TMO18003D0SGDENI1.0

2G-3G Mobility Algorithms - B10 - Page 1All Rights Reserved © Alcatel-Lucent 2008

All Rights Reserved © Alcatel-Lucent 2008

Alcatel-Lucent Evolium Base Station Subsystem

2G-3G Mobility Algorithms - B10

STUDENT GUIDE

TMO18003 D0 SG DEN I1.0Issue 01

All rights reserved © Alcatel-Lucent 2008 Passing on and copying of this document, use and communication of its contents not permitted without written authorization from Alcatel-Lucent



2G-3G Mobility Algorithms - B10Alcatel-Lucent Evolium Base Station Subsystem

2

Empty page

Switch to notes view!

This page is left blank intentionally




3

Terms of Use and Legal Notices

Switch to notes view!1. Safety Warning

Both lethal and dangerous voltages may be present within the products used herein. The user is strongly advised not to

wear conductive jewelry while working on the products. Always observe all safety precautions and do not work on the

equipment alone.

The equipment used during this course may be electrostatic sensitive. Please observe correct anti-static precautions.

2. Trade Marks

Alcatel-Lucent and MainStreet are trademarks of Alcatel-Lucent.

All other trademarks, service marks and logos (“Marks”) are the property of their respective holders, including Alcatel-

Lucent. Users are not permitted to use these Marks without the prior consent of Alcatel-Lucent or such third party owning

the Mark. The absence of a Mark identifier is not a representation that a particular product or service name is not a Mark.

Alcatel-Lucent assumes no responsibility for the accuracy of the information presented herein, which may be subject to

change without notice.

3. Copyright

This document contains information that is proprietary to Alcatel-Lucent and may be used for training purposes only. No

other use or transmission of all or any part of this document is permitted without Alcatel-Lucent’s written permission, and

must include all copyright and other proprietary notices. No other use or transmission of all or any part of its contents may

be used, copied, disclosed or conveyed to any party in any manner whatsoever without prior written permission from

Alcatel-Lucent.

Use or transmission of all or any part of this document in violation of any applicable legislation is hereby expressly

prohibited.

User obtains no rights in the information or in any product, process, technology or trademark which it includes or

describes, and is expressly prohibited from modifying the information or creating derivative works without the express

written consent of Alcatel-Lucent.

All rights reserved © Alcatel-Lucent 2008

4. Disclaimer

In no event will Alcatel-Lucent be liable for any direct, indirect, special, incidental or consequential damages, including

lost profits, lost business or lost data, resulting from the use of or reliance upon the information, whether or not Alcatel-

Lucent has been advised of the possibility of such damages.

Mention of non-Alcatel-Lucent products or services is for information purposes only and constitutes neither an

endorsement, nor a recommendation.

This course is intended to train the student about the overall look, feel, and use of Alcatel-Lucent products. The

information contained herein is representational only. In the interest of file size, simplicity, and compatibility and, in some

cases, due to contractual limitations, certain compromises have been made and therefore some features are not entirely

accurate.

Please refer to technical practices supplied by Alcatel-Lucent for current information concerning Alcatel-Lucent equipment

and its operation, or contact your nearest Alcatel-Lucent representative for more information.

The Alcatel-Lucent products described or used herein are presented for demonstration and training purposes only. Alcatel-

Lucent disclaims any warranties in connection with the products as used and described in the courses or the related

documentation, whether express, implied, or statutory. Alcatel-Lucent specifically disclaims all implied warranties,

including warranties of merchantability, non-infringement and fitness for a particular purpose, or arising from a course of

dealing, usage or trade practice.

Alcatel-Lucent is not responsible for any failures caused by: server errors, misdirected or redirected transmissions, failed

internet connections, interruptions, any computer virus or any other technical defect, whether human or technical in

nature

5. Governing Law

The products, documentation and information contained herein, as well as these Terms of Use and Legal Notices are

governed by the laws of France, excluding its conflict of law rules. If any provision of these Terms of Use and Legal

Notices, or the application thereof to any person or circumstances, is held invalid for any reason, unenforceable including,

but not limited to, the warranty disclaimers and liability limitations, then such provision shall be deemed superseded by a

valid, enforceable provision that matches, as closely as possible, the original provision, and the other provisions of these

Terms of Use and Legal Notices shall remain in full force and effect.




4

Blank Page






5

Course Outline

About This CourseCourse outline

Technical support

Course objectives

1. Topic/Section is Positioned HereXxx

Xxx

Xxx

2. Topic/Section is Positioned Here






1. 2G-3G Mobility

1. Objectives of the Mobility Algorithms between 2G and 3G

2. PLMN and Radio Access Technology Selection

3. Cell Selection

4. Cell Reselection from 2G to 3G

5. Handover from 2G to 3G

6. Impacts of 2G3G Mobility on CS and PS Services




6

Course Outline [cont.]






7

Course Objectives


Welcome to 2G-3G Mobility Algorithms - B10

Upon completion of this course, you should be able to:

� Describe radio algorithms and radio parameters of the Alcatel-Lucent BSS and UTRAN sub-

systems which are responsible for the mobility between 2G and 3G RAT

� Describe the objectives of the mobility algorithms from BSS to UTRAN

� Describe how the Network Operator or the User can favor either 2G or 3G at PLMN selection

� Describe how the mobile selects a 2G cell or a 3G cell after RAT selection

� Describe the 2G radio measurements used for Inter-RAT cell reselection and Inter-RAT

Handover

� Describe the phases of cell selection and reselection, the associated 2G algorithms and

parameters

� Describe the phases of Inter-RAT handovers, the associated 2G algorithms and parameters

� Describe the impact of the Inter-RAT mobility on CS and PS services.




8

Course Objectives [cont.]






9

About this Student Guide

� Switch to notes view!Conventions used in this guide

Where you can get further information

If you want further information you can refer to the following:

� Technical Practices for the specific product

� Technical support page on the Alcatel website: http://www.alcatel-lucent.com

Note

Provides you with additional information about the topic being discussed.

Although this information is not required knowledge, you might find it useful

or interesting.

Technical Reference (1) 24.348.98 – Points you to the exact section of Alcatel-Lucent Technical

Practices where you can find more information on the topic being discussed.

WarningAlerts you to instances where non-compliance could result in equipment

damage or personal injury.




10

About this Student Guide [cont.]

� Switch to notes view!





11

Self-assessment of Objectives

� At the end of each section you will be asked to fill this questionnaire

� Please, return this sheet to the trainer at the end of the training


Instructional objectives Yes (or globally yes)

No (or globally no)

Comments

1 To be able to XXX

2

Contract number :

Course title :

Client (Company, Center) :

Language : Dates from : to :

Number of trainees : Location :

Surname, First name :

Did you meet the following objectives ?

Tick the corresponding box

Please, return this sheet to the trainer at the end of the training

��




12

Self-assessment of Objectives [cont.]


Instructional objectives Yes (or Globally yes)

No (or globally no)

Comments

Thank you for your answers to this questionnaire

Other comments

��

Section 1 � Module 1 � Page 1


3JK11184AAAAWBZZA Issue 01

Do not delete this graphic elements in here:

1�1All Rights Reserved © Alcatel-Lucent 2008

Module 1Objectives of the Mobility Algorithms between 2G and 3G


Section 12G-3G Mobility

Alcatel-Lucent Evolium Base Station Subsystem2G-3G Mobility Algorithms - B10

TMO18003 D0 SG DEN I1.0

Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � Objectives of the Mobility Algorithms between 2G and 3G

1 � 1 � 2

Blank Page


First editionLast name, first nameYYYY-MM-DD01

RemarksAuthorDateEdition

Document History






1 � 1 � 3

Module Objectives

Upon completion of this module, you should be able to:

� Describe the objectives of the radio algorithms implemented in BSS and UTRAN in order to manage the mobility of the user in the network






1 � 1 � 4

Module Objectives [cont.]







