1.wcdma rno special guide inter-rat roaming and handover-20050316-a-2.0

WCDMA RNO Special Guide Inter-RAT Roaming and Handover Internal Open

2005-09-12 All rights reserved , Total69

Document code Product name WCDMA RNP

Target readers Product version 2.0

Edited by WCDMA RNP Document version 1.0

WCDMA RNO Special Guide

Inter-RAT Roaming and Handover

(For internal use only)

Drafted by: WCDMA RNP Date: March 3, 2005

Reviewed by: Date:

Reviewed by: Date:

Approved by: Date:

Huawei Technologies Co., Ltd.

All rights reserved



Revision Records

Date Revised version Description Author

March 3, 2005 1.00 First draft completed Jiao Anqiang

2005-03-16 2.00 Change the version, no content updated. Qinyan



Contents

Chapter 1 Overview of Inter-RAT Roaming and Handover ........................................................... 7

Chapter 2 Inter-RAT Roaming .......................................................................................................... 7 2.1 Definition of Roaming ............................................................................................................ 7 2.2 PLMN Selection and Reselection .......................................................................................... 8

2.2.1 PLMN Selection and Reselection Flow ....................................................................... 8 2.2.2 PLMN Selection/Reselection Effect in the Inter-RAT Roaming ................................ 12

2.3 Cell Reselection ................................................................................................................... 13 2.3.1 3G to 2G Cell Reselection Process .......................................................................... 13 2.3.2 2G to 3G Cell Reselection Procedure....................................................................... 17

Chapter 3 Inter-RAT Handover in CS Domain .............................................................................. 18 3.1 WCDMA-GSM Handover..................................................................................................... 18 3.2 GSM–WCDMA Handover .................................................................................................... 20

Chapter 4 Inter-RAT Handover in PS Domain .............................................................................. 24 4.1 WCDMA –GPRS Handover ................................................................................................. 24 4.2 GPRS –WCDMA Handover ................................................................................................. 27

Chapter 5 Common Radio Parameters and Data Configuration ................................................ 29 5.1 3G -2G Cell Reselection Parameters .................................................................................. 29 5.2 2G - 3G Cell Reselection Parameters ................................................................................. 31 5.3 3G -2G Handover Parameters ............................................................................................ 32

5.3.1 Handover Decision Process ..................................................................................... 32 5.3.2 Handover Parameters ............................................................................................... 33

5.4 Upgrade Required for GSM-WCDMA Cell Reselection ...................................................... 34 5.5 Data Configuration for Supporting Roaming and Handover between WCDMA and GSM/GPRS ............................................................................................................................... 38

5.5.1 2G MSC Data Configuration ..................................................................................... 38 5.5.2 Data Configuration Added by BSC ........................................................................... 38 5.5.3 Data Configuration Added by 3G MSC ..................................................................... 39 5.5.4 Data Configuration Added by RNC ........................................................................... 39

Chapter 6 Inter-RAT Roaming and Handover Strategies ............................................................ 40 6.1 Common Inter-RAT Handover Strategies ........................................................................... 40

6.1.1 Coverage Based Handover ...................................................................................... 40 6.1.2 Load Based Handover .............................................................................................. 40 6.1.3 Service Based Handover .......................................................................................... 41 6.1.4 Huawei Inter-RAT Roaming and Handover Strategies ............................................. 41

6.2 Inter-RAT Roaming and Handover Application Strategies .................................................. 43 6.2.1 Difficult Reselection and Handover to a 2G Network ............................................... 43 6.2.2 Easy Reselection and Handover to a 2G Network ................................................... 43

Chapter 7 FAQs ............................................................................................................................... 44 7.1 Inter-RAT Ping-pong Reselection ........................................................................................ 44

7.1.1 Phenomenon Description ......................................................................................... 44 7.1.2 Problem Analysis ...................................................................................................... 44 7.1.3 Solutions ................................................................................................................... 45

7.2 Inter-RAT Ping-pong Handover of PS ................................................................................. 45 7.2.1 Phenomenon Description ......................................................................................... 45 7.2.2 Problem Analysis ...................................................................................................... 45 7.2.3 Solutions ................................................................................................................... 46

7.3 Failure in handover from 3G to 2G Network ....................................................................... 47 7.3.1 Phenomenon Description ......................................................................................... 47 7.3.2 Problems Analysis .................................................................................................... 47 7.3.3 Solution ..................................................................................................................... 48

Chapter 8 Appendix 1: 2G Measurement by UE .......................................................................... 49 8.1 Introduction .......................................................................................................................... 49 8.2 Measurement on a GSM System in the CELL DCH State .................................................. 50

8.2.1 Measurement of RSSI in GSM Cell Carrier .............................................................. 51



8.2.2 Confirmation and Reconfirmation of BSIC in GSM Cell Carrier ............................... 52 8.2.3 Selection of CMSS .................................................................................................... 55

8.3 Measurement on a GSM System by UE in the CELL FACH State ..................................... 55 8.4 Measurement on a GSM System by UE the in IDLE/CELL PCH/URA PCH State ............. 58

Chapter 9 Appendix 2: Compression Mode and Parameters Configuration ............................ 59

Chapter 10 Appendix 3: Compression Mode Start/Stop ............................................................. 66 10.1 Event 2d: The estimated quality of the currently used frequency is below a certain threshold ................................................................................................................................................... 66 10.2 Event 2 f: The estimated quality of the currently used frequency is above a certain threshold ................................................................................................................................................... 67

List of Tables

Table 1 CN common GSM-MAP NAS system information ................................................................. 9

Table 2 PS domain system information ............................................................................................ 10

Table 3 EFLOCI content ................................................................................................................... 10

Table 4 EFPSLOCI content............................................................................................................... 10

Table 5 Timing for cell reselection by UE ......................................................................................... 14

Table 6 Parameters in WCDMA S rule ............................................................................................. 15

Table 7 Parameters in WCDMA R rule ............................................................................................. 15

Table 8 3G–2G cell reselection parameters ..................................................................................... 29

Table 9 2G–3G cell reselection parameter ....................................................................................... 31

Table 10 3G–2G handover parameters ............................................................................................ 33

Table 11 New added table: Description of 3G neighbor cells ........................................................... 34

Table 12 Modified table: system information data (added field) ....................................................... 35

Table 13 Filling method of fields in SI2quater ................................................................................... 35

Table 14 Filling method of fields modified in SI3 .............................................................................. 37

Table 15 Number of GSM carrier RSSI ............................................................................................ 51

Table 16 Combination of TGL1, TGL2, and TGD in GSM ................................................................ 51

Table 17 Combination of TGL1, TGL2, and TGD in UTRAN ............................................................ 52

Table 18 Gap length and maximum time difference ......................................................................... 53

Table 19 Nidentify_abort values of sample sequence in compression mode .......................................... 53

Table 20 Values of Nre-confirm_abort and Tre-confirm_abort in patterns .......................................................... 54

Table 21 Relationship between length of measurement occasion and number of GSM carrier RSSI samples ............................................................................................................................................. 57

Table 22 Relationship between measurement occasion length and max. time difference ............... 57

Table 23 Parameter and meanings. .................................................................................................. 61



List of Figures

Figure 1 Roaming in core network ...................................................................................................... 8

Figure 2 UE flow in the idle mode ....................................................................................................... 9

Figure 3 PLMN auto selection/reselection ........................................................................................ 12

Figure 4 WCDMA–GSM handover signaling flow ............................................................................. 19

Figure 5 WCDMA–GSM handover signal tracing ............................................................................. 19

Figure 6 GSM–WCDMA handover flow ............................................................................................ 21

Figure 7 GSM–WCDMA handover signaling tracing ........................................................................ 21

Figure 8 WCDMA–GPRS handover flow (1) ..................................................................................... 24

Figure 9 WCDMA–GPRS handover flow (2) ..................................................................................... 25

Figure 10 WCDMA–GPRS handover signaling tracing .................................................................... 25

Figure 11 GPRS–WCDMA handover (1) .......................................................................................... 27

Figure 12 GPRS–WCDMA handover (2) .......................................................................................... 27

Figure 13 Indoor 3G RSCP distribution ............................................................................................ 48

Figure 14 Frames in compression mode .......................................................................................... 59

Figure 15 CMSS parameters ............................................................................................................ 60



WCDMA RNO Inter-RAT Roaming and Handover Guide

Key words: Inter-RAT, roaming, handover

Abstract: This document describes the roaming and handover between WCDMA and GSM, including the

detailed process, radio parameters configuration, and strategy, and lists the present problems

and solutions.

Acronyms and abbreviations

Acronyms Full spelling

BSIC Base Station Identify Code

CFN Connection Frame Number

CPICH Common Pilot Channel

FDD Frequency Division Duplex

GPRS General Packet Radio Service

GSM Global System for Mobile Communications

RNC Radio Network Controller

RSSI Received Signal Strength Indicator

SB Synchronization Burst

SFN System Frame Number

TGCFN Transmission Gap Connection Frame Number

TGL Transmission Gap Length

TGPL Transmission Gap Pattern Length

UE User Equipment

UTRAN Universal Terrestrial Radio Access Network

WCDMA Wideband Code Division Multiple Access



Chapter 1 Overview of Inter-RAT Roaming and

Handover

The existing GSM/GPRS network coverage is complete. At the early stage, when WCDMA

is commercially available, out of the consideration of costs, the operators do not construct a

3G network at a large scale. Therefore, the WCDMA network coexists with GSM/GPRS

network for a period.

To guarantee the investment of operators on GSM/GPRS devices, WCDMA network must be

compatible with the GSM/GPRS network. Therefore, the roaming and handover between

GSM/GPRS and WCDMA must be implemented. Inter-RAT roaming and handover aim to

provide uninterrupted and better Quality of Service (QoS) for the communication between

the users at the borders of different systems. Especially at the early stage of 3G network

construction, when 3G network cannot implement seamless coverage, 2G network helps

ensure no call drop and smooth transition to 3G network.

Chapter 2 Inter-RAT Roaming

2.1 Definition of Roaming

―Roaming‖ is always closely related to HLR. If the original access network of a mobile user

is HLR, the user camps on the home location. If a mobile user moves from the HLR and

accesses another radio area of a different MSC/VLR, ―roaming‖ is performed. The serving

area is the roaming area. Because the serving network changes, the subscription information

of user transits from the original VLR to the new VLR. In this way, the user can enjoy the

services specified in the subscription information at the roaming network. Figure 1 shows the

original access area and roaming area are MSC/VLR of HLR and roaming area.

The mobile user may also move from the roaming area and access a radio area of another

MSC/VLR except HLR and the roaming area. In this case, the same process shown in 1.1.1.1

1.1)a.Figure 1 is present. And then the roaming is performed. Namely, the original access

area and roaming area in 1.1.1.1 1.1)a.Figure 1 become the MSC/VLR of new roaming area

after the user moves from HLR and the MSC/VLR of latest access area respectively.

The roaming between WCDMA and GSM is completed by HPLMN reselection and cell

reselection. Routing area or location area updates.



Figure 1 Roaming in core network

2.2 PLMN Selection and Reselection

2.2.1 PLMN Selection and Reselection Flow

When UE is powered on or is roaming, UE first must search a network and acquire the

service from the network.

In the idle mode, the behaviors of UE contain PLMN selection and reselection, cell selection

and reselection, and location registration. Figure 2 shows their relationship.

Original access area HLR New roaming area

UE location update request

Insert user data

Update

location area

UE location update acceptance Updated location

Area responds

Delete user data



PLMN Selection

and Reselection

Location

Registration

PLMNs

available

PLMN

selected

Location

Registration

response

RegistrationArea

changes

Indication

to user

User selectionof PLMN

Automatic/Manual selection

CM requests

NAS Control

Radio measurements

Cell Selection

and Reselection

Figure 2 UE flow in the idle mode

After UE is powered on, UE performs the following:

1) Select a Public Land Mobile Network (PLMN).

2) Select a cell of the PLMN.

3) Obtain the information of neighbor cells through the broadcast of system messages.

4) Camp on a cell with the best signal from all the cells.

5) Initiate a location registration procedure.

6) Successfully camp on the cell, if succeeded.

The functions of cell resident are:

Enable UE to receive the system information broadcast through the PLMN.

Initiate a random access procedure in the cell.

Receive the network paging.

Receive the cell broadcast services.

After UE camps on the cell and location registration succeeds, the signal strengths of existing

cell and neighbor cell change with the UE moving. UE needs to select the most proper cell,

meanly a cell reselection procedure. The cell reselection must confirm to a rule. The rule is

detailed later.

When reselecting another cell, UE finds that the cell belongs to another location area (LA) or

routing area (RA), and initiates a location update flow to enable the network to obtain the

latest location information of UE. SIB1 includes CN common GSM-MAP NAS system

information and PS domain system information. UE judges whether LA or RA changes based

on the LAC and RAC information in theSIB1.

Table 1 CN common GSM-MAP NAS system information

8 7 6 5 4 3 2 1



LAC octet 1

octet 2

Table 2 PS domain system information

8 7 6 5 4 3 2 1

RAC octet 1

Spare NMO octet 2

If the location registration or update fails (for example, the network rejects UE), or UE leaves

the coverage areas of the PLMN, UE reselects a usable PLMN.

PLMN selection/reselection aims to select a usable PLMN. To select a usable PLMN, UE

keeps a PLMN list. The PLMNs are arranged in the list based on the priority, and UE

searches a PLMN with the highest priority. UE can select/reselects automatically and

manually the PLMN. The auto selection/reselection of PLMN means that UE selects

automatically a PLMN based on the priority. The manual selection/reselection of PLMN

means that the system provides all the PLMNs for a user and the user selects a PLMN.

In the RLMN list, registered PLMN (RPLMN) has the highest priority. RPLMN is the

successfully registered PLMN last time. UMTS Subscriber identity module (USIM) contains

―EFLOCI‖ and ―EFPSLOCI‖, and the two files record the RPLMN information.

Table 3 EFLOCI content

Bytes Description M/O Length

1 to 4 TUEI M 4 bytes

5 to 9 LAI M 5 bytes

10 RFU M 1 byte

11 Location update state M 1 byte

Table 4 EFPSLOCI content

Bytes Description M/O Length

1 to 4 P-TUEI M 4 bytes

5 to 7 P-TUEI signature value M 3 bytes

8 to13 RAI M 6 bytes

14 Routing Area update state M 1 byte

In the two files, LAI (= MCC + MNC + LAC) and RAI (=LAI+RAC) contain Mobile

Country Code (MCC) and Mobile Network Code (MNC), that is, RPLMN.

