WCDMA RNO Handover Procedure Analysis Guidance

Product name Confidentiality level WCDMA RNP For internal use only

Product version V100R001 Total 92pages

WCDMA RNO Handover Procedure Analysis

Guidance

For internal use only

Prepared by URNP-SANA Date 2004-2-19 Reviewed by Date Reviewed by Date Granted by Date

Huawei Technologies Co., Ltd.

All rights reserved

WCDMA RNO Handover Procedure Analysis For internal use only

2005-07-02 All rights reserved , Total92

Revision record

Date Revision version change Description

Author 2003-10-30 Initial transmittal Zang Liang

2003-11-18 Initial transmittal revised Zang Liang



Table of Contents

1 Handover Concept................................................................................................................. 7 2 Classification of Handovers ................................................................................................... 7 2.1 Soft Handover.................................................................................................................. 7

2.1.2 Softer handover ......................................................................................................... 8 2.1.3 Soft Handover ............................................................................................................ 9

2.2 Hard Handover .............................................................................................................. 12 2.2.1 Inter-frequency Hard Handover................................................................................ 12 2.2.2 Intra-frequency Hard Handover................................................................................ 14 2.2.3 Inter-RAT Hard Handover ........................................................................................ 15

3 Signaling Procedures and Message Analyses of Handover Procedures............................. 16 3.1 Measurement Control and Measurement Report........................................................... 17

3.1.1 Measurement Procedures........................................................................................ 17 3.1.2 Measurement Control .............................................................................................. 19 3.1.3 Measurement Report ............................................................................................... 24

3.2 Soft Handover Procedure Analysis ................................................................................ 27 3.2.1 General Description of the Active Set Update Procedure ........................................ 27 3.2.2 Analysis of Soft Handover Related IEs .................................................................... 28 3.2.3 Active Set Update Procedure................................................................................... 34 3.2.4 Soft Handover Signaling Procedures Analysis......................................................... 39

3.3 Hard Handover Procedure Analysis............................................................................... 46 3.3.1 General Description of the Hard Handover Procedure............................................. 46 3.3.2 Analysis of Hard Handover Related IEs................................................................... 50 3.3.3 Hard Handover Signaling Procedure ....................................................................... 75

3.4 Inter-RAT Handover Procedure Analysis....................................................................... 79 3.4.1 General Description of the inter-RAT handover procedure ...................................... 79 3.4.2 Analysis of Inter-RAT Hard Handover Related IEs .................................................. 81 3.4.3 Inter-RAT Hard Handover Signaling Procedure....................................................... 87

4 Performance Analysis of Handover Procedure.................................................................... 90 4.1 Performance Indicators and Analysis of Soft Handover................................................. 90 4.2 Hard Handover Performance Indicators and Analysis ................................................... 91



List of Tables

Table1 IEs in a measurement control message................................................................... 20 Table2 IEs in a measurement report message .................................................................... 25 Table3 Measured results IE ................................................................................................. 25 Table4 Event results IE........................................................................................................ 26 Table5 IEs in an active set update message ....................................................................... 28 Table6 Table 6 Radio link addition information IE................................................................ 31 Table7 IEs in an active set update complete message........................................................ 31 Table8 IEs in an active set update failure message............................................................. 33 Table9 Active set update failure causes .............................................................................. 33 Table10 IEs in a RADIO BEARER ESTABLISHMENT message........................................... 50 Table11 IEs in a RADIO BEARER RECONFIGURATION message ..................................... 56 Table12 IEs in a RADIO BEARER RELEASE message........................................................ 61 Table13 IEs in a TRANSPORT CHANNEL RECONFIGURATION message ........................ 67 Table14 IEs in a PHYSICAL CHANNEL RECONFIGURATION message............................. 72 Table15 IEs in a HANDOVER FROM UTRAN COMMAND message ................................... 81 Table16 IEs in a HANDOVER TO UTRAN COMMAND message ......................................... 82



List of Figures

Figure 1 Softer handover (Intra-NodeB, Inter-cell and intra-frequency handover) ................... 9 Figure 2 Soft handover (Intra-NodeB, inter-cell and intra-frequency handover)..................... 10 Figure 3 Soft handover (intra-RNC, inter-NodeB and intra-frequency handover)................... 11 Figure 4 Soft handover (inter-RNS and intra-frequency handover)........................................ 12 Figure 5 Hard handover (intra-NodeB, inter-cell and inter-frequency handover).................... 13 Figure 6 Hard handover (intra-RNS, inter-NodeB and inter-frequency handover) ................. 13 Figure 7 Inter-frequency hard handover................................................................................. 14 Figure 8 Intra-frequency hard handover (inter-RNS without lur) ............................................ 15 Figure 9 Intra-frequency hard handover (of the PS BE service beyond the rate threshold) ... 15 Figure 10 Inter-RAT hard handover ................................................................................ 16 Figure 11 Measurement control and measurement report.............................................. 19 Figure 12 Measurement control procedure, normal case ............................................... 19 Figure 13 Measurement control procedure, failure case................................................. 20 Figure 14 Measurement report, normal case.................................................................. 25 Figure 15 Active Set Update procedure, successful case............................................... 27 Figure 16 Active Set Update procedure, failure case...................................................... 28 Figure 17 Active set update procedure (successful and failure cases) ........................... 34 Figure 18 Radio link addition signaling procedure .......................................................... 40 Figure 19 Radio link deletion signaling procedure .......................................................... 42 Figure 20 Combined radio link addition and deletion signaling procedure...................... 44 Figure 21 Radio bearer establishment, normal case ...................................................... 47 Figure 22 Radio bearer establishment, failure case........................................................ 47 Figure 23 Radio bearer reconfiguration, normal case..................................................... 48 Figure 24 Radio bearer reconfiguration, failure case ...................................................... 48 Figure 25 Radio bearer release, normal case................................................................. 48 Figure 26 Radio bearer release, failure case.................................................................. 48 Figure 27 Transport channel reconfiguration, normal case............................................. 49 Figure 28 Transport channel reconfiguration, failure case.............................................. 49 Figure 29 Physical channel reconfiguration, normal case............................................... 49 Figure 30 Physical channel reconfiguration, failure case................................................ 50 Figure 31 Hard handover signaling procedure (with Iur interface and the UE in CELL_DCH state) .................................................................................................................... 76

Figure 32 Cross-CN hard handover signaling procedure................................................ 78 Figure 33 Inter-RAT handover from UTRAN, successful case ....................................... 79 Figure 34 Inter-RAT handover from UTRAN, failure case .............................................. 80 Figure 35 Inter-RAT handover to UTRAN....................................................................... 80 Figure 36 UTRAN ⇒ GSM/BSS inter-RAT hard handover signaling procedure ............. 87 Figure 37 GSM/BSS ⇒ UTRAN inter-RAT hard handover signaling procedure ............. 89



WCDMA RNO Handover Procedure Analysis

Key words：Handover procedure, soft handover, hard handover, inter-RAT handover

Abstract：This document introduces the classification of WCDMA handovers, analyzes in

details the signaling procedures of handover measurement, soft handover, hard handover and inter-RAT hard handover procedures, and describes the handover performance indicators.

List of abbreviations：

Abbreviations Full spelling



1 Handover Concept Handovers are an inevitable issue where a mobile communication system is concerned, and

play a very important role in a WCDMA system. It is one of the most important methods to

implement a seamless coverage and improve the communication quality.

In short, a handover is to transfer a UE connection from one radio link to another to

accommodate the change of radio link caused by UE’s crossing over cells, load adjustment of

network or other reasons.

2 Classification of Handovers Handovers are of two types, i.e. soft handover and hard handover. Roughly speaking, the

difference between them is that in a soft handover a new connection is established before the

existing one is disconnected, while in a hard handover it is the vice versa.

Soft handovers can be further categorized into softer handover and soft handover.

Hard handovers can be further categorized into intra-frequency hard handover,

inter-frequency hard handover and inter-system handover.

2.1 Soft Handover

Definition: A soft handover means that there will always remain at least one radio link

between the UE and UTRAN when radio links are added or removed. The merits of soft

handovers are as follows:

Without interrupting communications, soft handovers can improve the handover success

rate.

Soft handovers implement selection combination and achieve diversity gain and therefore

can improve the coverage and radio link performance.

Featured with high handover performance and low call-drop possibility when failed, soft

handovers can improve the call quality of UEs on cell edges.

However, a soft handover can occur only when the target handover cell and source

handover cell operate at the same frequency, and the UE in the soft handover state must keep

communicating with the two (or more) cells simultaneously, thus taking up more radio

resources in the downlink.

A soft handover is an intra-frequency handover of which the target and source cells must

meet either of the following two conditions:

1） Belong to the same RNC;

2） Belong to different RNCs with a lur interface between them.

Soft handovers can be categorized into softer handover and soft handover. The difference

between them is that in a softer handover radio links are combined within the NodeB, while in a



soft handover radio links are combined within the RNC. They are defined in details in subsequent

sections respectively.

2.1.2 Softer handover

A softer handover happens between cells of the same frequency and same base station

(NodeB). Radio links are combined within a NodeB. As a special kind of soft handover, softer

hand over implements the uplink RAKE combination (with the downlink being already RAKE

combination) with more combination gain and better link performance than soft handover, while

using no extra lub/lur interface resources.

A softer handover will cause the following activities:

Altering the serving cell, with the target and source cells belonging to the same base station;

Changing the allocation of physical channels, e.g. parameters such as channelization code

and scrambling code;

Combining radio links within the NodeB.

The procedures of a softer handover are illustrated in Figure 1 below, with the radio links

combined (RAKE combination) within the NodeB.

Figure 1 (i) shows that there is a radio link between the UE and the source cell before the

handover occurs.

Figure 1 (ii) shows that the softer handover occurs, and the UE is in macro diversity handover

state with the two links combined within NodeB.

Figure 1 (iii) shows that the softer handover completes and the radio link between the UE and

the source cell is removed.



SRNSUTRAN

SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(iii)

Intra Node B (Inter Cell)

Figure 1 Softer handover (Intra-NodeB, Inter-cell and intra-frequency handover)

2.1.3 Soft Handover

1. A soft handover happens between different cells of the same frequency and same NodeB.

Radio links are combined within the RNC rather than within NodeB (softer handover) because of

the NodeB implementation or signaling reasons. Its network structure is the same as that of a

softer handover, but with a different implementation mechanism.

An intra-NodeB, inter-cell and intra-frequency soft handover will cause the following

activities:

Altering the serving cell, with the target and source cells belonging to the same base

station;

Re-allocating physical and transport channels, e.g. parameters such as channelization

code and scrambling code;

Combining radio links within the RNC.

The procedures of an intra-NodeB soft handover are illustrated in Figure 2 below.


handover occurs.

Figure 2 (ii) shows that the soft handover occurs, and the UE is in macro diversity handover

state with the two links combined within the RNC.

Figure 2 (iii) shows that the soft handover completes and the radio link between the UE and

source cell is removed.



SRNSUTRAN

SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(iii)


Figure 2 Soft handover (Intra-NodeB, inter-cell and intra-frequency handover)

2. An intra-RNC and inter-NodeB soft handover will cause the following activities:

Altering the serving cell, with the target and source cells belonging to different base

stations in the same RNC;



Combining radio links within the RNC.

The procedures of an intra-RNC and inter-NodeB soft handover are illustrated in Figure 3

below.


handover occurs.


state with the two links combined within the RNC.

Figure 3 (iii) shows that the soft handover completes and the radio link between the UE and




SRNSUTRAN

SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(iii)

Inter Node B (Intra RNS)

Figure 3 Soft handover (intra-RNC, inter-NodeB and intra-frequency handover)

3. An inter-RNC, inter-NodeB and intra-frequency soft handover will cause the following

activities:

Altering the serving cell, with the target and source cells belonging to different base

stations in different RNCs;

Changing the allocation of physical and transport channels, e.g. parameters such as

channelization code and scrambling code;

Combining radio links within SRNC.

The procedures of such a soft handover are illustrated in Figure 4 below, with the radio links

combined within the SRNC via a lur interface.


handover occurs.


state with the two links combined within the SRNC via the lur interface.

Figure 4 (iiI) shows that the soft handover completes and the radio link between the UE and




SRNSUTRAN

DRNS

SRNSUTRAN

RNS SRNSUTRAN

DRNS

CN(UMTS)

SRNC RNC

NodeB NodeB NodeB NodeB

N/Ap1 N/Ap2

(i)CN(UMTS)

SRNC DRNC


N/Ap1 N/Ap2

(ii)

CN(UMTS)

SRNC DRNC


N/Ap1 N/Ap2

(iii)

Inter RNSSoft Handover

Figure 4 Soft handover (inter-RNS and intra-frequency handover)

2.2 Hard Handover

A hard handover happens when the UE releases the original radio link and then sets up a

new one. Because a hard handover will release the existing connection before setting up a new

one, it will cause temporary communication interruption.

Hard handovers can be further categorized into intra-frequency hard handover,

inter-frequency hard handover and inter-system handover.