1 � 1 � 5

Table of Contents

Switch to notes view!Page

1 Presentation of the Objectives 71.1 Providing Access to the Service 81.2 Providing Continuity of Service 91.3 Providing the Required Quality for the Service 10

2 Radio Algorithm Parameters Setting 112.1 Distribution of Mono-Mode 2G / Bi-Mode 2G-3G Users 122.2 Density of 3G Sites Compared to 2G 132.3 Call Mix for CS and PS Services 14






1 � 1 � 6

Table of Contents [cont.]








1 � 1 � 7

1 Presentation of the Objectives






1 � 1 � 8


1.1 Providing Access to the Service

� Sufficient coverage, resource and quality

2GRAT

3GRAT

BEST COVERAGE

BEST RESOURCE

BEST QUALITY

BEST COVERAGE

BEST QUALITY

The first objective of the 2G-3G mobility is to provide every time and everywhere the access to the service

with the best possible coverage, quality and resource availability.

RAT: Radio Access Technology






1 � 1 � 9


1.2 Providing Continuity of Service

� In case of 3G coverage holes, the 2G layer is used to provide continuity of service:

� 3G border areas

� Indoor

� Site delay

HO 3G coverage

2G coverageSub-urban area

3GBTS

3G coverage

Hole!

2G coverage

3G2Gonly

Another objective of the 2G-3G mobility/interoperability is to provide continuity of service.






1 � 1 � 10


1.3 Providing the Required Quality for the Service

� Strategy is to keep 3G subscribers on 3G layer:

� to guarantee a good bit rate for PS service

� to promote 3G

� to limit impact on 2G network

3G2G

3G

TODAY

TODAY

TODAY

TODAY

AVAILAB

LE !

AVAILAB

LE !

AVAILAB

LE !

AVAILAB

LE !

COVERED

CITY !

COVERED

CITY !

Even if this training covers only 2G- to-3G scenarios, these objectives can be fully reached only if entire 2G-

3G mobility is available (2G to 3G and 3G to 2G).

Concerning the limitation of the impact on 2G, we deal with the case where the 2G network is already

highly loaded.






1 � 1 � 11

2 Radio Algorithm Parameters Setting






1 � 1 � 12


2.1 Distribution of Mono-Mode 2G / Bi-Mode 2G-3G Users

� As the strategy is to keep bi-mode MS on 3G cells, in case of high 3G MS penetration (> 50% for example), 3G cells can be overloaded.

� So, it is necessary to use other criteria to unload 3G areas:Only 3G MSs performing data transfer are kept on 3G cells.

………

VIDEOrunning

CALL

29604765

Peter Falk

VIDEOrunning

VIDEOrunning

VIDEOrunning

CALL

29604765

Peter Falk

CALL

29604765

Peter Falk

………………

………

………

………………

3G

2G

A compromise has to be found: Keep 3G MS on 3G area.

But if there are too many 3G MSs or too much traffic, then 2G is preferred for Voice.






1 � 1 � 13

2 Radio Algorithm Pparameters Setting

2.2 Density of 3G Sites Compared to 2G

� The density of the 3G sites also has to be taken into account.Particularly if the traffic is High (anyway, in case of low traffic, the 3G is preferred).

HIGH TRAFFICLOW 3G DENSITY

HIGH TRAFFICHIGH 3G DENSITY

3G

3GCS

traffic

PStraffic

CStraffic

See above:Depend on 3G MS penetration

CALL

29604765

Peter Falk

2G 2G

3GVIDEOrunning?

If the traffic is:

� low, all bi-mode MSs can stay on 3G.

� High with:

� low 3G coverage, 2G area will be preferred for voice while 3G area will be preferred for Data.

� High 3G coverage, it will depend on 3G MS penetration: if the 3G MS penetration is low, all traffic

(CS + PS) can be kept on 3G area.

Hightraffic ?

High 3Gpenetration ?

High 3Gcoverage ?

Voice?

Bimode MS

3G 2G

N

Y

Y

Y

Y

N

N

N






1 � 1 � 14


2.3 Call Mix for CS and PS Services

� Due to the importance of Bit Rates for PS services, if everybody cannot be kept on 3G cell for one or several of the reasons seen before, PStraffic will be preferred…

IN ORDER TO REACH THE OBJECTIVES MENTIONED AT THE BEGINNING OF THIS CHAPTER.

If ensuring a good quality is not possible or if there is not enough space for everybody on 3G layer, then

only PS traffic will be kept, while CS traffic will be sent on 2G layer if possible.






1 � 1 � 15

Exercise

� In the table below, on which RAT should the CS and PS services of bi-mode users be favored?

� Possible answers:

� On 3G for CS and PS

� On 2G for CS and PS

� On 3G for PS, On 2G for CS

� On 3G for CS, On 2G for PS

� Depends on …

Density of 3G Sites

3G Traffic

Same as 2G

Lower than 2G

HIGHLOW

2G RAT 3G RAT






1 � 1 � 16

Self-assessment on the Objectives

� Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module

� The form can be found in the first partof this course documentation






1 � 1 � 17

End of ModuleObjectives of the Mobility Algorithms between 2G and 3G






Module 2PLMN and Radio Access Technology Selection




TMO18003 D SG DEN I1.0

Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � PLMN and Radio Access Technology Selection

1 � 2 � 2

Blank Page




Document History






1 � 2 � 3

Module Objectives


� Describe how the network operator or the user can give priority to an RATrather than to another one






1 � 2 � 4








1 � 2 � 5

Table of Contents


1 Data Stored in the USIM 71.1 List 81.2 Management and Usage 9

2 PLMN and RAT Selection Algorithm 112.1 Switch on 122.2 Automatic Mode 132.3 Manual Mode 14






1 � 2 � 6









1 � 2 � 7

1 Data Stored in the USIM






1 � 2 � 8


1.1 List

� User-Controlled PLMN Selector data field

� Operator-Controlled PLMN Selector list

� User-Controlled PLMN Selector list

� Access Technology identifier (e.g. UTRAN or GERAN)

� Registered PLMN

� Group of equivalent PLMNs (to the registered one in case of shared PLMN)

� Forbidden PLMN data field** (may be extended in ME* memory)

� Interval between attempts (for periodic network selection attempts)

� Population number (Access Class 0 to 9 randomly allocated)

� Special category(ies) (PLMN Staff, Emergency Services, etc.)

A “User-Controlled PLMN Selector data field” exists on the USIM to allow the user to indicate a preference

for network selection.

A list of preferred networks controlled by the user.

A list of preferred networks controlled by the operator.

An Access technology Identifier to identify the preferred RAT.

The registered PLMN (on which the mobile is camping) is also stored.

If registration is unsuccessful, the UE shall ensure that there is no registered PLMN stored in the SIM/USIM.

It shall also be possible to indicate to the UE that a group of PLMNs are equivalent to the registered PLMN

regarding PLMN selection, cell selection/re-selection and handover (case of shared PLMN).

* ME: Mobile Equipment

** Another forbidden list is stored in ME: “Forbidden PLMNs for GPRS service”






1 � 2 � 9


1.2 Management and Usage

User-Controlled PLMN Selector data field My preferred Network

My preferredNetworks list:

Net1 GERANNet2 GERAN *Net3 GERANNet1 UTRANNet4 UTRAN

Operator preferredNetworks list:

Net4 UTRANNet1 UTRANNet4 GERANNet1 GERANNet3 GERANOperator-Controlled

PLMN Selector list

User-Controlled PLMN Selector list

Access Technology identifier

USIM

Under user

control

Under operator

control

My camping PLMNUnder UE / Network control

Equivalence with Registered PLMN

RegisteredPLMNidentity

User-Controlled PLMN Selector data field can be updated by the subscriber.

Operator-Controlled PLMN Selector data field can be updated by the operator.

Preferred PLMNs in priority order (multiple occurrences possible with different Access Technology

identifiers).