Whatever UE selects a PLMN automatically or manually, after UE is powered on, UE first

attempts to select a RPLMN. If succeeded, the succeeding operations are not present. If failed,

UE generates a PLMN list (the PLMNs are arranged based on the priority) as follows:



1) HPLMN

2) PLMN in the ―User Controlled PLMN Selector with Access Technology‖ of USIM file

3) PLMN in the ―Operator Controlled PLMN Selector with Access Technology‖ of USIM

file

4) PLMN (arranged randomly) with better signal quality

5) Other PLMNs (arranged based on the signal quality from good to bad)

In the USIM, the file ―EFIMSI‖ records IMSI (MCC+MNC+MSIN), and UE obtains the

HPLMN.

2) and 3) are EFPLMNwAcT and EFOPLMNwACT in the USIM. 4) and 5) are searched

by UE based on the frequency.

UE searches the PLMN one by one based on the PLMN list, and attempts a location

registration.

Although UMTS evolves from GSM, their access technologies are UTRAN and GERAN

respectively. Therefore, specify the preferential access technology for each PLMN. The

priority of access technologies are specified in the file ―...with Access Technology‖. If the

priority is not specified, select GERAN.

In the following two cases, reselect a PLMN:

Reselect the PLMN required by a user:

Under any conditions, a user can manually initiate a PLMN reselection.

Reselection when a user registers VPLMN: After a user registers in a VPLMN due to

the handover/roaming, UE can judge that VPLMN and HPLMN have the same MCC

but a different MNC. At that time, UE tries to return to HPLMN. The solution is that UE

finds HPLMN periodically. The period is specified by USIM defined in the file

―EFHPLMN‖. It ranges from six minutes to eight hours. The operators can disable this

function by setting 0 to this period in the file ―EFHPLMN‖ .

Error! Reference source not found. describes the procedure of PLMN selection or

reselection.



Null Switch on, no SIM

Switch on with SIM

Yes

SIM inserted

Selectregistered

PLMN

Is

there a

RPLMN

?

No SIM

No

TryingRPLMN

C

Registrationsuccess

Registrationfailure

A B

FIndicateselectedPLMN

LU response"Roamingnot allowed"

E A TryingPLMN

On VPLMN ofhome country

and timeoutoccurs

D

AYes

AnyallowablePLMNs

available?

On PLMN

C

Loss of radiocoverage of

selected PLMN **

Select first *PLMN in list

Select next *PLMN in list

Userre-selection

Registrationsuccessful

Registrationfailure, more in list

B

Registrationfailure, no morein list

D

Move lastselected PLMNtemporarily into

(d) on list

NoAny

PLMNs

& Allowable?

availableSelect RPLMNor HPLMN if

none

Initiate HPLMNsearch

GHPLMNsearch inprogress

HPLMN not found

HPLMNfound

ESelect

HPLMN

F

Yes

C

Select firstavailable and

allowable PLMNin list

AG

No

Wait forPLMNs

to appear

PLMN availableand allowable

PLMN availableand allowable,which is notRPLMN

E A

* "List" consists of points i) to v) except in caseof a user re-selection in which case “list”consists of points i) to vi)

** Includes effective loss of coverage due to LAs being forbiddenin all potentially suitable cells

Registered

Switch Off

SIM removed or invalid SIM

User reselection

Figure 3 PLMN auto selection/reselection

2.2.2 PLMN Selection/Reselection Effect in the Inter-RAT Roaming

The PLMN selection/reselection can realize the Inter-RAT roaming without upgrading GSM

network and WCDMA network.



A user can return to a WCDMA network from a GSM network through the PLMN reselection.

To ensure a smooth transition from a GSM network to WCDMA network within WCDMA

network coverage areas for a WCDMA user, the WCDMA network and GSM network have a

different PLMN, and the WCDMA network is set as a HPLMN in the USIM. The operators

determine the PLMN selection time.

The strategy for reselection and handover between 3G and 2G network in the project of S

commercial office is like this. When meet Inter-RAT measurement initiation conditions and

the signal in 2G network is better than in 3G network, UE reselects from 3G to 2G network

by system information configuration parameters. UE returns to 3G network from 2G network

by periodical reselection of HPLMN. The detailed strategy is as following.

The handover between 2G and 3G includes following situations:

1) In idle state, UE hands off from 3G network to 2G network in two ways.

If the UE drops from 3G network, it reselects 3G network or 2G network in several

minutes. During the dropping, the UE only use limited emergency services, without

normal services.

If the UE reselects a 2G network from a 3G network, it returns to 3G network by

periodical reselection of HPLMN.

2) When the UE enjoys services, it hands off to 2G network in two ways.

The UE hands off to 2G network. It stops services then. It camps on 2G network.

The UE keeps using services in 3G, without handover to 2G. It stops services in 3G

network. and then returns to idle state. In this state, the UE returns to 2G network.

3) When the UE camps on 2G, it returns to 3G by periodical reselection of HPLMN in idle

state. If the 3G cell to be camped on satisfies the residing conditions, it returns to 3G

network six minutes later. In USIM card the period for HPLMN reselection is six minutes.

2.3 Cell Reselection

In the idle state, Inter-RAT selection can be realized through cell selection and reselection

functions. In this function when selection from GSM to WCDMA, GSM system must be

upgraded. In additional, the two systems have different criteria for signal quality. Therefore,

special attention must be paid to the parameters related to cell selection and reselection.

Otherwise, improper cell selection or ping-pong selection may occur.

2.3.1 3G to 2G Cell Reselection Process

When a UE is powered on, it first selects a PLMN. Then it selects the first cell in the PLMN.

After the UE enters the Camped Normally state, it measures.

I. Inter-RAT Measurement

In the serving cell, the UE measures CPICH Ec/Io and CPICH RSCP at least once in each

DTX period (as the following table).



If in the serving cell Squal>SsearchRAT, the UE need not measure the Inter-RAT cells.

Otherwise, the UE starts to measure. In this equation,

Squal = CPICH_EcNo measure – Qqualmin

CPICH_EcNo is the measured value of pilot in the serving cell.

SsearchRAT and Qqualmin are parameters in system information.

After the UE starts to measure the inter-RAT signal, according to the measurement controlled

information in the system information of the serving cell, it measures the signal strength of

the GSM BCCH carrier of each GSM neighboring cell at least in every TmeasureGSM. It

will confirm the BSICs of four strongest GSM BCCHs at least every 30 seconds, and sorts

the confirmed BSICs in order according to reselection criterio (R criterion). If the UE detects

a BSIC not defined in the SI, it does not consider this GSM BCCH when cell reselection. If

the UE fails to decode the BSIC in a GSM BCCH carrier, it does not consider the GSM

BCCH carrier yet.

If Treselection value is not 0 and the signal of a GSM cell is better than that of the serving

cell, the UE evaluates the GSM cell in Treselection period. If the GSM cell remains optimal

during the period, the UE reselects this cell.

The UE measures GSM cells in a time related to DRX period. The relationship is showed in

Table 5. UE must confirm the BSIC of the cell before reselection in Treselection.

Table 5 Timing for cell reselection by UE

DRX cycle

length [s]

Nserv

[number of

DRX cycles]

TmeasureFDD [s]

(number of

DRX cycles)

TevaluateFDD [s]

(number of

DRX cycles)

TmeasureTDD [s]

(number of

DRX cycles)

TevaluateTDD [s]

(number of

DRX cycles)

TmeasureGSM [s]

(number of

DRX cycles)

0.08 4 0.64 (8 DRX

cycles)

2.56 (32 DRX

cycles)

0.64 (8 DRX

cycles)

2.56 (32 DRX

cycles)

2.56 (32 DRX

cycles)

0.16 4 0.64 (4) 2.56 (16) 0.64 (4) 2.56 (16) 2.56 (16)

0.32 4 1.28 (4) 5.12 (16) 1.28 (4) 5.12 (16) 5.12 (16)

0.64 4 1.28 (2) 5.12 (8) 1.28 (2) 5.12 (8) 5.12 (8)

1.28 2 1.28 (1) 6.4 (5) 1.28 (1) 6.4 (5) 6.4 (5)

2.56 2 2.56 (1) 7.68 (3) 2.56 (1) 7.68 (3) 7.68 (3)

5.12 1 5.12 (1) 10.24 (2) 5.12 (1) 10.24 (2) 10.24 (2)

II. Evaluation Rules in Reselection

As mentioned above, UE evaluates in Treselection. Then what is the evaluation rule?

1) UE selects cells that accord with an S rule.

S rule is a basic requirement in cell reselection. It is also used in cell selection. UE selects the

cells only satisfy the S rule.



for FDD cells: Srxlev > 0 AND Squal > 0

for TDD cells: Srxlev > 0

for GSM cells: Srxlev > 0

Wherein,

Squal = Qqualmeas – Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Table 6 Parameters in WCDMA S rule

Squal

Cell Selection quality value (dB)

Applicable only for FDD cells.

Srxlev Cell Selection RX level value (dB)

Qqualmeas

Measured cell quality value. The quality of the received signal expressed in

CPICH Ec/N0 (dB) for FDD cells.

Applicable only for FDD cells.

Qrxlevmeas

Measured cell RX level value. This is received signal, CPICH RSCP for FDD

cells (dBm), P-CCPCH RSCP for TDD cells (dBm) and the averaged

received signal level as specified in [10] for GSM cells (dBm).

Qqualmin Minimum required quality level in the cell (dB). Applicable only for FDD

cells.

Qrxlevmin Minimum required RX level in the cell (dBm)

Pcompensation max(UE_TXPWR_MAX_RACH – P_MAX, 0) (dB)

UE_TXPWR_MAX_R

ACH

Maximum TX power level an UE may use when accessing the cell on RACH

(read in system information) (dBm)

P_MAX Maximum RF output power of the UE (dBm)

In all cells that accord with S rule, UE adopts the R rule as following to list cells in order.

Rs = Qmeas,s + Qhysts

Rn = Qmeas,n - Qoffsets,n

Table 7 Parameters in WCDMA R rule



S N S means servicing cell. N means neighboring cell.

Qoffset1s,n

This specifies the offset between the two cells. It is used for TDD and GSM

cells and for FDD cells in case the quality measure for cell selection and

re-selection is set to CPICH RSCP.

Qoffset2s,n

This specifies the offset between the two cells. It is used for FDD cells in case

the quality measure for cell selection and re-selection is set to CPICH Ec/No.

Qhyst1s

This specifies the hysteresis value (Qhyst). It is used for TDD and GSM cells

and for FDD cells in case the quality measure for cell selection and re-selection

is set to CPICH RSCP.

Qhyst2s

This specifies the hysteresis value (Qhyst). It is used for FDD cells if the

quality measure for cell selection and re-selection is set to CPICH Ec/No.

Qmeas

Quality value. The quality value of the received signal derived from the

averaged CPICH Ec/No or CPICH RSCP for FDD cells, from the averaged

P-CCPCH RSCP for TDD cells and from the averaged received signal level for

GSM cells. The averaging of these measurement quantities are performed as

specified in [10] and [11]. For FDD cells, the measurement that is used to

derive the quality value is set by the

Cell_selection_and_reselection_quality_measure information element.

Treselections Time-to-trigger for cell reselection, (s)

UE lists cells in order according to the R rule above. In FDD and GSM cells, UE uses CPICH

RSCP and GSM BCCH RSSI respectively to obtain Qmean, s and Qmean, n, and then calculates R

value. UE uses the offset parameter Qoffset1s, n to calculate Rn and uses the hysteresis

parameter Qhyst1s to calculate Rs.

With calculation to the R value above:

1) If the R value of a GSM neighboring cell is larger than that in the serving cell, and UE

satisfies confirmation and requirement on Treselection, UE reselects the GSM cell.

2) If the R value in an FDD cell is the largest,

And quality measurement target is CPICH RSCP in selection and reselection of cell, UE

reselects the FDD cell.

And quality measurement target is CPICH Ec/No, the UE needs to list all FDD cells in

order the second time according to the R rule and selects the best FDD cell. Qmeas,n

and Qmeas,s can be got from CPICH Ec/No and then FDD cells’ R values can be

calculated where Qoffest2s, n is instead of Qoffsets, n to calculate Rn and Qhyst2s is

instead of Qhysts to calculate Rs.

If UE selects a new cell, it needs to satisfy the following conditions:

The new cell is better than the serving cell in Treselection.

UE has camped on the serving cell for over one second.



2.3.2 2G to 3G Cell Reselection Procedure

I. Inter-RAT measurement

For UE in Multi_RAT, 3G cell reselection list includes other access technology cells and

frequency. If RLA_C in the serving cell is compared with Qsearch_I threshold, the parameter

Qsearch_I (Qsearch_I means the idle state of CS domain, Qsearch_C_Initial means building

the connection phase of CS domain and Qsearch_P means GPRS domain.) controls whether

to start Inter-RAT measurements.

If 3G cell reselection list includes only one UTRAN frequency, UE can identify within 30s

and reselects a new UTRAN cell. When a different UTRAN frequency appears in the list, 30s

adds to the allowable time. If the same frequency appears in the list, no extra time adds to the

allowable time.

An UE in a Multi_RAT can monitor 64 UTRAN cells. Depending on capacity of UE, the

cells are divided as follows:

FDD cells include at most three FDD frequencies. Each frequency can be used in 32

cells at most.

TDD cells include at most three TDD frequencies. Each frequency can be used in 32

cells at most.

II. Algorithm for Reselection from GSM to UTRAN

If 3G cell reselection list in GSM cell system information includes UTRAN frequency, UE

needs to update RLA_C (average received level) in the serving cell and at least six strongest

non-serving GSM cells at least every other 5s.

If in 5s, RSCP measured in UTRAN cell by UE is XXX_Qoffset larger than RLA_C in the

serving cell and non-serving GSM cells, and Cpich_EcNo in the UTRAN cell (in FDD type)

is not less than FDD_Qmin, the UE reselects the UTRAN cell. XXX_Qoffest increases 5 dB

15 seconds before the UE reselects cell.

Note: FDD_Qmin and XXX_Qoffset are from BCCH broadcast in the serving cell. XXX

means different radio technique and mode.

UE can not reselect UTRAN cell until 5 seconds after the UE reselects a proper GSM cell. If

more than one UTRAN cell satisfies criterions above, UE selects the cell with the strongest

RSCP.



Chapter 3 Inter-RAT Handover in CS Domain

3.1 WCDMA-GSM Handover

In the case of WCDMA–GSM handover, if UE only performs CS services, the operators

perform WCDMA–GSM CS domain handover.

The typical handover procedure is as follows, measurement control—>measurement

report—>handover decision—>handover implementation.

1) At the measurement control stage, the network sends a measurement control message to

notify UE of measured parameters.

2) At the measurement report stage, UE sends the network a measurement report message.

3) At the handover decision stage, the network judges the handover based on the

measurement report.

4) At the handover implementation stage, UE and the network perform signaling process

and make response.

During a WCDMA–GSM handover, when a user is located at the edge of WCDMA network

and the Inter-RAT handover is required, WCDMA RNC notifies dual-mode UE of Inter-RAT

measurement. UE measures other system and reports the measurement result, and RNC

judges whether to perform an Inter-RAT handover signaling flow based on the result.

