inter-frequency handover

Type Description

Coverage-based inter-frequency handover

If a moving UE leaves the coverage of the currentfrequency, the RNC needs to trigger the coverage-basedinter-frequency handover to avoid call drops.

QoS-based inter-frequencyhandover

According to the Link Stability Control Algorithm, theRNC needs to trigger the QoS-based inter-frequencyhandover to avoid call drops.

Load-based inter-frequency blind handover

To balance the load between inter-frequency con-coveragecells, the RNC chooses some UEs and performs the inter-frequency blind handover according to user priorities andservice priorities.

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3-4

Type Description

Speed-based inter-frequencyhandover

When the Hierarchical Cell Structure (HCS) applies, thecells are divided into different layers according to

coverage. The macro cell has a larger coverage and a lower priority, whereas the micro cell has a smaller coverage anda higher priority.

Inter-frequency handover can be triggered by the UE speedestimation algorithm of the HCS. To reduce frequenthandovers, the UE at a higher speed is handed over to a cellunder a larger coverage, whereas the UE at a lower speed ishanded over to a cell under a smaller coverage. For detailedinformation about the cooperation between HCS handoverand inter-frequency handover, see Interoperability BetweenHCS Handover and Inter-Frequency Handover.

The coverage-based inter-frequency measurement and the QoS-based inter-frequencymeasurement can coexist.

The InterFreqHOSwitch parameter is used to determine the type of inter-frequencyhandover. According to the switch, the RNC chooses the inter-frequency measurement control

parameters to implement handover measurement based on coverage, QoS, speed, and othertypes.

INTER_FREQ_COV: The cell supports coverage-based inter-frequency handover. INTER_FREQ_COV_NCOV: The cell supports coverage-based and speed-estimation-

triggered inter-frequency handover. INTER_FREQ_TA: The inter-frequency handover is triggered by HCS traffic absorption.

This function itself contains the coverage-based function.

The HO_INTER_FREQ_HARD_HO_SWITCH parameter is used to determine whetherto allow load-based inter-frequency handover.

For detailed description of QoS-based inter-frequency blind handover switches, see the RateControl Parameter Description .

3.4 Inter-RAT Handover (3G to 2G)

3.4.1 Inter-RAT Handover IntroductionInter-RAT handover refers to the handover performed between 3G network and 2G network.The handover causes can be coverage limitation, link stability, or load limitation of the UMTSnetwork. This document mainly describes the 3G-to-2G handover.

Inter-RAT handover provides continuous coverage, load sharing, and HCS services, whichfully utilizes the existing 2G network resources and thus reduces operator's cost.

Based on the handover triggering causes, the 3G-to-2G handover can be categorized as fivetypes, as described in Table 3-3.

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3-5

Table 3-3 3G-to-2G handover types

Type Description

Coverage-based3G-to-2Ghandover

The coverage of the 3G network is incontinuous at the initial stage.On the border of the coverage, the poor signal quality of the 3Gnetwork triggers the 3G-to-2G measurement. If the signal quality ofthe 2G network is good enough and all the services of the UE aresupported by the 2G network, the coverage-based 3G-to-2G handoveris triggered.

QoS-based 3G-to-2G handover

According to the Link Stability Control Algorithm, the RNC needs totrigger the QoS-based 3G-to-2G handover to avoid call drops.

Load-based 3G-to-2G handover

If the load of the 3G network is heavy and all the RABs of the UE aresupported by the 2G network, the load-based 3G-to-2G handover istriggered.

Service-based 3G-to-2G handover

Based on layered services, the traffic of different classes is handedover to different systems. For example, when an Adaptive Multi Rate(AMR) speech service is requested, this service can be handed overto the 2G network.

Speed-based 3G-to-2G handover

When the Hierarchical Cell Structure (HCS) applies, the cells aredivided into different layers according to coverage. The macro cellhas a larger coverage and a lower priority, whereas the micro cell hasa smaller coverage and a higher priority.

The 3G-to-2G handover can be triggered by the UE speed estimationalgorithm of the HCS. To reduce the frequencies of handover, the UEat a higher speed is handed over to a cell under a larger coverage,

whereas the UE at a lower speed is handed over to a cell under asmaller coverage. For detailed information, see HCS HandoverAlgorithms.

Note:

The principles of the 3G-to-2G handover based on HCS speedestimation are similar to those of inter-frequency handover.

3.4.2 Rules for Enabling 3G-to-2G HandoverBefore handover, the RNC checks whether all the preconditions for the 3G-to-2G handoverare met. The preconditions include service handover indicators, service requirements, andhandover rules.

Before deciding the 3G-to-2G handover, the RNC considers 2G cell capability, servicecapability and UE capability.

2G cell capability

2G cell capability is configured through the parameter RATCELLTYPE . This parameter indicates whether the cell supports the GSM, GPRS, or EDGE.

Service capability

The Required 2G Capability ( Req2GCap ) specifies the capability of 2G cells required by inter-RAT handover. This indicates whether the service is supported by the GSM,GPRS, or EDGE. For the default value provided by the RNC, see Table 3-6.

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3-6

UE capability

Upon the reception of the UE capability information message, the RNC decides whetherto start the inter-RAT measurement. The information indicates whether the UE supportsthe GSM, GPRS, or EDGE.

