09-WCDMA RNO Handover Principal_20051214

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    Huawei Confidential. All Rights Reserved

    WCDMA Handover Principal and

    Analysis1.0

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    Internal Use 1

    Why mobile systems need

    handover?It is decided by the characters of

    mobile system:

    The mobility of UE

    The mobile system is composed by

    cells which the coverage ability is

    limited.

    Providing the continuous service in

    mobile system is the basic element inQoS.

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    Internal Use 2

    Object

    Upon completion this course, you will

    be able to:

    The basic definitions of Handover The algorithms of handover

    decision

    The handover flow

    The parameters of handover

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    Internal Use 3

    Chapter 1 Introduction of Handover

    Chapter 2 Measurement of Handover

    Chapter 3 The Basic Handovers

    Chapter 4 Blind Handover and

    Direct Retry Algorithm

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    Internal Use 4

    The Purpose of Handover

    Providing the continuous service in mobile system is the basic

    element in QoS.

    The load balance: sharing the resource

    The hierarchy divided by speed and service: high efficiency of usingresource

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    Internal Use 5

    The Basic Concepts of Handover

    Active Set Monitored Set Detected set Event reporting

    Event reporting to Periodic reporting Periodic reporting Radio Link (RL)

    Radio Link Set (RLS) Combination way:

    maximum ratio combination selection combination

    The soft handover gain

    CPICH Soft handover, softer handover, hard handover Blind handover

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    The Categories of Handover

    According to the signaling characters:

    Soft handover (softer handover)

    Hard handover According to the properties of source cell and target cell

    Intra-frequency handover

    Inter-frequency handover

    Inter-mode handover (FDD TDD) Inter-system handover (UMTS GSM/CDMA2000)

    According to the purpose of handover

    Based on Coverage

    Based on Load (Optional)

    Based on mobility of UE (Optional)

    Based on Service (Optional)

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    The Characters of Different Handovers

    Item Soft Handover Hard Handover

    The numbers of RL

    in active set after

    handover

    Several One

    Interruption duringhandover

    No Yes

    The frequencies of

    cells

    Only happened

    in Intra-

    frequency cells

    Can be happened in

    Intra-frequency cells or

    Inter-frequency cells

    Comparison between soft handover and hard handover:

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    The Characters of Different Handovers

    During softer handover, the uplink signaling are

    combined in NodeB by maximum ratio combination, butduring soft handover they are combined in RNC by

    selection combination.

    Compare to later one, the maximum ration combination

    can get more gain. So the performance of maximum

    ration combination is better.

    Since softer handover is completed in NodeB, it do not

    consume transport resource of Iub.

    Comparison between soft handover and softer handover:

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    RNC

    NodeB 2NodeB 1

    Soft Handover

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    RNC (WFMR)

    NodeB

    Softer Handover

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    Hard Handover

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    Three Steps of Handover

    Decision

    Execute

    Measurement

    Measurement Measurement control Measurement execution and

    the result processing The measurement report Mainly accomplished by UE

    Decision Based on Measurement The application and

    distribution of resource Mainly accomplished by

    RRM in RNC

    Execution The process of signaling Support the failure drawback Measurement control refresh

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    Questions

    The differences among Soft handover,softer handover and hard handover

    Typical application scenarios

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    Summary

    This chapter focus on the purpose of handovers and the

    categories of handover in WCDMA.

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    Chapter 1 Introduction of Handover

    Chapter 2Measurement of Handover

    Chapter 3 The Basic Handovers

    Chapter 4 Blind Handover and

    Direct Retry Algorithm

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    Chapter 2 Measurement of Handover

    Section 1 Measurement control and

    measurement report

    Section 2 The basic definitions of measurement

    Section 3 Intra-frequency measurement event

    Section 4 Inter-frequency and

    inter-system measurement event

    Section 5 UE internal measurement

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    Measurement Control and Measurement

    Report

    Measurement Control

    UE UTRAN

    MEASUREMENT CONTROL

    Measurement Control, normal case

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    Measurement Control and Measurement

    Report

    Measurement report

    UE UTRAN

    MEASUREMENT REPORT

    Measurement report, normal case

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    Chapter 2 Measurement of Handover

    Section 1 Measurement control and

    measurement report

    Section 2 The basic concepts of measurement

    Section 3 Intra-frequency measurement event

    Section 4 Inter-frequency and

    inter-system measurement event

    Section 5 UE Internal Measurement

    Th B i C t f M t

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    The Basic Concepts of Measurement