WCDMA adopts the access method CDMA , so the UEs being connected work at a specified

frequency. To continue a call in the case of measurement on other system, WCDMA system

and dual-mode UEs must enable the compression mode (if the UE has only one transceiver, it

must enable compression mode. If the UE have two transceivers, it can test GSM cells

without enabling compression mode).



UE NodeB RNC 3G MSC 2G MSC BSS

Measurement Report(2D)

RL Recfg Prep

RL Recfg Ready

Physical Channel Reconfiguration

RL Recfg Commit

Physical Channel Reconfiguration cmp

Measurement Control(InterRAT)

Measurement Report(GSM)

Relocation Required

Relocation Command

Prepare Handover

Handover Request

Handover Request ACK

Prepare Handover RSP

Handover From UTRAN CMD

Handover Complete

IU release command

IU release complete

RRC Con Release Req

RRC Con Release Cmp

RL Del Req

RL Del Rsp

Figure 4 WCDMA–GSM handover signaling flow

WCDMA–GSM handover signal tracing

The flow at UTRAN side is as follows:

1. When a UE moves outside at the edge of a cell in the WCDMA system, and 2D event report

conditions of RNC configuration are satisfied, the UE reports a measurement report, 2D event

occurrence. In this case, the signal quality of WCDMA frequency is worse, and other frequencies

or the signal sources of other systems are required.

2. RNC enables the compression mode to measure other frequency or system. It delivers a ―RL

RECONFIG PREPARE‖ message to NodeB to prepare the compression mode. This message

includes compression mode sample sequence (CMSS) and related parameters. They are TGSN,



TGL, TGD, TGPL, compression method, downlink compression frame type, and power control

parameters in the compression mode.

3. NodeB returns a ―RL RECONFIG READ‖ message to RNC after the resources are ready.

4. RNC delivers again a ―PHYSICAL CHANNEL RECONFIG‖ message to a UE to prepare the

compression mode. This message includes activation time, CMSS and related parameters. They

are TGCFN, TGMP, TGSN, TGL, TGD, TGPL, RPP, ITP, compression method, downlink

compression frame type, and power control parameters in the compression mode.

5. After confirming that UE received the ―PHYSICAL CHANNEL RECONFIG‖ message, RNC

delivers a ―RL RECONFIG COMMIT‖ message to NodeB and tells the time to start

compression mode.

6. After the data configuration, the UE returns a ―PHYSICAL CHANNEL RECONFIG

COMPLETE‖ message to RNC. At that time, compression mode starts.

7. RNC immediately delivers the measurement control and UE performs inter-RAT measurement.

The measurement control message includes related parameters such as GSM cell list, cell

frequency information, and measurement filter coefficient.

8. UE reports RSSI measurement value of each GSM cell.

9. UE reports BSIC Ack. of each GSM cell.

10. If the handover conditions are satisfied, RNC sends a transition request to CN. The request

includes transition type (Inter-RAT handover requires UE), transition cause (often relocation

desirable for radio reasons), source PLMN, source SAI and destination CGI (including

destination PLMN, and LAC).

11. After assigning the related resources at the GSM side, CN delivers a ―RELOCATION

COMMAND‖ message to RNC, which includes layer 3 information, cell, and GSM allocation

related resources.

12. RNC delivers a ―HANDOVER FROM UTRAN COMMAND‖ message to UE. This message

includes RAB ID, activation time, GSM frequency, and GSM message in the BIT form.

13. Because UE disables the transmission when performing GSM configuration, no signal is in the

downlink and NodeB reports a ―SIR ERROR‖ message. This message is optional in the flow.

14. After UE accesses GSM, CN again delivers an ―IU RELEASE COMMAND‖ message to notify

RNC of releasing the resources of UE in the WCDMA.

15. RNC immediately returns an ―IU RELEASE COMPLETE‖ message to CN. The radio resources

of NodeB are released in the following two messages. The air interface does not send a ―RNC

connection release‖ message, because the UE is not present in the WCDMA system.

3.2 GSM–WCDMA Handover

In the case of GSM–WCDMA handover, when GSM cell has WCDMA neighbor cells,

the measurement control message is delivered through the system message. The dual-mode

UE performs inter-RAT measurement and reports the measurement result. BSC judges



whether to start inter-RAT handover signaling flow based on the result. GSM adopts TDMA,

so the inter-RAT measurement is performed in idle timeslot, and the GSM system has no

problems of supporting compression mode.

UE NodeB RNC 3G MSC 2G MSC BSS

RL setup requeset

RL setup response

RL Restore Indicaton

Handover Complete

UTRAN Capacity Info

UE Capacity Info Enquiry

Relocation RequesetPrepare Handover

Handover Request

Handover Command

Send end signal requeset

Inter System to UTRAN Ho cmd (Handover to UTRAN Command)

Clear command

Clear complete

UTRAN Capacity Info Confirm

UE Capacity Info Confirm

Relocation Requeset ACK

Prepare Handover RSP

Relocation Complete

Send end signal responseUE Capacity Info

Figure 5 GSM–WCDMA handover flow

Figure 6 GSM–WCDMA handover signaling tracing


1. According to handover algorithm and measurement information, the source BSS in the GSM

system judges that the UE hands over to UTRAN cell. After the BSS sends a handover request to

CN, MSC sends a ―RANAP_RELOCATION_REQUEST‖ message to RNC. This message

carries IMSI of UE, CN domain ID, target cell ID, encryption information, integrity protection



information, IU signaling connection ID, handover cause, RAB configuration information, and

user plane related information.

2. The RNC allocates radio resources for this transition, and configures the NodeB by executing

command RL SETUP. The NodeB transmits and receives radio signals.

3. After establishing the RL successfully, the NodeB returns a ―RL SETUP RESPONSE‖ message.

4. The RNC allocates radio resources and other parameter packets for UE. They are U-RNTI, RAB

information, transmission layer information and physical layer information. The parameters are

configured for UE through the following three modes:

a. Complete configuration: define the parameters at each layer

b. Pre-configuration (pre-definition): several parameter templates are broadcast through

the SI16 and the template sequence and necessary parameters are configured for the UE. The

UE monitors the SI of UTRAN and obtains the parameter configuration based on the

template sequence.

c. Pre-configuration (by default): the 25.331 specifies 10 types of default parameters,

and sets an ID for each type of default parameter. The RNC configures default configuration

ID and other necessary information for the UE.

RNC forwards the information in a ―RELOCATION REQUEST ACKNOWLEGE‖

message (in the RNC Container cell) of IU interface to BSS by the CN, and then to the UE.

According to RNC-configured default parameter ID, the UE obtains related access

parameters from the pre-configuration (by default) in the SI. It synchronizes directly with

the NodeB in the downlink and the uplink radio transmission is performed after the

synchronization.

5. After detecting the uplink synchronization, the NodeB sends a ―RL RESTORE IND‖ message to

RNC.

6. After receiving a ―RL RESTORE IND‖ message from the NodeB, the RNC sends a

―RELOCATION DETECT‖ message to CN, and notifies UE of 2G–3G handover. This message

includes no other contents.

7. The UE sends a ―HANDOVER TO UTRAN COMPLETE‖ message to RNC, and it indicates

that terminal handover completes. This messasge also contains CN domain encryption sequence

and activation time.

8. The RNC sends a ―UTRAN MOBILITY INFORMATION‖ message to UE after receiving the

―HANDOVER TO UTRAN COMPLETE‖ message, and sends the values of timer, CN domain

related information, and UE ID to the UE.

9. After receiving a ―HANDOVER TO UTRAN COMPLETE‖ form the UE, the RNC returns a

―RELOCATION COMPLETE‖ message to CN while sending a ―UTRAN MOBILITY

INFORMATIO‖ to the UE. This message includes no contents. After the RNC receives an ACK

of SI17 from UE, 2G–3G handover flow completes.



The messages later are a measurement and control process for UE and NodeB and a

process of capability query.



Chapter 4 Inter-RAT Handover in PS Domain

4.1 WCDMA –GPRS Handover

WCDMA—>GPRS handover is used in WCDMA PS services handover to a GPRS

system. The RNC side automatically orders the UE through the signaling to perform cell

reselection of other system to trigger the inter-RAT handover. If the slow PS services have

small traffic and UE may be in CELL PCH and URA PCH state, UE initiates automatically a

cell reselection based on the parameters in the system information to perform an inter-RAT

handover. The inter-RAT handover flow initiated by RNC is as follows:

SourceRNC BSCSGSN(3G)

Cell change order from UTRAN

UEBTSNodeB

Imm Ass

Chl Req

Chl Rqd

SGSN(2G)

RA update ReqSGSN Cntxt

Req

SGSN Cntxt Rsp

SGSN Cntxt Req

SGSN Cntxt Rsp

HLR

Send Authentication Info

Send Authentication ACK

Authentication and Ciphering Request

Authentication and Ciphering ResponseSGSN Cntxt

ACK

forward packetsforward

packecks

GGSN

Update PDP cntxt Req

Update PDP cntxt Rsp

Update GPRS Location

MSC/VLR

(2G)MSC/VLR(3G)

SRNS Data Forward

Command

Figure 7 WCDMA–GPRS handover flow (1)



SourceRNC BSCSGSN(3G) UEBTSNodeBSGSN(2G)HLR

Cancel Loc

GGSN

Iu Rel Cmd

Iu Rel Complete

RL Rel Req

RL Rel Rsp

Rel Req

Rel Conf

Cancel Loc

ACK

Insert Subscriber Data

Insert Subscriber Data ACK

Update GPRS Location ACK

MSC/VLR(2

G)

MSC/VLR(3

G)

Update Location ACK

Update Location

Cancel Location

Cancel Location ACK

Ins Subscriber Data ACK


Update Location Accept

RA Update Accept

RA Update Accept Complete

TMSI Reallocation CompleteBSS Packet Flow Context

Procedure

Location Update Req

Figure 8 WCDMA–GPRS handover flow (2)

Figure 9 WCDMA–GPRS handover signaling tracing


1. The UE reports 2D measurement and serving cell quality is worse.

2. RNC sends a ―RL RECONFIG PREPARE‖ message to NodeB, and NodeB starts the

compression mode. This message includes CMSS and related parameters. They are TGSN, TGL,

TGD, TGPL, compression method, downlink compression frame type, and power control

parameters in the compression mode.

3. After the resources are prepared, NodeB returns a ―RL RECONFIG READY‖ message to RNC.



4. RNC delivers again a ―PHYSICAL CHANNEL RECONFIG‖ message to the UE to prepare the

compression mode. This message includes activation time, compression mode sequence and

related parameters. They are TGCFN, TGMP, TGSN, TGL, TGD, TGPL, RPP, ITP, compression

methods, downlink compression frame type, and power control parameters in compression

mode.

5. After the UE receives a ―PHYSICAL CHANNEL RECONFIG‖ message, the RNC delivers a

―RL RECONFIG COMMIT‖ message to the NodeB, and notifies NodeB of start time of

compression mode.

6. After the UE completes the related configuration based on new data configuration, it returns a

―PHYSICAL CHANNEL RECONFIG COMPLETE‖ message to the RNC. The compression

mode starts.

7. The RNC immediately delivers the measurement and control to notify the UE of measurement

on other system. It carries GSM cell list, frequency information of each cell, and measurement

filter coefficients.

8. The UE reports RSSI measurement value of each GSM cell based on the measurement report.

9. The UE reports BSIC verification of each GSM cell based on the measurement report.

10. If the handover conditions are satisfied, the RNC initiates a transition flow. It sends a ―CELL

CHANGE ORDER FROM UTRAN‖ message to the UE, and notifies the UT side to initiate a

cell reselection process and hands over to a GPRS system. This message includes destination cell

BSIC, BAND IND (900 M network or 1800 M network), BCCH ARFCN, and NC mode.

11. The UE requires cell reselection to GPRS cell and disables WCDMA transmission. The ―SIR

ERROR‖ report from NodeB is not a mandatory message in the flow.

12. The UE requires cell reselection to GPRS cell, and disables WCDMA transmission. The ―RL

FAILURE‖ from NodeB is not a mandatory message in the flow.

13. After the UE accesses the cell of other system, if the restore of PDP content is not required, the

RNC can receive directly an ―IU RELEASE COMMAND‖ message of IU interface. If the

restore is required, the RNC obtains the SRNS CONTEXT information from the RNC, and the

source RNC receives a ―SRNS CONTEXT REQUEST‖ of IU interface. This message includes

RAB ID.

14. The RNC returns a ―SRNS CONTEXT RESPONSE‖ message to CN and notifies the

uplink/downlink SN of GTP and PDCP in the RAB ID.

15. The CN sends a ―SRNS DATA FORWARD COMMAND‖ message to RNC and notifies the user

plane of data transmission. In this message, the CN notifies RNC of destination transmission

layer address and tunnel ID of each RAB data forwarding.

16. After the data transmission, the CN delivers an ―IU RELEASE COMMAND‖ message to notify

RNC of releasing the UE.



17. The RNC immediately returns an ―IU RELEASE COMPLETE‖ message to CN. The radio

resources of NodeB are released in the following two messages. The air interface does not send a

―RNC connection release‖ message, because the UE is not present in the WCDMA system.

4.2 GPRS –WCDMA Handover

SourceRNC BSCSGSN(3G)

RR-Cell Change Order

UEBTSNodeBSGSN(2G)

SGSN Cntxt Req

HLR

Send Authen InfoSend Authent ACK Authentication and Ciphering Request

Authentication and Ciphering Response

SGSN Cntxt ACK

Cancel Location

GGSN

Update PDP cntxt ReqUpdate PDP cntxt Rsp

Update GPRS Loc

Cancel Loc ACK

MSC/VLR(2

G)MSC/VLR(3G)

RRC Connect Setup Req

RL Setup ReqRL Setup Rsp

AAL2 Setup Req

AAL2 Setup Rsp

DL SyncUL Sync

RRC Conn SetupRRC Conn Setup Cmp

Initial DTInit UE(RA update Req)

SGSN Cntxt Rsp

forward packets

Figure 10 GPRS–WCDMA handover (1)

SourceRNC BSCSGSN(3G) UEBTSNodeBSGSN(2G)HLRGGSN

Ins Subscriber Dat

Ins Subscrib Dat ACK

Update GPRS Loc ACK

MSC/VLR(2

G)MSC/VLR(3G)

Location Update Req

Update Location ACK

Update Location

Cancel Location

Cancel Location ACK

Ins Subscriber Data ACK


Update Location AcceptRA Update Accept

RA Update Accept Complete TMSI Reallocation Complete

RAB Ass Req

RAB Ass Rsp

RL Recfg Prep

RL Recfg Ready

AAL2 Setup ReqAAL2 Setup Rsp

DL Sync

UL Sync

RB Setup

RB Setup Complete

RL Recfg Commit

Service Req

Figure 11 GPRS–WCDMA handover (2)




1. The UE selects the cell of UTRAN after the reselection, and initiates a RRC connection setup

flow in the UTRAN cell. The setup cause is ―INTERRAT CELLRESELECTION‖

2. After the RRC connection setup, the UE initiates automatically an INIT DT flow to establish the

SCCP connection of IU interface and signaling connection of CN NAS layer. UE NAS layer

exchanges the messages with CN NAS layer during the DT.