1 � 2 � 10


1.2 Management and Usage [cont.]

15 (Staff) , 14 (Emergency)

Forbidden PLMN data field

USIM

Under operator

control

POP 7

Under UE / Network

control

PLMN “Bozou”

18 minutes

Population number

Interval betweenattempts

Special categories

Population number:

Under specific circumstances (and not under normal operating conditions). For example, during states of

emergency, or where 1 out of 2 or more co-located PLMNs has failed, it will be desirable to prevent UE

users from making access attempts (including emergency call) or responding to pages in specified area.

The class(es) of subscribers barred from network access should be broadcast on cell basis.

The network operator can prevent overload of the access channel under critical conditions.

Each UE is member of one randomly allocated mobile populations, defined as Access Classes 0 to 9.

In addition, mobiles may be members of one out of 5 (or more) special categories (Access Classes 11 to 15).

These are allocated to specific high-priority users as follows. (The enumeration is not meant as a priority

sequence):

Special Categories:

Class15-PLMN Staff; Class14-Emergency Services; Class13-Public Utilities (e.g. water/gas suppliers); Class12-

Security Services; Class11-For PLMN Use.

An additional control bit known as "Access Class 10" indicates if network access for Emergency Calls is

allowed for UEs with access classes 0 to 9 or without an IMSI.

Forbidden PLMN Data Field:

When a registration attempt by the UE is rejected by a network with an indication of "permanent" PLMN

restriction, the PLMN identity shall be written to a list of "Forbidden PLMNs".

Interval between attempts:

Interval between which periodic network selection shall be attempted. Shall be between 6 minutes and 8

hours, with a step size of 6 minutes. One value is designated to indicate that no periodic attempts shall be

made.

In the absence of a permitted value in the SIM/USIM, or the SIM/USIM is phase 1 and therefore does not

contain the datafield, then a default value of 60 minutes shall be used by the UE.

(Ref: 3GPP TS 22.011)






1 � 2 � 11

2 PLMN and RAT Selection Algorithm






1 � 2 � 12


2.1 Switch on

� The MS supports both manual and automatic modes.

� The MS switches on: the last mode is selected by default.

� The user can switch from one mode to another at any time.

� The selected and available PLMNs are displayed.

� Normal operation

Switch Onor

Coveragecoming back

RegisteredPLMN present

In USIM

Covered byRegistered PLMN

NewLA LU

Registrationsuccess

NetworkselectionEquivalent

AutomaticOr

Manualmode

../..

Y

N

Y Y Y

N

N

NY






1 � 2 � 13


2.2 Automatic Mode

� The MS selects and attempts registration on other PLMNs:

HPLMN+ preferred RATin specified

order

"User-ControlledPLMN Selector with

RAT“

"Operator-Controlled PLMNSelector with

RAT"

Other PLMN/RAT with SufficientQuality (random

Order)

OtherPLMN/RAT with best

quality

No Registered

or equivalent

PLMN coverage

Registration

N N

N

N

“No Service”displayed

N

Y

Y

YY

Y

To be selected, a PLMN must not be in the “Forbidden PLMN” data field of the SIM/USIM or in the extension

of this field in the Mobile memory.

At least one cell identified as belonging to the PLMN must support the voice service.






1 � 2 � 14


2.3 Manual Mode

� The MS indicates all available PLMNs, the forbidden ones inclusive, in the same order as for the selection in Automatic mode:

� HPLMN

� PLMNs of "User-Controlled PLMN Selector" data field

� PLMNs of "Operator-Controlled PLMN Selector" data field

� PLMN/RAT combinations with sufficient received signal level

� PLMN/access technology combinations in order of decreasing signal strength

N u ll S w it c h o n , n o S IM

S w itc h o n w i th S IM

Y e sS IM in s e r te d

S e le c tr e g is te r e d

P L M N

Is

t h e re a

R P L M N

?

N o S IM

N o

T ry in gR P L M N

C

R e g is t r a t io ns u c c e s s

R e g is t r a t io nf a i lu r e

A B

In d ic a tes e le c te dP L M N

L U r e s p o n s e" R o a m in gn o t a l lo w e d "

E A T r y in gP L M N

O n V P L M Na n d t im e o u to c c u r s

D

AY e se s

A n ya l lo w a b leP L M N sa v a i la b le

?

O n P L M N

C

L o s s o f r a d ioc o v e r a g e o f

s e le c t e d P L M N * *

S e le c t f i r s t *P L M N in l i s t

S e le c t n e x t *P L M N in l i s t

U s e rr e - s e le c t io n

R e g is t r a t io ns u c c e s s f u l

R e g is t r a t io nfa i lu r e , m o re in l is t

B

R e g is t r a t io nfa i lu r e , n o m o r ein l is t

D

M o v e la s ts e le c te d P L M Nte m p o r a r i l y in to

l is t

N oA n y

P L M N s

& a l lo w a b le?

a v a i la b leS e le c t R P L M No r H P L M N i f

n o n e

H ig h e r p r io r i t yP L M NP L M N s e a r c h

GP L M N

b a c k g ro u n ds e a r c h

H ig h e r p r io r i t yP L M N n o t P L M N fo u n d

E A

Y e s

C

S e le c t f i r s ta v a i la b le a n d

a l lo w a b le P L M Nin l is t

AG

N o

W a it fo r P L M N s

to a p p e a r

P L M N a v a i la b lea n d a l lo w a b le

P L M N a v a i la b lea n d a l lo w a b le ,w h ic h is n o tR P L M N

E A

R e g is t e r e d

S w it c h O f f

S IM r e m o v e do r in v a l id S IM

U s e r r e s e le c t io n

H ig h e r p r io r i t y

f o u n d

N u l l S w it c h o n , n o S IM




P L M N

Is

t h e re a

R P L M N

?

N o S IM

N o

T ry in gR P L M N

C



A B





D

AY e se s


?

O n P L M N

C








B


D


l is t

N oA n y

P L M N s

& a l lo w a b le?


n o n e


GP L M N



E A

Y e s

C






P L M N

Is

t h e re a

R P L M N

?

N o S IM

N o

T ry in gR P L M N

C



A B





D

AY e se s


?

O n P L M N

C








B


D


l is t

N oA n y

P L M N s

& a l lo w a b le?


n o n e


GP L M N



E A

Y e s

C



AG

N o

W a it fo r P L M N s

to a p p e a r

P L M N a v a i la b lea n d a l lo w a b le

P L M N a v a i la b lea n d a l lo w a b le ,w h ic h is n o tR P L M N

E A

R e g is t e r e d

S w it c h O f f

S IM r e m o v e do r in v a l id S IM

U s e r r e s e le c t io n

H ig h e r p r io r i t y

f o u n d






1 � 2 � 15

Exercise

� What are the 3 entities capable of decision for RAT selection?

� What are the different fields present in SIM/USIM?






1 � 2 � 16









1 � 2 � 17

End of ModulePLMN and Radio Access Technology Selection






Module 3Cell Selection





Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � Cell Selection

1 � 3 � 2

Blank Page




Document History






1 � 3 � 3

Module Objectives


� Describe the Alcatel-Lucent BSS and UTRAN radio algorithms responsible for 2G cell selection and 3G cell selection






1 � 3 � 4








1 � 3 � 5

Table of Contents


1 2G Cell Selection Algorithm 71.1 Principle 81.2 Parameters 91.3 Algorithm 10

2 3G Cell Selection Algorithm 112.1 Principle 122.2 Parameters 142.3 Algorithms 15






1 � 3 � 6









1 � 3 � 7

1 2G Cell Selection Algorithm






1 � 3 � 8


1.1 Principle

� At startup (IMSI Attach), the MS selects a cell with best C1

� Once “camped on” one cell (in idle mode)…

� … the MS can decide to reselect another cell if:

� the C1 criterion is too low.

� the MS cannot decode downlink messages.

� the current cell has become forbidden (e.g. barred).

� the MS cannot access the cell.

� there is a better cell, regarding the C2 criterion (as seen in reselection section).






1 � 3 � 9


1.2 Parameters

� The C1 criterion ensures that, if a call is attempted, it will be madewith a sufficient downlink and uplink received level.