The rules for enabling the 3G-to-2G handover are based on the Service HandoverIndicator and the three types of capability. The rules vary according to the types of inter-RAT handover.

Rules for Enabling Coverage- and QoS-based 3G-to-2G HandoverThe RNC initiates the coverage- or QoS-based UMTS-to-GSM handover only when ServiceHandover Indicator is set as follows:

HO_TO_GSM_SHOULD_BE_PERFORM HO_TO_GSM_SHOULD_NOT_BE_PERFORM

The following tables describe the impacts of different types of capability on handoverdecision. If the capability of all 2G neighboring cells does not meet the requirement, the inter-RAT measurement will not be triggered.

Table 3-4 Impacts of different types of capability on handover decision

CellCapability

UE Capability Service Capability (Required by 2G)

EDGE GPRS GSM

EDGE EDGE Allowed Allowed Allowed

GPRS Allowed Allowed Allowed

GSM Not allowed Not allowed Allowed

Not supported by2G

Not allowed Not allowed Not allowed

GPRS EDGE Allowed Allowed Allowed

GPRS Allowed Allowed Allowed


Not supported by2G


GSM EDGE Not allowed Not allowed Allowed

GPRS Not allowed Not allowed Allowed


Not supported by2G


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3-7

Rules for Enabling Load- and Service-based 3G-to-2G HandoverThe RNC initiates the load-based 3G-to-2G handover only when Service Handover Indicatoris set as follows:

HO_TO_GSM_SHOULD_BE_PERFORM HO_TO_GSM_SHOULD_NOT_BE_PERFORM

The RNC initiates the service-based 3G-to-2G handover only when the Service HandoverIndicator is set to HO_TO_GSM_SHOULD_BE_PERFORM.

The following three tables describe the impacts of different types of capability on handoverdecision.

Table 3-5 Impacts of different types of capability on handover decision

Cell

Capability UE Capability Service Capability (Required by 2G)

EDGE GPRS GSM

EDGE EDGE Allowed Allowed Allowed

GPRS Not allowed Allowed Allowed


Not supported by 2G Not allowed Not allowed Not allowed

GPRS EDGE Not allowed Allowed Allowed

GPRS Not allowed Allowed Allowed



GSM EDGE Not allowed Not allowed Allowed

GPRS Not allowed Not allowed Allowed



If the capability of all neighboring 2G cells does not meet the requirement, the inter-RATmeasurement will not be triggered.

Switches for Service-based 3G-to-2G HandoverTo perform the service-based 3G-to-2G handover, the RNC must turn on the related switchesfor services in the CS and PS domains.

When a single CS service is initially set up by the UE, the RNC allows the 3G-to-2Gservice-based handover if CSServiceHOSwitch is set to ON .

When a single PS service is initially set up by the UE, the RNC allows the service-based3G-to-2G handover if PSServiceHOSwitch is set to ON .

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For the CS and PS combined services, no service-based handover is triggered.

Service Handover Indicator

The IE Service Handover Indicator indicates the CN policy for the service handover to the 2Gnetwork. This IE is indicated in the Radio Access Bearer (RAB) assignment signalingassigned by the CN, or in Table 3-6 provided by the RNC side.

The algorithm switch HoSwitch: HO_INTER_RAT_RNC_SERVICE_HO_SWITCHdecides whether the service attribute of inter-RAT handover is based on the RNC or the CN.

If the switch is set to ON , the service attribute of inter-RAT handover is based on the parameter configured on the RNC side.

If the switch is set to OFF , the service attribute of inter-RAT handover is first based onthe CN when the indicator is contained in the RAB assignment signaling assigned by theCN. If the CN does not allocate a service indicator, the service attribute of inter-RAThandover is based on the RNC side.

Through the SHIND parameter, the service handover indicators are set as follows:

HO_TO_GSM_SHOULD_BE_PERFORM: means that the handover to the 2G networkis performed when 2G signals are available.

HO_TO_GSM_SHOULD_NOT_BE_PERFORM: means that the handover to the 2Gnetwork is performed when 3G signals are weak but 2G signals are strong.

HO_TO_GSM_SHALL_NOT_BE_PERFORM: means that the handover to the 2Gnetwork is not performed even when 3G signals are weak but 2G signals are strong.

Figure 3-2 shows an example of rules for the indicator of the 3G-to-2G handover based onload and service.

Figure 3-2 Example of rules for indicator of 3G-to-2G handover based on load and service

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By default, the RNC does as follows:

For a UE with a single signaling RAB, the RNC supports the handover to the GSM. Butit is not recommended.

For the UE accessing combined services (with CS services), the RNC sets the servicehandover indicator of the UE to that of the CS service, because the CS service has thehighest QoS priority.

For the UE accessing combined services (with only PS services), the RNC sets theservice handover indicator of the UE to that of the PS service, because the PS service hasthe highest QoS priority

If the service handover indicators are not configured by the CN, each indictor can be set to theservice parameter index of a service on the RNC. Each service parameter index is the index ofone typical service RAB, which involves a set of service type, source description, CN domainID, and maximum rate (bit/s).

Table 3-6 describes the service handover indicators recommended by Huawei.