3. The CN sends a ―RAB ASSIGNMENT REQUEST‖ message through IU interface to notify RNC

of allocating related resources. This message carries RAB ID, QoS parameter, GPT-U

uplink/downlink SN, and PDCP SN.

4. RNC allocates related resources and notifies NodeB by executing command RL SETUP.

5. The RNC sends a ―RB SETUP REQUEST‖ message to the UE. This message carries PDCP

downlink SN.

6. The UE returns a ―RB SETUP COMPLETE’ message to RNC. This message carries UE side

downlink PDCP SN. The RNC configures PDCP uplink SN sent by CN and PDCP downlink SN

returned by UE for the PDCP example corresponding to the specified RAN.

7. The RNC returns a ―RAB ASSIGNMENT RESPONSE‖ message to CN.

8. During the service flow restore, RNC PDCP example discards the datagram with small downlink

PDCP SN of downlink PDCP SN from the CN corresponding to the UE. The UE must discard

the datagram whose uplink PDCP SN is smaller than uplink PDCP SN configured by

UTRAN/CN.



Chapter 5 Common Radio Parameters and Data

Configuration

5.1 3G -2G Cell Reselection Parameters

The network planning and optimization engineers use the parameters in the following table. The RNC

version is subject to C03B130.

Table 8 3G–2G cell reselection parameters

Name Meaning Default parameter

configuration

MML command of

modification and

query

Functi

on

range

Qhyst1s It is hysteresis of cell

selection/reselection R

criteria serving cell CPICH

RSCP measurement value.

Value range: 0–20

Physical range: 0–40db, with

the step of 2

Qhyst1s is defaulted to 2

(4dB)

Setting by executing

command ADD

CELLSELRESEL, query

by executing command

LST CELLSELRESEL,

and modification by

executing command

MOD CELLSELRESEL

Cell

Qhyst2s It is hysteresis of cell


criteria serving cell CPICH

Ec/No measurement value.

This parameter is optional. If

there is no configuration, it is

the value of measurement

hysteresis 1 parameter.

Value range: 0–20

Physical range: 0–40dB,

with the step of 2

Qhyst2s is defaulted to 1

(2dB), and Qhyst2s is

optional. If there is no

configuration, it is the

value of measurement

hysteresis


command ADD

CELLSELRESEL, query

by executing command

LST CELLSELRESEL,

and modification by

executing command

MOD CELLSELRESEL

Cell

QOffset1Sn It is the offset value of cell


criteria neighbor cell CPICH

RSCP measurement value.

Value range: -50–50

Physical range: -50–50dB

0 For intra-frequency cell

reselection, setting by

executing command

ADD

INTRAFREQCELL,

query by executing

command LST

INTRAFREQCELL,

and modification by

executing command

MOD

INTRAFREQCELL.

For inter-frequency cell


executing command

ADD

INTERFREQCELL,

query by executing

command LST

INTERFREQCELL,

Cell



and modification by

executing command

MOD

INTERFREQCELL.

For Inter-RAT cell


executing command

ADD

INTERRATNCELL,

query by executing

command LST

INTERRATNCELL,

and modification by

executing command

MOD

INTERRATNCELL

QOffset2Sn It is the offset value of cell


criteria neighbor cell CPICH

Ec/No measurement value.

Value range: -50–50

Physical range: -50–50dB

0 Same as above Cell

Qqualmin Cell selection/reselection

minimum quality standard. It

is S criteria parameter of cell

selection in the idle mode,

and indicates the required

minimum quality standard

Ec/Io during the cell

selection, and it is subject to

FDD.

Value range: -24 – 0

Physical range: -24dB–0dB

-18 Setting by executing

command ADD

CELLSELRESEL,

query by executing

command LST

CELLSELRESEL, and

modification by

executing command

MOD

CELLSELRESEL

Cell

Qrxlevmin Minimum access level -58, that is, -115dBm

Ssearch,RAT During the cell reselection

evaluation, it is the standard

whether to start

measurement on other

system. During the cell

reselection evaluation, if

serving cell quality <=

Ssearch, RAT, the UE starts

the measurement on other

system. For the FDD cell,

Squal indicates the serving

cell quality, and

Squal=Qqualmeas-Qqualmin

.

Value range:

Integer(-32..20), with the

step of 2, and unit of dB

Ssearch, RAT is defaulted

to 2 (that is, 4dB)

Treselections If the signal quality of other

cells (UE-measured CPICH

Ec/No) is in the quality of

current resident cell within

the time specified by the

parameter, the UE updates

the resident cell. This

parameter avoids inter-cell

1



ping-pong reselection of the

UE.

Note: ―0‖ is a default

corresponds to the default

value in the protocol, but

does not mean 0s.

value range: 0–31

physical unit: s

Qrxlevmin_GSM GSM cell reselection

minimum access level

-50, that is, -99dBm Setting by executing

command ADD

INTERRATNCELL,

query by executing

command LST

INTERRATNCEL, and

modification by

executing command

MOD

INTERRATNCEL

Cell

For the meanings and adjustment effect of parameters, see Guide to WCDMA RNP System Parameter

Setting.

5.2 2G - 3G Cell Reselection Parameters

Table 9 2G–3G cell reselection parameter

PRAMETER

NAME PARAMETER DESCRIPTION

PARAMETER

RANGE

CONFIGURAT

ION

Qsearch_I

Search for 3G cells if signal level is below

(0-7) or above (8-15) threshold

0 = - 98 dBm, 1 = - 94 dBm, … ,

6 = - 74 dBm, 7 = (always)

8 = - 78 dBm, 9 = - 74 dBm, … ,

14 = - 54 dBm, 15 = (never).

Default value = (never).

0-15 7

XXX_Qoffset

Applies an offset to RLA_C for cell

re-selection to access technology/mode

XXX (one or more)

0 = - (always select a cell if acceptable),

1 = -28 dB, 2 = -24 dB, … , 15 = 28 dB.

Default value = 0 dB.

0-15 0

FDD_Qmin(old)

A minimum threshold for Ec/No for

UTRAN FDD cell re-selection,

0 = -20 dB, 1 = -19 dB, ..., 7 = -13 dB.

Default value = -20 dB.

0-7 7

FDD_Qmin (update

using the GP-032221)

A minimum threshold for Ec/No for

UTRAN FDD cell re-selection,

0= -20dB, 1= -6dB, 2= -18dB, 3= -8dB, 4=

-16dB, 5= -10dB, 6= -14dB, 7= -12dB.

Default value= -12dB

0-7 7



In addition, three time parameters are fixed in UE and determine the frequency of reselection from 2G

to 3G.

1. The cell reselection to 3G only when 3G cell RSCP in the FDD is higher the RLA_C+

XXX_Qoffset of 2G serving cell and other non-serving cells, and the timer for Ec/No exceeding

FDD_Qmin keeps 5 seconds continuously.

2. In case of a cell reselection occurring within the previous 15 seconds, XXX_Qoffset is increased

by 5 dB

3. Cell reselection to UTRAN shall not occur within 5 seconds after the UE has reselected a GSM

cell from an UTRAN cell if a suitable GSM cell can be found.

5.3 3G -2G Handover Parameters

5.3.1 Handover Decision Process

Periodical report criterion is used in the Inter-RAT handover decision.

According to the 25.331 protocol, 2D event indicates that the quality of active set is less than a

threshold. In the current handover algorithms (including inter-frequency handover algorithm), 2D event

report is the criterion for starting compression mode and measurement on inter-frequency/inter-RAT. The

quality of UE active set is worse in the case of measurement on other system, only the quality of other

system is measured. If the quality of UE active set is better, that is, UTRAN receives 2F event report,

compression mode disables and measurement on other system stops. For decision mode of 2D/2F event,

see the protocol 3GPP TS 25.331.

Periodical report Inter-RAT handover decision algorithm is as follows:

The network receives a periodical report after layer 3 filter and compares the measurement result on

other system with preset threshold.

if

Mother_RAT + CIO >= Tother_RAT + H/2 (1)

Start delay Trigger-Timer.

In the formula (1),

Mother_RAT indicates measurement result on other system.

Cell Individual Offset (CIO) indicates the offset for the cells of other system.

Tother_RAT indicates quality threshold of other system.

―H‖ indicates the hysteresis, and the hysteresis setting can reduce misoperation due to

signal jilter.

After the delay Trigger-Timer starts, before the timer expires, and if

Mother_RAT + CIO < Tother_RAT - H/2 (2)

the delay Trigger-Timer stops, and the network waits for receiving the measurement report of other system.

Otherwise, if the delay Trigger-Timer expires, the Inter-RAT handover decision is performed.



5.3.2 Handover Parameters

The network planning and optimization engineers use the parameters in the following table during the

cell reselection. The RNC version is subject to C03B130.

Table 10 3G–2G handover parameters

Name Meaning Default parameter

configuration

MML command of

query and

modification

Functi

on

range

FilterCoef Layer 3 filter

coefficient of

measurement on

other system

D3 For RNC oriented other

system handover

algorithm parameter:

setting by executing

command SET

INTERRATHO, and

query by executing

command LST

INTERRATHO.

For cell oriented other

system handover

algorithm parameter,

adding by executing

command ADD

CELLINTERRATHO,

query by executing

command LST

CELLINTERRATHO,

and modification by

executing command

MOD

CELLINTERRATHO

RNC/

Cell

GsmRSSICSThd,

GsmRSSIPSThd, and

GsmRSSISIGThd

Other system

handover decision

threshold

21, that is, -90dBm

HystThd Other system

handover hysteresis

4, that is, 2dB

TimeToTrigForVerify Time to trigger for

other system verify

delay

0, that is, 0s

TimeToTrigForNonVerify Time to trigger for

other system

non-verify delay

65535, that is, handover to

non-verify GSM cell is not

allowed

PenaltyTimeForSysHo Penalty time for

other system

handover

30, that is, 30s

InterRatCSThdFor2DRSCP,

InterRatPSThdFor2DRSCP,

InterRatSigThdFor2DRSCP,

InterRatCSThdFor2FRSCP,

InterRatPSThdFor2FRSCP, and

InterRatSigThdFor2FRSCP

RSCP is other

system

measurement

start/stop threshold

of measurement

value (CS, PS, and

single signaling)

InterRatCSThdFor2DRSCPI

nterRatPSThdFor2DRSCP is

defaulted to

-95,InterRatCSThdFor2FRS

CPInterRatPSThdFor2FRSC

P is defaulted to

-90,InterRatSigThdFor2DRS

CP

InterRatSigThdFor2FRSCP

is defaulted to -115

For RNC oriented other

system handover



command SET

INTERFREQHO, and

query by executing

command LST

INTERFREQHO.

For cell oriented other

system handover


Adding by executing

command ADD

CELLINTERFREQHO

, query by executing

command LST

CELLINTERFREQHO

, and modification by

executing command

MOD

CELLINTERFREQHO

RNC/

Cell

InterRATCSThdFOR2DEcNo,

InterRATPSThdFOR2DEcNo,

InterRATSigThdFOR2DEcNo,

InterRATCSThdFor2FEcNo,

InterRATPSThdFOR2FEcNo, and

InterRATSigThdFOR2FEcNo

Ec/No is other

system

measurement

start/stop threshold

of measurement

value (CS, PS and

single signaling)

-24, that is, -24dBm

HYSTTHD This parameter and

other system

quality threshold

determine whether

to trigger

Inter-RAT

handover decision.

This value

decreases in the

areas with small

shadow fading and

4



the value increases

in the areas with

large shadow

fading.

CellIndividalOffset Other system

handover cell

individual offset.

Original

measurement value

of this cell + this

offset= the

measurement

value. The

measurement value

is used for the

handover decision

of UE

0 Setting by executing

command ADD

INTERRATNCELL,

query by executing

command LST

INTERRATNCELL,

and modification by

executing command

MOD

INTERRATNCELL

Cell

Note:

1. This table sets compression mode start/stop threshold, and Inter-RAT handover threshold based on signaling, CS,

and PS respectively.

2. The new protocol CR specifies that the UE does not report GSM measurement not verified.

5.4 Upgrade Required for GSM-WCDMA Cell Reselection

GSM must support related data configuration and system information to support

inter-RAT cell selection/reselection.

GSM needs to add WCDMA neighboring cell configuration and related cell reselection

data.

Table 11 New added table: Description of 3G neighbor cells

Field Display name Data type Field

length

Value range

Cell ID Cell ID unsigned

integer

2 bytes 0–511

Cell ID Cell ID character

group

128 bytes None

Downlink

channel No.

Downlink

channel No.

unsigned

integer

2 bytes 0–16383

Scramble Scramble unsigned

integer

2 bytes 0–511

Diversity

identification

Diversity

identification

Unsigned

character

1 byte 0–1

Mobile

country code

Mobile

country code

unsigned

integer

2 bytes 000–999



MSISDN MSISDN unsigned

character

1 byte 00–99

Location area

ID

Location area

ID

unsigned

integer

2 bytes 0–65535

RNC ID RNC ID unsigned

integer

2 bytes 0–4095

CELL ID CELL ID unsigned

integer

2 bytes 0–65535

Handover

target cell

receiving

level

threshold

Handover

target cell

receiving

level

threshold

unsigned

character

1 byte 0–63

Table 12 Modified table: system information data (added field)

Name Data type Field

length

Value

range

Search 3G cell threshold in idle

mode

unsigned

character

1 byte 0–15

3G cell reselection level offset unsigned

character

1 byte 0–15

3G cell reselection level

threshold

unsigned

character

1 byte 0–7

Search 3G cell threshold in

dedicated mode

unsigned

character

1 byte 0–15

GSM must add or modify system information to notify UE of the cell reselection of

WCDMA neighbor cells.

1. Modify SI2ter

SI2 and SI2bis support neighbor GSM cell list of resident cell. If the handover between

GSM and UTRAN is supported, the UTRAN neighbor cell of resident cell must notify the

UE. Compared with the definition of SI2ter in GSM 04.08 protocol, frequency number

information and cell reselection parameter of neighbor 3G cell are added to that in the 3GPP

04.18 protocol, so the filling method of fields in the SI2ter must change.

For the SI2ter sent to BTS from BSC, before the change, there are four idle bytes in the

―Rest Octets‖IE of SI2ter based on the GSM 04.08. After the change, SI2ter ―Rest Octets‖IE

length of SI2ter is the same, but the contents change as 3G cell reselection related

information based on the 3GPP 04.18 protocol. Because the number of bytes is restricted, the

example of each SI2ter includes the description of only one 3G cell frequency number, and

does not carry an optional parameter 3G Measurement Description (this parameter is carried

in SI2quater).