    The measurement values of Handover

    Intra-frequency and inter-frequency: CPICH RSCP CPICH

    Ec/N0Path loss Inter-frequencyCPICH RSCPCPICH Ec/N0

    Inter-systemGSM Carrier RSSI BSIC IdentificationBSIC

    Reconfirmation

    The reporting methods of measurement

    Periodic reporting

    Event reporting

    The events of reporting

    Intra-frequency events1A,1B,1C,1D,1F

    Inter-frequency events2D,2F,2B,2C Inter-system events3A,3C

    Others6G,6F

    M t M d l

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    Internal Use 21

    Measurement Model

    Layer 1filtering

    Layer 3filtering Evaluation

    of reporting

    criteria

    A DB C

    C'

    parameters parameters

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    Internal Use 22

    Reporting Criterion

    Reporting Criterion

    Decision formula: for example, 1A event :1.Path Loss

    2.Other measurement

    Relative threshold, Absolute threshold, Hysteresis, Time

    to trigger

    ),2/(10)1(1010 11

    aBest

    N

    i

    iNew HRLogMWMLogWLogMA

    ),2/(10)1(1010 11

    aBest

    N

    i

    iNew HRLogMWMLogWLogMA

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    Internal Use 23

    Key Parameters

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    Internal Use 24

    Chapter 2 Measurement of Handover

    Section 1 Measurement control and

    measurement report

    Section 2 The basic definitions of measurement

    Section 3 Intra-frequency measurement events

    Section 4 Inter-frequency and

    inter-system measurement eventsSection 5 UE Internal Measurement

    Intra frequency Measurement Events

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    Internal Use 25

    Intra-frequency Measurement Events

    All intra-frequency measurement report events are identified with

    1X :

    1AA primary pilot channel enters the reporting range. Whenthe active set of UE is full, UE stops reporting 1A event;

    1BA primary pilot channel leaves the reporting range;

    1CThe primary pilot channel in a non active set is better than

    the primary pilot channel in an active set;

    1DThe best cell changes;

    1EThe measurement value of a primary pilot channel exceeds

    the absolute threshold

    1F, The measurement value of a primary pilot channel is lower

    than the absolute threshold

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    Internal Use 26

    Chapter 2 Measurement of Handover

    Section 1 Measurement control and

    measurement report

    Section 2 The basic definitions of measurement

    Section 3 Intra-frequency measurement events

    Section 4 Inter-frequency and

    inter-system measurement eventsSection 5 UE Internal Measurement

    Inter frequency Measurement Events

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    Internal Use 27

    Inter-frequency Measurement Events

    Inter-frequency measurement events are identified with 2X 2A: The best frequency changes;

    2B: The estimated quality value of the used frequency is lower thana certain threshold, and that of the non-used frequency is higher

    than a certain threshold;

    2C: The estimated quality value of the non-used frequency is higher

    than a certain threshold;

    2DThe estimated quality value of the used frequency is lower than a

    certain threshold

    2E:The estimated quality value of the non-used frequency is lower

    than a certain threshold

    2F:The estimated quality value of the used frequency is higher thana certain threshold

    Inter system Measurement Events

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    Internal Use 28

    Inter-system Measurement Events

    Inter-system measurement events are identified with

    3X 3A:The estimated quality value of the used UTRAN frequency

    is lower than a certain threshold, and that of the other system

    is higher than a certain threshold;

    3B: The estimated quality value of the other system is lower

    than a certain threshold; 3C: The estimated quality value of the other system is higher

    than a certain threshold;

    3D: The best cell in the other system changes

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    Internal Use 29

    Chapter 2 Measurement of Handover

    Section 1 Measurement control and

    measurement report

    Section 2 The basic definitions of measurement

    Section 3 Intra-frequency measurement events

    Section 4 Inter-frequency and

    inter-system measurement eventsSection 5 UE Internal Measurement

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    Internal Use 30

    UE Internal Measurement

    UE Internal measurement events are identified with 6X

    6G: The time difference between downlink receiving anduplink transmission of the UE is shorter than an absolute

    threshold;

    6F: The time difference between downlink receiving and

    uplink transmission of the UE is bigger than an absolute

    threshold;

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    Internal Use 31

    Questions

    How many events are there in intra-frequency measurement?What are they?

    How many events are there in UE internal measurement?