� The C1 criterion is based on 2 parameters, broadcast on BCCH:

� RXLEV_ACCESS_MIN [dBm]

� minimum level to access the cell

� MS_TXPWR_MAX_CCH [dBm]

� maximum level for MS emitting






1 � 3 � 10


1.3 Algorithm

� The C1 criterion is evaluated every 5 seconds (minimum):

� C1 = A - MAX(0,B) > 0

� A = RxLev - RXLEV_ACCESS_MIN

� assess that the MS received level is sufficient

� B = MS_TXPWR_MAX_CCH - P

� P maximum power of MS

� assess that the BTS received level will be sufficient

� if MS_TXPWR_MAX_CCH < P

� If A > 0 & B < 0 OK, if B > 0, it can be compensated by A

� A >> 0 means that the MS is closer to the BTS






1 � 3 � 11







1 � 3 � 12


2.1 Principle

� In 3G, a cell is not defined only with a frequency but with bothfrequency and Scrambling Code (SC).

� The cell search procedure is performed by the UE in 3 steps:� Slot synchronization

� Using Primary Synchronization Channel (PSCH)- The same PSCH is used over all the system.- The “Pick” in the band with the best signal level is selected.

� Frame synchronization and code-group identification� Using Secondary Synchronization Channel (SSCH).- SSCH is different from one cell to another.

� Scrambling-code identification� The UE determines the scrambling code used by the cell (symbol-by-symbol correlation over the CPICH with all codes within the code group identified in the second step).

The primary scrambling code has been identified.The Primary CCPCH can be detected.The system and cell specific BCH information can be read.

BUT IS IT THE BEST CELL? IS A RESELECTION NECESSARY?

If the conditions for selection (Level and Quality) are not fulfilled,

then

the "pick" in the band with the second best signal level is selected... Etc.






1 � 3 � 13


2.1 Principle [cont.]

� Depending on the signal strength and quality level, the UE will decide to perform or not a reselection.

� For this reselection, the UE can search for a cell over:

� the same frequency (IntraFreq): here in blue (other scrambling code)

� different frequencies (InterFreq): here in red

� all available frequencies (including 2G): here in green

AccesspendingPSCH

SSCH xPSCH

SSCH z

PSCH

SSCH y

GSM






1 � 3 � 14


2.2 Parameters

� To decide for level and quality:

� Qqualmin

� Qrxlevmin

� sibMaxAllowedUlTxPowerOnRach

� To decide for reselection:

� sIntraSearch

� sInterSearch

� sSearchRatGsm

Squal = CPICH_Ec/No - qQualMin

sIntraSearch

sInterSearch

sSearchRatGsmMeasurement

on same frequency

Measurement on other

frequencies Measurement on other RAT

Good

Bad

These parametersdo not concern

BSS but UTRAN tuning






1 � 3 � 15


2.3 Algorithms

� Cell Selected if:

� Squal > 0 ⇔ CPICH_Ec/No > QqualMin

� and

� Srxlev > 0 ⇔ CPICH_RSCP > Qrxlevmin + Pcompensation

� With:

� Squal = Qqualmeas – Qqualmin

� Srxlev = Qrxlevmeas – Qrxlevmin – Pcompensation

� Pcompensation = max (sibMaxAllowedUlTxPowerOnRach – P_MAX, 0)

Pcompensation is an uplink constraint.

Indeed, the cell is disadvantaged if the class of the UE doesn’t allow it to transmit over sibMaxAllowedUlTxPowerOnRach.

P_MAX depends on the UE class (see notes).

The measured Quality (Qqualmeas) is called CPICH_Ec/No.

The measured Level (Qrxlevmeas) is called CPICH_RSCP.

P_MAX depends on the UE Class

+21 dBm4

+24 dBm3

+27 dBm2

+33 dBm1

P_MAXUE Class






1 � 3 � 16


2.3 Algorithms [cont.]

� The UE looks for another cell to select:

� “inside” the same frequency (intraFreq)

� IF Squal ≤ sIntraSearch

� Over other FDD frequencies (interFreq)

� IF Squal ≤ sInterSearch

� Over frequencies of other RAT (interRat)

� IF Squal ≤ sSearchRatGsm

+21 dBm4

+24 dBm3

+27 dBm2

+33 dBm1

P_MAXUE Class






1 � 3 � 17

Exercise

� Case 1: After 2G RAT selection

� Which cell is the selected one among those proposed in the table below?

� 2W MS

� RXLEV_ACCESS_MIN = -95 dBm

� MS_TXPWR_MAX_CCH = 30 dBm

RXLEV_ACCESS_MIN -99-90 -90-95

MS_TXPWR_MAX_CCH 3933 3033

-88

-89

-91

CELL32G

-81-90-87Case 3

-83-99-87Case 2

-92

CELL22G

-90-95Case 1

CELL42G

CELL12G

CELL

MEASUREMENT

Accesspending

?






1 � 3 � 18

Exercise

� Case 2: After 3G RAT selection

� Which cell is the selected one among all those that are proposed in the table below?

� QqualMin =

� QrxlevMin =

� sibMaxAllowedUlTxPowerOnRach = 26

CELL33G

UE Class 2

UE Class 1

CPICH_Ec/N0

CELL23G

UE Class 4

CPICH_RSCP

CELL42G

CELL13G

CELL

MEASUREMENT






1 � 3 � 19









1 � 3 � 20

End of ModuleCell Selection






Module 4Cell Reselection from 2G to 3G





Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � Cell Reselection from 2G to 3G

1 � 4 � 2

Blank Page




Document History






1 � 4 � 3

Module Objectives


� Describe the Alcatel-Lucent BSS radio algorithms responsible for 2G to 3G cell reselection and the related parameters

� Estimate the impact of a parameter value modification






1 � 4 � 4








1 � 4 � 5

Table of Contents


1 System Information and Packet System Information Messages 71.1 Where and When? 81.2 What in SI2ter? 91.3 What in SI2quarter? 101.4 What in PSI3quarter? 11

2 Inter-RAT Measurements 122.1 What Is Measured? 132.2 2G MS States Impacting 3G Reselection 142.3 NC2 Activation Impact on 3G Reselection 152.4 When Is 2G to 3G Cell Reselection Enabled ? 162.5 When Is 3G Cell Sought After? 17

3 2G to 3G Cell Reselection Algorithm 203.1 Algorithm 213.1 Summary 22

4 Fast 3G Reselection 234.1 Objective 244.2 Principle 25






1 � 4 � 6









1 � 4 � 7

1 System Information and Packet System Information Messages






1 � 4 � 8


1.1 Where and When?

� 2G to 3G MS autonomous cell reselection is supported in NC0 for:

� Circuit Idle mode.

� Packet Idle mode.

� Packet transfer mode.

� The MFS and BSC shall know UMTS frequencies. Frequencies and useful parameters must be broadcast to Mobiles.

� The BSS schedules:

� SI2ter and/or SI2quarter (with or without Extended BCCH) for that.

� PSI3quarter too if PBCCH is available.

Location (SI2ter or SI2quarter) is given by flags in SI3 and depends on…(see notes)

� 2G/TD-SCDMA (3G TDD) networks Inter-operability is possible from B10.

B10

SI: System Information

EN_2G_TO_3G

CELL_RESELECTION

≠ 0

Is 2G TO 3G Cell Reselection Enabled?

Nb of UTRAN FDD

neighbor frequency

to describe ≥ 1

Nb of UTRAN TDD

neighbor frequency

to describe ≥ 1

CELL

≠

EVOLIUM

CELL

≠

EVOLIUM

Nothing SI2quarter SI2ter

At least one 3G frequency to describe?

Cell is not an Evolium one?