Table 13 Filling method of fields in SI2quater



Name Meaning Filling method

BA_IND The network discriminates the

measurement report from an UE is based

on which BA list. In idle state, an UE

constructs a set of BA list based on SI2,

SI2bis, SI2ter, and SI2quater. In a

dedicated mode, an UE constructs

another set of BA list based on SI5,

SI5bis, SI5ter, and MEASUREMENT

INFORMATION.

Fill in ―0‖

3G_BA_IND Similar to BA_IND Fill in ―0‖

MP_CHANGE_

MARK

Whether neighbor cell list information

changes

After the neighbor cell relation or SI

changes, the digit of the first example

is a reverse value of the digit when

SI2quater is delivered. In other

circumstances, the value of this digit is

the same when SI2quater is sent last

time. Under any conditions, the value

of this digit is the same as that in the

first example

SI2quater_INDE

X

SN of SI2quater example The first example is numbered 0, and

the second example is numbered 1, and

so on

SI2quater_COU

NT

Total number of SI2quater example The number of examples in SI2quater

of 3G neighbor cell relation subtracts 1

Index_Start_3G 3G neighbor cell information of this

example is added to the start point of the

item in 3G neighbor cell list

If this example is numbered n, and

0–n-1example describes M 3G

neighbor cells, the field in the example

is numbered m

Repeated

UTRAN FDD

neighbor cells

Detail the UTRAN cell FDD_ARFCN indicates cell frequency

number.

FDD_indic0 indicates whether

scramble in the

FDD_CELL_INFORMATION has 0.

NR_OF_FDD_CELLS indicates the

number of cells in the

FDD_CELL_INFORMATION

FDD_CELL_INFORMATION

indicates the result of scramble set

compression from the algorithm in the

GSM 04.08 Anex J

REPORT_TYPE 0 indicates common measurement report

and 1 indicates enhanced measurement

report

Fill in ―0‖

SERVING_BAN

D_REPORTING

The measurement report includes at least

the number of neighbor GSM cells with

the same band with serving cell

Used in EMR, and fill in ―0‖

Qsearch_I The threshold of 3G cell search

For specific meanings, see 3GPP 0508

Fill in ―3G cell search threshold in idle

mode‖



protocol

Qsearch_C_Initi

al

Which value is used for search cell

threshold in Connect state before the

threshold is obtained. ―0‖ indicates

Qsearch_I, and 1 indicates ―always

search‖

Fill in ―0‖

FDD_Qoffset Cell reselection offset: reselect 3G cell

only when average received level of 3G

cell is FDD_QoSffset larger than serving

cell

Fill in ―3G cell reselection level offset‖

FDD_REP_QU

ANT

The index in the measurement report

―0‖ indicates RSCP, and ―1‖ indicates

Ec/N0

Fill in ―0‖

FDD_MULTIR

AT_REPORTIN

G

The measurement reports includes the

number of UTRAN FDD cell

Fill in ―0‖

FDD_Qmin 3G cell reselection level threshold:

reselect the candidate cell only when

received level of 3G cell must larger than

FDD_Qmin

Fill in ―3G cell reselection level

threshold‖

Qsearch_P Cell reselection level threshold in the

packet idle mode

For specific meanings, see 3GPP 0508

protocol

Fill in ―cell reselection threshold in

idle mode‖

3G_SEARCH_P

RIO

Whether to allow 3G cell search if BSIC

must be demodulated.

―0‖ indicates No, and ―1‖ indicates Yes.

Fill in ―1‖

3. Modify SI3

Whether SI2tquater message and whether UE reports a ―UTRAN CLASSMARK

CHANGE‖ message are added to the ―Rest Octet‖IE of SI3 defined in the 3GPP 04.18

protocol, so the SI3 must be modified.

Table 14 Filling method of fields modified in SI3

Name Meaning Filling method

3G Classmark

Sending Restriction

Whether to send a ―UTRAN CLASSMARK

CHANGE‖ message. ―L‖ indicates No and H

indicates Yes

Fill in ―L‖

SI2quater Indicator Send SI2quater on which channel.

0 indicates BCCH, and 1 indicates extended

BCCH

Fill in ―0‖



5.5 Data Configuration for Supporting Roaming and Handover

between WCDMA and GSM/GPRS

When the functions are supported:

Roaming and handover between 3G and GSM/GPRS

PLMN selection

UE transition to 3G network from 2G network through cell reselection

UE transition to 2G network from 3G network through cell reselection

2G and 3G network must configure related data.

5.5.1 2G MSC Data Configuration

Add the records of 3G MSC/VLR number in the cell table of location area. RNC ID

= MCC + MNC + LAC + RNC-ID, location area class is ―GCI‖, and location area

type is ―neighbor VLR area‖.

Add related LAI record, 3G MSC/VLR number. LAI = MCC + MNC + LAC, the

location area class is ―LAI‖, and location area type is ―neighbor VLR area‖.

Change MAP version to ―PHASE 2PLUS‖ in MAP function flow configuration

table.

Configure MTP layer data to ensure signaling transmission between 2G MSC and 3G

MSC.

Configure SCCP layer data, and the records of 3G MSC in GT table, SCCP SSN

table and SCCP DSP table to ensure inter-MSC MAP handover related signaling

transmission.

Configure inter-MSC trunk data, and it is the same as common data configuration

5.5.2 Data Configuration Added by BSC

When the roaming from GSM to WCDMA is supported, the GSM BSS must deliver the

following SI:

Add WCDMA cell and configure the data, including downlink frequency number,

primary scramble, diversity identification, MCC, MNC, LAC, RNC-ID, and

CELL-ID.

Add other system cell measurement and roaming control messages related to UE in

the IDLE mode, including Qsearch_I, FDD_Qoffset, and FDD_Qmin.

The above messages are sent to UE through SI 2ter and 2quater.

UE reselects other system cells based on the above messages.

When the handover from GSM to WCDMA is supported, the GSM BSS must deliver the

following SI:



Add WCDMA cell and configure the data, including downlink frequency number,

primary scramble, diversity identification, MCC, MNC, LAC, RNC-ID, CELL-ID,

and level threshold for handover to the cell.

Add other system cell measurement and control messages in Connect sate, including

Qsearch_C.

The above messages are sent to UE through SI MEASUREMENT INFOMATION.

When the level of serving cell meets Qsearch_C, the UE measures the 3G cells and

reports periodically the result to BSC.

BSC initiates a handover to a WCDMA system.

5.5.3 Data Configuration Added by 3G MSC

Add 2G MSC neighbor location cell information in 3G MSC location cell table.

LAI = MCC + MNC + LAC, the location area class is “LAI”, and location area

type is “neighbor VLR area”.

Add related 2G MSC/VLR number, GCI=MCC+MNC+LAC+CI, location area class

is ―GCI‖, and location area type is ―neighbor VLR area‖.

Add related 2G MSC/VLR number.

Configure MTP layer data to ensure signaling transmission between 2G MSC and 3G

MSC

Configure SCCP layer data, and the records of 2G MSC in GT table, SCCP SSN

table and SCCP DSP table to ensure inter-MSC MAP handover related signaling

transmission.

Configure inter-MSC trunk data, and it is the same as common data configuration

5.5.4 Data Configuration Added by RNC

If the roaming from WCDMA to GSM/GPRS is supported, UTRAN must deliver the

following SI:

Add GSM cell and configure the data, including MCC, MNC, LAC, GSM CELL ID,

NCC, BCC, FREQ_BAND, Frequency Number and CIO;

ADD GSMCELL: MCC="460", MNC="10", LAC="0x0fa0", CID="0x0102", NCC=0,

BCC=0, BCCHARFCN=60, BANDIND=DCS1800_BAND_USED,

RATCELLTYPE=GSM;

ADD INTERRATNCELL: CELLID=123, MCC="460", MNC="10", LAC="0x0fa0",

CID="0x0102", CELLINDIVIDALOFFSET=50, QOFFSET1SN=-50, QRXLEVMIN=-58;

Configure FACH measurement occasion, and configure whether perform FDD

measurement on other system, TDD measurement on TDD and measurement on

other system in the FACH measurement occasion. If the roaming on other system is



required, the measurement on other system starts in the FACH measurement occasion.

Otherwise, RNC does not deliver GSM neighbor cell information through the SIB11.

MOD CELLMEAS: CELLID=123, INTERFREQINTERRATMEASIND=INTER_RAT,

FACHMEASIND=REQUIRE, FACHMEASOCCACYCLELENCOEF=3;

Execute command MOD CELLSELRESEL to configure the SsearchRAT of GSM

system.

After the data configuration, SsearchRAT and GSM neighbor cell information are

sent in SIB3 and SIB11 respectively.

If the handover from WCDMA to GSM/GPRS is supported, UTRAN must deliver the

following SI:

Add the GSM cell and configure the information, including MCC, MNC, LAC, GSM

CELL ID, NCC, BCC, FREQ_BAND, Frequency Number, and CIO.

Execute command MOD CELLMEAS to configure measurement and control on

other system.

Chapter 6 Inter-RAT Roaming and Handover Strategies

6.1 Common Inter-RAT Handover Strategies

6.1.1 Coverage Based Handover

In the coverage areas without 3G system, the coverage based handover or cell

reselection is required for smooth transition from GSM to WCDMA.

In the areas with 3G coverage only, the GSM system also support coverage based

handover or cell reselection to ensure handover between GSM and 3G and cell reselection,

and smooth transition to 3G without a GSM system.

6.1.2 Load Based Handover

Load based handover or cell reselection is used for load sharing between GSM and

WCDMA. The handover is trigger based on the cell load measured by a GSM or WCDMA

network.

For example, whatever the GSM network load is, non-transparent CS data hands over to

WCDMA network to ensure better throughput. When the GSM system load is heavy, partial

voice and transparent data hand over to a WCDMA network. Load based handover adopted

in a GSM network early helps reduce the high load of a GSM network and extra investment

on the GSM network for the operators.



In the packet switched domain, the network controls the cell reselection to realize the

service and load cause based cell reselection, that is, the network can order the terminal to

change the cell or system.

Load based handover and cell reselection aim to use fully two systems to avoid the extra

usage of the other system when one system has idle capacity.

Load balancing strengthens the capacity of the overall system. The capacity of the

overall system is greater than the sum.

6.1.3 Service Based Handover

Service based handover introduces the service stream in a GSM system or WCDMA

system. Even though the source cell has no overload, the service based load is performed.

During the load based handover/cell reselection or call setup, the service information can be

used. The operators introduce the voice to a GSM system through the function, and all the

VPs and packet data to a WCDMA system to reduce the investment on a 3G circuit network

and a 2G packet network.

The service priority information is saved in the CN (MSC/VLR or SGSN), and tells the

GSM system and radio access part of a 3G system through Iu_PS, Iu_CS, A, or Gb interface.

The complete service handover is performed by CN and access network together. The

CN indicates the access network to hand the service over to a GSM system through optional

cell ―service handover‖ in RAB assignment message, or requires it in a 3G network, or has

no requirement. According to the protocol, ―service handover‖ has three possibilities:

Handover to GSM should be performed

Handover to GSM should not be performed.

Handover to GSM shall not be performed.

If the access network performs Inter-RAT handover based on the requirement of

―service handover‖, the CN control Inter-RAT handover is more flexible. The services

handover to a GSM system help the operators make good use of 2G devices.

6.1.4 Huawei Inter-RAT Roaming and Handover Strategies

To reduce the effect of GSM network and signaling exchange, improve the handover

success ratio, and avoid ping-pong handover cell reselection, Inter-RAT interoperation

strategies are as follows:

The voice service supports the handover from WCDMA to GSM, instead of from

GSM to WCDMA. The GSM network has a good coverage, the operators need not

hand a call over to a WCDMA network through the Inter-RAT handover.

Consequently, the GSM system can avoid frequent ping-pong handover and signal

exchange between WCDMA and GSM without the upgrade.



When a connected dual-mode UE resides in a WCDMA network and moves from

a GSM/WCDMA coverage area to a GSM coverage area and is at the border of

WCDMA network, the WCDMA network initiates a handover from WCDMA to GSM

based on measurement report. The GSM network at the border supports the handover

from WCDMA to GSM.

When a connected dual-mode UE resides in a GSM network and moves from a

GSM coverage area to GSM/WCDMA coverage area, the handover from a GSM

network to WCDMA network must be avoided. When the call ends, and the UE is in

idle state, the UE resides in a WCDMA network through PLMN reselection or cell

reselection.

When the UE support handover from WCDMA to GSM only, PLMN reselection,

or cell reselection to WCDMA network, the upgrade for a GSM network is not

required.

The data service supports the handover from a WCDMA network to a GSM network

through cell reselection.

When a connected dual-mode UE resides in a WCDMA network, moves from

GPRS/WCDMA coverage area to GPRS coverage area and is at the border of WCDMA

network, the WCDMA network performs a network side-initiated cell reselection and helps

the dual-mode cell reselects the GPRS network.

When a connected dual-mode UE resides in a GPRS network and moves from GPRS

coverage area to GPRS/WCDMA coverage area, the UE performs data domain handover

through intra-GPRS cell reselection. At that time, handover to a WCDMA network is

not required. Otherwise, the upgrade of GSM access network is required.

When the UE is in idle state, resides in a WCDMA network, and moves to the border of

WCDMA coverage area, it roams to a GSM network through PLMN reselection or cell

selection. If the UE resides in a GSM network and moves to WCDMA coverage area (it

is also in the GSM coverage area), it resides in a 3G network through periodical PLMN

reselection (if the UE resides in a 3G network through cell reselection, the UE resides in

a WCDMA network from a GSM network, and the upgrade of a GSM network is

required).

Namely, the WCDMA network and GSM network are configured a different

PLMN-Id. If a WCDMA network is configured as HPLMN in the USIM, the GSM

network is VPLMN. After an UE powers on, it selects the WCDMA network by priority

during the PLMN selection, and resides in the WCDMA cell. After the UE resides in a

GSM network due to handover/cell reselection, the UE reselects HPLMN periodically

because the GSM network is VPLMN. The reselection period is determined in the USIM.

It ranges from six minutes to eight hours and is defaulted to one hour.



6.2 Inter-RAT Roaming and Handover Application Strategies

6.2.1 Difficult Reselection and Handover to a 2G Network

When the coverage in a 3G network is better than that in a 2G network, the UE must

reside in the 3G network.

If an UE is in IDLE state, and 2G level is better than 3G Delta dB, the UE reselects the

2G network. Delta dB is determined by Qoffset1sn. According to WCDMA R criterion,

Qoffset1sn is a key adjustment parameter and configurable in the network. If Qoffset1sn

(ranging from -50 to 50dB, and defaulted to 0) increases, handover to a 2G network is

difficult, for example, it is set to 50dB.