    How many events are there in inter-frequency measurement?

    What are they?

    S

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    Internal Use 32

    Summary

    This chapter covers intra-frequency measurement, inter-

    frequency measurement, inter-system measurement and UE

    internal measurement from their definitions and applicationscenarios.

    Summary

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    Internal Use 33

    Chapter 1 Introduction of Handover

    Chapter 2 Measurement of Handover

    Chapter 3The Basic HandoversChapter 4 Blind Handover and

    Direct Retry Algorithm

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    Internal Use 34

    Chapter 3 The Basic Handovers

    Section 1 Soft Handover

    Section 2 Intra-frequency Hard Handover

    Section 3 Inter-frequency Hard Handover

    Section 4 Inter-system Hard Handover

    Section 5 HSDPA Handover

    Section 6 Compressed Mode

    B i f I t d ti f S ft H d

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    Internal Use 35

    Brief Introduction of Soft Handover

    Characters of Soft Handover During handover, UE has several RLs with different cells----

    active set. The handover among different cells which are in same RLS can

    be softer handover.

    Soft handover:

    Selection combination in uplink

    Maximum combination in downlink

    Softer handover Maximum combination in uplink and downlink

    B i f I t d ti f S ft H d

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    Internal Use 36

    Brief Introduction of Soft Handover

    Advantages Soft handover gain:

    Multi-Cell gain: Multiple irrelated soft handover branches lowthe required margin for fading

    Macro Diversity Combining gain: Gain for the linkdemodulation of the soft handover:

    Load balance: Different cells receive the signals from UE inuplink, which can decrease the transmission power of UE. AndUE receive signal from different cells, which also can decreasethe transmission power of base station.

    Decrease the possibility of call drop caused by ping-ponghandover.

    Disadvantages More resource needed in downlink, especially for the code

    resource of BE service. Usually, the gain of downlink power is negative. When the downlink power from different cells is not balanced, it

    will bring side-effect.

    Measurement of Soft Handover

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    Internal Use 37

    Measurement of Soft Handover

    The measurement of soft handover/softer handover

    Measurement valueCPICH RSCPCPICH Ec/NoPathloss

    Process of MeasurementLayer 1 filter, Layer 2 filter Reporting way

    Periodic reporting

    Event reporting

    Event type1A1B1C1D1F

    UE measures the time difference between CFN and SFN

    Reporting rules: trigger condition, Relative threshold,

    Absolute threshold, Hysteresis, Time to trigger

    Event reporting to periodic reporting

    The Events of Soft Handover Measurement

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    Internal Use 38

    The Events of Soft Handover Measurement

    Soft/softer handover measurement events

    Intra-frequency events reporting:

    1AA primary pilot channel enters the reporting range.When the active set of UE is full, UE stops reporting 1A event;

    1BA primary pilot channel leaves the reporting range;

    1CThe primary pilot channel in a non active set is better

    than the primary pilot channel in an active set;

    1DThe best cell changes;

    1EThe measurement value of a primary pilot channel

    exceeds the absolute threshold

    1F, The measurement value of a primary pilot channel is

    lower than the absolute threshold

    The Decision Algorithm of Soft Handover

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    Internal Use 39

    The Decision Algorithm of Soft Handover

    Soft/softer handover decision

    1Aadd RL into active set

    1BDelete RL from active set

    1Creplace cell

    1Dchange best cell

    The Execution of Soft Handover

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    Internal Use 40

    The Execution of Soft Handover

    Soft handover execution

    The update principal of measurement control

    Configure the neighbor cells and the parametersaccording to best cell

    RLC mode

    AM mode is used for measurement control

    UM mode is used for measurement reporting

    The compensation and restriction of soft handover

    From event reporting to periodic reporting

    Parametersthe time value for periodic reporting,

    the number for reporting times

    Soft Handover Flow (add RL)

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    Internal Use 41

    Soft Handover Flow (add RL)

    The execution of soft handover (add RL)

    Soft Handover Flow (del RL)

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    Internal Use 42

    Soft Handover Flow (del RL)

    The execution of soft handover (del RL)