Y

Y

Y

Y

N

N

NNY

N

PSI3quarter

Nb of UTRAN FDD

neighbor frequency

to describe ≥ 1

EN_2G_TO_3G

CELL_RESELECTION

= 1 or 2

Master PDCHIs

present

Y

Y

Y






1 � 4 � 9


1.2 What in SI2ter?

� Up to 3 FDD frequencies

� FDD_ARFCN (known as UARFCN in 3GPP)

� 3G Measurement Parameters Description

� Qsearch_I (Search or not for 3G cells in Idle mode)

� FDD_Qoffset (Offset added to Received Level Average of GSM cells)

� FDD_Qmin (Minimum Ec/No Threshold for 3G cell reselection)

� In addition, Qsearch_P_PTM is sent in PMO with PACCH (see note).

Note:

A 3G cell is completely defined by a Frequency and a Primary scrambling code (refer to the 3G Cell

Selection Algorithm chapter).

As only the frequencies are provided, the MS will have to detect which Scrambling codes are used in the 3G

neighbor cells (blind search procedure).

In addition, a flag 3G_BA_IND (toggle) informs the MS each time a change of frequencies occurs in the list.

(this is not a settable parameter)

PTM: Packet Transfer Mode (GPRS/EGPRS)

PACCH is the Associated Control Channel used in GPRS mode for signaling purposes.

PMO is the Packet Measurement Order message sent to the MS when entering in PTM (when NC2 is

activated).






1 � 4 � 10


1.3 What in SI2quarter?

� Up to 3 FDD frequencies and/or 3 TDD frequencies� FDD_ARFCN_LIST / TDD_ARFCN_LIST

� 3G Measurement Parameters� Qsearch_I

� FDD_Qoffset

� FDD_Qmin

� TDD_Qoffset (Offset added to Received Level Average of GSM cells)

� GPRS 3G Measurement Parameters Description (if there is no PBCCH)� Qsearch_P (Search or not for 3G cells in GPRS)

� SEARCH_3G_PRIO (Search for 3G cells in priority) (see note)

� 3G Additional Measurement Parameters(Available only if EN_CPICH_2G_3G_Reselection = 1)

� FDD_Qmin_Offset (Offset added to FDD_Qmin value)

� FDD_RSCPmin (Minimum RSCP threshold for 3G cell reselection)

B10

The MS shall attempt to check the BSIC for as many non-serving cell BCCH carriers as possible and as often

as possible, and at least every 10 seconds.

A multi-RAT MS is allowed to extend this period to 13 seconds in order to monitor FDD cells.

(the MS may use “search frames” that are not required for BSIC decoding for that).

IF the neighbor cell list contains cells from other RATs

AND

IF SEARCH_3G_PRIO = 1

THEN

The MS may search 3G cells more frequently than if SEARCH_3G_PRIO = 0

So, SEARCH_3G_PRIO forces the MS to search either for more 2G cells or more 3G cells.

The 3 following parameters appear in B10:

� FDD_Qmin_Offset:

Used with FDD_Qmin parameter so that Rel-5 onwards mobiles can put some dBs offset (0 to 14) to

FDD_Qmin value. It makes sufficient quality UTRAN coverage look larger to Rel-5 onwards MSs using GERAN

cell

� FDD_RSCPmin:

Gives the MS the minimum threshold of RSCP for 3G cell reselection (-84 to –114 dBm)

� EN_CPICH_2G_3G_RESELECTION:

� 0: Only Ec/No measurement is used.

� 1: CPICH Ec/No and RSCP measurements must be used.

In addition, 2G/TD-SCDMA (3G TDD) networks Inter-operability is possible from B10.






1 � 4 � 11


1.4 What in PSI3quarter?

� Up to 3 FDD frequencies

� FDD_ARFCN_LIST

� 3G MEASUREMENT Parameters

� FDD_GPRS_Qoffset (= FDD_Qoffset in B9 MR0)

� FDD_Qmin

� Qsearch_P (= Qsearch_I in B9 MR0)






1 � 4 � 12

2 Inter-RAT Measurements






1 � 4 � 13


2.1 What Is Measured?

� An MS camping on a 2G cell measures 2 characteristics of 3G cells:

� CPICH Ec/No: the received energy per chip divided by the power density in the band:

� mostly determined by the system load.

� can be seen as Interference level.

AND IF EN_CPICH_2G_3G_Reselection = 1

� CPICH RSCP (Received Signal Code Power: the received power on one code measured on the Primary CPICH:

� gives an indication about coverage.

� can be seen as level strength.

CPICH RSCP measurement appears from B10 in order to avoid ping-pong(see notes)

B10

In B9, only CPICH Ec/No is taken into account by the MS to decide for 3G reselection.

It can trigger reselection on a 3G cell with a bad CPICH RSCP. The MS comes back.

This situation leads to 2G-3G ping-pong.

In B10, the MS measures the 3G cell CPICH RSCP too and triggers reselection only if both CPICH Ec/No and

CPICH RSCP are good.

There is no more 2G-3G ping-pong.

EN_CPICH_2G_3G_Reselection appears in B10.






1 � 4 � 14

2 Inter-RAT measurements

2.2 2G MS States Impacting 3G Reselection

� GPRS idle mode or Standby mode:

� Either the MS is GPRS detached (unknown in SGSN) and only IMSI attached (GSM)(*).

� Or the MIS is GPRS attached but TREADY is expired (**).

� GPRS Ready PIM:The MS is GPRS attached and T_READY is running.

� GPRS Ready PTM:The MS is transferring packet data.

STANDBY PTM PIM STANDBY

t

TBF running T_READY

IDLE

(*) (**)

T_READY is an SGSN parameter.






1 � 4 � 15


2.3 NC2 Activation Impact on 3G Reselection

� NC2 can be:

� De-activated (NETWORK_CONTROL_ORDER = 0)=> MS autonomous reselection in all cases

� Activated (NETWORK_CONTROL_ORDER = 2)

� during PTM only (NC2_DEACTIVATION_MODE = 0)

� during PTM and PIM (NC2_DEACTIVATION_MODE = 1)

NC0 NC0 / NC2 NC0NC2 / NC0


t

IDLE

NC0






1 � 4 � 16


2.4 When Is 2G to 3G Cell Reselection Enabled ?

� It depends on EN_2G_TO_3G_CELL_RESELECTION (see note)

� 0: Disabled

� ≠≠≠≠ 0: Enabled

but 3G cell is not necessarily sought after…

EN_2G_TO_3GTDD_CELL_RESELECTION (for TDD network)






1 � 4 � 17


2.5 When Is 3G Cell Sought After?

� It depends on 3 parameters:

� EN_2G_TO_3G_CELL_RESELECTION (see note)

� NC2_DEACTIVATION_MODE

� Qsearch

� EN_2G_TO_3G_CELL_RESELECTION(used here to choose the 3G search activation mode)

� = 1: Yes even if the MS is in GMM Ready state

� = 2: Yes except if the MS is in GMM Ready state

� = 3: Yes even if the MS is in GMM Ready state and Network_Control_Order > 1(NC2 is used)In this case, NC2 will be automatically deactivated when entering in PTM.

Value 3 should be used only in case of good 3G coverage.

TEST IT !

B10

EN_2G_TO_3GTDD_CELL_RESELECTION for TDD network

Value “3” for EN_2G_TO_3G_CELL_RESELECTION and EN_2G_TO_3GTDD_CELL_RESELECTION appears in B10.






1 � 4 � 18


2.5 When Is 3G Cell Sought After? [cont.]

� If the 3G search is activated (previous slide), it is really actual only if the level received by the MS from the 2G serving cell is below or abovethe Qsearch threshold.