If an UE is in Connect state, CellIndividualOffset (ranging from -50 to 50dB, and

defaulted to 0) increases to avoid handover to a 2G network, for example, it is set to -50 dB.

6.2.2 Easy Reselection and Handover to a 2G Network

The 3G network has better coverage than 2G network in some areas, for example, the

2G network has DAS in the indoors but 3G network does not. When a connected UE moves

from a 3G coverage area to 2G coverage area, it must transit smoothly to a 2G network

without call dropped. When the UE is in IDLE state, it transits smoothly to a 2G network

without call dropped, and Qoffset1sn is set to 0.

When the UE is in Connect state, you can increase the start/stop threshold of

compression mode and start early the compression mode to measure 2G signals (such as

-90/-85dBm), and set CellIndividualOffset to 0. This operation aims to increase the overlay

areas of 3G and 2G and fast handover to 2G when the 3G signal decreases fast from outdoors

to indoors.



Chapter 7 FAQs

7.1 Inter-RAT Ping-pong Reselection

7.1.1 Phenomenon Description

In part of the office building of a commercial deployment, the UMTS-GSM dual-mode UE

performs frequent ping-pong reselection of cells between 3G and 2G network in the idle state.

―2G‖ and ―3G‖ flag are displayed in the screen of Siemens U15 and Moto A835 UEs.

―WCP‖ and ―GCP‖ are displayed in the screen of the Qualcomm test UE frequently. The

reselection from 3G network to 2G network takes 1min on average. The reselection from 2G

network to 3G network takes 1–2mins on average. During the testing, the location of the UE

and the circumstance keep fixed.

7.1.2 Problem Analysis

The reselection from 3G network to 2G network is as follows:

1) When the pilot signal quality Ec/Io in 3G cells minus Qqualmin is less than the

Inter-RAT measurement start threshold SsearchRAT, the UE started to measure the 2G

neighbor cell.

2) When the quality of signal in 2G neighbor cells satisfies the cell reselection criteria and

lasts for Treselection, the UE selects 2G cells.

3G RSCP is below -90 dBm at the borders of 3G network. However the 2G RSCP ranges

from -60 dBm to -70 dBm with signals of good quality. Therefore, once the UE starts to

measure the 2G neighbor cells and the signal in the cell fails to be better in Treselection, the

UE reselects the 2G cells.

The key parameter in reselection from 3G network to 2G network in test is SsearchRAT. The

rational configuration of the reselection delay timing parameter Treselection helps solve

ping-pong reselection.

The reselection from 2G network to 3G network is as follows:

1) When the signal strength of 2G serving cell satisfies the Inter-RAT start threshold

Qsearch_I, the 3G neighbor cells are measured. From optimized 3G strategy, the current

configuration is 7 (always start).

2) When the signal strength RSCP of the 3G cell minus the current RLA_C (the average

signal strength in 2G serving and non-serving cells) is greater than FDD_Qoffest, and it

lasts 5s, the 3G cell can serve as the target cell to be reselected. The current

FDD_Qoffset is 7 (always reselect 3G cells).



3) When the signal quality Ec/Io of the 3G cell is greater than or equal to FDD_Qmin

threshold, the 3G cell can serve as the target cell to be reselected.

4) In the cells that satisfy the previous conditions, the UE select the cell of best quality as

the target cell to be reselected.

Therefore, the key parameter in from 2G network to 3G is FDD_Qmin. The default

configuration is -12 dB.

7.1.3 Solutions

In network optimization, the operator can take the following adjustment:

1) The operator increases the interval between SsearchRAT and FDD_Qmin. According to

the default parameters, if 3G CPICH Ec/Io is greater than -12 dB in the GSM system,

the UE reselects 3G network. If 3G CPICH Ec/Io is less than or equal to -14 dB, the UE

reselects the GSM network from 3G network. In the current parameters configuration,

the signal fluctuation of 3G CPICH Ec/Io decides the frequency of cell reselection. If

the signal fluctuation is over 1 dB, the ping-pong reselection occurs. In field test of 3G

cells, if Ec/Io is less than -14 dB, the UE drops off the network easily, so the

SsearchRAR cannot be less, and FDD_Qmin can be increased. The value range of

FDD_Qmin is over small, so it can be only set to its maximum value -13 dB. Since the

protocol of September 2003, the value range of FDD_Qmin is increased through CR

GP-032221 (see 5.2 for details). If the UE is updated according to GP-032221, the

FDD_Qmin is increases completely. If FDD_Qmin is set to -8 dB, compared with the

start measurement threshold -14 dB of reselection from 3G network to 2G network,

FDD_Qmin has a space of 6 dB. In this way, the ping-pong reselection caused by signal

fluctuation is less likely.

2) Treselection is increased. If the default configuration is 1s, the Treselection can be set to

5s. In this way, the reselection between 3G network and 2G network is reduced.

7.2 Inter-RAT Ping-pong Handover of PS


The UE performing PS domain services hands off between 3G network and 2G network.

7.2.2 Problem Analysis

For Inter-RAT handover of CS and PS, the services for CS and PS are different in handover

between 2G to 3G network.

1) In CS service, after handover from 3G network to 2G network and after release of

services in 2G network, the UE reside again in 3G cell through reselection from 2G

network to 3G network or reselection of PLMN.



2) In PS service, after the reselection from 3G network to 2G network started by the

network, the UE re-accesses the 2G network. In services transmission, the UE

performing PS services may return to 3G network through reselection between 2G

network and 3G network. According to the analysis of 3.1 , in the reselection of the

cells performing PS domain services from 2G network to 3G network, the actual

working factor is the configuration of FDD_Qmin (measuring Ec/Io). If Ec/Io is greater

than FDD_Qmin, the UE reselects 3G network. Whether the UE has handed off from

3G network to 2G network is judged through measuring RSCP in condition of the cell as

a border cell. Measuring RSCP cannot assure that Ec/Io is greater than FDD_Qmin, so

no mechanism can avoid ping-pong handover.

The solutions lie in as follows:

1) The measurement target of 2G and 3G network is unified. If this cannot be performed,

the following method is adopted.

2) The start parameters in compression mode and reselection threshold from 2G network to

3G network is adjusted.

7.2.3 Solutions

I. Unification of Measurement Target in 3G and 2G Network

When there are more than one 3G cells, the change of Ec/Io indicates the change of 3G cell

quality. If the cell attribute is configured as ―cell of the carrier center‖ and the measurement

target in 2D event is Ec/Io, the measurement target between 3G and 2G network is Ec/Io. The

default parameter of 2D/2F with the measurement target Ec/Io is -24 dB. The parameter can

be adjusted to -12/-10 dB to avoid ping-pong handover (see the configuration of Mauritius

commercial deployment Emtel). 7.1.3 is a reference for next adjustment.

In addition, the new 3GPP TS 05.08 protocol defines the RSCP (FDD_RSCP) that can

measure 3G network in reselection from 2G network to 3G network. Now only Ec/Io can be

tested. The adjustment fits the 3G cells the cell attribute of which is ―carrier border cell‖.

However many current NEs does not support this.

II. Adjustment of Start Parameters in Compression Mode and Reselection Threshold

from 2G to 3G Network

The adjustment fits the 3G cells the attribute of which is ―carrier border cell‖. Only 3G Ec/Io

can be measured in reselection from 2G network to 3G network. The start/stop threshold in

compression mode can be lowered to -105/-100 dBm. 7.1.3 is a reference for the next

adjustment.



7.3 Failure in handover from 3G to 2G Network


In the office building of a commercial deployment, when the UE makes a voice call in areas

covered by 3G network and moves towards the areas covered by 2G network, the call drops

easily. The call succeeds one or two times every ten times.

7.3.2 Problems Analysis

The 2G neighbor cells configuration of the 3G network cells that cover the office building in

the WCDMA network parameters is examined. The 2G cells that cover office building need

to be confirmed in the 2G neighbor cells list. UMTS outdoor macrocells are used to perform

3G coverage in the office building, the test route is switched by passing two iron doors. After

the operator opens the door, enters, and closes the door, the signal attenuates sharply. Figure

12 shows the UMTS signal distribution observed by a Scanner.

The signal attenuates sharply, so the handover is not performed in time, and then the call

drops. The key solution is to adjust the Inter-RAT switching parameters. This leads to an

earlier and faster handover.

The operator does as follows:

1) Change the cell independent offset (CIO) in the GSM neighbor cell from 0 dB to 5 dB.

The UE hands off to the GSM cell more easily. Call still drops in test.

2) Change 2D RSCP Threshold from -95 dBm to -85 dBm to -75 dBm. The Inter-RAT

measurement starts earlier. Call still drops in test.

3) Change GSM RSSI Thd from -90 dBm to -95 dBm. The UE hands off to GSM cells

more easily. Call still drops in test.

4) Change 2D Trigger Time from 640ms to 320ms to 0ms. The Inter-RAT measurement

starts more easily. Call still drops in test. Change the parameter back to 640ms.

5) Change the cell location attribute from ―carrier border‖ to ―carrier center‖ (the

associated measurement changes from RSCP to Ec/Io). Change 2D Ec/Io Threshold

from -24 dB to -10 dB. Call still drops in test.

6) Change Inter RAT handover trigger time from 5000ms to 2000ms. The UE performs

Inter-RAT more quickly. Calldrop is improved.

7) Recover the parameter changed in Step 5 as it was.

8) Change Inter RAT handover trigger time from 2000ms to 1000ms. The UE performs

Inter-RAT handover more quickly. Calldrop is solved.

The adjustment results in that the change to the parameter Inter RAT handover trigger time is

the most effective to complete Inter-RAT handover. Now the parameter is changed to

TimeToTrigForVerify in RNC C03B130. The default is 0. This triggers handover more easily.



Figure 12 Indoor 3G RSCP distribution

7.3.3 Solution

The operator checks as follows:

1) Examine that 2G neighbor cells are validly configured.

2) Reduce TimeToTrigForVerify (TimeToTrigForNonVerify needs no change. The current

protocol defines that the UE needs not to report on NonVerify) to make UE hand off to

2G network more quickly.

3) Increase GSM CIO. This increases the possibility of handover to 2G network, but

increases the coverage of 2G network and reduces the coverage of 3G, therefore this

step need consideration.

4) Increase the GSM RSSI handover threshold. This increases the coverage of 2G network,

but reduces the coverage of 3G network, therefore this step need consideration.

5) Increase 2D/2F threshold in compression mode to start compression mode earlier.



Chapter 8 Appendix 1: 2G Measurement by UE

8.1 Introduction

The network side must decide whether to measure a GSM system according to the UE

capability. If a UE does not support the cell channel number in a neighbor GSM system or

GSM/GPRS systems, the UE cannot measure the GSM system and the services cannot hand

over to a GSM system or GSM/GPRS systems. If the UE supports the channel numbers in

these neighbor cells, the UE capability decides whether to start the compression mode to

measure a GSM system.

If the UE requires a compression mode, the UE starts a compression mode to measure a

GSM system in transmission gaps.

If the UE does not require a compression mode, the UE may have two set of transceivers

and can measure directly a GSM system.

The measurement on a GSM system includes GSM carrier RSSI measurement, initial

confirmation of BSIC measurement, and BSIC reconfirmation measurement. The three

measurements use three different sample sequences in compression mode. Wherein, the BSIC

consists of network color code (NCC) and base station color code (BCC). The BSIC

discriminates neighbor cells. The NCC identifies the network. The BCC discriminates cells

that use the same BCCH channel number at different network borders. When the UE accesses

GSM cells randomly, the random access signaling includes the BSIC value of the GSM cell

to be accessed. The BSS compares the BSIC value with that of the serving cell. If the two

values are different, the BSS rejects the access request. During the measurement on other

system, the UE can measure observation time difference as follows:

T (GSM-SFN) = T(RXGSMj) - T(RXSFNi)

wherein,

T (RXSFNi) is the starting time of the frame (SFN = 0) on P-CCPCH in the UTRAN

cell i. The transmission of SFN on P-CCPCH is a timing reference on all physical

channels.

T (RXGSMj) is the starting time of a 51 multiframe on GSM BCCH carrier j. The

multiframe is the closest to T (RXSFNi). If T (RXGSMj) is equal to T (RXSFNi), T

(GSM-SFN) is equal to 0.

The GSM measurement may need three CMSSs simultaneously. The compression mode

affects the system capacity, so how to use compression mode sequence is also important.

In the serial compression mode, the UE does as follows:

1) Measure the GSM RSSI.



2) Re-configures the compression mode to complete initial confirmation of BSIC

measurement.

3) Re-configure the compression mode again to complete reconfirmation of BSIC

measurement.

In this way, the time for using compression mode and transmission signaling increases.

In the parallel compression mode, the UE does as follows:

1) Configure multiple compression mode sequences and activate them while measuring a

GSM system.

2) Set ―TPGS Status Flag‖ as ―Active‖, and assure no overlapped transmission gaps of

three compression mode sequences.

3) Assure that at least one frame in three consecutive frames is not compressed and the

ending time of the first transmission gap in two consecutive compression frames is at

least eight timeslots earlier than the starting time of the second transmission gap.

Before performing Inter-RAT handover to services, the UE need consider service attribute,

neighbor cell attribute and UE capability. If ―RAB ASSIGNMENT REQUEST‖ has a

―Service Handover‖ IE, the UE assigns the services using respectively three values based on

the IE.

―Handover to GSM shall not be performed‖ means the service cannot be handed over to

a GSM system.

―Handover to GSM should be performed‖ means the service needs to be handed over to

a GSM system as possible.

―Handover to GSM should not be performed‖ means the service needs not to be handed

over to a GSM system as possible.

The neighbor cell attributes indicate that the cell is in a GSM system or GPRS system, or

other types, such as TDD, and CDMA2000. The UE capability means whether the UE

supports Inter-RAT channel number. If no, the UE cannot perform the measurement on other

system.

8.2 Measurement on a GSM System in the CELL DCH State

In a WCDMA system, the handover to a GSM system is performed to process a connected

UE through RSSI measurement, confirmation and reconfirmation of BSIC. Since a WCDMA

system and a GSM system use different frequencies, the UE decide whether to use

compression mode to measure the GSM system according to UE capability.



8.2.1 Measurement of RSSI in GSM Cell Carrier

I. UE requring a compression mode

When a UE supports the measurement on a GSM system in a compression mode, the

transmission gap of GSM RSSI measurement must satisfy the minimum number on GSM

RSSI carrier measurement in Table 15. The measurement is based on mode sequence.

Table 15 Number of GSM carrier RSSI

TGL Number of GSM carrier RSSI samples in each gap.

3 1

4 2

5 3

7 6

10 10

14 15

The UTRAN side must configure the CMSS for GSM RSSI measurement. The combination

of TGL1, TGL2, and TGD in each compression mode sequence satisfies Table 16.