Table 3-6 Service handover indicators (default values)

RABIndex

TrafficDirection

CNDomainID

TrafficClass

MaxRate(bit/s)

SourceDescription

Service HandoverIndicator

Required2GCapability

0Uplink anddownlink

CS_DOMAIN

CONVER SATIONAL

12200 SPEECHHO_TO_GSM_SHOULD_NOT_BE_PERFORM GSM

1 Uplink anddownlinkCS_DOMAIN

CONVER SATIONAL

23850 SPEECH HO_TO_GSM_SHOULD_NOT_BE_PERFORM GSM

2Uplink anddownlink

CS_DOMAIN

CONVER SATIONAL

28800UNKNOWN

HO_TO_GSM_SHALL_ NOT_BE_PERFORM GSM

3Uplink anddownlink CS_DOMAIN

CONVER SATIONAL

32000 UNKNOWNHO_TO_GSM_SHALL_

NOT_BE_PERFORM GSM

4Uplink anddownlink CS_DOMAIN

CONVER SATIONAL

56000 UNKNOWN HO_TO_GSM_SHALL_ NOT_BE_PERFORM GSM

5Uplink anddownlink

CS_DOMAIN

CONVER SATIONAL

64000UNKNOWN


6 Uplink anddownlinkCS_DOMAIN

STREAMING 57600

UNKNOWN


11Uplink anddownlink PS_DOMAIN

CONVER SATIONAL


NOT_BE_PERFORM GSM

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RABIndex

TrafficDirection

CNDomainID

TrafficClass

MaxRate(bit/s)

SourceDescription




CONVER SATIONAL

16000UNKNOWN

HO_TO_GSM_SHALL_ NOT_BE_PERFORM EDGE


CONVER SATIONAL


NOT_BE_PERFORM EDGE


CONVER SATIONAL

64000UNKNOWN


16Uplink anddownlink

PS_DOMAIN

CONVER SATIONAL

38800UNKNOWN



PS_DOMAIN

CONVER SATIONAL

39200UNKNOWN



CONVER SATIONAL


NOT_BE_PERFORM EDGE

19 Uplink anddownlink PS_DOMAINCONVER SATIONAL


NOT_BE_PERFORM EDGE

21 Uplink anddownlinkPS_DOMAIN

STREAMING 8000

UNKNOWN



STREAMING 16000

UNKNOWN



STREAMING 32000

UNKNOWN



PS_DOMAIN

STREAMING 64000

UNKNOWN



STREAMING 128000

UNKNOWN



STREAMING 144000

UNKNOWN



PS_DOMAIN

STREAMING 256000

UNKNOWN



PS_DOMAIN

STREAMING 384000

UNKNOWN


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RABIndex

TrafficDirection

CNDomainID

TrafficClass

MaxRate(bit/s)

SourceDescription




PS_DOMAIN

INTERACTIVE 0

UNKNOWN

HO_TO_GSM_SHOULD_NOT_BE_PERFORM GPRS


INTERACTIVE 8000

UNKNOWN



INTERACTIVE 16000

UNKNOWN



PS_DOMAIN

INTERACTIVE 32000

UNKNOWN



PS_DOMAIN

INTERACTIVE 64000

UNKNOWN



PS_DOMAIN

INTERACTIVE 128000

UNKNOWN

HO_TO_GSM_SHOULD_NOT_BE_PERFORM EDGE


PS_DOMAIN

INTERACTIVE 144000

UNKNOWN



PS_DOMAIN

INTERACTIVE 256000

UNKNOWN



PS_DOMAIN

INTERACTIVE 384000

UNKNOWN


49 Uplink PS_DOMAININTERACTIVE 608000

UNKNOWN


50 DownlinkPS_DOMAIN

INTERACTIVE 768000

UNKNOWN


51 Downlink PS_DOMAININTERACTIVE 1024000

UNKNOWN


52 Uplink PS_DOMAININTERACTIVE 1440000

UNKNOWN



UNKNOWN



UNKNOWN



INTERACTIVE 2048000

UNKNOWN


56 UplinkPS_DOMAIN

INTERACTIVE 2880000

UNKNOWN


57 DownlinkPS_DOM

AIN

INTERAC

TIVE3600000

UNKNO

WN

HO_TO_GSM_SHALL_

NOT_BE_PERFORMEDGE

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RABIndex

TrafficDirection

CNDomainID

TrafficClass

MaxRate(bit/s)

SourceDescription



58 UplinkPS_DOMAIN

INTERACTIVE 5740000

UNKNOWN



UNKNOWN



UNKNOWN



INTERACTIVE 13900000

UNKNOWN




UNKNOWN




UNKNOWN



PS_DOMAIN

BACKGR OUND 0

UNKNOWN



PS_DOMAIN

BACKGR OUND 8000

UNKNOWN



PS_DOMAIN

BACKGR OUND 16000

UNKNOWN



BACKGR OUND 32000

UNKNOWN



PS_DOMAIN

BACKGR OUND 64000

UNKNOWN



BACKGR OUND 128000

UNKNOWN



BACKGR OUND 144000

UNKNOWN



BACKGR OUND 256000

UNKNOWN



BACKGR OUND 384000

UNKNOWN


79 Uplink PS_DOMAINBACKGR OUND 608000

UNKNOWN



BACKGR OUND 768000

UNKNOWN


81 DownlinkPS_DOM

AIN

BACKGR

OUND1024000

UNKNO

WN

HO_TO_GSM_SHALL_

NOT_BE_PERFORMEDGE

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RABIndex

TrafficDirection

CNDomainID

TrafficClass

MaxRate(bit/s)