2.2.1 Inter-frequency Hard Handover

1. An intra-NodeB, inter-cell and inter-frequency hard handover will cause the following

activities:

Altering the UE cell, with the target and source cells belonging to the same NodeB;

Changing the frequency;


code and scrambling code.

Re-allocating transport channels, e.g. the number of transport channels and TFS.

The procedures of such a hard handover are illustrated in Figure 5 below. The radio link

between the UE and the cell as shown in Figure 5 (i) is released first before the radio link

between the UE and the cell as shown in Figure 5 (ii) is set up.



SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)


Figure 5 Hard handover (intra-NodeB, inter-cell and inter-frequency handover)

2. An intra-RNC, inter-NodeB and inter-frequency hard handover can only take place

between adjacent NodeBs at different frequencies, and will cause the following activities:

Altering the serving cell, with the target and source cells belonging to different NodeBs

in the same RNC;





The procedures of such a hard handover are illustrated in Figure 6 below. The radio link

between the UE and the cell as shown in Figure 6 (i) is released first before the radio link

between the UE and the cell as shown in Figure 6 (ii) is set up.

.

SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)


Figure 6 Hard handover (intra-RNS, inter-NodeB and inter-frequency handover)



3. An inter-RNS and inter-frequency handover via the lur interface without changing the

SRNC will cause the following activities :

Altering the serving cell, with the target and source cells belonging to different RNCs;





Figure 7 (i) shows the original radio link with the UE.

Figure 7 (ii) shows that the UE releases the original radio link, sets up another one in the target

cell and then sets up a new radio link via the lur interface with the original SRNC.

SRNSUTRAN

RNS SRNSUTRAN

DRNS

CN(UMTS)

SRNC RNC


N/Ap1 N/Ap2

(i)CN(UMTS)

SRNC DRNC


N/Ap1 N/Ap2

(ii)

Inter RNSHard Handover

Figure 7 Inter-frequency hard handover

2.2.2 Intra-frequency Hard Handover

1. The procedures of an intra-UTRAN, inter-RNS and intra-frequency handover without lur

interface are illustrated in Figure 8 below. Figure 8 (i) shows the original radio link with the UE.

Figure 8 (ii) shows that the UE releases the original radio link, sets up another one in the target

cell and then sets up a new radio link with the new SNRC.



SRNSUTRAN

RNS RNSUTRAN

SRNS

CN(UMTS)

SRNC RNC


N/Ap1 N/Ap2

(i)CN(UMTS)

RNC SRNC


N/Ap1 N/Ap2

(ii)

Inter RNS (Intra UTRAN)No Iur

Figure 8 Intra-frequency hard handover (inter-RNS without lur)

2. An intra-frequency hard handover also occurs for the handover of a high-speed PS Best

Effort service which is beyond the rate threshold, because a soft handover would use too much

capacity in the downlink. Figure (i) shows the original radio link with the UE. Figure (ii) shows that

the UE releases the original radio link and then sets up another one between adjacent

intra-frequency cells in the same SRNC.

SRNSUTRAN

SRNSUTRAN

CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(i)CN(UMTS)

SRNC

NodeB NodeB

N/Ap1

(ii)


Figure 9 Intra-frequency hard handover (of the PS BE service beyond the rate threshold)

2.2.3 Inter-RAT Hard Handover

Figure 10 illustrates inter-RAT handovers between WCDMA FDD system and GSM system.

Figure 10 (i) and (ii) illustrate an inter-RAT handover from the 3G WCDMA to the 2G GSM.

Figure 10 (iii) and (iv) illustrate an inter-RAT handover from the 2G GSM to the 3G WCDMA.

Figure 10 (v) and (vi) illustrate another kind of inter-RAT handover from the 2G GSM to the 3G

WCDMA.

Figure 10 (i) shows the original radio link with the UE in the WCDMA system. Figure 10 (ii)



shows that the UE releases the original radio link and sets up another one in the GSM system.

Figure 10 (iii) shows the original radio link with the UE in the GSM system. Figure 10 (iv) shows

that the UE releases the original radio link and sets up another one in the WCDMA system.

Figure 10 (v) shows the original radio link with the UE in the GSM system. Figure 10 (vi) shows

that the UE releases the original radio link and sets up two links in the WCDMA system.

RNSUTRAN

SRNSUTRAN

SRNSUTRAN

SRNSUTRAN

CN (UMTS)N/Ap1 N/Ap2



SRNC

NodeB NodeB

(i) (ii)

RNC

NodeB NodeB

(iii)

SRNC

NodeB NodeB

(iv)

GSM/GPRS BSS RNC

NodeB NodeB

GSM/GPRS BSS

GSM/GPRS BSS GSM/GPRS BSS


RNSUTRAN

RNC

NodeB NodeB

(v) (vi)

Intra CNUTRAN/GSM

GSM/GPRS BSS

SRNSUTRAN

CN (UMTS)

SRNC

NodeB NodeB

GSM/GPRS BSS

CN (UMTS)N/Ap1 N/Ap2 N/Ap1 N/Ap2

Figure 10 Inter-RAT hard handover

3 Signaling Procedures and Message Analyses of Handover Procedures

A typical handover procedure is as follows: measurement controlàmeasurement



reportàhandover decisionàhandover implementationànew measurement control.

At the measurement control stage, the UTRAN will send measurement control messages to

inform the UE of the parameters to be measured. At the measurement report stage, the UE will

send measurement report messages to the UTRAN. At the handover decision stage, the UTRAN

will make a handover decision based on the measurement report received. At the handover

implementation stage, the UE and UTRAN will implement the signaling procedure and respond

to signaling messages.

The handover decision stage will be described in details in the “Handover Algorithm

Analysis”, and therefore, will not be repeated here.

3.1 Measurement Control and Measurement Report

3.1.1 Measurement Procedures

The UE measurements are classified into the following 7 types:

Intra-frequency measurements.

Inter-frequency measurements.

Inter-RAT measurements.

Traffic volume measurements: Measurements on uplink traffic volume.

Quality measurements: Measurements of quality parameters, e.g. downlink transport

BLER (Block Error Rate).

UE-internal measurements: Measurements of UE transmission power and RSSI

(Received Signal Level).

UE positioning measurements: Measurement of UE position.

Because various functions or procedures in the UTRAN, such as cell reselection, handover

and power control, will use these measurements, the UE shall support a number of

measurements running in parallel, and shall also support that each measurement is controlled

and reported independent of others.

Cells that the UE measures are classified into three different categories, i.e. Active Set,

Monitored Set and Detected Set.

UTRAN may control any measurement in the UE either by broadcasting system information

and/or by transmitting MEASUREMENT CONTROL message. The latter message includes the

following measurement control information:

1. Measurement identity: A reference number that should be used by the UTRAN when

setting up, modifying or releasing the measurement and by the UE in the measurement report.

2. Measurement command: One out of three different measurement commands.

- Setup: Setup a new measurement.

- Modify: Modify a previously defined measurement, e.g. to change the reporting criteria.

- Release: Stop a measurement and clear all information in the UE that are related to that



measurement.

3. Measurement type: One of the types listed above describing what the UE shall measure.

Presence or absence of the following control information depends on the measurement type.

4. Measurement objects: The objects the UE shall measure, and corresponding object

information.

5. Measurement quantity: The quantity the UE shall measure. This also includes the

filtering of the measurements.

6. Reporting quantities: The quantities the UE shall include in the report in addition to the

quantities that are mandatory to report for the specific event.

7. Measurement reporting criteria: The triggering of the measurement report, e.g.

periodical or event-triggered reporting.

8. Measurement Validity: Defines in which UE states the measurement is valid.

9. Measurement reporting mode: This specifies whether the UE shall transmit the

measurement report using AM or UM RLC.

10. Additional measurement identities: A list of references to other measurements. When

this measurement triggers a measurement report, the UE shall also include the reporting

quantities for the measurements referenced by the additional measurement identities.

When the reporting criteria are fulfilled, for example, a specified event occurred or the time

of periodical reporting comes, the UE shall send a MEASUREMENT REPORT message to

UTRAN.

In the “measurement reporting mechanism” field of a measurement control message, the

network will inform the UE which events should be reported. All the events concerning

intra-frequency measurements are labeled “1X”; those concerning inter-frequency

measurements are labeled “2X”; those concerning inter-system measurements are labeled “3X”.

An inter-frequency/inter-RAT hard handover may require to start up the compressed mode for

inter-frequency/inter-system measurements.

Figure 11 shows the signaling procedures of the measurement control and reporting procedures.

The SRNC-RRC sends a MEASUREMENT CONTROL message to the UE-RRC to ask the UE

to perform a measurement and report it. The UE-RRC sends a primitive to the UE-L1 layer to

configure it for the measurement. The UE-L1 layer, after the primary smooth processing, sends a

primitive to the UE-RRC to report the measurement results. The UE-RRC, after the secondary

smooth processing, sends a MEASUREMENT REPORT message to the SRNC-RRC when the

reporting criteria are fulfilled.



UE-RRC UE-L1 SRNC-RRC

Uu Iub

MEASUREMENT CONTROL

Reportingcriteriafulfilled

CPHY-Measurement-REQ

CPHY-Measurement-IND

MEASUREMENT REPORT

CPHY-Measurement-IND

Measurement

Measurement

Figure 11 Measurement control and measurement report

3.1.2 Measurement Control

The purpose of the measurement control procedure is to setup, modify or release a

measurement in the UE. The normal and failure cases of the measurement control procedure are

illustrated respectively in Figure 12 and Figure 13 below.

UE UTRAN

MEASUREMENT CONTROL

Figure 12 Measurement control procedure, normal case



UE UTRAN

MEASUREMENT CONTROL

MEASUREMENT CONTROL FAILURE

Figure 13 Measurement control procedure, failure case

1. Initiation of the measurement control procedure

The UTRAN may request a measurement by the UE to be setup, modified or released with a

MEASUREMENT CONTROL message, which is transmitted on the downlink DCCH using AM

RLC.

When a new measurement is created, UTRAN should set the IE "Measurement identity" to a

value, which is not used for other measurements. UTRAN may use several "Measurement

identity" for the same "Measurement type". In case of setting several "Measurement identity"

within a same "Measurement type", the measurement object or the list of measurement objects

can be set differently for each measurement with different "Measurement identity ".

When a current measurement is modified or released, UTRAN should set the IE

"Measurement identity" to the value, which is used for the measurement being modified or

released. In case of modifying IEs within a "Measurement identity", it is not needed for UTRAN to

indicate the IEs other than modified IEs, and the UE continues to use the current values of the

IEs that are not modified.

2. Information elements in a MEASUREMENT CONTROL message

IEs (information elements) in a MEASUREMENT CONTROL message are listed in the table

below. Table1 IEs in a measurement control message



Information Element/Group name

Need Multi Type and reference

Semantics description

Message Type MP Message Type

UE information elements RRC transaction identifier MP RRC

transaction identifier 10.3.3.36

Integrity check info CH Integrity check info 10.3.3.16

Measurement Information elements

Measurement Identity MP Measurement Identity10.3.7.48

Measurement Command MP Measurement Command 10.3.7.46

Measurement Reporting Mode

OP Measurement Reporting Mode 10.3.7.49

Additional measurements list OP Additional measurements list 10.3.7.1

CHOICE Measurement type CV command

>Intra-frequency measurement

Intra-frequency measurement 10.3.7.36

>Inter-frequency measurement

Inter-frequency measurement 10.3.7.16

>Inter-RAT measurement Inter-RAT measurement 10.3.7.27

>UE positioning measurement

UE positioning measurement 10.3.7.100

>Traffic Volume measurement

Traffic Volume measurement 10.3.7.68

>Quality measurement Quality measurement 10.3.7.56

>UE internal measurement UE internal measurement 10.3.7.77

Physical channel






information elements DPCH compressed mode status info

OP DPCH compressed mode status info 10.3.6.34

Notes on IEs in yellow:

Measurement identity: Used to identify different types of measurements or the same type of

measurements with different objects. Because one measurement control message is used to

assign one measurement ID, the UE in the DCH mode should receive at least two succeeding

measurement control messages. A measurement ID is assigned by the UTRAN to set up a

measurement, used by it to modify or release the measurement and used by the UE to send a

certain type of measurement report. Up to 16 (depending upon the "Measurement Identity")

measurements can be initiated simultaneously in the UE. According to the present handover

algorithms, Measurement identity can be 1,2,9, of which “1” is used for intra-frequency

measurements and assistant soft handover decisions, including 1a~1f events; “2” is used to

activate or de-activate the compressed mode, including 2d and 2f events; “9” is used for

inter-frequency periodical measurements.

Measurement command: The type of the UTRAN-initiated measurement control. Three

types are available, i.e. Setup, Modify and Release. Another measurement setup message will

be ignored if the measurement has been set up.

Measurement Reporting Mode: Including the Measurement Report Transfer Mode and

Periodical Reporting/Event Trigger Reporting Mode. The Measurement Report Transfer Mode

includes the AM (Acknowledged Mode) and UM (Unacknowledged Mode), which should be

selected based on the report type. In the case of an event report, the AM RLC should be used to

ensure a successful transfer. In the case of a periodical report, the UM RLC should be selected.