Table 16 Combination of TGL1, TGL2, and TGD in GSM

TGL1 [slots] TGL2 [slots] TGD [slots]

3 - undefined

4 - undefined

5 - undefined

7 - undefined

10 - undefined

14 - undefined

3 3 15…269

4 4 15…269

5 5 15…269

7 7 15…269

10 10 15…269

14 14 15…269

When the UE is in the CELL DCH state, the measurement period of GSM RSSI (TMeasurement

Period, GSM) is 480ms. The measurement precision of GSM RSSI by the UE must satisfy the

specifications in the TS45.008 protocol. In a measurement period, the UE can sample at least



three GSM RSSI values for each centralized GSM carrier. If the UE cannot sample enough

values of each GSM carrier, it measures as more GSM carriers as possible within a

measurement period. If time is limited, the UE must sample at least three values. The GSM

carriers not measured in this period are measured in the next measurement period. Namely,

the period reported to higher level by L1 is an integer times of measurement period.

II. UE requiring no compression mode

The measurement period is 480ms. The UE must collect at least three RSSI measurement

values in each GSM carrier. The UE must allocate sampling points as averagely as possible to

GSM carriers within each measurement period.

8.2.2 Confirmation and Reconfirmation of BSIC in GSM Cell Carrier

The BSIC confirmation in GSM cell includes initial confirmation of BSIC and

reconfirmation of BSIC.

I. UE requiring a Compression Mode

The UTRAN side must configure the CMSS of measurement on GSM Initial confirmation of

BSIC or GSM BSIC reconfirmation. The combination of TGL1, TGL2, and TGD in each

compression mode sequence satisfies Table 17.

Table 17 Combination of TGL1, TGL2, and TGD in UTRAN

TGL1 [slots] TGL2 [slots] TGD [slots]

5 - undefined

7 - undefined

10 - undefined

14 - undefined

5 5 15…269

7 7 15…269

10 10 15…269

14 14 15…269

The network side measures GSM cells through BSIC confirmation and non-BSIC

confirmation.

If BSIC confirmation is adopted, the UE reports GSM cell verified by BSIC and measures

the ‖BSIC initial confirmation‖ and ―BSIC reconfirmation‖ within the respective gaps.

If the CMSSs of ―BSIC reconfirmation‖ and ―BSIC initial confirmation‖ are not activated

simultaneously, or CMSS of ―BSIC reconfirmation‖ is not activated within one frame after

CMSS of ―BSIC initial confirmation‖ is deactivated, the BSIC is taken as the

non-confirmation BSIC after the UE reports related measurement information. The UE



evaluates the event and submits event trigger reports after BSIC confirmation. The periodical

reports are submitted within a specified interval. Even though the BSIC is not confirmed, the

report indicates BSIC is not confirmed. A GSM cell is taken as a confirmed cell after at least

one ―BSIC initial confirmation‖. The GSM cell must reconfirm the BSIC within Tre-confirm_abort.

Otherwise, the BSIC is taken as a non-confirmed cell. In a compression gap, if the middle

time point of GSM synchronization burst and that of valid compression gap satisfy the

requests in Table 18, the UE must decode BSIC.

Table 18 Gap length and maximum time difference

Gap length

[slots]

Maximum time

difference [s]

5 500

7 1200

10 2200

14 3500

1) Initial confirmation of BSIC

At the beginning, there is no timing relationship between FDD cells and GSM cells. The

initial confirmation of BSIC includes searching BSIC and decoding BSIC. The UE initials

BSIC confirmation within sample sequence transmission gap of BSIC initial measurement in

a GSM system. For GSM cells in the measurement control identifier, the UE arranges the

GSM RSSI measurement values (after L3 filter) from strong to weak. The UE decodes the

SCH in the first eight cells requiring BSIC confirmation. The arranged GSM RSSI

measurement values must be recently valid measurement result. When decoding an unknown

BSIC, the UE attempts to decode BSIC within compression gaps for measurement on ―BSIC

initial confirmation‖. If the UE decodes the BSIC successfully, the UE at once decodes the

next unknown BSIC on the carrier with maximum GSM RSSI. The cells with decoded BSIC

enter the ―BSIC reconfirmation‖. If the UE fails to decode the BSIC on BCCH within TGPL

* Nidentify_abort, the UE stops the BSIC confirmation of the GSM carrier, and continues to

confirm the next unknown BSIC on the carrier with maximum GSM RSSI. The GSM carriers

with failed confirmation can perform the ―BSIC confirmation‖ after the UE attempts to

decode all the eight BSICs on the carrier with maximum GSM RSSI.

Table 19 lists the Nidentify_abort values of CMSS.

Table 19 Nidentify_abort values of sample sequence in compression mode

GL1

[slots]

GL2

[slots]

TGD

[slots]

TGPL1

[frames]

TGPL2

[frames]

Tidentify abort

[s]

Nidentify_abort

[patterns]

Pattern 1 7 - undefined 3 TGPL1 1.56 52




Pattern 3 7 7 47 8 TGPL1 2.88 36

Pattern 4 7 7 38 12 TGPL1 2.88 24



Pattern 7 14 14 45 12 TGPL1 1.44 12


Pattern 9 10 10 75 12 TGPL1 2.88 24

Note:

Nidentify_abort is the number of UE attempting to decode BSIC at least twice.

Tidentify_abort is the duration corresponding to Nidentify_abort CMSSs.

2) BSIC Reconfirmation

The UE traces and decodes the BSIC passing BSIC initial confirmation. The UE starts BSIC

reconfirmation within the transmission gap for CMSS of ―GSM BSIC reconfirmation‖. The

UE maintains the timing relationship of eight confirmed GSM cells during the ―BSIC

reconfirmation‖ using the timing information of each GSM cell of ―BSIC initial

confirmation‖. The UE updates the timing relationship when succeeding in decoding BSIC.

In each CMSS for ―GSM BSIC reconfirmation‖, the UE tries to decode the GSM cell BSIC

within the transmission gap.

If the UE can decode more than one GSM BSICs within a transmission gap, the UE first

decodes the recently-decoded BSIC in the GSM cell.

If the UE fails to decode the BSIC twice, or it cannot complete ―GSM BSIC

reconfirmation‖ within Tre-confirm_aborts, it aborts the ―GSM BSIC reconfirmation‖, and

takes the GSM cell as a cell without the ―BSIC initial confirmation‖.

The UE performs ―BSIC reconfirmation‖ to the eight GSM cells with maximum GSM RSSI.

Table 20 lists the values of Nre-confirm_abort and Tre-confirm_abort from pattern 1 to pattern 15.

Table 20 Values of Nre-confirm_abort and Tre-confirm_abort in patterns

TGL1

[slots]

TGL2

[slots]

TGD

[slots]

TGPL1

[frames]

TGPL2

[frames]

Tre-confirm_abort

[s]

Nre-confirm_abort

[patterns]




Pattern 4 7 7 69 23 TGPL1 10.12 44

Pattern 5 7 7 69 8 TGPL1 2.64 33




Pattern 7 14 14 60 8 TGPL1 0.80 10



Pattern 10 7 7 47 8 TGPL1 2.64 33

Pattern 11 7 7 38 12 TGPL1 2.64 22


Pattern 13 14 14 45 12 TGPL1 1.20 10


Pattern 15 10 10 75 12 TGPL1 2.64 22

Note:

Nre-confirm_abort is the repeated times of CMSS within Tre-confirm_abort

II. UE requiring no compression mode

Once the UE succeeds in decoding the BSIC in a GSM cell, the cell is taken as a ―confirmed‖

cell. Otherwise it is a ―non-confirmed‖ cell. The UE must confirm BSIC according to its

sensitivity and reference interface standard specified in the protocol TS45.005.

8.2.3 Selection of CMSS

A UE need measure several items during the GSM cell measurement. The UE measures these

items within transmission gap. Therefore, the transmission gaps for each measurement items

must not be overlapped. Namely, the UE cannot measure RSSI and confirm BSIC within one

transmission gap. This adds requests to the selection of CMSS. Since the sample sequences

are periodical, the UE must not overlap the measurement transmission gaps during repeated

measurement items. In addition, The UE needs to increase the probability of obtaining

measurement item results.

8.3 Measurement on a GSM System by UE in the CELL FACH State

According to the protocol 25.133, a UE in the CELL FACH state can monitor at most 32

WCDMA intra-frequency cells or 32 WCDMA inter-frequency cells. The 32 WCDMA cells

use three channel numbers, two of which are different from the current channel number. The

UE can support 32 inter-frequency GSM cells or monitor at most 16 intra-frequency cells in

idle period in downlink (IPDL) measurement gap. The protocol also defines as follows:



In the CELL FACH state, the UE must continuously measure confirmed intra-frequency

cells and search new intra-frequency or inter-frequency cells indicated by the network.

If the intra-frequency cells are configured in monitor set, and the signals satisfy that

CPICH Ec/Io is equal to or greater than -20 dB and SCH_Ec/Io is equal to or greater

than -20 dB, the UE must detect the signal within Tidentify,intra (defined in the protocol

25.133).

If the inter-frequency cells are configured in a monitor set, the signals satisfy that

CPICH Ec/Io is equal to or greater than -20 dB and SCH_Ec/Io is equal to or greater

than -17 dB, the UE must detect the signal within Tidentify,inter (defined in the protocol

25.133).

The measurement occasion is specified SIB11 or SIB12.

If the parameter ―FACH Measurement occasion cycle length coefficient‖ is provided in

the ―FACH measurement occasion info‖:

When the UE does not support the measurement while monitoring SCCPCH, the

UE performs inter-frequency measurement or Inter-RAT measurement at specified

measurement occasion.

When the UE supports the measurement while monitoring SCCPCH, the UE

performs inter-frequency measurement or Inter-RAT measurement at different

time.

If the parameter ―FACH Measurement occasion cycle length coefficient‖ is not provided

in the ―FACH measurement occasion info‖, the UE performs measurement while

receiving SCCPCH only according to its capability.

The measurement occasion is calculated as follows:

SFN div N = C_RNTI mod M_REP + n * M_REP

wherein,

M_REP = 2^k. K is ―FACH Measurement occasion cycle length coefficient‖, and its

value ranges from 1 to 12 (integer).

N is the number of frames included in the maximum TTI on SCCPCH monitored by

UE.

C_RNTI is the C_RNTI allocated by CRNC, and it is not empty.

N = 0, 1, 2…, the SFN must be smaller than maximum value.

From the previous formula,

C_RNTI mod M_REP decides the offset of measurement occasion in a measurement

period.

M-REP decides measurement period.

n is a temporary variable for the convenience of understanding.

If the UE decides a measurement on other system after the cell reselection and evaluation, it

performs the measurement at the SFN point that satisfies the previous formulas.



The protocol 25.133 defines the following rules in the GSM measurement occasion:

One of every two measurement occasions is allocated to measurement on ―Initial

confirmation of BSIC measurement‖.

In the remaining measurement occasions, 3/4 of them are allocated to RSSI

measurement and 1/4 of them are allocated to ―BSIC reconfirmation measurement‖.

The measurement period of GSM carrier RSSI is 480ms. The measurement precision of GSM

RSSI by UE must follow the protocol TS45.008. The UE can sample at least three GSM

RSSI values for each centralized GSM carrier. If there are too many carriers and the

measurement cannot be completed within a period, the measurement continues in the next

period and each carrier is sampled for at least three times. Different length of measurement

occasion decides different sampling number, so the number of carriers measured in a

measurement period is different.

Table 21 Relationship between length of measurement occasion and number of GSM carrier RSSI samples

Length of measurement occasion

(frames)

Number of GSM carrier RSSI samples in each

measurement occasion, NGSM carrier RSSI.

1 16

2 32

4 64

8 128

―BSIC initial confirmation‖ measurement means that the UE continuously captures the

synchronous burst (SB) of the six cells with maximum RSSI in neighbor GSM cells and

decodes BSIC.

If the UE succeeds in decoding BSIC, it continues to decode the BSIC of next cell.

If the UE fails to decode BSIC within T (identity, GSM), it stops ―BSIC confirmation‖

measurement of the cell and then performs the ―BSIC confirmation‖ of the next cell.

―BSIC reconfirmation‖ measurement means that the UE performs ―BSIC reconfirmation‖

after BSIC initial confirmation. The maximum time for BSIC reconfirmation of a cell is T

(re-confirm, GSM). The BSIC of each cell need be confirmed at least once within 6 x T

(re-conform, GSM). Otherwise, the BSIC of the cell is considered as unconfirmed. Frequency

switch takes some time in measurement occasion. The protocol 133 defines that the middle

point of SB and that of measurement occasion are valid within the same range in the case of

―BSIC initial confirmation‖ and ―BSIC reconfirmation‖.

Table 22 Relationship between measurement occasion length and max. time difference

Measurement occasion

length [frames]

Maximum time difference

[s]

1 4100

2 9100



4 19100

8 39100

8.4 Measurement on a GSM System by UE the in IDLE/CELL

PCH/URA PCH State

In the measurement of GSM carrier RSSI, the UE measures RSSI of each GSM carrier at

least every other T (measure, GSM). The UE samples RSSI at least four times on each carrier

within the measurement period. T (measure, GSM) is decided by DRX cycle length (see the

appendix in 2.3 ).

The BSIC confirmation measurement is as follows:

1) The UE selects the four strongest cells.

2) Each cell confirms the BSIC value every other 30m.

3) If a GSM cell detects that BSIC changes, the cell is taken as a new cell.



Chapter 9 Appendix 2: Compression Mode and

Parameters Configuration

In the WCDMA FDD mode, to perform hard handover of different frequency and handover

from FDD to TDD and handover to GSM system, the UE need measure the target cell that

needs handover. The frequency to be measured is different from the serving frequency of UE.

Namely, measurement of different frequency is necessary.

In the WCDMA FDD mode, if the UE uses the downlink signal all the time, it need receive

downlink data continuously. Therefore, the receiver cannot receive signals of other frequency

while receiving the signal of the serving frequency. If the UE has only one set of transceiver,

idle slots is necessary in downlink radio frames. This is the compression mode.

Figure 13 shows the frames in compression mode.

One frame

(10 ms) Transmission gap available forinter-frequency measurements

Figure 13 Frames in compression mode

In the Figure 13, since the data transmission ratio of compression frames is higher, the power

need be increased. In the idle period the measurement of different frequency is performed.

In the downlink compression mode, if the UE uses the uplink frequency all the time and the

frequency to be measured is close to the uplink frequency, the uplink frequency may interfere

the frequency to be measured. To assure the validity of measurement, the UE must stop

transmitting in uplink. This is the uplink compression mode. In the duel-transceiver scheme,

if the frequency to be measured is close to the uplink frequency, the uplink compression

mode is necessary.

Figure 14 shows the CMSS parameters according to the protocol.