    Key Parameters

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    Key Parameters

    Relative threshold Set 1A, 1B value separately 1A < 1Bwhich makes deleting RL is more difficult, and it can

    avoid ping-pong handover Usually 1A: 3dB; 1B: 6dB

    Time to trigger Each event can be set separately Usually, 1B>1Awhich makes deleting RL is more difficult, and

    it can avoid ping-pong handover Usually, 1A: 320ms, 1B: 640ms

    Layer 3 filter coefficient Only one value for all intra-frequency measurement Sensitive to the delay of event trigger and ping-pong handover Usually3

    absolute threshold of soft handover

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    Internal Use 44

    Chapter 3 The Basic Handovers

    Section 1 Soft Handover

    Section 2Intra-frequency Hard Handover

    Section 3 Inter-frequency Hard Handover

    Section 4 Inter-system Hard Handover

    Section 5 HSDPA Handover

    Section 6 Compressed Mode

    The Characters of Intra-frequency Hard Handover

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    Internal Use 45

    The Characters of Intra frequency Hard Handover

    Characters UE only has one RL with one cell in the process of handover Disconnect UE with the original cell, then hand it over to target

    cell The working frequency of source cell and target cell are same

    Advantages Enhance the using efficiency of the OVSF code and hardware

    resource Disadvantages

    High call drop possibility because of the intra-frequencyinterference

    Application scenarios

    Without Iur interface between two RNCs or the Iur interface jam(only happened in inter-RNC handover)

    The different strategies can be used for different conditions, such

    as code resource condition, the QoS condition and so no.

    The Measurement, Decision and Execution of

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    Internal Use 46

    The Measurement, Decision and Execution of

    Intra-frequency Hard Handover

    Measurement

    Similar to soft handover

    Decision

    1D event

    Execution

    UE reports CFN-SFN information

    Synchronization hard handover

    Use the original DOFF value

    Continuous CFN

    UE does not report CFN-SFN information

    The hard handover based on timingRe-configure DOFF

    Calculate CFN according to DOFF

    Intra-frequency Hard Handover Flow

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    Internal Use 47

    q y

    Intra-frequency hard handover flow

    UE1.RADIO LINK SETUP REQUEST

    Target

    NODEB

    Source

    NODEBSRNC

    2. RADIO LINK SETUP RESPONSE

    3.ALCAP establish

    4. PHYSICAL CHANNEL RECONFIGURATION

    5. RADIO LINK

    FAILURE INDICATION

    6. PHYSICAL CHANNEL RECONFIGURATION COMPLETE

    7. RADIO LINK

    DELETION REQUEST

    8. RADIO LINK

    DELETION RESPONSE

    9.ALCAP release

    Key Parameters

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    Internal Use 48

    Key Parameters

    Handover decision threshold based on BE speed

    UE should do soft handover when the speed of BE service isless than the threshold.

    UE should do intra-frequency hard handover when the speed of

    BE service is greater than the threshold.

    The parameters about 1D event:

    time to triggerhysteresis

    The parameters should be set accord with the Qos

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    Internal Use 49

    Chapter 3 The Basic Handovers

    Section 1 Soft Handover

    Section 2 Intra-frequency Hard Handover

    Section 3Inter-frequency Hard Handover

    Section 4 Inter-system Hard Handover

    Section 5 HSDPA Handover

    Section 6 Compressed Mode

    The Brief Introduction of Inter-frequency

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    Internal Use 50

    q y

    Hard Handover Characters

    The working frequency is different after handover

    The compressed mode needed if the UE only has one receiver Usually, the timing re-initiation hard handover is used for hard

    handover Advantages

    Compare to intra-frequency hard handover, the success

    possibility is higher The load balance among cells with different frequencies Can realize the reasonable configuration for hierarchy cells

    Disadvantages Compressed mode results in extra radio resource occupied The timing re-initiation hard handover increase the time of

    handover and the risk of call drop Application scenarios

    Disconnected coverage Handover based on load Hierarchy cells

    The Inter-frequency Hard Handover Measurement

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    Internal Use 51

    Values and Events

    The Inter-frequency hard handover measurement values Measurement values:

    CPICH RSCPCPICH Ec/N0 Different handover purpose for different measurement type:

    In the edge of carrier coverage: CPICH RSCP

    In the center of carrier coverage: CPICH Ec/No

    The Measurement Values and Events of Inter-

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    Internal Use 52

    frequency Hard Handover

    Measurement reporting Periodic reporting

    Event reporting

    2A: The best frequency changes;

    2B: The estimated quality value of the used frequency is

    lower than a certain threshold, and that of the non-used

    frequency is higher than a certain threshold;

    2C: The estimated quality value of the non-used frequency is

    higher than a certain threshold;