The Event Trigger Reporting Mode is often used during handovers. Intra-frequency

measurements and soft handovers focus on 1a~1f events while inter-frequency measurements

and inter-frequency hard handovers focus on 2a events.

For details on other IEs, please refer to protocol 25.331 and reference document[5].

3. Procedure

Upon reception of a MEASUREMENT CONTROL message sent by the UTRAN on the

downlink DCCH using AM RLC, the UE will: - read the IE "Measurement command";

- if the IE "measurement command" has the value "setup":

- store this measurement in the variable MEASUREMENT_IDENTITY according to the IE

"measurement identity";



- for measurement types "inter-RAT measurement" or "inter-frequency measurement":

- if, according to its measurement capabilities, the UE requires compressed mode to

perform the measurements and a compressed mode pattern sequence with an

appropriate measurement purpose is simultaneously activated by the IE "DPCH

compressed mode status info"; or

- if, according to its measurement capabilities, the UE does not require

compressed mode to perform the measurements:

- for any other measurement type:

- begin measurements according to the stored control information for this

measurement identity.

- if the IE "Measurement command" has the value "modify":

- for all measurement control present in the MEASUREMENT CONTROL message:

- if a measurement was stored in the variable MEASUREMENT_IDENTITY associated to the identity by the IE "measurement identity":

- replace the corresponding information stored in variable MEASUREMENT_IDENTITY associated to the identity indicated by the IE "measurement identity";

- resume the measurements according to the new stored measurement control information.

- otherwise:

- set the variable CONFIGURATION_INCOMPLETE to TRUE;

- if the IE "measurement command" has the value "release":

- terminate the measurement associated with the identity given in the IE "measurement

identity";

- clear all stored measurement control information related associated to this

measurement identity in variable MEASUREMENT_IDENTITY.

- and the procedure ends.

If UTRAN instructs the UE to perform a measurement that is not supported by the UE, the UE shall:

- retain the measurement configuration that was valid before the MEASUREMENT

CONTROL message was received;

- set the IE "RRC transaction identifier" in the MEASUREMENT CONTROL FAILURE

message to the value of "RRC transaction identifier" in the entry for the MEASUREMENT



CONTROL message in the table "Accepted transactions" in the variable TRANSACTIONS

and clear that entry.

- set the cause value in IE "failure cause" to "unsupported measurement";

- submit the MEASUREMENT CONTROL FAILURE message to lower layers for

transmission on the DCCH using AM RLC;


If the variable CONFIGURATION_INCOMPLETE is set to TRUE, the UE shall:






and clear that entry;

- set the cause value in IE "failure cause" to "Configuration incomplete";




If the MEASUREMENT CONTROL message contains a protocol error, the UE shall:






and clear that entry;

- set the IE "failure cause" to the cause value "protocol error";




3.1.3 Measurement Report

The purpose of the measurement reporting procedure is to transfer measurement results

from the UE to UTRAN. The normal case of the measurement report is illustrated in figure below.



UE UTRAN

MEASUREMENT REPORT

Figure 14 Measurement report, normal case

In CELL_DCH state, the UE shall transmit a MEASUREMENT REPORT message on the

uplink DCCH when the reporting criteria stored in variable MEASUREMENT_IDENTITY are met

for any ongoing measurements that are being performed in the UE.

1. IEs in a measurement report message

IEs (information elements) in a MEASUREMENT REPORT message are listed in the table

below. Table2 IEs in a measurement report message





UE information elements

Integrity check info CH Integrity check info 10.3.3.16

Measurement Information Elements

Measurement identity MP Measurement identity 10.3.7.48

Measured Results OP Measured Results 10.3.7.44

Measured Results on RACH

OP Measured Results on RACH 10.3.7.45

Additional Measured results

OP 1 to <maxAdditionalMeas>

>Measured Results MP Measured Results 10.3.7.44

Event results OP Event results 10.3.7.7

IE “Measured results” is described in table below. Table3 Measured results IE





CHOICE Measurement

MP

>Intra-frequency measured results list

>Inter-frequency measured results list

>Inter-RAT measured results list

>Traffic volume measured results list

>Quality measured results list

>UE Internal measured results

>UE positioning measured results

This IE contains the measured results of the quantities as specified by the “reporting

quantities” in the measurement control message.

IE “Event results” is described in table below. Table4 Event results IE




CHOICE event result MP >Intra-frequency measurement event results

>Inter-frequency measurement event results

>Inter-RAT measurement event results

For IS-2000 results, include fields of the Pilot Strength Measurement Message from subclause 2.7.2.3.2.5 of TIA/EIA/IS-2000.5

>Traffic volume measurement event results

>Quality measurement event results

>UE internal measurement event results

>UE positioning measurement event results

For details on other IEs, please refer to protocol 25.331 and reference document[5].



2. Procedure

For the measurement, which triggered the MEASUREMENT REPORT message, the UE shall:

- set the IE "measurement identity" to the measurement identity, which is associated with

that measurement in variable MEASUREMENT_IDENTITY, i.e. the “measurement identity”

in the MEASUREMENT CONTROL message;

- set the IE "measured results" to include measurements according to the IE "reporting

quantity" of that measurement stored in variable MEASUREMENT_IDENTITY; and

- if all the reporting quantities are set to “false”,

- not set the IE "measured results";

- if the MEASUREMENT REPORT message was triggered by an event,

set the IE "Event results" according to the event that triggered the report.

The UE shall:

- transmit the MEASUREMENT REPORT message on the uplink DCCH using either AM or

UM RLC according to the stored IE "measurement reporting mode" associated with the

measurement identity that triggered the report.

When the MEASUREMENT REPORT message has been submitted to lower layers for transmission:

- the procedure ends.

3.2 Soft Handover Procedure Analysis

3.2.1 General Description of the Active Set Update Procedure

The purpose of the active set update procedure is to update the active set of the connection

between the UE and UTRAN. The UE should keep on using the old RLs while configuring the

new RLs. Also the UE should keep the transmitter turned on during the procedure. This

procedure is only used in FDD mode. The successful and failure cases of the active set update

procedure are illustrated respectively in Figure 15 and Figure 16 below.

UE UTRAN

ACTIVE SET UPDATE

ACTIVE SET UPDATE COMPLETE

Figure 15 Active Set Update procedure, successful case



UE UTRAN

ACTIVE SET UPDATE

ACTIVE SET UPDATE FAILURE

Figure 16 Active Set Update procedure, failure case

The procedure is initiated when UTRAN orders a UE in CELL_DCH state, to make the

following modifications of the active set of the connection:

a) Radio link addition;

b) Radio link removal;

c) Combined radio link addition and removal;

In case a) and c), UTRAN should:

- prepare new additional radio link(s) in the UTRAN prior to the command to the UE.

In all cases, the UTRAN should:

- send an ACTIVE SET UPDATE message on downlink DCCH using AM or UM RLC.

3.2.2 Analysis of Soft Handover Related IEs

1. ACTIVE SET UPDATE message

This message is sent by UTRAN to the UE.

RLC-SAP: AM ; Logical channel: DCCH.

IEs in an active set update message are listed in table below. Table5 IEs in an active set update message






RRC transaction identifier MP RRC transaction

identifier

10.3.3.36

Integrity check info CH Integrity check

info 10.3.3.16

Integrity protection mode

info

OP Integrity

protection mode

info 10.3.3.19



Ciphering mode info OP Ciphering mode

info 10.3.3.5

Activation time MD Activation time

10.3.3.1

Default value is

"now".

New U-RNTI OP U-RNTI

10.3.3.47

CN information elements

CN Information info OP CN Information

info 10.3.1.3

RB information elements

Downlink counter

synchronisation info

OP

>RB with PDCP

information list

OP 1 to

<maxR

BallRA

Bs>

This IE is needed for

each RB having

PDCP in the case of

lossless SRNS

relocation

>>RB with PDCP

information

MP RB with PDCP

information

10.3.4.22

Phy CH information elements

Uplink radio resources

Maximum allowed UL TX

power

MD Maximum

allowed UL TX

power 10.3.6.39

Default value is the

existing "maximum

UL TX power.

Downlink radio resources

Radio link addition

information

OP 1 to

<maxR

L-1>

Radio link addition

information required

for each RL to add

>Radio link addition

information

MP Radio link

addition

information

10.3.6.68



Radio link removal

information

OP 1 to

<maxR

L>

Radio link removal

information required

for each RL to

remove

>Radio link removal

information

MP Radio link

removal

information

10.3.6.69

TX Diversity Mode MD TX Diversity

Mode 10.3.6.86


existing TX diversity

mode.

SSDT information OP SSDT

information

10.3.6.77

The IE in yellow is an important IE which will be described in detail hereinafter.

An active set update message mainly contains such IEs as Message Type, UE information

elements, CN information elements, RB information elements and Phy CH information elements,

which are described below.

Message Type: Used to identify the message, mandatory.

UE information elements: Including the following IEs:

-RRC transaction identifier: Used to identify the RRC, mandatory.

-Integrity check info: Used for integrity check, conditional.

-Integrity protection mode info: Used for integrity protection, optional.

-Ciphering mode info: Used for ciphering, optional.

-Activation time: Used to specify the activation time with “now” as its default value,

mandatory.

-New U-RNTI: Used to configure the new UTRAN RNTI, optional.

CN information elements: Used to describe the CN information, optional.

RB information elements: Including the following IEs:

-Downlink counter synchronisation info: Used to describe the downlink counter

synchronisation information, optional.

Phy CH information elements: Including IEs Uplink radio resources element and Downlink

radio resources.

Uplink radio resources: Including the following IE:

-Maximum allowed UL TX power: Used to specify the maximum allowed uplink TX power

with the existing maximum UL TX power as its default value, mandatory.

Downlink radio resources: Including the following IEs:

-Radio link addition information: Used for radio link addition, optional.



-Radio link removal information: Used for radio link removal, optional.

-TX Diversity Mode: Used to specify the TX diversity mode with the existing TX diversity

mode as its default value, mandatory.

-SSDT information: Used to describe SSDT information, optional.

IE “Radio link addition information” is described in the table below. Table6 Table 6 Radio link addition information IE


Need Multi Type and reference Semantics description

Primary CPICH info MP Primary CPICH info

10.3.6.60

Downlink DPCH info for

each RL

MP Downlink DPCH info for

each RL 10.3.6.21

TFCI combining indicator OP TFCI combining

indicator 10.3.6.81

SCCPCH Information for

FACH

OP SCCPCH Information

for FACH

10.3.6.70

The “Primary CPICH info” represents the scrambling code of the cell for the purpose of cell

identification. Because there are a total of 512 primary scrambling codes, the value of this IE is

within the range of 0~511. An error in this IE will result in a failed downlink synchronization of the

physical layer, thus causing the active set update procedure, namely, soft handover, to fail.

The “Downlink DPCH info for each radio link” mainly contains the elements of the downlink

DPCH, such as “DPCH frame offset” and “DL channelisation code”. An error in sending or

receiving either of these two elements will cause the soft handover to fail.

2. ACTIVE SET UPDATE COMPLETE message

This message is sent by the UE to UTRAN.

RLC-SAP: AM; logical channel: DCCH.

IEs in an Active Set Update Complete message are listed in table below. Table7 IEs in an active set update complete message






RRC transaction identifier MP RRC

transaction

identifier

10.3.3.36




info 10.3.3.16

Uplink integrity protection

activation info

OP Integrity

protection

activation info

10.3.3.17

RB Information elements

Radio bearer uplink

ciphering activation time

info

OP RB activation

time info

10.3.4.13

Uplink counter


OP

>RB with PDCP

information list

OP 1 to

<maxR

BallRA

Bs>

This IE is needed for

each RB having

PDCP in the case of

lossless SRNS

relocation

>>RB with PDCP

information

MP RB with PDCP

information

10.3.4.22

>START list MP 1 to

<maxC

Ndomai

ns>

START [40] values for

all CN domains.

>>CN domain identity MP CN domain

identity 10.3.1.1

>>START MP START

10.3.3.38

START value to be

used in this CN

domain.

Message Type: Used to identify the message type, mandatory.




-Uplink integrity protection activation info: Used for uplink integrity protection, optional.


-Radio bearer uplink ciphering activation time info: Used to describe the radio bearer uplink



ciphering activation time information, optional.

-Uplink counter synchronisation info: Used to describe the uplink counter synchronisation

information, optional.

3. Active Set Update Failure message

This message is sent by the UE to UTRAN.

RLC-SAP: AM; logical channel: DCCH.

IEs in an Active Set Update Failure message are listed in table below. Table8 IEs in an active set update failure message






RRC transaction

identifier

MP RRC

transaction

identifier

10.3.3.36


info 10.3.3.16

Failure cause MP Failure cause

and error

information

10.3.3.14





-Failure cause, the mandatory item, is used to report the failure cause.

An active set update failure message is used by the UE to report to the RNC the failure

cause of the active set update procedure. It is very important to analyze soft handover failures

that have caused a high call-drop ratio.