-47-98 -50-54-70-74-78-110

RXlev

Always Never

Search 3G IF Rxlev DL >

Search 3G IF Rxlev DL <

0 1 2 3 54 6

8 9

7

10 1312 1411

15

Qsearch tuning areas

Coded values :

Low High

Coded value (binary): Value (dBm): Text displayed at OMC level

0 -98 -98 dBm (below)

1 -94 -94 dBm (below)

2 -90 -90dBm (below)

3 -86 -86dBm (below)

4 -82 -82 dBm (below)

5 -78 -78 dBm (below)

6 -74 -74 dBm (below)

7 -70 Always search for 3G neighbor cells

8 -78 -78 dBm (above)

9 -74 -74 dBm (above)

10 -70 -70 dBm (above)

11 -66 -66 dBm (above)

12 -62 -62 dBm (above)

13 -58 -58 dBm (above)

14 -54 -54 dBm (above)

15 -50 Never search for 3G neighbor cells






1 � 4 � 19


2.5 When Is 3G Cell Sought After? [cont.]

� But Qsearch can take different values depending on the MS state:

� Qsearch_I in Idle mode (SI2ter & SI2quarter)

� Qsearch_P in GPRS (SI2quarter)

� Qsearch_P_PTM in PTM (PACCH)

� Note that Qsearch_P_PTM is sent to the MS in Packet Measurement Order (PMO) when entering in Packet Transfer Mode (PTM) and is by default set to –50 (never search).

Qsearch_I Qsearch_P_PTM Qsearch_P Qsearch_I


t

IDLE

When NC2 is used, 3G cell monitoring is systematically deactivated in PTM: Q_search_P is set to Never in

the PMO(NC2) at DL TBF establishment.

3G cells can be monitored in PTM even when NC2 is not used for some UEs.

and

EN_2G_TO_3G_CELL_RESELECTION

is set to “Enabled with 3G search activated while the UE/MS is in GMM ready state”:

so

Q_search_P is set to Q_search_P_PTM (default: never search) in the PMO at DL TBF establishment.






1 � 4 � 20

3 2G to 3G Cell Reselection Algorithm






1 � 4 � 21


3.1 Algorithm

� The MS reselects a 3G cell IF for a period of 5s:

� CPICH RSCP (3G) > RLA (2G) + FDD_Qoffset if MS is in CS modeor CPICH RSCP (3G) > RLA (2G) + FDD_GPRS_Qoffset if MS is in PS mode

for 2G serving and all suitable 2G neighbors (see note)

AND

� CPICH Ec/No (3G) ≥ FDD_Qmin - FDD_Qmin_Offset

AND

� CPICH RSCP (3G) ≥ FDD_RSCPminif FDD_RSCPmin is broadcast (EN_CPICH_2G_3G_RESELECTION = 1) else, this criterion is not effective

� Anti Ping-Pong: In case a cell reselection occurs within the previous 15 seconds, FDD_Qoffset is increased by 5 dB.

B10

"Suitable 2G neighbors" means the 2G cells the MS can reselect (received level > RXLEV_ACCESS_MIN, not

barred, BCCH decodable, etc. ). See 2G to 2G Reselection in the GSM Radio Fine Tuning training.

The 3 following parameters appear in B10:

� FDD_Qmin_Offset:

Used with FDD_Qmin parameter so that Rel-5 onwards mobiles can put some dBs offset (0 to 14) to

FDD_Qmin value. It makes sufficient quality UTRAN coverage look larger to Rel-5 onwards MSs using GERAN

cell.

� FDD_RSCPmin:

Gives the MS the minimum threshold of RSCP for 3G cell re-selection (-84 to –114 dBm).

� EN_CPICH_2G_3G_RESELECTION:

� 0: Only Ec/No measurement is used.

� 1: CPICH Ec/No and RSCP measurements must be used.






1 � 4 � 22


3.1 Summary

� To reselect a 3G cell, 5 conditions must be met:

� The reselection must be Enabled for the mode corresponding to the state of the MS.EN_2G_TO_3G_CELL_RESELECTION

� The 3G search must be active (depends on the 2G serving received level).Qsearch_X

� The 3 radio conditions of the reselection algorithm must be met.FDD_Qoffset FDD_GPRS_Qoffset FDD_Qmin FDD_Qmin_Offset FDD_RSCPmin

B10






1 � 4 � 23

4 Fast 3G Reselection

B10






1 � 4 � 24


4.1 Objective

� An MS ending in 2G cell, a CS call started in 3G cell

� performs an LA/RA update to camp on 2G.

� reselects 3G cell.

� performs an LA update to camp on 3G.

� In order to avoid double LA update, the 3G reselection must be speeded up at 2G CS call release.

B10






1 � 4 � 25


4.2 Principle

� GSM allows to send the optional Information Element (IE) “cell selection indicator” after release of all TCHs and SDCCH” in the CHANNEL RELEASE message, indicating the frequency on which the MS shall start a cell selection.

� When 3G frequency is indicated, the MS shall as quickly as possible camp on a suitable cell of this frequency.

� This is performed in the Alcatel-Lucent BSS IF

EN_FAST_3G_RESELECTION = 1

� No useless LUs are performed anymore.

� The 3G reselection is speeded up.

� Can be useless if 2G to 3G HOs are enabled.

B10






1 � 4 � 26

Exercise

� Which radio parameters in the table below can be used to inhibit 2G to 3G reselection?

� Which value will prevent this reselection?

EN_2G_TO_3GTDD_CELL_RESELECTION

FDD_GPRS_Qoffset


Qsearch_I

EN_FAST_3G_RESELECTION

PARAMETER VALUEINHIBITION

Y / N






1 � 4 � 27

Exercise

� Is a 2G to 3G reselection attempted or not?

� If yes, which is the 3G target cell selected?

� Voir l’exo sous excel dans repertoire GA

CPICH RSCP

CPICH Ec/No

Max RLA (2G cells) measured

MS STATE

NETWORK_CONTROL_ORDER


FDD_Qoffset

FDD_GPRS_Qoffset

Qsearch_PTM

Qsearch_P

Qsearch_I

FDD_Qmin

FDD_Qmin_Offset

FDD_RSCPmin

EN_CPICH_2G_3G_RESELECTION

YES OR NOT

(coded value)

(coded value)

(coded value)

(coded value)

(coded value)

(coded value)

(coded value)

(coded value)

Including serving

CASE1 CASE2 CASE3

-78

-22

-92

READY PTM

-80

-28

-78

READY PTM

2

1

3

3

5

6

6

7

15

5

5

0

4

6

6

0

4

11

7

13

0 1






1 � 4 � 28

Exercise

� What are the impacts on 2G to 3G cell reselection?

NNINCREASEZZZ

NNDECREASEYYY

NNINCREASEXXX

DECREASE

MODIFICATION

MODIFICATION

N

SPEED-UP

2G to 3G RESELECTION

N

SLOW-DOWN

AAA

LESSMOREPARAMETER

PARAMETER






1 � 4 � 29









1 � 4 � 30

End of ModuleCell Reselection from 2G to 3G






Module 5Handover from 2G to 3G





Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � Handover from 2G to 3G

1 � 5 � 2

Blank Page




Document History






1 � 5 � 3

Module Objectives


� Describe the Alcatel-Lucent BSS radio algorithms responsible for2G to 3G Handover and the related parameters

� Estimate the impact of a parameter value modification






1 � 5 � 4








1 � 5 � 5

Table of Contents


1 Measurement Information Message 71.1 WHERE? 81.2 WHEN? 91.3 WHAT? 10

2 Inter-RAT Measurements 122.1 Are Measurements Performed? 132.1 What Does the MS Measure? 142.2 What Is Reported? 15

3 2G to 3G Handover Algorithm 163.1 Cause 31 Detection 173.2 HO Candidate Cell Evaluation 183.3 HO Management 20

4 2G to 3G HO Based on 2G Cell Load 254.1 Objective 264.2 Principle 274.3 Example 28






1 � 5 � 6









1 � 5 � 7

1 Measurement Information Message






1 � 5 � 8


1.1 WHERE?

� Information Messages are sent by the network to the MS on the SACCH.

� If not, all information fits into one message. The remaining information will be sent in other instances of this message.

Note: the SACCH frame occurrence is 480ms.






1 � 5 � 9


1.2 WHEN?

� When EN_3G_HO is set to Enabled

And there is at least one UTRAN FDD neighbor frequency to describe.

And the cell is Evolium.

And the MS classmark information indicates UMTS FDD supported.

And the MS Utran classmark is available.