SourceDescription



82 UplinkPS_DOMAIN

BACKGR OUND 1440000

UNKNOWN


83 Downlink PS_DOMAINBACKGR OUND 1536000

UNKNOWN



UNKNOWN



PS_DOMAIN

BACKGR OUND 2048000

UNKNOWN


86 UplinkPS_DOMAIN

BACKGR OUND 2880000

UNKNOWN



BACKGR OUND 3600000

UNKNOWN


88 UplinkPS_DOMAIN

BACKGR OUND 5740000

UNKNOWN



BACKGR OUND 7200000

UNKNOWN



BACKGR OUND 10100000

UNKNOWN



UNKNOWN



BACKGR OUND 21000000

UNKNOWN



UNKNOWN


Note:Rows without RAB index are all NA.

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4-1

4 Intra-Frequency Handover Algorithms4.1 Intra-Frequency Handover Procedure

The intra-frequency handover procedure is divided into three phases: handover measurement,handover decision, and handover execution.

After the UE transits to the CELL_DCH state in connected mode during a call, the RNC sendsa MEASUREMENT CONTROL message to instruct the UE to take measurements and reportthe measurement event results.

The MEASUREMENT CONTROL message carries the following information:

Event trigger threshold Hysteresis value

Event trigger delay time Neighboring cell list

Upon the reception of an event report from the UE, the RNC makes a handover decision and performs the corresponding handover, as shown in Figure 4-1.

Figure 4-1 Intra-frequency handover procedure

4.2 Intra-Frequency Handover MeasurementIn the measurement phase, the UE takes measurements according to the MEASUREMENT

CONTROL message received from the RNC. When the event triggering conditions are met,

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4-2

the UE sends measurement reports to the RNC according to the rules defined in theMEASUREMENT CONTROL message.

4.2.1 Intra-Frequency Handover Measurement QuantitiesIntra-frequency handover uses Ec/No or RSCP of the CPICH as the measurement value. Intra-frequency handover measurement events can be configured through the parameterIntraFreqMeasQuantity .

The UE performs layer 3 filtering on measurement values before it decides measurementevents and sends measurement reports. The measurement model, as shown in Figure 4-2, isdefined in 3GPP25.302. Figure 4-2 shows the position of layer 3 filtering in the measurement

procedure.

Figure 4-2 Measurement model in the WCDMA system

Figure 4-2 also shows the measurement points of the model, where

A: measurement value of the physical layer

B: measurement value obtained after layer-1 filtering. The value is weighted by the layer3 filtering coefficient.

C: measurement value obtained after layer 3 filtering. This value is controlled by thehigher layer. Filtering coefficient C is applicable to event reports and periodic reports.

C': another measurement value. C' and C are measured in the same way. D: measurement report information (message) of Uu or Iub transmission. Parameters (a) include the layer 3 filtering system and Parameters (b) include the

measurement report configuration.

The calculation is based on the following formula:

Fn = (1 - ) x Fn-1 + x Mn Fn: measurement value obtained after the nth filtering Fn-1: measurement value obtained after the (n-1)th filtering Mn: measurement value of the nth physical layer = 1/2(k/2) : k is determined by the parameter which is the layer 3 filtering coefficient of

intra-frequency handover measurement.

When is set to 1, k = 0 and layer 3 filtering is not performed.

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4-3

4.2.2 Intra-Frequency Handover Measurement EventsIn intra-frequency handover, the UE reports measurement results to the RNC through eventreporting.

Event Description

1A A primary CPICH enters the reporting range. This indicates that the quality of acell is close to the quality of the best cell in the active set. A relatively highcombined gain can be achieved when the cell is added to the active set.

1B A primary CPICH leaves the reporting range. This indicates that a cell has a lowerquality than the best cell in the active set. The cell has to be deleted from theactive set.

1C A non-active primary CPICH becomes better than an active primary CPICH. Thisindicates that the quality of a cell is better than the quality of the worst cell in the

active set. The RNC replaces a cell in the active set with a cell in the monitoredset.

1D The best cell changes.

1J RAN10.0 provides the solution to the issue of how to add an HSUPA cell in aDCH active set to an E-DCH active set. Event 1J is added to the 3GPP protocol.This event is triggered when a non-active E-DCH but active DCH primaryCPICH becomes better than an active E-DCH primary CPICH.

Triggering of Event 1AEvent 1A is triggered under the following condition:

10 x Log(M New ) + CIO New W x 10 x Log( A N

i

i M

1

) + (1 - W) x 10 x Log(M Best ) - (R 1a - H 1a/2)

M New is the measurement value of the cell in the reporting range. CIO New is equal to the sum of CIO and CIOOffset , which adjusts the cell boundary in

the handover algorithms. This parameter is determined by network planning according toactual environment configuration. To facilitate handover in neighboring cellconfiguration, the parameter is set as a positive value; otherwise, the parameter is set as a

negative value. W represents Weighted factor , which is determined by the parameter Weight . The total

quality of the best cell and the active set is specified by W. M i is the measurement value of a cell in the active set. NA is the number of cells not forbidden to affect the reporting range in the active set. The

parameter CellsForbidden1A indicates whether adding the cell to the active set affectsthe relative threshold of event 1A.