The active set update failure causes mainly include common failure causes and protocol

error causes, which are listed in table below. Table9 Active set update failure causes

Active set update failure type Active set update failure cause Configuration unsupported Physical channel failure

Common failure cause

Incompatible simultaneous reconfiguration



Compressed mode runtime error Cell update occurred Invalid configuration Configuration incomplete

Unsupported measurement ASN.1 violation or encoding error Message type non-existent or not implemented Message not compatible with receiver state Information element value not comprehended Conditional information element error

Protocol error cause

Message extension not comprehended

3.2.3 Active Set Update Procedure

Successful and failure cases of the active set update procedure are illustrated in Figure 17.

Please refer to relevant sections for details on the procedure. The figure clearly describes the

successful and failure cases of the reception of an Active Set Update message by the UE and

reception of an Active Set Update Complete/Failure message by the UTRAN. Sections 2.1.2

through 2.1.8 has detailed each sub-procedure. In failure cases, the handovers will fail, thus

increasing the call-drop rate.

Figure 17 Active set update procedure (successful and failure cases)

SRNC sends an Active Set Update message to the UE

UE procedure, successful case UE procedure, failure case

Reception of the message by the UE, successful case

Reception of the message by the UTRAN, successful case

Configuration

Reception of the message by the UTRAN, failure case

Invalid configurat

Incompatible

Invalid

Wrong Section

a

Section h

Section c

Section d

Section d

Section h

Section f

Section e

Handover succeeds Handover fails



1. Reception of an ACTIVE SET UPDATE message by the UE (successful case)

Upon reception of an ACTIVE SET UPDATE message the UE shall act upon all received

information elements as specified in the protocol. The UE shall:

- first add the RLs indicated in the IE "Radio Link Addition Information";

- remove the RLs indicated in the IE "Radio Link Removal Information". If the UE active set

is full or becomes full, an RL, which is included in the IE "Radio Link Removal Information" for

removal, shall be removed before adding RL, which is included in the IE "Radio Link Addition

Information" for addition;

- if the ACTIVE SET UPDATE message contained the IE "Ciphering mode info"::

- include and set the IE "Radio bearer uplink ciphering activation time info" to the value of

the variable RB_UPLINK_CIPHERING_ACTIVATION_TIME_INFO;

- if the ACTIVE SET UPDATE message contained the IE "Integrity protection mode info"

with the IE "Integrity protection mode command" set to "Modify":

- include and set the IE "Integrity protection activation info" to the value of the variable

INTEGRITY_PROTECTION_ACTIVATION_INFO;

- if the variable PDCP_SN_INFO is non-empty:

- include the IE "RB with PDCP information list" in the ACTIVE SET UPDATE

COMPLETE message and set it to the value of the variable PDCP_SN_INFO;

- if the ACTIVE SET UPDATE message includes the IE "TFCI combining indicator"

associated with a radio link to be added:

- configure Layer 1 to soft combine TFCI (field 2) of this new link with those links already in

the TFCI (field 2) combining set;

- if the received ACTIVE SET UPDATE message included the IE "Downlink counter

synchronisation info":

- calculate the START value,

- include the calculated START values for each CN domain in the IE "START list" in the

IE "Uplink counter synchronisation info" in the ACTIVE SET UPDATE COMPLETE message;

- set the IE "RRC transaction identifier" in the ACTIVE SET UPDATE COMPLETE message

to the value of "RRC transaction identifier" in the entry for the ACTIVE SET UPDATE message in

the table "Accepted transactions" in the variable TRANSACTIONS, and clear that entry;

- transmit an ACTIVE SET UPDATE COMPLETE message on the uplink DCCH using AM

RLC without waiting for the Physical Layer synchronization;

- if the IE "Integrity protection mode info" was present in the ACTIVE SET UPDATE

message:

start applying the new integrity protection configuration in the uplink for signalling radio

bearer RB2 from and including the transmitted ACTIVE SET UPDATE COMPLETE message;

- if the variable PDCP_SN_INFO is empty:



- if the ACTIVE SET UPDATE message contained the IE "Ciphering mode info":

- when RLC has confirmed the successful transmission of the ACTIVE SET UPDATE

COMPLETE message:

- perform the actions below;

- if the ACTIVE SET UPDATE message did not contain the IE "Ciphering mode info":

- when RLC has been requested to transmit the ACTIVE SET UPDATE COMPLETE

message:

- perform the actions below;

- if the variable PDCP_SN_INFO is non-empty:

- when RLC has confirmed the successful transmission of the ACTIVE SET UPDATE

COMPLETE message:

- for each radio bearer in the variable PDCP_SN_INFO:

- if the IE "RB started" in the variable ESTABLISHED_RABS is set to

"started":

- configure the RLC entity for that radio bearer to "continue";

- clear the variable PDCP_SN_INFO;

- if the ACTIVE SET UPDATE message contained the IE "Ciphering mode info":

- set the IE "Reconfiguration" in the variable CIPHERING_STATUS to FALSE; and

- clear the variable RB_UPLINK_CIPHERING_ACTIVATION_TIME_INFO;

- if the ACTIVE SET UPDATE message contained the IE "Integrity protection mode info":

- set the IE "Reconfiguration" in the variable INTEGRITY_PROTECTION_INFO to FALSE; and

- clear the variable INTEGRITY_PROTECTION_ACTIVATION_INFO;

- the procedure ends on the UE side.

2. Unsupported configuration in the UE (failure case)

If UTRAN instructs the UE to use a configuration that it does not support, the UE shall:

- keep the active set as it was before the ACTIVE SET UPDATE message was received;

- transmit an ACTIVE SET UPDATE FAILURE message on the DCCH using AM RLC;

- set the IE "RRC transaction identifier" in the ACTIVE SET UPDATE FAILURE message to the value of "RRC transaction identifier" in the entry for the ACTIVE SET UPDATE message in the table "Accepted transactions" in the variable TRANSACTIONS; and

- clear that entry;

- set the IE "failure cause" to "configuration unsupported";

- when the ACTIVE SET UPDATE FAILURE message has been submitted to lower layers for transmission:




3. Invalid configuration (failure case)

If any of the following conditions are valid:

- a radio link indicated by the IE "Downlink DPCH info for each RL" in the IE "Radio link

addition information" has a different spreading factor than the spreading factor for the radio links

in the active set that will be established at the time indicated by the IE "Activation time"; and/or

- a radio link in the IE "Radio link addition information" is also present in the IE "Radio Link Removal Information"; and/or

- the IE "Radio Link Removal Information" contains all the radio links which are part of or will be part of the active set at the time indicated by the IE "Activation time"; and/or

- the variable INVALID_CONFIGURATION is set to TRUE:

the UE shall:

- keep the active set as it was before the ACTIVE SET UPDATE message was received;

- transmit an ACTIVE SET UPDATE FAILURE message on the DCCH using AM RLC;


- clear that entry;

- set the IE "failure cause" to "Invalid configuration";

- When the ACTIVE SET UPDATE FAILURE message has been submitted to lower layers for transmission:


4. Incompatible simultaneous reconfiguration (failure case)

If the variable INCOMPATIBLE_SECURITY_RECONFIGURATION becomes set to TRUE

due to the received ACTIVE SET UPDATE message, the UE shall:

- transmit a ACTIVE SET UPDATE FAILURE message on the uplink DCCH using AM RLC;


- clear that entry;

- set the IE "failure cause" to the cause value "incompatible simultaneous reconfiguration";

- when the ACTIVE SET UPDATE FAILURE message has been delivered to lower layers for transmission:

- set the variable INCOMPATIBLE_SECURITY_RECONFIGURATION to FALSE;

- continue with any ongoing processes and procedures as if the ACTIVE SET UPDATE message has not been received;




If the variable ORDERED_RECONFIGURATION is set to TRUE; and

- if the activation time for the procedure that has set variable ORDERED_RECONFIGURATION and the activation time for the Active Set Update procedure are within a time window of 5 frames, the UE may:



- clear that entry;

- set the IE "failure cause" to the cause value "incompatible simultaneous reconfiguration";




5. Reception of the ACTIVE SET UPDATE COMPLETE message by the UTRAN (successful case)

When the UTRAN has received the ACTIVE SET UPDATE COMPLETE message,

- the UTRAN may remove radio link(s) that are indicated to remove to the UE in case b)

and c); and

- the procedure ends on the UTRAN side.

6. Reception of the ACTIVE SET UPDATE FAILURE message by the UTRAN (failure case)

When the UTRAN has received the ACTIVE SET UPDATE FAILURE message, the UTRAN

may delete radio links that were included in the IE "Radio Link Addition Information" for addition.

The procedure ends on the UTRAN side.

7. Invalid ACTIVE SET UPDATE message (failure case)

If the ACTIVE SET UPDATE message contains a protocol error causing the variable

PROTOCOL_ERROR_REJECT to be set to TRUE according to clause 9, the UE shall perform

procedure specific error handling as follows. The UE shall:


- set the IE "RRC transaction identifier" in the ACTIVE SET UPDATE FAILURE message to the value of "RRC transaction identifier" in the entry for the ACTIVE SET UPDATE message in the table "Rejected transactions" in the variable TRANSACTIONS; and

- clear that entry;




- include the IE "Protocol error information" with contents set to the value of the variable PROTOCOL_ERROR_INFORMATION;


- continue with any ongoing processes and procedures as if the invalid ACTIVE SET UPDATE message has not been received;


8. Reception of an ACTIVE SET UPDATE message in wrong state (failure case)

If the UE is in another state than CELL_DCH state upon reception of the ACTIVE SET

UPDATE message, the UE shall perform procedure specific error handling as follows. The UE

shall:



- clear that entry;


- include the IE "Protocol error information" with the IE "Protocol error cause" set to "Message not compatible with receiver state";



- and the procedure ends

3.2.4 Soft Handover Signaling Procedures Analysis

This section focuses on signaling procedures of three typical soft handover procedures,

which are radio link addition, radio link removal and combined radio link addition and removal.

Soft handovers only apply to FDD mode. All the procedures described below are soft handover

procedures with lur interface. Intra-RNC soft handover procedures are simpler than them, that is,

without the SRNC-DRNC part of each procedure. The procedures described in this section are

typical examples only. The signaling procedure of an actual handover must be analyzed on a

case-to-case basis.

Radio link addition signaling procedure analysis Conditions for the soft handover-radio link addition signaling procedure are as follows:

-One or more radio links have been set up between the UE and SRNC;

-A new radio link between the UE and SNRC will be set up through a new NodeB and new

RNC.



Because only one radio link between the UE and UTRAN will be set up, no macro diversity

combination/splitting will occur in the DRNS. The figure below illustrates the soft handover-radio

link addition signaling procedure.

UE Node BDrift RNS

DriftRNC

ServingRNC

DCH-FPDCH-FP6. Downlink Synchronisation

RNSAP RNSAP1. Radio Link Setup

Request

Start TX

NBAP NBAP2. Radio Link Setup

Request

RNSAP RNSAP

4. Radio Link SetupResponse

NBAP NBAP


Start RX

Decision to setupnew RL

RRCRRC9. DCCH : Active Set Update Complete

RRCRRC8. DCCH : Active Set Update

[Radio Link Addition]

ALCAP Iur Bearer Setup5. ALCAP Iub Bearer Setup

DCH-FPDCH-FP7. Uplink Synchronisation

Figure 18 Radio link addition signaling procedure

Signaling procedure:

1. Having decided to set up a new radio link in a new cell under the control of another RNC

(DRNC), the SRNC sends a “Radio Link Setup Request” message to the DRNC via RNSAP,

requesting the later to prepare necessary radio resources. Because the new radio link is the first

one set up between the UE and DRNC, a new lur signaling connection should be set up, which

will bear the UE related RNSAP signaling messages.

Message “Radio Link Setup Request” contains the following parameters: Cell ID, TFS,

TFCS, frequency and uplink scrambling code.



2. The DRNC judges whether it can fulfill the request for radio resources, and if yes, sends a

NBAP message “Radio Link Setup Request” to the NodeB for it to activate the uplink RX.



3. The NodeB assigns radio resources on request, and upon the successful completion of

the allocation, sends a NBAP message “Radio Link Setup Response” to the DRNC.

Message “Radio Link Setup Response” contains the following parameters : Signaling end

and transport addressing information message includes the following parameters: signaling end,

transport layer addressing information (AAL2 addressing and AAL2 binding ID for the data

bearer).

4. The DRNC sends a “Radio Link Setup Response” message to the SRNC via RNSAP.

Message “Radio Link Setup Response” contains the following parameters: Transport layer

addressing information (AAL2 addressing and AAL2 binding ID for the data bearer) and adjacent

cell information.

5. The SRNC initiates the establishment of the lur/lub bearer via protocol ALCAP, and

includes in the request an AAL2 binding ID used to bind the lub bearer with a DCH.

6/7. The NodeB and SRNC exchange DCH FP frames “Downlink Synchronization” and

“Uplink Synchronization” to set up bearer synchronization. NodeB activates the downlink TX.