And the Service Handover Information is[available and different from“Handover to UTRAN or cdma2000 shall not be performed”or“Handover to UTRAN or cdma2000 should not be performed”]

OR [not available and EN_2G_3G_HO_NO_SERVICE_HO = 1]

EN_2G_3G_HO_NO_SERVICE_HO allows handovers towards 3G cells for a given MS when I.E. Service

Handover is missing and the load in the serving cell is high (see THR_CELL_LOAD_3G_REQ), default = 1

(disable). This allows to force 2G to 3G HO in case of a loaded 2G serving cell.






1 � 5 � 10


1.3 WHAT?

� List of Information Messages sent if EN_3G_HO is set to disabled

� FDD_ARFCN_LISTUp to 3 FDD frequencies and/or 3 TDD frequencies

� Qsearch_CThreshold for searching for 3G cells in dedicated mode.(Same principle as explanation for Qsearch in the Cell Reselection from 2G to 3G section).

� SEARCH_3G_PRIOThe MS may search 3G cells more frequently if SEARCH_3G_PRIO = 1

� FDD_REP_QUANTType of measurement reported by the MS (CPICH RSCP or CPICH Ec/No)






1 � 5 � 11

1 Measurement Information message

1.3 WHAT? [cont.]

� FDD_MULTIRAT_REPORTING

Number of the strongest 3G cells to be reported by the MS.

� FDD_REPORTING_OFFSET

Offset that the MS shall apply to measurements before reporting.

� FDD_REPORTING_THRESHOLD

Threshold above which the MS shall report the measurements.






1 � 5 � 12







1 � 5 � 13


2.1 Are Measurements Performed?

� Depends on Qsearch_C (Connected mode):

the level received by the MS from the 2G serving cell must be below or above the threshold:

� SEARCH_3G_PRIOMore time (frames) can be granted to theMS to measure 3G neighbors if set to 1 (less for 2G neighbors in compensation)

-47-98 -50-54-70-74-78-110

RXlev

Always Never

Search 3G IF Rxlev DL >

Search 3G IF Rxlev DL <

0 1 2 3 54 6

8 9

7

10 1312 1411

15

Qsearch tuning areas

Coded values :

Low High






1 � 5 � 14


2.1 What Does the MS Measure?

� Depends on FDD_REP_QUANT:

� FDD_REP_QUANT = 0 then only CPICH RSCP is reported by the MS

� FDD_REP_QUANT = 1 then only CPICH Ec/No is reported by the MS

� Value 0 is not supported for FDD_REP_QUANT

Then only CPICH Ec/No is reported by the MS

(Linked to level => coverage evaluation only)






1 � 5 � 15


2.2 What Is Reported?

� FDD_MULTIRAT_REPORTING

Number of the strongest 3G cells reported by the MS (from 0 to 3, Default=2)

if EN_3G_HO is set to disabled, this parameter is considered as equal to zero (the MS doesn’t report any 3G cells)

� FDD_REPORTING_OFFSET (Default=0)

Offset that the MS shall apply to measurements before the reportingstep size = 6dB (0 : 0dB, 1 : 6dB, … 7 : 42dB)

� FDD_REPORTING_THRESHOLD (Default=0)

Threshold above which the MS shall report the measurementsstep size = 6dB0 : 0 : Always report the 3G neighbor cells1 : 6 : 6 dB2 : 12 : 12 dB..7 : 42 : Never report the 3G neighbor cells






1 � 5 � 16

3 2G to 3G Handover Algorithm






1 � 5 � 17


3.1 Cause 31 Detection

� The only cause of 2G to 3G HO is the cause 31.

� The only measurement taken into account for detection is Ec/No

� The cause 31 is detected IF

� AV_ECNO(n) ≥ THR_ECNO_HO

AND

� EN_3G_HO = Enable

� Size of window for ECNO averaging: A_ECNO_HO

AV_ECNO(n): Average Ec/No of the 3G neighbor cell n

Range: -110 to –47 dBm

Bin coded: 0 (-110) to 63 (-47)

Step size: 1 dBm

The 2G-3G handover cause 31 has no specific priority since it is checked with a different trigger than the

other handover causes (same behavior as for causes 29 (TFO) and 30 (CS to PS)).






1 � 5 � 18


3.2 HO Candidate Cell Evaluation

ORDERING

PROCESS

RAW

CELL LIST

CAUSE 31

DETECTION

3G cell with highest averaged Ec/No

3G cell

3G cell

3G cell with lowest averaged Ec/No

2G cell if any

2G cell if any

2G cell if any

2G cell if any

. . .

� Ranking

� Then, HO Preparation Process removes or not 3G cells from the listdepending on both values of:� 2G_3G_HO_Allowed state

� Service Handover for the concerned MS

see table on next slide ../..

3G cells put on the TOP

The 2G_3G_HO_Allowed state is provided to HOP by the Resources Allocation and Management (RAM)

process.

The value of 2G_3G_HO_Allowed state depends on the 2G serving cell load (as detailed in the next

chapter).

The Service Handover for the concerned MS is provided by NASS (Normal Assignment) or by ECC (External

Channel Change).

There is no specific checking on the Service Handover. If present, the contents of this I.E. (Information

message) shall be stored by the BSC, to be further used in case of 2G to 3G handover.

3GPP TS 48.008: In case of Assignment Request received from the MSC with Service Handover IE included

and indicating that "Handover to UTRAN or cdma2000 should be performed", the BSS may trigger, if

possible, a directed retry towards a 3G cell. Such a feature is not supported.






1 � 5 � 19


3.2 HO Candidate Cell Evaluation [cont.]

(2G cell Loaded) (2G cell not loaded)

* Only one supported

2G_3G_HO_Allowed =forbidden

Service Handover I.E.value

“Handover to UTRANor cdma2000 shallnot be performed”



I.E. missing (orundefined value

present in the I.E.) *

2G_3G_HO_Allowed = allowed

Remove 3G cells fromthe raw cell list


raw cell list is not modified

IF EN_2G_3G_HO_NO_SERVICE_HO = 1raw cell list is not modified

IF EN_2G_3G_HO_NO_SERVICE_HO = 0remove 3G cells from the raw cell list




raw cell list is not modified






1 � 5 � 20

3 2G to 3G handover algorithm

3.3 HO Management

� PARAMETERS

� MAX_ADJ_CELL_3G_HO� Maximum number of 3G target cells for 2G-3G handover adjacency.

� Min= Max=Default=12 (Not settable at OMCR)

� T_HO_REQD_LOST USED DURING PREPARATION� Supervision of the MSC response after sending of HANDOVER REQUIRED.

� step size = 1sec Min=6 Max=120 Default=30

� Must be > T7 (Timer controlling the repetition of HANDOVER REQUIRED)

� RESP_REQ� This flag controls “Response request” OIE inclusion in HANDOVER REQUIRED.

� 0: IE not included (Default), 1: IE included

� T3121 USED DURING EXECECUTION� Used to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost (DROP).step size = 0.1sec Min=0 Max=25.5 Default=14

RESP_REQ: Default value depends on MSC type.

For external directed retries (or 2G to 3G HO), the serving BSC does not know whether or not the external

target cells (towards which the directed retry is triggered) are congested. Therefore, Alcatel-Lucent

recommends to set RESP_REQ to 1 if EN_EXT_DR is set to enabled in order to get a Handover Reject

message from the MSC in case all target cells are congested and thus to attempt other procedures.






1 � 5 � 21


3.3 HO Management [cont.]

UE/MS Serving BTS Target RNC MSCServing BSC

Measurements Result HO Detection

Preparation

Execution

Start T_HO_REQD_LOSTHO REQUIRED

HO COMMAND

Prepare HO

Relocation Request

Relocation Request Ack

Prepare HO Resp

Stop T_HO_REQD_LOST

INTER SYSTEMTO UTRAN HO CMD

DR (INTER SYSTEMTO UTRAN HO CMD)

Start T3121

HO COMPLETE

Relocation detect

Relocation Complete

End Signal Request

CLEAR COMMAND

CLEAR COMPLETE

��

��

��

��

��

��

Stop T3121

MC924cSuccess

MC924cPreparations

MC924dAttempts

� SUCCESS CASE

(1) Need of Handover to 3G cell is detected (see the Cause 31 Detection and HO Candidate Cell Evaluation

parts of this section.).