DOCUMENTTYPE

TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere

Transmission

Transmission gap 2

gap 2

TGSN TGSN

TGL2 TGL2

TG pattern 2

#TGPRC

gap 1

Transmission Transmission

gap 1

TGD TGD

TGPL1 TGPL2

TG pattern 1 TG pattern 2

TGL1 TGL1

#1 #2 #3 #4 #5

TG pattern 1TG pattern 1 TG pattern 2 TG pattern 1 TG pattern 2

Figure 14 CMSS parameters

The Compression mode sequence consists of pattern 1 and pattern2 alternately. Each pattern

includes one or two transmission gaps. The UTRAN allocates the parameters in compression

mode to UE through signaling.

Figure 14 includes parameters for gap orientation as follows:

TGCFN is the connection frame number of the radio frame where the first gap of CMSS

is. Namely, it is the starting point of compression mode.

TGSN is the starting timeslot number of radio frame of which the connection frame

number is TGCFN. A radio frame includes 15 timeslots.

TGL1 and TGL2 are the durations of the first and second gap respectively by timeslots.

TGD is the distance of starting points between gap 1 and gap 2 (unit: slot).

TGPL1 and TGPL2 are the length of pattern 1 and pattern 2 respectively (unit: slot).

The starting point of the first gap is defined through TGCFN and TGSN. The starting point of

the second gap is determined by TGCFN, TGSN, and TGD. The starting point of each pattern

is determined by TGCFN, TGSN, TGD, TGPL1, and TGPL2.

The compression mode includes dual-frame mode and single-frame mode according to

transmission gap length.

In the single-frame mode, all timeslots of the transmission slot are in the same frame.

In the dual-frame mode, the timeslots of a transmission slot are in two frames.

According to the protocol, two transmission slots cannot exist in the same frame

simultaneously. The gap length over seven timeslots must adopt dual-frame mode.



There are three ways to realize compression mode: puncturing, the spreading factor reduction,

higher layers dispatching.

The compression mode sample command (SET TGPSCP) is set as an internal one. With it

CMSS is changed. The parameter often needs no change.

Table 23 Parameter and meanings.

ID Name Meaning

CMCFCELLT

YPE

Cell type in

compression

mode

Value range: WALKING_SPEED_AND_HOT_SPOT_CELL (in walking

and hot spot cells), MID_SPEED_AND_HOT_SPOT_CELL (in hot-spot

cells with medium speed), HIGH_SPEED_AND_HOT_SPOT_CELL (in

hot-spot cells with high speed),

LOW_SPEED_AND_MEDIUM_COVERAGE_CELL (in

medium-coverage cells with low speed),

HIGH_SPEED_AND_MEDIUM_COVERAGE_CELL (in

medium-coverage cells with high speed),

LOW_SPEED_AND_HIGH_COVERAGE_CELL (in high-coverage cells

with low speed), LOW_SPEED_AND_HIGH_COVERAGE_CELL (in

medium-coverage cells with low speed), OTHER_CELL (in other cells)

Physical unit: none

Content: the cell type in compression mode. The compression mode

parameters are configured according to cell types. Different cells use

different CMSSs. Each cell type in compression mode respectively

corresponds to the spreading factor reduction in downlink compression

mode and puncturing.

Recommended value: hot-spot cell with medium speed

CMMETHOD Method in

compression

mode

Value range: PUNCTURING, SPREADING_FACTOR_REDUCTION

(spreading factor reduction)

Physical unit: none

Content: PUNCTURING (the puncturing way),

SPREADING_FACTOR_REDUCTION (the spreading factor reduction

parameter)

Physical unit: none

CmMeasType Measurement

type in

compression

mode

Value range: CMCF_MEAS_TYPE_FDD (used in measurement of

different frequency), CMCF_MEAS_TYPE_GSM (used in measurement

of different frequency), CMCF_MEAS_TYPE_FDD_GSM (used in

coexistence of measurement of different frequency and of Inter-RAT)

Physical unit: none

Content: the measurement type for the compression mode sequence

Recommended value: none



ID Name Meaning

TGMP Compression

mode target

Value range: FDD_MEASUREMENT,

GSM_CARRIER_RSSI_MEASUREMENT,

GSM_INITIAL_BSIC_IDENTIFICATION,

GSM_BSIC_RE-CONFIRMATION

Physical unit: none

Content: the aim to perform measurement in compression mode


NIDABORT The maximum

repeated times

of coding BSIC

by UE

Value range: 1–128

Physical unit: none

Content: the maximum repeated times of initial confirmation of BSIC in a

GSM cell


TRECONFAB

ORT

The allowable

maximum time

for

reconfirmation

of BSIC

Value range: 1–20

Physical value range: 0.5–10.0, the step is 0.5

Physical unit: s

Content: the maximum times for reconfirmation of BSIC in a GSM cell


TGSN TGSN Value range: 0–14

Physical unit: slot

Content: the starting timeslot number of the first gap in the first

compressed frame in CMSS


TGL1 TGL1 Value range: 1–14

Physical unit: slot

Content: the length of gap 1, in the unit of slot


TGL2 TGL2 Value range: 1–14

Physical unit: slot

Content: the length of gap 2, in the unit of slot


TGD TGD Value range: 15–270

Physical unit: slot

Content: the starting timeslot position offset of compression slot 2

compared with TGSN. 270 indicates undefined. If only one compression

slot is in CMSS, the configuration is undefined, namely, 270




ID Name Meaning

TGPL1 TGPL1 Value range: 1–144

Physical unit: frame

Content: the length of CMSS 1, in the unit of frame


TGPL2 TGPL2 Value range: 1–144

Physical unit: frame

Content: the length of CMSS 2, in the unit of frame


RPP RPP Value range: MODE0, MODE1

Physical unit: none

Content: MODE0 indicates the mode 0, and MODE1 indicates the mode 1.


ITP ITP Value range: MODE0, MODE1

Physical unit: none

Content: MODE0 indicates the mode 0, and MODE1 indicates the mode 1.


DLFRAMETY

PE

Downlink

frame type

Value range: A, B

Physical unit: none

Content: the frame of type A is the common frame in compression mode,

and for the frame of type B, the TPC bit is inserted in compression mode

to optimize power control capacity


NODEBDELT

ASIR2VALID

NodeB

DeltaSIR2 valid

identity

Value range: Valid, Invalid

Physical unit: none

Content: valid means that NodeB DeltaSIR2 value is valid, and namely,

the NodeB DeltaSIR2 value may not be equal to the NodeB DeltaSIR1

value; Invalid means that the NodeB DeltaSIR2 value is invalid, and

namely the NodeB DeltaSIR2 value is equal to NodeB DeltaSIR1 value.


NODEBDELT

ASIRAFTER2

VALID

NodeB

DeltaSIRAfter2

valid identity


Physical unit: none

Content: valid means that NodeB DeltaSIRAfter2 value is valid, and

namely, the NodeB DeltaSIRAfter2 value may not be equal to the NodeB

DeltaSIRAfter1 value; Invalid means that the NodeB DeltaSIRAfter2

value is invalid, and namely the NodeB DeltaSIRAfter2 value is equal to

NodeB DeltaSIRAfter1 value.




ID Name Meaning

NODEBDELT

ASIR1

NodeB

DeltaSIR1

Value range: 0–30

Physical range: 0–3, the step is 0.1

Physical unit: dB

Content: the added value of downlink target (SIR) of the frame where

TGL1 is


NODEBDELT

ASIRAFTER1

NodeB

DeltaSIRAfter1

Value range: 0–30

Physical range: 0~3, the step is 0.1

Physical unit: dB

Content: the added value of downlink target (SIR) of the next frame where

TGL1 is


NODEBDELT

ASIR2

NodeB

DeltaSIR2

Value range: 0–30


Physical unit: dB

Content: the added value of downlink target (SIR) of the frame where

TGL2 is


NODEBDELT

ASIRAFTER2

NodeB

DeltaSIRAfter2

Value range: 0–30

Physical unit: 0–3, the step is 0.1

Physical unit: dB

Content: the added value of downlink target (SIR) of the next frame where

TGL2 is


UEDELTASIR

2VALID

UE DeltaSIR2

valid identity


Physical unit: none

Content: valid means that UE DeltaSIR2 value is valid, and namely, the

UE DeltaSIR2 value may not be equal to the UE DeltaSIR1 value; Invalid

means that the UE DeltaSIR2 value is invalid, and namely the UE

DeltaSIR2 value is equal to UE DeltaSIR1 value.


UEDELTASIR

AFTER2VALI

D

UE

DeltaSIRAfter2

valid identity


Physical unit: none

Content: valid means that UE DeltaSIRAfter2 value is valid, and namely,

the UE DeltaSIRAfter2 value may not be equal to the UE DeltaSIRAfter1

value; Invalid means that the UE DeltaSIRAfter2 value is invalid, and

namely the UE DeltaSIRAfter2 value is equal to UE DeltaSIRAfter1

value.




ID Name Meaning

UEDELTASIR

1

UE DeltaSIR1 Value range: 0–30


Physical unit: dB

Content: the added value of uplink target (SIR) in the frame where TGL 1

is


UEDELTASIR

AFTER1

UE

DeltaSIRAfter1

Value range: 0–30


Physical unit: dB

Content: the added value of uplink target (SIR) in the next frame where

TGL 1 is


UEDELTASIR

2

UE DeltaSIR2 Value range: 0–30


Physical unit: dB

Content: the added value of uplink target (SIR) in the frame where TGL 2

is


UEDELTASIR

AFTER2

UE

DeltaSIRAfter2

Value range: 0–30


Physical unit: dB

Content: the added value of uplink target (SIR) in the next frame where

TGL 2 is




Chapter 10 Appendix 3: Compression Mode Start/Stop

Now Huawei adopts 2D/2F start/stop compression mode.

The frequency quality estimate used in events 2a, 2b 2c, 2d, 2e and 2f is defined as:

,10)1(10101

jBestj

N

i

jijjfrequencyfrequencyj LogMWMLogWLogMQjA

The variables in the formula are defined as follows ("the virtual active set on frequency

j" should be understood as the active set if frequency j is the used frequency. If frequency j is

a non-used frequency, the way the virtual active set is initiated and updated is described in

25.331.

Qfrequency j is the estimated quality of the virtual active set on frequency j.

Mfrequency j is the estimated quality of the virtual active set on frequency j.

Mi j is a measurement result of cell i in the virtual active set on frequency j.

NA j is the number of cells in the virtual active set on frequency j.

MBest j is the measurement result of the cell in the virtual active set on frequency j with

the highest measurement result.

Wj is a parameter sent from UTRAN to UE and used for frequency j.

If the measurement result is CPICH-Ec/No then MFrequency, Mi j and MBest are expressed

as ratios.

If the measurement result is CPICH-RSCP or PCCPCH-RSCP then MFrequency, Mi j and

MBest are expressed in mW.

10.1 Event 2d: The estimated quality of the currently used frequency

is below a certain threshold

A UE shall be able to perform this measurement and the corresponding event reporting

without requiring compressed mode.

When an inter-frequency measurement configuring event 2d is set up, the UE shall:

1> create a variable TRIGGERED_2D_EVENT related to that measurement, which

shall initially be set to FALSE;

1> delete this variable when the measurement is released.

When event 2d is configured in the UE within a measurement, the UE shall:

1> if equation 1 below has been fulfilled for the used frequency during the time

"Time to trigger":

2> if the variable TRIGGERED_2D_EVENT is set to FALSE:

3> set the variable TRIGGERED_2D_EVENT to TRUE;



3> send a measurement report with IEs set as below:

4> set in "inter-frequency event results": "inter-frequency event identity" to "2d" and

no IE "Inter-frequency cells", not taking into account the cell individual offset;

4> include in IE "Inter-frequency measured results list" the measured

results for the used frequency, not taking into account the cell individual offset;

4> set the IE "additional measured results" according to 25.331, not taking into

account the cell individual offset.

1> if the variable TRIGGERED_2D_EVENT is set to TRUE and if equation 2 is

fulfilled for the used frequency:

2> set the variable TRIGGERED_2D_EVENT to FALSE.

Triggering condition:

Equation 1:

2/22 ddUsedUsed HTQ

The variables in the formula are defined as follows:

QUsed is the quality estimate of the used frequency.

TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.

H2d is the hysteresis parameter for the event 2d.

Leaving triggered state condition:

Equation 2:

2/22 ddUsedUsed HTQ



TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.

H2d is the hysteresis parameter for the event 2d.

10.2 Event 2 f: The estimated quality of the currently used frequency

is above a certain threshold

A UE shall be able to perform this measurement and the corresponding event reporting

without requiring compressed mode.

When an inter-frequency measurement configuring event 2f is set up, the UE shall:

1> create a variable TRIGGERED_2F_EVENT related to that measurement, which

shall initially be set to FALSE;

1> delete this variable when the measurement is released.

When event 2f is configured in the UE within a measurement, the UE shall:

1> if equation 1 below has been fulfilled for the used frequency during the time

"Time to trigger":

2> if the variable TRIGGERED_2F_EVENT is set to FALSE:



3> set the variable TRIGGERED_2F_EVENT to TRUE;

3> send a measurement report with IEs set as below:

4> set in "inter-frequency event results": "inter-frequency event identity" to "2f",

and no IE "Inter-frequency cells";

4> include in IE "Inter-frequency measured results list" the measured results for the

used frequency, not taking into account the cell individual offset;

4> set the IE "additional measured results" according to 25.331, not taking into

account the cell individual offset.

1> if the variable TRIGGERED_2F_EVENT is set to TRUE and if equation 2 is

fulfilled for the used frequency:

set the variable TRIGGERED_2F_EVENT to FALSE.

Triggering condition:

Equation 1:

2/22 ffUsedUsed HTQ



TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.

H2f is the hysteresis parameter for the event 2f.

Leaving triggered state condition:

Equation 2:

2/22 ffUsedUsed HTQ



TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.

H2f is the hysteresis parameter for the event 2f.



List of references:

1. Huawei Engineers, White Paper for Inter-RAT Interoperation, 2003/12

2. Chen Gong, WCDMA Radio Network Optimization Inter-RAT Cell Reselection and Handover Guide,

2004/6

3. Hu Zhongji, UAE Business Technical Summary--- Arrangement and Analysis for Algorithm

Requirement, 2004/5

4. Hu Zhongji, UAE Commercial Office Inter-RAT Handover Summary,2004/5

5. S Project Team, Sunday 3G 2G Reselection and Handover Optimization Guide, 20040905,2004/01

6. Peng Honghua, Inter-RAT Roaming and Handover, ppt,2003/05

7. U Project Team, WCDMA RNO Inter-RAT handover Description and parameter setting, 2004/02

8. 3GPP TS 25.304/25.331/25.133/05.08

1.wcdma rno special guide inter-rat roaming and handover-20050316-a-2.0

Documents