8. The SRNC sends an “Active Set Update” message, which contains radio link addition

parameters, to the UE over the DCCH.

Parameters: Update type, cell ID, downlink scrambling code, power control information and

adjacent cell information.

9. After configuring the parameters based on the RRC message, the UE sends a RRC

message “Active Set Update Complete” to the SRNC.

Radio link deletion signaling procedure analysis Conditions for the soft handover-radio link deletion signaling procedure are as follows:


-An existing UE-SRNC radio link via the DRNC will be deleted.

The figure below illustrates the soft handover-radio link deletion signaling procedure.



UE Node BDrift RNS

DriftRNC

ServingRNC


Decision to deleteold RL

RNSAP RNSAP

3. Radio Link DeletionRequest

NBAP NBAP

4. Radio Link DeletionRequest

RNSAP RNSAP

6. Radio Link DeletionResponse

NBAP NBAP

5. Radio Link DeletionResponse

Stop RX and TX

RRCRRC1. DCCH : Active Set Update

[Radio Link Deletion]

ALCAP Iur Bearer Release7. ALCAP Iub Bearer Release

Figure 19 Radio link deletion signaling procedure


1. Having decided to delete a radio link, the SRNC sends a RRC message “Active Set

Update”, which contains radio link deletion parameters, to the UE over the DCCH.

Parameters: Update type and cell ID.

2. UE deactivates the downlink RX of the radio link to be deleted and send a RRC message

“Active Set Update Complete” to the SRNC.

3. The SRNC sends a “Radio Link Deletion Request” message to the DRNC via RNSAP.

Parameters: Cell ID and transport layer addressing information.

4. The DRNC sends a NBAP message “Radio Link Deletion Request” to NodeB for it to stop

the TX and RX.


5. The NodeB deactivates radio resources and sends a NBAP message “Radio Link

Deletion Response” to the DRNC.

6. “Radio Link Deletion Response”. The DRNC sends a RNSAP message “Radio Link

Deletion Response” to the SRNC.

7. The SRNC initiates the release of the lur/lub bearer via protocol ALCAP.



Combined radio link addition and deletion signaling procedure analysis Conditions for the soft handover-combined radio link addition and deletion signaling

procedure are as follows:


-A new radio link between the UE and SNRC will be set up through a new NodeB and new

RNC.

-An existing UE-SRNC radio link via a NodeB in the SRNC will be deleted.

The figure below illustrates the soft handover-combined radio link addition and deletion

signaling procedure.



7. Uplink Synchronisation

RNSAP RNSAP

1. Radio Link SetupRequest

Start TX

RNSAP RNSAP


NBAP NBAP2. Radio Link Setup Request

NBAP NBAP3. Radio Link Setup Response

Start RX

Decision to setupnew RL and

release old RL

NBAP 10. Radio Link Deletion Request

NBAP NBAP11. Radio Link Release Response

Stop RX and TX

12. ALCAP Iub Data Transport Bearer Release


RRCRRC8. DCCH : Active Set Update Command

[Radio Link Addition & Deletion]

NBAP

UE Node BDrift RNS

Node BServing RNS

DriftRNC

ServingRNC

ALCAP Iur Bearer Setup5. ALCAP Iub Data Transport Bearer Setup

DCH-FPDCH-FP

DCH-FPDCH-FP

6. Downlink Synchronisation

Figure 20 Combined radio link addition and deletion signaling procedure


1. Having decided to set up a new radio link in a new cell under the control of another RNC

(DRNC), the SRNC sends a “Radio Link Setup Request” message to the DRNC via RNSAP,

requesting the later to prepare necessary radio resources. Because the new radio link is the first

one set up between the UE and DRNC, a new lur signaling connection should be set up, which

will bear the UE related RNSAP signaling messages.





2. The DRNC judges whether it can fulfill the request for radio resources, and if yes, sends a

NBAP message “Radio Link Setup Request” to its NodeB for it to activate the uplink RX.



3. The NodeB assigns radio resources on request, and upon the successful completion of

the allocation, sends a NBAP message “Radio Link Setup Response” to the DRNC.

Message “Radio Link Setup Response” contains the following parameters : Signaling end

and transport addressing information message includes the following parameters: signaling end,

transport layer addressing information (AAL2 addressing and AAL2 binding ID for the data

bearer).

4. The DRNC sends a “Radio Link Setup Response” message to the SRNC via RNSAP.

Message “Radio Link Setup Response” contains the following parameters: Transport layer

addressing information (AAL2 addressing and AAL2 binding ID for the data bearer) and adjacent

cell information.

5. The SRNC initiates the establishment of the lur/lub bearer via protocol ALCAP, and


6/7. The NodeB and SRNC exchange DCH FP frames “Downlink Synchronisation” and

“Uplink Synchronisation” to synchronize the bearer. NodeB activates the downlink TX. 8. The SRNC sends an “Active Set Update” message, which contains radio link addition and

deletion parameters, to the UE over the DCCH.

Parameters: Update type, cell ID, downlink scrambling code, power control information and

adjacent cell information.

9. After configuring the parameters based on the RRC message, the UE deactivates the

downlink RX of the radio link to be deleted and activate the downlink RX of the radio link to be

added, and sends a RRC message “Active Set Update Complete” to the SRNC. 10. The SRNC sends a NBAP message “Radio Link Deletion Request” to NodeB for it to

stop the TX and RX.


11. The NodeB deactivates radio resources and sends a NBAP message “Radio Link


12. The SRNC initiates the release of the lur/lub bearer via protocol ALCAP.



3.3 Hard Handover Procedure Analysis

3.3.1 General Description of the Hard Handover Procedure

Hard handovers include intra-frequency, inter-frequency and inter-RAT hard handovers, of

which the inter-RAT hard handover procedure is complicated and will be described in section 3.3.

Hard handovers can be also categorized into timing re-initialised hard handovers and

timing-maintained hard handovers in terms of the synchronization method.

1. Timing re-initialised hard handover

The purpose of the timing re-initialised hard handover procedure is to remove all the RL(s) in

the active set and establish new RL(s) along with a change in the UL transmission timing and the

CFN in the UE according to the SFN of the target cell. This procedure is initiated when UTRAN

does not know the target SFN timing before hard handover

Timing re-initialised hard handover initiated by the UTRAN is normally performed by using

the procedure "Physical channel reconfiguration", but may also be performed by using either one

of the following procedures:

- "radio bearer establishment";

- "Radio bearer reconfiguration";

- "Radio bearer release"; or

- "Transport channel reconfiguration".

If IE "Timing indication" has the value "initialise", UE shall:

- execute the Timing Re-initialised hard handover procedure by following the procedure

indicated in the subclause relevant to the procedure chosen by the UTRAN.

2. Timing-maintained hard handover

The purpose of the Timing-maintained hard handover procedure is to remove all the RL(s) in

the active set and establish new RL(s) while maintaining the UL transmission timing and the CFN

in the UE. This procedure can be initiated only if UTRAN knows the target SFN timing before

hard handover. The target SFN timing can be known by UTRAN in the following 2 cases:

- UE reads SFN when measuring "Cell synchronisation information" and sends it to the

UTRAN in MEASUREMENT REPORT message.

- UTRAN internally knows the time difference between the cells.

Timing-maintained hard handover initiated by the network is normally performed by using

the procedure "Physical channel reconfiguration", but may also be performed by using either one

of the following procedures:

- "radio bearer establishment";

- "Radio bearer reconfiguration" ;

- "Radio bearer release"; or



- "Transport channel reconfiguration".

If IE "Timing indication" has the value "maintain", UE shall initiate the Timing-maintained

hard handover procedure by following the procedure indicated in the subclause relevant to the

procedure chosen by the UTRAN.

The reconfiguration procedures are used to perform timing-maintained hard handovers, i.e.

radio bearer establishment procedure, radio bearer reconfiguration procedure, radio bearer

release procedure, transport channel reconfiguration procedure and physical channel

reconfiguration procedure, which are described as below.,

The radio bearer establishment procedure is used to establish new radio bearer(s). The

normal and failure cases of this procedure are illustrated respectively in Figure 21 and Figure 22.

UE UTRAN

RADIO BEARER SETUP

RADIO BEARER SETUP COMPLETE

Figure 21 Radio bearer establishment, normal case

UE UTRAN

RADIO BEARER SETUP

RADIO BEARER SETUP FAILURE

Figure 22 Radio bearer establishment, failure case

The radio bearer reconfiguration procedure is used to reconfigure parameters for a radio

bearer or signaling link. The normal and failure cases of this procedure are illustrated

respectively in Figure 23 and Figure 24.



UE UTRAN

RADIO BEARER RECONFIGURATION

RADIO BEARERRECONFIGURATION COMPLETE

Figure 23 Radio bearer reconfiguration, normal case

UE UTRAN


RADIO BEARERRECONFIGURATION FAILURE

Figure 24 Radio bearer reconfiguration, failure case

The radio bearer release procedure is used to release radio bearer(s). The normal and

failure cases of this procedure are illustrated respectively in figures 24 and 25.

UE UTRAN

RADIO BEARER RELEASE

RADIO BEARER RELEASE COMPLETE

Figure 25 Radio bearer release, normal case

UE UTRAN


RADIO BEARER RELEASE FAILURE

Figure 26 Radio bearer release, failure case

The transport channel reconfiguration procedure is used to reconfigure transport channel



parameters. The normal and failure cases of this procedure are illustrated respectively in figures

Figure 27 and Figure 28.

UE UTRAN

TRANSPORT CHANNELRECONFIGURATION

TRANSPORT CHANNELRECONFIGURATION COMPLETE

Figure 27 Transport channel reconfiguration, normal case

UE UTRAN

TRANSPORT CHANNELRECONFIGURATION

TRANSPORT CHANNELRECONFIGURATION FAILURE

Figure 28 Transport channel reconfiguration, failure case

The physical channel reconfiguration procedure is used to establish, reconfigure and release

physical channels. The normal and failure cases of this procedure are illustrated respectively in

Figure 29 and Figure 30.

UE UTRAN

PHYSICAL CHANNELRECONFIGURATION

PHYSICAL CHANNELRECONFIGURATION COMPLETE

Figure 29 Physical channel reconfiguration, normal case



UE UTRAN

PHYSICAL CHANNELRECONFIGURATION

PHYSICAL CHANNELRECONFIGURATION FAILURE

Figure 30 Physical channel reconfiguration, failure case

3.3.2 Analysis of Hard Handover Related IEs

This section analyzes hard handover related reconfiguration IEs in the following messages:

RADIO BEARER ESTABLISHMENT



TRANSPORT CHANNEL RECONFIGURATION

PHYSICAL CHANNEL RECONFIGURATION

1. RADIO BEARER ESTABLISHMENT message

This message is sent by the UTRAN to the UE to establish new radio bearer(s). It can be

used to reconfigure transport and physical channels.

RLC-SAP: AM; Logical channel: DCCH.

IEs in a RADIO BEARER ESTABLISHMENT message are listed in table below. Table10 IEs in a RADIO BEARER ESTABLISHMENT message


Need

Multi Type and reference



UE Information Elements


transaction

identifier

10.3.3.36


info 10.3.3.16

Integrity protection mode info OP Integrity

protection

mode info

10.3.3.19

Ciphering mode info OP Ciphering



mode info

10.3.3.5


10.3.3.1

Default value is

"now"


10.3.3.47

New C-RNTI OP C-RNTI

10.3.3.8

RRC State Indicator MP RRC State

Indicator

10.3.3.10

UTRAN DRX cycle length

coefficient

MD UTRAN DRX

cycle length

coefficient

10.3.3.49


existing value of

UTRAN DRX cycle

length coefficient

CN Information Elements


info 10.3.1.3

UTRAN mobility information elements

URA identity OP URA identity

10.3.2.6

RB Information Elements

Signalling RB information to

setup list

OP 1 to

<maxS

RBsetu

p>

For each signalling

radio bearer

established

>Signalling RB information to

setup

MP Signalling RB

information to

setup 10.3.4.24

RAB information to setup list OP 1 to

<maxR

ABsetu

p>

For each RAB

established

>RAB information for setup MP RAB

information for

setup 10.3.4.10

RB information to be affected OP 1 to



list <maxR

B>

>RB information to be

affected

MP RB information

to be affected

10.3.4.17

Downlink counter


OP

>RB with PDCP information

list

OP 1 to

<maxR

BallRA

Bs>

This IE is needed

for each RB having

PDCP in the case

of lossless SRNS

relocation

>>RB with PDCP information MP RB with PDCP

information

10.3.4.22

TrCH Information Elements

Uplink transport channels

UL Transport channel

information common for all

transport channels

OP UL Transport

channel

information

common for all

transport

channels

10.3.5.24

Deleted TrCH information list OP 1 to

<maxTr

CH>

>Deleted UL TrCH

information

MP Deleted UL

TrCH

information

10.3.5.5

Added or Reconfigured TrCH

information list

OP 1 to

<maxTr

CH>

>Added or Reconfigured UL

TrCH information

MP Added or

Reconfigured

UL TrCH

information



10.3.5.2

CHOICE mode OP

>FDD

>>CPCH set ID OP CPCH set ID

10.3.5.3

>>Added or Reconfigured

TrCH

information for DRAC list

OP 1 to

<maxTr

CH>

>>>DRAC static information MP DRAC static

information

10.3.5.7

>TDD (no data)

Downlink transport channels

DL Transport channel


transport channels

OP DL Transport

channel

information

common for all

transport

channels10.3.5

.6


<maxTr

CH>

>Deleted DL TrCH

information

MP Deleted DL

TrCH

information

10.3.5.4


information list

OP 1 to

<maxTr

CH>

>Added or Reconfigured DL

TrCH information

MP Added or

Reconfigured

DL TrCH

information

10.3.5.1

PhyCH information elements



Frequency info MD Frequency info

10.3.6.36


existing value of

frequency

information



power

MD Maximum

allowed UL TX

power

10.3.6.39


existing maximum

UL TX power

CHOICE channel

requirement

OP

>Uplink DPCH info Uplink DPCH

info 10.3.6.88

>CPCH SET Info CPCH SET Info

10.3.6.13


CHOICE mode MP

>FDD

>>Downlink PDSCH

information

OP Downlink

PDSCH

information

10.3.6.30

>TDD (no data)

Downlink information

common for all radio links

OP Downlink

information

common for all

radio links

10.3.6.24

Downlink information per

radio link list

OP 1 to

<maxR

L>

Send downlink

information for

each radio link

>Downlink information for

each radio link

MP Downlink

information for

each radio link

10.3.6.27

Analysis of IEs:





-RRC transaction identifier : Used to identify the RRC, mandatory.





mandatory.