MBest is the measurement value of the best cell in the active set. R 1a is the reporting range or the relative threshold of soft handover. The threshold

parameters of the CS non-VP service, VP service, and PS service are as follows:

IntraRelThdFor1ACSVP

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4-4

IntraRelThdFor1ACSNVP

IntraRelThdFor1APS

For the PS and CS combined services, the threshold for CS services is used.

For the single signaling connection of the UE, the threshold for CS services is used.

H1a represents 1A hysteresis , the hysteresis value of event 1A

Figure 4-3 shows the triggering of event 1A. In this procedure, the default parameter valuesare used.

If the signal quality of a cell that is not in the active set is higher than Th1A for a period oftime specified by TrigTime1A (that is, Time to trigger in Figure 4-3) , the UE reports event1A.

Th 1A = (CPICH Ec/No of the best cell in the active set) - (reporting range for event 1A)

If Weighted factor > 0, then Th 1A = (general signal quality of all the cells in the activeset) - (reporting range for event 1A).

Reporting range for event 1A is equal to the value of IntraRelThdFor1ACSVP ,IntraRelThdFor1ACSNVP , or IntraRelThdFor1APS .

Figure 4-3 Triggering of event 1A

A: signal quality curve of the best cell in the active set B: signal quality curve of a cell in the monitored set C: curve of Th 1A

Triggering of Event 1BEvent 1B is triggered under the following condition:

10 x Log(M old) + CIO old W x 10 x Log( B N

i

i M

1

) + (1-W) x 10 x Log(M Best ) - (R 1b-H1b/2)

MOld is the measurement value of the cell that becomes worse.

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4-5

CIO Old is equal to the sum of CIO and CIOOffset , which is the offset between the cell inthe reporting range and the best cell in the active set.

W represents Weighted factor , used to weight the quality of the active set. The totalquality of the best cell and the active set is specified by the parameter Weight .

M i is the measurement value of a cell in the active set. NB is the number of cells not forbidden to affect the reporting range in the active set. The

parameter CellsForbidden1B indicates whether adding the cell to the active set affectsthe relative threshold of event 1B.

MBest is the measurement value of the best cell in the active set. R 1b is the reporting range or the relative threshold of soft handover. The threshold

parameters of the CS non-VP service, VP service, and PS services are as follows:

IntraRelThdFor1BCSVP

IntraRelThdFor1BCSNVP

IntraRelThdFor1BPS

For the PS and CS combined services, the threshold for CS services is used.

If the UE currently has only signaling connections, the threshold for CS services is used.

H1b is the hysteresis value of event 1B, which is determined by the parameter Hystfor1B .

Configuration rule and restriction

The value of IntraRelThdFor1BCSNVP has to be larger than that ofIntraRelThdFor1ACSNVP .

The value of IntraRelThdFor1BCSVP has to be larger than that ofIntraRelThdFor1ACSVP .

The value of IntraRelThdFor1BPS has to be larger than that of IntraRelThdFor1APS .

Figure 4-4 shows the triggering of event 1B. In this procedure, the default parameter valuesare used.

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4-6

Figure 4-4 Triggering of event 1B

A: signal quality curve of the best cell in the active set B: signal quality curve of the best cell in the monitored set C: curve of Th 1B

Th 1B = (CPICH Ec/No of the best cell in the active set) - (reporting range for event 1B)

where Reporting range for event 1B is equal to the value of IntraRelThdFor1BCSVP ,

IntraRelThdFor1BCSNVP , or IntraRelThdFor1BPS . If Weight > 0, then Th 1B = (general signal quality of all the cells in the active set) -

(reporting range for event 1B).

If the signal quality of a cell in the active set is lower than Th 1B for a period of time specified by TrigTime1B (Time to trigger in the figure), the UE reports event 1B.

Triggering of Event 1C

Event 1C is triggered under the following condition:10 x Log(M New ) + CIO New 10 x Log(M InAS ) + CIO InAS + H 1c/2

M New is the measurement value of the cell in the reporting range. CIONew is the cell individual offset value of the cell in the reporting range. It is equal to

the sum of CIO and CIOOffset , which is the offset between the cell in the reportingrange and the best cell in the active set.

M InAS is the measurement value of the worst cell in the active set. H1c is the hysteresis value of event 1C, which is determined by the parameter

Hystfor1C .

Figure 4-5 shows the triggering of event 1C. In this procedure, the default parameter valuesare used.

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4-7

Figure 4-5 Triggering of event 1C

A: signal quality curve of the best cell in the active set B: signal quality curve of a cell in the active set C: signal quality curve of the worst cell in the active set D: signal quality curve of a cell in the monitored set E: curve of Th 1C

Th 1C = (CPICH Ec/No of the worst cell in the active set) + (hysteresis/2)

where Hysteresis is equal to the value of Hystfor1C .