    2DThe estimated quality value of the used frequency is lower

    than a certain threshold

    2E:The estimated quality value of the non-used frequency islower than a certain threshold

    2F:The estimated quality value of the used frequency is

    higher than a certain threshold

    Compressed Mode Initiation in Inter-frequency

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    Internal Use 53

    p q y

    Hard Handover

    Conditions for measurement initiated 2D eventcan be used to enable the compressed mode

    to perform inter-frequency measurement. Enable inter-frequency measurement by moving speed

    estimation algorithm Conditions for Measurement stopping

    2F eventAfter the best cell is changed, the cell does not contain

    inter-frequency neighbor cells. Inter-frequency measurement timer expired Because the moving speed of UE is changed, the inter-

    frequency handover measurement is stopped by cell

    hierarchy algorithm.

    Cells Hierarchy Algorithm Based on UE

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    Internal Use 54

    Moving Speed

    When UE is in one of the hierarchy cells, the moving speed

    estimation algorithm is initiated Handover events in a while decides whether the speed of UE

    satisfies the current cell hierarchy condition

    UE is remained in the current cell if the speed is medium.

    If the speed is very high, it will be handed over to higher

    hierarchy cell. And if not, hand it over to lower hierarchy cell. UEsmoving speed decided the result.

    If the hierarchy is configured by different frequencies, theinter-frequency blind handover or inter-frequencymeasurement handover can be initiated.

    If the hierarchy is configured by one frequency, the intra-frequency handover can be initiated.

    Inter-frequency Hard Handover Decision

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    Internal Use 55

    Algorithm

    The inter-frequency hard handover decision

    The coverage triggers the handover

    2B event

    the quality in the used frequency is lower than absolute

    threshold, but the quality in another non-used frequency

    is higher than another absolute threshold.

    The load triggers handover

    2C event

    the quality in another frequency is higher than an

    absolute threshold

    The Execution of Inter-frequency Hard Handover

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    Internal Use 56

    q y

    The execution of Inter-frequency hard handover UE report the timing information

    UE with two receivers does not need compressed mode.

    Synchronization hard handoverUsing the original DOFF

    Continued CFN UE does not report timing information

    UE with a single receiver has to initiate compressed mode

    If the NodeB of target cell is not the same one which the cellsin active set belong to

    the timing re-initiation hard handover

    Re-configure DOFF

    Calculate the CFN according to DOFF

    If the NodeB of target cell is the same one which the cells inactive set belong to Calculate the target cell timing relationship

    Synchronization hard handover

    Using the original DOFF

    Continued CFN

    Inter-frequency Hard Handover Flow

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    Internal Use 57

    Signaling flow

    UE

    1.RADIO LINK SETUP REQUEST

    TargetNODEB

    SourceNODEB SRNC

    2. RADIO LINK SETUP RESPONSE

    3.ALCAP established

    4. PHYSICAL CHANNEL RECONFIGURATION

    5. RADIO LINK

    FAILURE INDICATION

    6. PHYSICAL CHANNEL RECONFIGURATION COMPLETE

    7. RADIO LINK

    DELETION REQUEST

    8. RADIO LINK

    DELETION RESPONSE

    9.ALCAP released

    Key Parameters (I)

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    Internal Use 58

    Key Parameters (I)

    Inter-frequency coverage handover parameters:

    Inter-frequency measurement reporting: periodic reporting or

    event reporting Inter-frequency measurement values: CPICH Ec/No or CPICH

    RSCP

    Inter-frequency measurement layer 3 filter coefficient, delay

    trigger time and hysteresis

    Inter-frequency initiated and stopped threshold: Considering thedifferent demands of CPICH Ec/No and CPICH RSCP for PS

    domain and CS domain, the different 2D and 2F parameters are

    configured.