-New C-RNTI: Used to configure the new CRNC RNTI, optional.

-RRC State Indicator: Used to describe the RRC state of the UE, mandatory.

-UTRAN DRX cycle length coefficient: Used to specify the UTRAN’s discontinuous RX cycle

length, mandatory.


UTRAN mobility information elements: Used to describe UTRAN mobility information,

especially the “URA identity”, optional.


-Signalling RB information to setup list: Used to describe each signaling radio bearer to be

set up, optional.

-RAB information to setup list: Used to describe each radio access bearer, optional.

-RB information to be affected list: Used to describe each radio bearer to be affected,

optional.



TrCH Information Elements: Including IEs Uplink transport channels and Downlink transport

channels.

Uplink transport channels: Including the following IEs:

-UL Transport channel information common for all transport channels: Used to describe UL

transport channel information common for all transport channels, optional.

-Deleted TrCH information list: Used to list the transport channels to be deleted, optional.

-Added or Reconfigured TrCH information list: Used to list the transport channels to be

added or reconfigured, optional.

-CHOICE mode: Used to describe the chosen mode (FDD or TDD), optional.

Downlink transport channels: Including the following IEs:

-DL Transport channel information common for all transport channels: Used to describe the

downlink transport information common for all transport channels, optional.






Phy CH information elements: Including IEs Uplink radio resources and Downlink radio

resources, of which the radio bear frequency is mandatory with “current frequency” as its default

value.

Uplink radio resources: Including the following IEs:



-CHOICE channel requirement: Used to choose the channel requirement, optional.


-CHOICE mode: Used to describe the chosen mode (FDD or TDD), mandatory.

-Downlink information common for all radio links: Used to describe the downlink information

common for all radio links, optional.

-Downlink information per radio link list: Used to describe the downlink information of each

radio link, optional.

2. RADIO BEARER RECONFIGURATION message

This message is sent by the UTRAN to the UE to reconfigure QoS related parameters for a

radio bearer. The message can be used to change the MAC multiplexing and reconfigure the

transport and physical channels.


IEs in a RADIO BEARER RECONFIGURATION message are listed in table below.

Table11 IEs in a RADIO BEARER RECONFIGURATION message


Need

Multi Type and reference Semantics description


UE Information elements


identifier 10.3.3.36

Integrity check info CH Integrity check info

10.3.3.16

Integrity protection mode info OP Integrity protection

mode info 10.3.3.19

Ciphering mode info OP Ciphering mode info

10.3.3.5


10.3.3.1

Default

value is

"now"

New U-RNTI OP U-RNTI 10.3.3.47

New C-RNTI OP C-RNTI 10.3.3.8



RRC State Indicator MP RRC State Indicator

10.3.3.10


coefficient

MD UTRAN DRX cycle

length coefficient

10.3.3.49

Default

value is the

existing

value of

UTRAN

DRX cycle

length

coefficient

CN information elements

CN Information info OP CN Information info

10.3.1.3


URA identity OP URA identity 10.3.2.6


RAB information to

reconfigure list

OP 1 to <

maxRABs

etup >

>RAB information to

reconfigure

MP RAB information to

reconfigure 10.3.4.11

RB information to

reconfigure list

OP 1to

<maxRB>

>RB information to

reconfigure

MP RB information to

reconfigure 10.3.4.18

RB information to be

affected list

OP 1 to

<maxRB>


affected

MP RB information to be

affected 10.3.4.17





transport channels

OP UL Transport channel

information common

for all transport

channels 10.3.5.24




<maxTrCH

>

>Deleted UL TrCH

information

MP Deleted UL TrCH

information 10.3.5.5

Added or Reconfigured

TrCH

information list

OP 1 to

<maxTrCH

>


TrCH information

MP Added or

Reconfigured UL

TrCH information

10.3.5.2

CHOICE mode OP

>FDD

>>CPCH set ID OP CPCH set ID 10.3.5.3


TrCH


OP 1 to

<maxTrCH

>



>TDD (no data)




transport channels

OP DL Transport channel

information common

for all transport

channels 10.3.5.6


<maxTrCH

>

>Deleted DL TrCH

information

MP Deleted DL TrCH


Added or Reconfigured

TrCH

information list

OP 1 to

<maxTrCH

>


TrCH information

MP Added or

Reconfigured DL

TrCH information

10.3.5.1





10.3.6.36

Default

value is the

existing

value of

frequency

information



power

MD Maximum allowed UL

TX power 10.3.6.39

Default

value is the

existing

maximum

UL TX

power

CHOICE channel

requirement

OP

>Uplink DPCH info Uplink DPCH info

10.3.6.88


10.3.6.13


CHOICE mode MP

>FDD

>>Downlink PDSCH

information

OP Downlink PDSCH


>TDD (no data)



OP Downlink information

common for all radio

links 10.3.6.24


radio link list

OP 1 to

<maxRL>


each radio link

MP Downlink information

for each radio link

10.3.6.27



Analysis of IEs:








mandatory.



-RRC State Indicator: Used to describe the RRC state of the UE, mandatory.


length, mandatory.





-RAB information to reconfigure list: Used to describe each radio access bearer to be

reconfigured, optional.

-RB information to reconfigure list: Used to describe each radio link to be reconfigured,

optional.


optional.


channels.


















value.











3. RADIO BEARER RELEASE message

This message is sent by the UTRAN to release radio bearer(s). The message can be used

to reconfigure the transport and physical channels.


IEs in a RADIO BEARER RELEASE message are listed in table below. Table12 IEs in a RADIO BEARER RELEASE message







identifier

10.3.3.36


info 10.3.3.16


protection mode

info 10.3.3.19


info 10.3.3.5


10.3.3.1

Default value is

"now"






Indicator

10.3.3.10


coefficient

MD UTRAN DRX

cycle length

coefficient

10.3.3.49

Default value is

the existing value

of UTRAN DRX

cycle length

coefficient



info 10.3.1.3

Signalling Connection

release indication

OP CN domain

identity 10.3.1.1



10.3.2.6

RB Information Elements

RAB information to

reconfigure list

OP 1 to <

maxRAB

setup >

>RAB information to

reconfigure

MP RAB information

to reconfigure

10.3.4.11

RB information to release list MP 1 to

<maxRB

>

>RB information to release MP RB information to

release 10.3.4.19

RB information to be affected

list

OP 1 to

<maxRB

>


affected

MP RB information to

be affected

10.3.4.17

Downlink counter


OP




list

OP 1 to

<maxRB

allRABs>

This IE is needed

for each RB

having PDCP in

the case of

lossless SRNS

relocation


information

10.3.4.22





transport channels

OP UL Transport

channel

information

common for all

transport

channels

10.3.5.24


<maxTrC

H>

>Deleted UL TrCH

information

MP Deleted UL TrCH

information

10.3.5.5


information list

OP 1 to

<maxTrC

H>


TrCH information

MP Added or

Reconfigured UL

TrCH information

10.3.5.2

CHOICE mode OP

>FDD


10.3.5.3


TrCH


OP 1 to

<maxTrC

H>




information

10.3.5.7

>TDD (no data)




transport channels

OP DL Transport

channel

information

common for all

transport

channels

10.3.5.6


<maxTrC

H>

>Deleted DL TrCH

information

MP Deleted DL TrCH

information

10.3.5.4


information list

OP 1 to

<maxTrC

H>


TrCH information

MP Added or

Reconfigured DL

TrCH information

10.3.5.1



10.3.6.36

Default value is

the existing value

of frequency

information



power

MD Maximum

allowed UL TX

power 10.3.6.39

Default value is

the existing

maximum UL TX

power

CHOICE channel OP



requirement


10.3.6.88


10.3.6.13


CHOICE mode MP

>FDD

>>Downlink PDSCH

information

OP Downlink PDSCH

information

10.3.6.30

>TDD (no data)



OP Downlink

information

common for all

radio links

10.3.6.24


radio link list

OP 1 to

<maxRL>

Send downlink

information for

each radio link to

be set-up


each radio link

MP Downlink

information for

each radio link

10.3.6.27

Analysis of IEs:








mandatory.



-RRC State Indicator: Used to describe the RRC state of the UE. Mandatory.




length, mandatory.


Signalling Connection release indication: Used to describe the signaling connection release

indication.




-RAB information to reconfigure list: Used to describe each radio access bearer to be

reconfigured, optional.

-RB information to reconfigure list: Used to describe each radio link to be reconfigured,

optional.


optional.




channels.
















value.













4. TRANSPORT CHANNEL RECONFIGURATION message

This message is sent by the UTRAN to the UE to reconfigure transport channels. The

message can be used to reconfigure the physical channel and TFC subset.


IEs in a TRANSPORT CHANNEL RECONFIGURATION message are listed in table below.

Table13 IEs in a TRANSPORT CHANNEL RECONFIGURATION message


Need

Multi Type and reference





transaction

identifier

10.3.3.36


info 10.3.3.16


protection mode

info 10.3.3.19


info 10.3.3.5


10.3.3.1

Default value is

"now"


10.3.3.47

New C-RNTI OP C-RNTI

10.3.3.8


Indicator

10.3.3.10

UTRAN DRX cycle length MD UTRAN DRX Default value is



coefficient cycle length

coefficient

10.3.3.49

the existing value

of UTRAN DRX

cycle length

coefficient



info 10.3.1.3



10.3.2.6


Downlink counter


OP


list

OP 1 to

<maxRBall

RABs>

This IE is needed

for each RB

having PDCP in

the case of

lossless SRNS

relocation


information

10.3.4.22





transport channels

OP UL Transport

channel

information

common for all

transport

channels

10.3.5.24


information list

OP 1 to

<maxTrCH

>


TrCH information

MP Added or

Reconfigured

UL TrCH



information

10.3.5.2

CHOICE mode OP

>FDD


10.3.5.3


TrCH


OP 1 to

<maxTrCH

>


information

10.3.5.7

>TDD (no data)




transport channels

OP DL Transport

channel

information

common for all

transport

channels

10.3.5.6


information list

OP 1 to

<maxTrCH

>


TrCH information

MP Added or

Reconfigured

DL TrCH

information

10.3.5.1



10.3.6.36

Default value is

the existing value

of frequency

information


Maximum allowed UL TX MD Maximum Default value is



power allowed UL TX

power 10.3.6.39

the existing

maximum UL TX

power

CHOICE channel

requirement

OP

>Uplink DPCH info Uplink DPCH

info 10.3.6.88


10.3.6.13


CHOICE mode MP

>FDD

>>Downlink PDSCH

information

OP Downlink

PDSCH

information

10.3.6.30

>TDD (no data)



OP Downlink

information

common for all

radio links

10.3.6.24


radio link list

OP 1 to

<maxRL>

Send downlink

information for

each radio link


each radio link

MP Downlink

information for

each radio link

10.3.6.27

Analysis of IEs:








mandatory.







length, mandatory.








channels.














value.













5. PHYSICAL CHANNEL RECONFIGURATION message

This message is sent by the UTRAN to the UE to reconfigure physical channels, e.g.

assigning, replacing and releasing a group of physical channels.