If the signal quality of a cell not in the active set is higher than Th 1C for a period of timespecified by TrigTime1C (Time to trigger in the figure), the UE reports event 1C, as shownin the figure.

The UE reports event 1C for qualified cells after the number of cells in the active set reachesthe maximum value. The maximum number of cells in the active set can be set by theMaxCellInActiveSet parameter.

Triggering of Event 1DEvent 1D is triggered under the following condition:

10 x Log(M NotBest ) + CIO NotBest 10 x Log(M Best ) + CIO Best + H 1d/2

M NotBest is the measurement value of a cell that is not the best cell. CIO NotBest is equal to the sum of CIO and CIOOffset , which is the offset between the

cell in the reporting range and the best cell in the active set. MBest is the measurement value of the best cell in the active set. CIO Best is the cell individual offset value of the best cell. This parameter is not used for

event 1D. H1d is the hysteresis value of event 1D, which is determined by the parameter Hystfor1D .

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4-8

Figure 4-6 shows the triggering of event 1D. In this procedure, the default parameter valuesare used.

Figure 4-6 Triggering of event 1D

A: signal quality curve of the best cell in the active set B: signal quality curve of a cell in the active set or the monitored set C: curve of Th 1D Hysteresis is equal to the value of Hystfor1D .

If the signal quality of a cell not in the active set is higher than Th 1D for a period of time

specified by TrigTime1D (Time to trigger in the figure), the UE reports event 1D.

Triggering of Event 1JEvent 1J is triggered under the following condition:

10 x Log(M New ) + CIO New 10 x Log(M InAS ) + CIO InAS + H 1j/2

MNew is the measurement result of the cell not in the E-DCH active set but in the DCHactive set.

CIO New and CIO InAS refer to the offset of each cell. M InAS is the measurement result of the cell in the E-DCH active set with the lowest

measurement result. H1J is the hysteresis parameter for event 1J and is determined by Hystfor1J . If the measurement result is CPICH-Ec/No, M New and M InAS are expressed as ratios. If the measurement result is CPICH-RSCP, M New and M InAS are expressed in mW.

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4-9

Figure 4-7 Triggering of event 1J

A: signal quality curve of a cell in the E-DCH active set B: signal quality curve of the worst cell in the E-DCH active set C: signal quality curve of a cell not in the E-DCH active set but included in DCH active

set D: signal quality curve of a cell not in the E-DCH active set but included in DCH active

set

In Figure 4-7, the hysteresis and the cell individual offsets for all cells equal 0.

The first measurement report is sent when primary CPICH D becomes better than primaryCPICH B. The "cell measurement event result" of the measurement report contains theinformation of primary CPICH D and CPICH B.

On the assumption that the E-DCH active set has been updated after the first measurementreport (E-DCH active set is now primary CPICH A and primary CPICH D), the second reportis sent when primary CPICH C becomes better than primary CPICH A. The "cellmeasurement event result" of the second measurement report shows that primary CPICH C is

better than primary CPICH A in quality.

The following parameters need to be set on the RNC LMT:

Hystfor1J : hysteresis of event 1F

TrigTime1J : time to trigger event 1J PeriodMRReportNumfor1J : number of periodic reports for event 1J ReportIntervalfor1J : report interval for event 1J after change to the periodic report HO_INTRA_FREQ_RPRT_1J_SWITCH : measurement control switch for event 1J.

When the switch is ON , the UE version is R6 and event 1J is included in the intra-frequency measurement control message.

After receiving the intra-frequency measurement report from the UE, the RNC decideswhether to go to the execution phase, depending on the information in the report.

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4-10

4.2.3 Intra-Frequency Handover Neighboring Cell CombinationAlgorithm

After the active set is updated, the RNC updates the neighboring cell list by using theneighboring cell combination algorithm according to the status of the active set. This listincludes the new intra-frequency, inter-frequency, and inter-RAT neighboring cells. Thecombination methods of intra-frequency handover, inter-frequency handover, and inter-RAThandover are the same.

If the radio link of the Drift RNC (DRNC) is added to the active set, the Source RNC (SRNC) buffers the intra-frequency, inter-frequency, and inter-RAT neighboring cell lists of the DRNCuntil the radio link of the DRNC is released.

The neighboring cell combination result is contained in the MEASUREMENT CONTROLmessage and sent to the UE, which instructs the UE to perform intra-frequency, inter-frequency, and inter-RAT measurement and handover procedures.

The number of inter-frequency neighboring cells is configured as follows:

A maximum of 32 intra-frequency neighboring cells are configured. A maximum of 32 single-carrier inter-frequency neighboring cells are configured. A maximum of 64 multi-carrier inter-frequency neighboring cells are configured. A maximum of 32 inter-RAT neighboring cells are configured.

Neighboring Cell Combination SwitchHO_MC_NCELL_COMBINE_SWITCH is the neighboring cell combination switch.

If the switch is set to ON , measurement objects are chosen from the neighboring cells ofall the cells in the active set.

If the switch is set to OFF , measurement objects are chosen from the neighboring cellsof the best cell.

HO_MC_NCELL_COMBINE_SWITCH is set to ON by default.