T7 is started

T_HO_REQD_LOST is started to guard against no response from the MSC.

(2) The BSC initiates an intersystem to UMTS external channel change by sending a HANDOVER

REQUIRED message with the 3G cell in the top of the cell list.

Note: the HANDOVER REQUIRED message may contain the OIE “Response Request”

depending on the O&M parameter RESP_REQ.

(3) The MSC performs the handover required procedure with the target RNC. The protocol shown in the

figure is for example only: it may deviate, as it is not in the scope of this training.

(4) The MSC indicates to the serving BSS that the handover is accepted by the UMTS, in a HANDOVER

COMMAND message.

The L3 INTERSYSTEM TO UTRAN HANDOVER COMMAND is included in that HANDOVER COMMAND.

(5) The serving BSC: stops T_HO_REQD_LOST; sends the INTERSYTEM TO UTRAN HANDOVER IE

COMMAND to the UE/MS; starts T3121.

(6) The UE/MS on reception of the INTERSYTEM TO UTRAN HANDOVER COMMAND: disconnects the

old channel; synchronizes to the new cell and sends a HANDOVER COMPLETE message to the target RNC.

(7) The target RNC terminates the protocol to the MSC.

(8) The serving BSS RF channel and terrestrial resources are released. This is performed by the MSC

sending the CLEAR COMMAND (cause "Handover successful") , T3121 and T7 are stopped.






1 � 5 � 22




Measurements ResultHO Detection

Preparation

Start T_HO_REQD_LOSTHO REQUIRED

HO REQUIRED REJECT

Prepare HO

Relocation Request

Relocation Request Ack

Prepare HO RespStop T_HO_REQD_LOST

MC924cPreparations

MC924g

Preparations failures

Incremented only ifRESP_REQ = 1

� PREPARATION FAILURE






1 � 5 � 23



� EXECUTION FAILURE WITHOUT REVERSION

Execution

HO COMMAND



Start T3121

Relocation detect

CLEAR REQUEST

CLEAR COMPLETE

T3121 Expiry

MC924e

HO Failure withoutReversion(Drop)

MC924dAttempts


PREPARATION OK






1 � 5 � 24

3 2G to 3G handover algorithm


� EXECUTION FAILURE WITH REVERSION

Execution

HO COMMAND



Start T3121

Relocation detect

MC924f

HO Failure withReversion

to old channel

MC924dAttempts


COMING BACK TO2G CHANNEL

HANDOVER FAILURE(ROC)

PREPARATION OK






1 � 5 � 25

4 2G to 3G HO Based on 2G Cell Load






1 � 5 � 26


4.1 Objective

� In order to reduce the number of 2G to 3G HOs, the feature

“2G to 3G handover based on 2G load criteria”

allows to avoid HO when the 2G cell is NOT loaded.

THR_CELL_LOAD_3G_REQ threshold is used for that.

� So, the BSC will determine the 2G_3G_HO_Allowed State(as seen in the previous chapter)






1 � 5 � 27


4.2 Principle

� IF the last N_TRAFFIC_LOAD averages AV_TRAFFIC_LOAD (including the new one), verify:

� AV_TRAFFIC_LOAD > THR_CELL_LOAD_3G_REQ

� THEN 2G_3G_HO_Allowed = allowed

� IF the last N_TRAFFIC_LOAD averages AV_TRAFFIC_LOAD (including the new one), verify:

� AV_TRAFFIC_LOAD ≤ THR_CELL_LOAD_3G_REQ

� THEN 2G_3G_HO_Allowed = forbidden

� At initialization, 2G_3G_HO_Allowed is set to “allowed”.

� IF THR_CELL_LOAD_3G_REQ = 0

� Then the feature “2G to 3G handover based on 2G load criteria” is disabled.

GSM Radio Fine Tuning prerequisites:

The 2G cell traffic is evaluated (%) every TCH_INFO_PERIOD=5s (not settable).

The load is averaged over A_TRAFFIC_LOAD.

The number of consecutive load averages below or above the threshold before to take the decision is

N_TRAFFIC_LOAD.






1 � 5 � 28


4.3 Example

� With N_TRAFFIC_LOAD = 3 (recommended value for 3 or 4 TRXs)

� THR_CELL_LOAD_3G_REQ = 50%

� A_TRAFFIC_LOAD = 8 (recommended value for 3 or 4 TRXs)

12

3

12 1

23

1 212

AV_TRAFFIC_LOAD

T

A_TRAFFIC_LOAD X TCH_INFO_PERIOD = 40s

THR_CELL_LOAD_3G_REQ

2G_3G_HO_Allowed allowed forbidden allowed






1 � 5 � 29

Exercise 1

� Which radio parameters in the table below can be used to inhibit 2G to 3G handover?

� Which value will prevent this handover?

VALUE

P4

P3

P2

P5

P1

INHIBITION

Y / NPARAMETER






1 � 5 � 30

Exercise 2

� Is 2G to 3G handover attempted or not?

� If yes, which is the 3G target cell selected?






1 � 5 � 31

Exercise 3

� What are the impacts on 2G to 3G handover?

INCREASEZZZ

DECREASEYYY

INCREASEXXX

DECREASE

MODIFICATION

MODIFICATION

SPEED-UP

2G to 3G HANDOVER

SLOW-DOWN

AAA

LESSMOREPARAMETER

PARAMETER






1 � 5 � 32









1 � 5 � 33

End of ModuleHandover from 2G to 3G






Module 6Impacts of 2G3G Mobility on CS and PS Services





Issue 01





Alcatel-Lucent Evolium Base Station Subsystem � 2G-3G Mobility Algorithms - B102G-3G Mobility � Impacts of 2G3G Mobility on CS and PS Services

1 � 6 � 2

Blank Page




Document History






1 � 6 � 3

Module Objectives


� Describe the impact for the user on the provided service (CS or PS) when switching from 2G to 3G






1 � 6 � 4








1 � 6 � 5

Table of Contents


1 Mobile Camping in 2G and Moving to 3G 71.1 MS Using the CS Service 81.2 MS Using the PS Service 10






1 � 6 � 6









1 � 6 � 7

1 Mobile Camping in 2G and Moving to 3G






1 � 6 � 8


1.1 MS Using the CS Service

� What happens when the UE moves while having a CS service established?






1 � 6 � 9


1.1 MS Using the CS Service [cont.]

� When the UE moves while having a CS service established:

� the CS service (speech only or DTM in B10) is maintained thanks to a 2G to 3G handover.






1 � 6 � 10


1.2 MS Using the PS Service

� What happens when the UE moves while having a PS service established?






1 � 6 � 11


1.2 MS Using the PS Service [cont.]

� When the UE moves while having a PS service established:

� The PS service is maintained thanks to a 2G to 3G cell reselection.

� Reselection to 3G can still be performed when the UE is in GPRS Standbymode.

� In GPRS Ready mode, the reselection to 3G depends on the activation or not of the NC2 reselection mode (no CCO 2G to 3G in B10).






1 � 6 � 12









1 � 6 � 13

End of ModuleImpacts of 2G3G Mobility on CS and PS Services

@@COURSENAME - Page 1All Rights Reserved © Alcatel-Lucent @@YEAR

All Rights Reserved © Alcatel-Lucent @@YEAR

@@COURSENAME@@PRODUCT

1

Last But One Page



@@COURSENAME - Page 2All Rights Reserved © Alcatel-Lucent @@YEAR

All rights reserved © Alcatel-Lucent @@YEARPassing on and copying of this document, use and communication of its

contents not permitted without written authorization from Alcatel-Lucent

Documents

TMO18003D0SGDENI1.0