IEs in a PHYSICAL CHANNEL RECONFIGURATION message are listed in table below. Table14 IEs in a PHYSICAL CHANNEL RECONFIGURATION message







identifier 10.3.3.36

Integrity check info CH Integrity check info

10.3.3.16

Integrity protection mode

info

OP Integrity protection

mode info

10.3.3.19


info 10.3.3.5


10.3.3.1

Default value is

"now"




Indicator 10.3.3.10


coefficient

MD UTRAN DRX cycle

length coefficient

10.3.3.49

Default value is

the existing value

of UTRAN DRX

cycle length

coefficient


CN Information info OP CN Information info

10.3.1.3



10.3.2.6




Downlink counter


OP


list

OP 1 to

<max

RBall

RABs

>

This IE is needed

for each RB

having PDCP in

the case of

lossless SRNS

relocation

>>RB with PDCP

information

MP RB with PDCP

information

10.3.4.22



10.3.6.36

Default value is

the existing value

of frequency

information



power

MD Maximum allowed

UL TX power

10.3.6.39

Default value is

the existing value

of the maximum

allowed UL TX

power

CHOICE channel

requirement

OP


10.3.6.88


10.3.6.13

>CPCH set ID CPCH set ID

10.3.5.3


CHOICE mode MP

>FDD

>>Downlink PDSCH

information

OP Downlink PDSCH

information

10.3.6.30



>TDD (no data)



OP Downlink

information

common for all

radio links

10.3.6.24


radio link list

OP 1 to

<max

RL>

Send downlink

information for

each radio link


each radio link

MP Downlink

information for

each radio link

10.3.6.27

Analysis of IEs:








mandatory.





length, mandatory.









value.













3.3.3 Hard Handover Signaling Procedure

The procedure described in this section is based on lur interface with the UE in the CELL_DCH state. See figure below.



RNSAPRNSAP1. Radio LinkSetup Request

Note 1

UE Node BSource

Node BTarget

RNCSource

RNCtarget

SRNC

RRC RRC

10. DCCH : Physical Channel Reconfiguration CompleteNote 3

RRC

7. DCCH : Physical Channel ReconfigurationNote 3

RRC

6. ALCAP Iur DataTransport Bearer Setup

Note 1

NBAP NBAP2. Radio Link Setup Request

NBAP NBAP3. Radio Link Setup Response

NBAP NBAP12. Radio Link Deletion Request

NBAP NBAP13. Radio Link Deletion Response

4. ALCAP Iub Data Transport Bearer Setup

14. ALCAP Iub Data Transport Bearer Release

RNSAP RNSAP15. Radio Link Deletion ResponseNote 2

16. ALCAP Iur DataTransport Bearer Release

Note 2

RNSAP5. RL Setup

ResponseNote 1

RNSAP

RNSAP11. Radio Link Deletion RequestNote 2

RNSAP

NBAP NBAP8. Radio Link Failure Indication

RNSAP RNSAP9. Radio Link Failure IndicationNote 2

Figure 31 Hard handover signaling procedure (with Iur interface and the UE in CELL_DCH state)

Signaling procedure analysis:

1. SRNC sends a Radio Link Setup Request message to the target RNC.

Parameters: Target RNC identifier, s-RNTI, cell ID, TFS and TFCS.

2. The target RNC assigns RNTI and radio resources to the RRC and radio link and then

sends a NBAP message “Radio Link Setup Request” to the target NodeB.

Parameters: cell ID, TFS, TFCS, frequency, uplink scrambling code and power control

information, etc.



3. The target NodeB assigns radio link resources, activates the physical layer RX and sends

a NBAP message “Radio Link Setup Response” to the target RNC.

Parameters: signaling end, transport layer addressing information of the lub bearer.

4. The target RNC initiates the establishment of the lub bearer via protocol ALCAP, and


5. After completing the preparation, the target RNC sends a Radio Link Setup Response

message to the SRNC.

6. The SRNC initiates the establishment of the lur bearer via protocol ALCAP, and includes

in the request an AAL2 binding ID used to bind the lur bearer with a DCH.

7. The SRNC sends a RRC message “Physical Channel Reconfiguration” to the UE.

8. After the UE switches from the old link to the new link, the source NodeB detects a

synchronization failure in the old link and sends a NBAP message “Radio Link Failure Indication”

to the source RNC.

9. The source RNC sends a RNSAP message “Radio Link Failure Indication” to the SRNC.

10. After the RRC with the target RNC is set up and necessary radio resources are assigned,

the UE sends a RRC message “Physical Channel Reconfiguration Complete” to the SRNC.

11. The SRNC sends a RNSAP message “Radio Link Deletion Request” to the source RNC,

requesting it to release the radio resources assigned to the old link.

12. The source RNC sends a NBAP message “Radio Link Deletion Request” to the source

NodeB.

Parameters: Cell ID, transport layer addressing information.

m. The source NodeB releases the radio resources assigned to the old link and sends a

NBAP message “Radio Link Deletion Response” message to the source RNC.

13. The source RNC initiates the release of the lur bearer via protocol ALCAP.

14. After releasing the lur bearer, the source RNC sends a RNSAP message “Radio Link


15. The SRNC initiates the release of the lur bearer via protocol ALCAP, and includes in the

request an AAL2 binding ID used to bind the lur bearer with a DCH, which will be acknowledged

by the target RNC.

The signaling procedure of a cross-CN hard handover is illustrated in figure below.



SG SN

2 . R eloca tion R equ iredR A N A P R A N A P

R A N A P R A N A P3 . R eloca tion R eq uest

R A N A P R A N A P9. R eloca tion R eq uest

A ckn ow ledge

R A N A P R A N A P1 . R eloca tion R equ ired

U E R N CSo urce

R N CTa rg e t

M SC /SG S N

R A N A P R A N A P4 . R eloca tion R equest

R A N A P R A N A P

10 . R eloca tion R equ estA ckn ow ledg e

R A N A P R A N A P11 . R eloca tion C om m an d

R A N A P12 . R eloca tion C om m an d R A N A P

R A N A P R A N A P

14 . R eloca tionD etect

R R C13 . D C C H : Ph ysica l C h an n el R econ fig u ra tion N ote 1R R C

5. A L C A P Iu D a taT ra n sp or t B ea rer S etup

N ode BSou rc e

N ode BT a rge t

N B A P N B A P6. R ad io L in k Setup R equ est

N B A P N B A P7. R a d io L in k Setup R espon se

8 . A L C A P Iub D a ta T ran spor t B earer Setup

R A N A P R A N A P

18 . R eloca tionC om plete

R R C R R C17 . D C C H : P h ysica l C h an n el R econ figu ra tion C om p lete N ote 1

R A N A PR A N A P15 . R eloca tion D etect

R A N A P R A N A P19 . R eloca tion C om plete

R A N A P2 0 . Iu R elease C om m an d

R A N A P

N B A P N B A P1 6 . R ad io L in k Fa ilu re In d ica tion

R A N A P2 1 . Iu R elease C om m an d

R A N A P

2 2 . A L C A P Iu D a ta T ran spor t B earerR elease

R A N A P23 . Iu R elease C om p lete

R A N A P

R A N A P24 . Iu R elease C om plete

R A N A P

SG SN /M SC

Figure 32 Cross-CN hard handover signaling procedure

1./2. The SRNC sends a Relocation Required message to the source and target CN

nodes.

3./4. After completing the preparation, the CN node sends a Relocation Required

message to the target RNC to assign appropriate resources.

5. The target RNC and CN node establish a lu bearer between them.

6./7./8. The target RNC assigns RNTI and radio resources to the RRC and radio link and

sends a NBAP message “Radio Link Setup Request” to the target NodeB. The target NodeB

assigns radio link resources, activates the physical layer RX and sends a NBAP message “Radio

Link Setup Response” to the target RNC.



Parameters: Cell ID, TFS, TFCS, frequency, uplink scrambling code and power control

information, etc.

9./10. After completing the preparation, the RNC sends a Relocation Required Acknowledge

message to the CN.

11./12. After completing the preparation, the CN sends a Relocation Command message

to the SRNC.

13. The SRNC sends a RRC message “Physical Channel Reconfiguration” to the UE.

14./15./16. Upon detecting the UE, the target RNC sends a Relocation Detect message to

the two CN nodes. After the UE switches from the old link to the new one, the source NodeB

detects a RL failure in the old link and sends a Radio Link Failure Indication message to the

source RNC.

17. After the RRC with the target RNC is set up and necessary radio resources are

assigned, the UE sends a RRC message “Physical Channel Reconfiguration Complete” to the

target RNC.

18./19. After the UE is successfully handed over to the target RNC and resources are

assigned, the RNC sends a Relocation Complete message to all CN nodes.

20./21. The CN sends a Iu Release Command message to the SRNC.

22. The old RNC-CN lu bearer is released.

23./24. The old RNC sends a Iu Release Complete message to the CN to acknowledge the

release.

3.4 Inter-RAT Handover Procedure Analysis

3.4.1 General Description of the inter-RAT handover procedure

Inter-RAT handovers include handovers from UTRAN to another system (e.g. GSM) and

from another system to UTRAN.

Inter-RAT handover from UTRAN to another system

UE UTRAN

HANDOVER FROM UTRAN COMMAND

Figure 33 Inter-RAT handover from UTRAN, successful case



UE UTRAN

HANDOVER FROM UTRAN COMMAND

HANDOVER FROM UTRAN FAILURE

Figure 34 Inter-RAT handover from UTRAN, failure case

The purpose of the inter-RAT handover procedure is to, under the control of the network,

transfer a connection between the UE and UTRAN to another radio access technology (e.g.

GSM). This procedure may be used in CELL_DCH state. At present, this procedure is only used

in the circuit switching field.

The procedure is initiated when UTRAN orders a UE in CELL_DCH state, to make a

handover to a radio access technology other than UTRAN, e.g. GSM. To initiate the procedure,

UTRAN sends a HANDOVER FROM UTRAN COMMAND message.

Failure cases:

- UE fails to complete requested handover: The UE does not support the requested

handover scenario or cannot establish the connection to the target RAT.

-Invalid HANDOVER FROM UTRAN COMMAND message: The IE "Inter-RAT message"

received within the HANDOVER FROM UTRAN COMMAND message does not include a valid

inter RAT handover message in accordance with the protocol specifications for the target RAT.

- Unsupported configuration in HANDOVER FROM UTRAN COMMAND message: The

UTRAN instructs the UE to perform a non-supported handover scenario, e.g. multiple RAB or to

use a non-supported configuration.

Any of the above exceptions will cause a handover failure.

Inter-RAT handover from another system to UTRAN

UE UTRAN

HANDOVER TO UTRAN COMMAND (sent via other system)

HANDOVER TO UTRAN COMPLETE

Figure 35 Inter-RAT handover to UTRAN

The purpose of the inter-RAT handover procedure is to, under the control of the network,

transfer a connection between the UE and another radio access technology (e.g. GSM) to

UTRAN. The procedure is initiated when a radio access technology other than UTRAN, e.g.



GSM, using radio access technology-specific procedures, orders the UE to make a handover to

UTRAN.

In case UTRAN decides to uses a predefined or default radio configuration that is stored in

the UE, it should include the following information in the HANDOVER TO UTRAN COMMAND

message.

- the IE "U-RNTI" to be assigned;

- the IE "Predefined configuration identity", to indicate which pre-defined configuration of

RB, transport channel and physical channel parameters shall be used; or

- the IE "Default configuration mode" and IE "Default configuration identity", to indicate

which default configuration of RB, transport channel and physical channel parameters shall be

used;

- PhyCH information elements.

In case UTRAN does not use a predefined radio configuration that is stored in the UE, it

should include the following information in the HANDOVER TO UTRAN COMMAND message.

- the IE "U-RNTI" to be assigned;

- the complete set of RB, TrCH and PhyCH information elements to be used.

If an inter-RAT handover fails, the UE will handle the failure. Failure cases include:

Invalid Handover to UTRAN Command message.

Unsupported configuration in HANDOVER TO UTRAN COMMAND message.

UE fails to perform handover.

If the UE fails to establish the connection to the UTRAN, it usually will end the procedure,

e.g. releasing associated resources and resuming the pre-handover connection and send a

failure indicator via the source RAT. Upon reception of a failure indicator from another RAT, the

UTRAN will release associated resources and contexts related to this UE. An exception will

cause a handover failure.

3.4.2 Analysis of Inter-RAT Hard Handover Related IEs

1. HANDOVER FROM UTRAN COMMAND

Table15 IEs in a HANDOVER FROM UTRAN COMMAND message







transaction

identifier



10.3.3.36


info 10.3.3.16


10.3.3.1

Default value is

"now"


RAB information list OP 1 to

<maxRABs

etup>

For each RAB to

be handed over

>RAB info MP RAB info

10.3.4.8

Other information elements

Inter-RAT message MP Inter-RAT

message

10.3.8.8

Analysis of IEs:






mandatory.


-RAB information list: Used to describe each radio access bearer, optional.

Other information elements: Including the following IEs:

-Inter-RAT message: Used to specify the inter-RAT message.