    Inter-frequency handover based on coverage: the quality

    threshold of target cell Using frequency quality threshold in inter-frequency hard

    handover

    The minimum access threshold for inter-frequency handover

    Key Parameters (II)

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    Internal Use 59

    Key Parameters (II)

    Inter-frequency handover parameters caused by non-

    coverage ability Inter-frequency measurement layer 3 filter coefficient, delay trigger

    time and hysteresis

    Inter-frequency handover based on non-coverage ability

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    Internal Use 60

    Chapter 3 The Basic Handovers

    Section 1 Soft Handover

    Section 2 Intra-frequency Hard Handover

    Section 3 Inter-frequency Hard Handover

    Section 4Inter-system Hard Handover

    Section 5 HSDPA Handover

    Section 6 Compressed Mode

    The Brief Introduction of Inter-system Hard

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    Internal Use 61

    Handover

    Application scenarios WCDMA FDD GSM

    WCDMA FDD WCDMA TDD WCDMA FDD CDMA2000

    Characters Different radio access technology is used after handover Usually, compressed mode should be used to help the

    measurement Advantages For coverage, it can solve the problems from one system

    to another system For capacity, it can enhance the utilizing efficiency of old

    equipments(2G->3G)

    Disadvantages The flow is complicated, and it demands higher

    compatibility for equipments Demands more complicated UE

    The Measurement for Inter-system

    C

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    Internal Use 62

    Compressed Mode Initiated

    The inter-system measurement (GSM measurement)

    Measurement type:GSM Carrier RSSI

    BSIC Identification

    BSIC Reconfirmation

    The process of measurement: layer 1 filter, layer 3 filter

    Measurement reporting

    Event reporting

    2D Event: initiate GSM measurement

    2F Event: stop GSM measurement

    The Inter-system Hard Handover

    D i i Al ith

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    Internal Use 63

    Decision Algorithm

    The inter-system hard handover decision

    Inter-system handover caused by coverageEvent reporting:

    3A eventThe estimated quality value of the used

    UTRAN frequency is lower than a certain threshold, and

    that of the other system is higher than a certain

    threshold .Periodic reporting:

    EvaluationAccording to the periodic reported GSM

    RSSI measurement value and the BSIC confirming state

    of target cell of GSM system, and meanwhile the UE

    evaluates the GSM RSSI of target cell is greater than theabsolute threshold, then consider the cell confirmed by

    BSIC.

    The Inter-system Hard Handover

    D i i Al ith

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    Internal Use 64

    Decision Algorithm

    The inter-system hard handover decision

    Inter-system handover caused by non-coverageEvent reporting

    3C event: The estimated quality value of the other

    system is higher than a absolute threshold.

    Inter-system Handover Flow

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    Internal Use 65

    The execution of inter-system handover

    1. RelocationRequired 2. Prepare

    Handover3. Handover

    Request

    4. HandoverRequest Ack

    12. Iu ReleaseCommand

    13. Iu ReleaseComplete 14. Send End

    Signal Response

    5. PrepareHandover6. Relocation

    Command7.DCCH: Handover

    from UTRAN Command8. Handover

    Detect

    9. Handover Complete

    10. HandoverComplete

    11. SendEnd

    UE Node B SRNC CN MSC BSC

    Key Parameters (I)

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    Internal Use 66

    y ( )

    Inter-system handover caused by coverage parameters Inter-system measurement initiated and stopped threshold:

    Considering the different demands of CPICH Ec/No and CPICHRSCP for PS domain and CS domain, the different 2D and 2Fparameters are configured

    Inter-system measurement values (2D, 2F)

    CPICH Ec/No

    CPICH RSCP BSIC confirmed (Optional) Inter-system handover caused by coverage parameters

    configure the GSM RSSI threshold of CS domain and PSdomain separately

    Using inter-system frequency quality handover threshold Configure the delay trigger time, hysteresis for each event

    Key parameters (II)

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    Internal Use 67

    y ( )

    Inter-system handover caused by non-coverage parameters The period of inter-system measurement report

    The decision threshold for inter-system handover: configure theCS, PS, signaling separately

    Time delay trigger : configure BSIC with acknowledged andunacknowledged mode

    Inter-frequency measurement layer 3 filter coefficient and

    hysteresis Penalty time

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    Internal Use 68

    Chapter 3 The Basic Handovers

    Section 1 Soft Handover

    Section 2 Intra-frequency Hard Handover

    Section 3 Inter-frequency Hard Handover

    Section 4 Inter-system Hard Handover

    Section 5HSDPA Handover

    Section 6 Compressed Mode

    The Brief Introduction HSDPA Handover

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    Internal Use 69

    Application Scope

    Related to the handover between the HS-DSCH channel

    of HSDPA

    The service cell update of HSDPA

    HSDPADCH

    Purpose

    the service which data rate satisfied the threshold ofHSDPA should use the HSDPA resource. To realize the

    maximum traffic volume, the service cell with HS-DSCH

    should be the best cell in the active set.