Description of the Neighboring Cell Combination AlgorithmAfter obtaining the intra-frequency neighboring cells of each cell in the active set, the RNCcalculates the union neighboring cell set of the intra-frequency cells, which is referred as S all,

by using the following method. This method can also be used to generate the S all of inter-frequency or inter-RAT cells.

1. The intra-frequency, inter-frequency, and inter-RAT neighboring cells of each cell in thecurrent active set are obtained.

2. The RNC sequences the cells in the active set in descending order of CPICH Ec/Noaccording to the latest measurement report (event 1A, 1B, 1C, or 1D) from the UE. The

best cell is based on event 1D, whereas other cells are based on the latest measurementreport.

3. The cells in the active set are added to S all.4. The neighboring cells of the best cell in the active set are added to Sall. NprioFlag ( the

flag of the priority ) and Nprio ( the priority of the neighboring cell ), which are set foreach neighboring cell, are used to change the order of adding the neighboring cells to

Sall.

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4-11

When NprioFlag is switched to FALSE , NPrio is cleared.

When NprioFlag is switched to TRUE , NPrio is set simultaneously.

5. The neighboring cells of other cells in the active set are added to Sall in descending order by CPICH Ec/No values of these cells in the active set. The neighboring cells of thesame cell in the active set are added according to Nprio and the number of repeatedneighboring cell is recorded.

If there are more than 32 intra-frequency neighboring cells in S all, delete the repeatedneighboring cells whose number in S all is less. The top 32 neighboring cells are grouped intothe final S all.

If there are more than 64 (multi-carrier) or 32 (single-carrier) inter-frequency neighboringcells in S all, the top 64 or 32 neighboring cells are grouped into the final S all.

4.3 Intra-Frequency Handover Decision and ExecutionThe intra-frequency handover decision and execution procedure depends on the differentmeasurement events that the RNC receives.

4.3.1 Decision and ExecutionTable 4-1 lists different types of intra-frequency handover decision and execution based ondifferent events.

Table 4-1 Intra-frequency handover decision and execution

Event Decision and Execution

1A When receiving an event 1A report, the RNC decides whether to add a cell.

For event 1A, the UE can report more than one cell in the event list in onemeasurement report. These cells are in the list of the MEASUREMENTCONTROL message, and they are sequenced in descending order ofmeasurement quantity.

For the cells in the list, the RNC adds the radio link to the active set only if thenumber of cells in the active set does not reach the maximum value. Thisoperation is not required if the number of cells in the active set reaches aspecified value.

1B When receiving an event 1B report, the RNC decides whether to delete a cell.

For event 1B, if there is more than one radio link in the active set, the RNCdecides whether to delete a radio link. This operation is not required if there isonly one radio link in the active set.

1C When receiving an event 1C report, the RNC decides whether to change theworst cell.

For event 1C, the UE reports a list that contains good cells and the cells to bereplaced, and sequences the cells in descending order by measurement quantity.After receiving the list from the UE, the RNC replaces the bad cells in the activeset with the good cells in the list.

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4-12

Event Decision and Execution

1D As stipulated in related protocols, an event 1D report includes information aboutonly one cell. This cell can be listed in an active set or a monitored set. The RNC

learns that the quality of this cell is better than that of the serving cell and takesone of the following actions:

If the reported cell is in the active set, the RNC decides whether to change the best cell or reconfigure measurement control.

If the reported cell is in the monitored set, then: If the number of cells in the active set has not reached the maximum value, theRNC adds the cell to the active set.

If the number of cells in the active set has reached the maximum value, theRNC replaces the worst cell in the active set with the reported cell.

The best cell is changed to the reported cell.

The RNC determines whether the intra-frequency hard handover scenarios areapplicable. For detailed information, see Intra-Frequency Handover Types insection 3.1 Handover Types. If any scenario is applicable, the RNC performs anintra-frequency hard handover.

1J When receiving an event 1J report with information about the good cells and thecells to be replaced, the RNC proceeds as follows:

If the current number of cells in the E-DCH active set is smaller than the valueof MaxEdchCellInActiveSet , the uplink of the cell where event 1J is triggeredis reconfigured to E-DCH.

If the current number of cells in the E-DCH active set is equal to the value ofMaxEdchCellInActiveSet , the RNC searches the measurement report for the

non-serving E-DCH with the lowest measured quality in the E-DCH active set.Then, the uplink of the cell where event 1J is triggered is reconfigured fromDCH to E-DCH.

Minimum Quality Threshold for Soft HandoverWhen receiving an event 1A, 1C, or 1D report, the RNC adds a target cell to the active setonly when the CPICH Ec/No of the target cell is higher than the absolute thresholdSHOQualmin .

SHO: soft handover

Switch for Cross-Iur Intra-Frequency HandoverIf the RRC connection has been set up but the Radio Bearers (RBs) have not, whether a cross-Iur soft handover can be executed is determined byHO_MC_SIGNAL_IUR_INTRA_SWITCH of the SET CORRMALGOSWITCH

parameter. Only if the switch is set to ON , can the cross-Iur soft handover be executed.

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4.3.2 Rate Reduction After an SHO FailureIf the radio link addition for a soft handover fails, the rate reduction is triggered for R99 NRT(Non Real Time) services to increase the probability of a successful soft handover.