2. HANDOVER TO UTRAN COMMAND

Table16 IEs in a HANDOVER TO UTRAN COMMAND message




New U-RNTI MP U-RNTI Short

10.3.3.48


10.3.3.1

Default value is

"now"

Ciphering algorithm OP Ciphering

algorithm



10.3.3.4

CHOICE specification mode MP

>Complete specification



>>Signalling RB information

to setup list

MP 1 to

<maxSRBs

etup>

For each

signalling radio

bearer

established

>>>Signalling RB information

to setup

MP Signalling RB

information to

setup 10.3.4.24

>>RAB information to setup

list

OP 1 to

<maxRABs

etup>

For each RAB

established

>>>RAB information for setup MP RAB

information for

setup 10.3.4.10


>>UL Transport channel


transport channels

MP UL Transport

channel

information

common for all

transport

channels

10.3.5.24


TrCH information

MP 1 to

<maxTrCH

>

>>>Added or Reconfigured

UL TrCH information

MP Added or

Reconfigured

UL TrCH

information

10.3.5.2


>>DL Transport channel


MP DL Transport

channel



transport channels information

common for all

transport

channels

10.3.5.6


TrCH information

MP 1 to

<maxTrCH

>

>>>Added or Reconfigured

DL TrCH information

MP Added or

Reconfigured

DL TrCH

information

10.3.5.1


>>Uplink DPCH info MP Uplink DPCH

info 10.3.6.88

>>CHOICE mode MP

>>>FDD

>>>>CPCH SET Info OP CPCH SET

Info 10.3.6.13


>>>>Downlink PDSCH

information

OP Downlink

PDSCH

information

10.3.6.30

>>>TDD (no data)

>>Downlink information


MP Downlink

information

common for all

radio links

10.3.6.24

>>Downlink information per

radio link

MP 1 to

<maxRL>

>>>Downlink information for

each radio link

MP Downlink

information for

each radio link

10.3.6.27

>Preconfiguration



>>CHOICE Preconfiguration

mode

MP

>>>Predefined configuration MP Predefined

configuration

identity

10.3.4.5

>>>Default configuration

>>>>Default configuration

mode

MP Enumerated

(FDD, TDD)

Indicates

whether the

FDD or TDD

version of the

default

configuration

shall be used

>>>>Default configuration

identity

MP Default

configuration

identity

10.3.4.0

>>RAB info OP RAB info Post

10.3.4.9

One RAB is

established

>>Uplink DPCH info MP Uplink DPCH

info Post

10.3.6.89


>>CHOICE mode

>>>FDD

>>>>Downlink information


Downlink

information

common for all

radio links Post

10.3.6.25

>>>TDD (no data)

>>Downlink information per

radio link

MP 1 to

<maxRL>

Send downlink

information for

each radio link

to be set-up.

In TDD MaxRL

is 1.



>>>Downlink information for

each radio link

MP Downlink

information for

each radio link

Post

10.3.6.28

Frequency info MP Frequency info

10.3.6.36


power

MP Maximum

allowed UL TX

power

10.3.6.39

CHOICE mode MP

>FDD (no data)

>TDD

>>Primary CCPCH Tx Power MP Primary

CCPCH Tx

Power

10.3.6.59

Analysis of IEs:



mandatory.

-Ciphering algorithm: Used to specify the ciphering algorithm, optional.

-CHOICE specification mode: Used to choose the specification mode, mandatory.


-Signalling RB information to setup list: Used to describe each signaling radio bearer to be

set up, optional.

-RAB information to setup list: Used to describe each radio access bearer, optional.


-UL Transport channel information common for all transport channels: Used to describe

uplink transport channel information common for all transport channels, optional.


added or reconfigured, mandatory.



downlink transport information common for all transport channels, mandatory.


added or reconfigured, mandatory.




-Uplink DPCH info: Used to describe the uplink DPCH, mandatory.

-CHOICE mode: Used to describe the uplink mode (FDD or TDD), optional.



common for all radio links, mandatory.



-Preconfiguration: Used to describe the pre-configuration, mandatory.

3.4.3 Inter-RAT Hard Handover Signaling Procedure

Inter-RAT handover (from UTRAN) signaling procedure (UTRAN->GSM/BSS) The handover procedure described here is from 3G UMTS to 2G-MSC, namely, from

UTRAN to GSM/BSS. The signaling procedure on the GSM side will not be described here in

details for it is not covered by this document. The signaling procedure is illustrated in figure

below.

MAP/E MAP/E

2. PrepareHandover

BSSMAP BSSMAP

4. HandoverRequest Ack

RANAP RANAP

13. Iu ReleaseComplete

BSSMAP BSSMAP3. Handover

Request

MAP/E MAP/E

5. PrepareHandoverResponse

RANAP RANAP

6. RelocationCommand

BSSMAP BSSMAP

8. HandoverDetect

BSSMAP BSSMAP

10. HandoverComplete

MAP/E MAP/E

11. Send EndSignal

Request

MAP/E MAP/E

14. Send EndSignal Response

RANAP RANAP

1. RelocationRequired

UE Node B RNCServing

CN MSC BSC BTS

RRC

7. DCCH : Inter-System HandoverCommand

RRC[Hard Handover]

RR9. Handover Complete

RR

RANAP RANAP12. Iu Release

Command

Figure 36 UTRAN ⇒ GSM/BSS inter-RAT hard handover signaling procedure

1. The SRNC sends a RANAP message “Relocation Required” to CN.



2. The UMTS CN forwards the Relocation Required message to the GSM MSC via the

MAP/E interface.

3. Normal GSM signaling procedure; the MSC sends a BSSMAP message “Handover

Request” to the BSC.

4. Normal GSM signaling procedure; the BSC sends a BSSMAP message “Handover

Request Ack” to the MSC.

5. The GSM MSC/BSS completes the initialization procedure, and the MSC sends a MAP/E

message “Prepare Handover Response” to the CN.

6. The CN sends a RANPA message “Relocation Command” to the SRNC.

7. The SRNC sends a RRC message “HANDOVER FROM UTRAN COMMAND” to the UE

over the existing RRC to perform the inter-RAT handover.


Detect” the MSC.

9. Normal GSM signaling procedure; the UE sends a “Handover Complete” message to the

BSC.


Complete” to the MSC.

11. When the GSM detects the UE, the MSC sends a MAP/E message “Send End Signal

Request” to the CN.

12. The CN sends a RANAP message “lu Release Command” to the SRNC for it to initiate

the release of the resources assigned by the SRNC to the old link.

13. The SRNC releases the bearer resources and sends a “Iu Release Complete” message

to the CN.

14. The CN sends a MAP/E message “Send End Signal Response” to the MSC.

Inter-RAT handover (to UTRAN) signaling procedure (GSM/BSS ->UTRAN) The handover procedure described here is from 2G-MSC to 3G UMTS, namely, from

GSM/BSS to UTRAN. The signaling procedure on the GSM side will not be described here in

details for it is not covered by this document. The signaling procedure is illustrated in figure

below.



RANAP RANAP3. Relocation

Request

BSSMAP BSSMAP

1. HandoverRequired

RANAP RANAP

4. RelocationRequest Ack.

MAP/E MAP/E5. Prepare Handover

Response

MAP/E MAP/E

2. PrepareHandover

BSSMAP BSSMAP6. Handover

Command

MAP/E MAP/E11. Send End Signal

Request

BSSMAP BSSMAP12. ClearCommand

BSSMAP BSSMAP

13. ClearComplete

RANAP RANAP

10. Relocation Complete

UE Node B RNCTarget

CN MSC BSC BTS

MAP/E MAP/E14. Send End Signal

Response

RRC 9. DCCH : Handover Complete RRC

RR7. Handover Command

RR

RANAP RANAP

8. RelocationDetect

Figure 37 GSM/BSS ⇒ UTRAN inter-RAT hard handover signaling procedure

1. The BSC sends a “Handover Required” message to the GSM MSC.

2. The MSC sends a MAP/E message “Prepare Handover” to the UMTS CN.

3. The CN sends a RANAP message “Relocation Request” to the target RNC.

4. The target RNC sends a RANAP message “Relocation Request Acknowledge” to the CN.

5. The CN sends a MAP/E message “Prepare Handover Response” to the MSC.

6. The MSC sends a BSSMAP message “Handover Command” to the BSC.

7. The BSC sends a BSSMAP message “Handover Command” to the UE, which contains

the message HANDOVER TO UTRAN COMMAND sent by the UTRAN to UE.

8. Upon detecting the UE, the target RNC sends a “Relocation Detect” message to the CN.

9. After the RRC with the target RNC is set up and necessary radio resources are assigned,

the UE sends a RRC message “Handover Complete” to the target RNC.

10. Upon completion of the RRC setup, the target RNC sends a RANAP message

“Relocation Complete” to the CN.

11. The CN sends a MAP/E message “Send End Signal Request” to the MSC.

12. The MSC sends a “Clear Command” message to the BSC.

13. The BSC sends a “Clear Complete” message to the MSC.

14. The MSC sends a MAP/E message “Send End Signal Response“ to the CN.



4 Performance Analysis of Handover Procedure

4.1 Performance Indicators and Analysis of Soft Handover

From the perspective of network optimization, it is mainly concerned by three soft handover

performance indicators, i.e. soft handover success rate, soft handover ratio and handover delay.

The target of soft handover ratio is set up in initial stage of the coverage planning, and we can

change the exact ratio by adjusting the antenna and feeder system or power and handover

related parameters later on. The other two indicators directly reflect the soft handover

performance and are closely related to the capabilities of the RAN and UE as well as cooperation

among modules.

Soft handover success rate=number of successful soft handovers/number of soft handover

attempts.

Number of soft handover attempts: Measured by the RNC performance measurement

module. It will increase by 1 (including the RNC-oriented and cell-oriented measurement points)

while each time the RNC sends an ACTIVE SET UPDATE message. Repeat message for

whatever reason is excluded.

Number of successful soft handovers: Measured by the RNC performance measurement

module. It will increase by 1 (including the RNC-oriented and cell-oriented measurement points)

while each time the RNC receives an ACTIVE SET UPDATE COMPLETE message.

Due to the inherent merits of soft handovers, the soft handover success rate is usually very

high, close to 100%. The causes of soft handover failure are listed in table 3, and the statistical

numbers of failture are presented in the performance reports.

As for the soft handover delay, it will be focused on the analysis of the UTRAN structure

because the CN is not involved in the soft handover procedure. Based on the signaling

procedures described above, soft handover delays can be defined as follows:

Soft handover delay on the RNC side: The time delay from when the RNC sends a Radio

Link Setup Request message till it receives a Radio Link Deletion Response message. This is

the case of the combined radio link addition and deletion procedure. In other cases, the definition

depends upon the specific procedure.

Soft handover delay on the UE side: The time delay from when the UE receives an ACTIVE

SET UPDATE message till it sends an ACTIVE SET UPDATE COMPLETE message to the

UTRAN.

The two kinds of delays should be measured within the RNC and UE respectively to obtain

the accurate and actual delay of the soft handover procedure and locate network faults.



4.2 Hard Handover Performance Indicators and Analysis

The Major hard handover performance indicators are the hard handover success rate and

hard handover delay, which can reflect the cooperation and capabilities of UE, RAN and CN as

well as the compatibility between UTRAN and other systems.

Hard handover success rate=number of successful hard handovers/number of hard

handover attempts.

Number of hard handover attempts: It will increase by 1 while each time the SRNC sends a

Physical Channel Reconfiguration message. Repeat message for whatever reason is excluded.

Number of successful hard handovers: It will increase by 1 while each time the SRNC receives a

Physical Channel Reconfiguration Complete message.

The hard handover success rate is generally less than soft handover success rate, and a

hard handover failure is liable to result in a call drop. Because message Handover Command or

Handover Complete is transmitted through the GSM BSC other than the RNC, the RNC cannot

meausre the inter-RAT hard handover success rate yet.

Hard handover delay on the RNC side: The time delay from when the RNC sends a Radio

Link Setup Request message till it receives a Radio Link Deletion Response message.

Hard handover delay on the UE side: Time delay from when the UE receives a Physical

Channel Reconfiguration message or Inter-RAT Handover Command message till it sends a

Physical Channel Reconfiguration Complete message or Handover Complete message to the

UTRAN.

Because the UE does not have the test code for hard handover delay measurement, it is

impossible to obtain the accurate hard handover delay so far, and can only figure it out by

analyzing the serial port data.



List of reference ：

[1] 3GPP R99 25_series, 09/2002

[2] Hu Hanyin, 3G Mobile Communications System, 08/2001

[3] Xie Zhibin, 3G Handover Planning, 08/2001

[4] Zheng Wenlong, Handover Type Analysis Report, 10/2001

[5] Analysis Report on Measurement Control and Measurement Report Messages Used for

Handover, 10/2001

[6] Wang Zuofen, Ma Liyan, WCDMA RNC V100R002 RAA Hard Handover Outside Plant

Performance Test Report, 05/2003/

[7] Tu Rui, WCDMA RNC V100R002 RAA Soft Handover Outside Plant Test Report, 02/2003

[8] Dong Yan, Treatise on WCDMA RNP Traffic Measurement Inicator Analysis, 10/2002

WCDMA RNO Handover Procedure Analysis Guidance

Documents

Transcript of WCDMA RNO Handover Procedure Analysis Guidance