Estimation Procedure for Rate ReductionIf the RNC receives a 1A, 1C, or 1D measurement report, the RNC tries to add thecorresponding cell to the active set. If the addition fails, the RNC performs the estimation

procedure for rate reduction.

Figure 4-8 Estimation procedure for rate reduction

1. The RNC evaluates whether the measurement quantity of the cell failing to be admittedmeets the condition of rate reduction.

If the condition is met, the RNC performs a rate reduction process for the access serviceimmediately, as described in Procedure of Rate Reduction Execution.

If the condition is not met, the RNC performs the next step (Step 2).

The condition of rate reduction is as follows: Mnew > Mbest_cell - RelThdForDwnGrd

Mnew is the CPICH Ec/No measurement value of the cell failing to be admitted. M best_cell is the CPICH Ec/No measurement value of the best cell in the active set. RelThdForDwnGrd is configured through the parameter Relative threshold of SHO

failure .

2. The RNC evaluates whether the number of SHO failures in the cell exceeds theThreshold number of SHO failure .

If the number of SHO failures in the cell is smaller than the ShoFailNumForDwnGrd:

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4-14

If the timer has not been started, the RNC starts it.

If the timer has been started, the RNC increments the SHO failure counter by one.

The timer length is set through the parameter ShoFailPeriod .

The SHO failure counter of a cell is used to record the number of SHO failures in thiscell. For each UE, the RNC records the number of SHO failures in three cells at most.For SHO failures in any other cells, the RNC does not record the number.

Before the SHO failure evaluation timer expires, no action is taken and the RNC waitsfor the next measurement report period.

When the SHO failure evaluation timer expires, the RNC sets the SHO failure counter ofthe corresponding cell to 0 and ends the evaluation.

If the number of SHO failures in the cell is larger than or equal to the parameterShoFailNumForDwnGrd , the RNC performs a rate reduction process for the accessservice,

Procedure of Rate Reduction ExecutionFigure 4-9 Procedure of rate reduction execution

1. The RNC performs a rate reduction process for the access service. The method ofdetermining the access rate after the rate reduction is the same as that described in Rate

Negotiation of Load Control Parameter Description .

2. After the rate reduction succeeds, the RNC immediately attempts to add this cell to theactive set without measurement:

If the cell succeeds in admitting the UE, the RNC adds the radio link and sets the SHO

failure counter of the cell to 0 and ends the execution.

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If the cell fails to admit the UE, the RNC starts the Period of penalty timer for SHOfailure after down rate to avoid an increase in the rate triggered by DCCC within the

period. Also in this period, the RNC sets the SHO failure counter of the cell to 0 andends the execution.

If the RNC fails to perform a soft handover again, it performs the estimation procedure andthe execution procedure, as previously described.

4.4 Intra-Frequency Handover of HSDPAThis section describes the decision and execution of intra-frequency handover, and thehandover between a cell supporting the F-DPCH and a cell not supporting the F-DPCH afterthe introduction of HSDPA.

4.4.1 Decision and Execution of Intra-Frequency Handover

Handling of Event 1AAfter receiving an event 1A report, the RNC proceeds as follows:

If the number of cells in the active set does not reach the maximum value, the RNC addsthe cell to the active set.

If the number of cells in the active set reaches the maximum value, the RNC does notadd the radio link to the active set.

Handling of Event 1BAfter receiving an event 1B report, the RNC determines whether to delete a cell.

If the cell to be deleted is not an HSDPA serving cell, the cell is directly removed. If the cell to be deleted is an HSDPA serving cell, then:

If the new best cell supports HSDPA, the new best cell is reconfigured to be anHSDPA serving cell. If the reconfiguration fails, the service is reconfigured ontoDPCH.

If the new best cell does not support HSDPA, the service is reconfigured onto DPCHto ensure the continuity of the service.

Handling of Event 1CAfter receiving an event 1C report, the RNC decides whether to change the worst cell.

If the cell to be replaced is not an HSDPA serving cell, the cell is directly removed. If the cell to be replaced is an HSDPA serving cell, then:

If the best cell supports HSDPA, the best cell is reconfigured to be an HSDPA servingcell. If the reconfiguration fails, the service is reconfigured onto DPCH.

If the best cell does not support HSDPA, the service is reconfigured onto DPCH toensure the continuity of the service.

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Handling of Event 1DAfter receiving an event 1D report, the RNC proceeds as follows:

If the downlink service is carried on the HSDPA, then:

If the new best cell in the active set supports HSDPA and the HSPA hysteresis timerexpires, the new best cell is reconfigured to be an HSDPA serving cell. The HSPAhysteresis timer is restarted after the serving cell change and is to avoid frequentupdates at the boundary between two HSDPA cells. The timer length is specified bythe parameter HspaTimerLen .

Figure 4-10 shows an example of how to handle event 1D in this situation. Assumethat the UE moves from HSDPA cell 1 to HSDPA cell 2, that the two cells are intra-frequency neighboring cells, and that all the cells in the active set support HSDPA.The RNC updates the HSDPA serving cell according to the reported event and keepsthe HSDPA serving cell consistent with the best cell.

If the new best cell in the active set does not support HSDPA, the downlink service is

directed to the DCH through the reconfiguration.

Figure 4-10 Intra-frequency handover between HSDPA cel

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