    HSDPA Measurement

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    Internal Use 70

    HSDPA handover measurement

    Measurement type: CPICH RSCPCPICH Ec/N0Path

    loss

    The process of measurement: layer 1 filter coefficient and

    layer 3 filter coefficient

    Measurement reporting

    Periodic reportingEvent reporting

    Reporting type: 1A, 1B, 1C, 1D

    The event reporting converted to periodic

    reporting

    Service Cell Change Algorithm

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    Internal Use 71

    Change the service cell for HS-PDSCH in active set

    According to 1D event to decide the best cell, and hand it over

    to the cell.

    After handover, initiate the timer to forbid the ping-pong

    handover

    Change the service cell for HS-PDSCH after hard handover

    Establish the HSDPA channel in target cell with hard handover Establish DCH channel if the target cell can not support HSDPA

    Change the service cell for HS-PDSCH during soft handover

    The service should be handed over to the cell which support

    HSDPA when the best cell does not support HSDPA and the

    original service cell for HSDPA already deleted from active set.

    Direct Retry for HSDPA

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    Internal Use 72

    Direct retry from R99 cell to R5 cell Conditions

    UE in cell 1 requests to establish an BE/streaming RAB, orUE of Cell-FACH state has much BE/streaming data

    volume to transfer (Switch channel type from FACH to HS-DSCH)

    Existing cells: support HSDPA, with same coverage area

    Advantage: To make full use of HSDPA resource

    Direct retry

    HSDPA

    resource

    R5CELL ACarrier B

    R99CELL2 R99 CELL 1Carrier A

    Service Cell Update Flow

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    Internal Use 73

    Key Parameters

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    Internal Use 74

    HSDPA handover protecting timer

    Configure the T-HSDPA to avoid the influence for the dataservice caused by the ping-pong handover. During this period,

    the service cell for HSDPA can not be changed.

    The value scope ( 01024) seconds

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    Internal Use 75

    Chapter 3 The Basic HandoversSection 1 Soft Handover

    Section 2 Intra-frequency Hard Handover

    Section 3 Inter-frequency Hard Handover

    Section 4 Inter-system Hard Handover

    Section 5 HSDPA Handover

    Section 6Compressed Mode

    The Purpose of Compressed mode

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    Internal Use 76

    Purpose

    Measure the inter-frequency cell or inter-system cell under

    FDD mode

    Cause:

    Downlink compressed:

    Since one receiver only can work in one frequency, the

    UE has to stop working if it is going to measure the signalfrom another frequency cell. To ensure the downlink

    service unaffected, the remained data should be sent in

    the limited time.

    Uplink compressed

    UE should stop the uplink transmission when the uplinkworking frequency is very close to the measured

    frequency, for example GSM 1800/1900 is very close to

    the UMTS FDD uplink working frequency.

    Compressed Mode Sketch Map

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    Internal Use 77

    Compressed mode sketch map

    One frame

    (10 ms) Transmission gap available fo r

    inter-frequency measurements

    The realization Methods of Compressed mode

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    Internal Use 78

    Realization Methods SF/2

    Should use the replace scrambling code

    Advantage: easy to handle for RNCDisadvantage: occupied the resource of NodeB, decrease the

    utilizing efficiency of OVSF, influenced the coverage andincreased interference caused by the replace scrambling code.

    rate matching/puncturing

    Decrease the coding redundancyAdvantage: easy to handle for RNC; the SF 4 can be used; no

    influence to utilizing efficiency of OVSF

    Disadvantage: limited to the property of channel coding;decreased the coding gain

    higher layer schedulingMAC can restrict TFCS to change the downlink data rate.

    Advantage: the interference is lower

    Disadvantage: complicated for higher layer, only fit for non-timing data service.

    Questions

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    Internal Use 79

    What are the differences between soft handover and softer

    handover?

    What is compressed mode?

    Draw out the hard handover signaling flow.

    Summary

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    Internal Use 80

    This chapter focus on the basic handovers in WCDMA: soft handover,

    softer handover, intra-frequency hard handover, inter-frequency hardhandover and inter-system hard handover. It also introduced the

    application scenarios for these different handovers

    Meanwhile, compressed mode is introduced in this chapter

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    Internal Use 81

    Chapter 1 Introduction of Handover

    Chapter 2 Measurement of Handover

    Chapter 3 The Basic Handovers

    Chapter 4Blind Handover and

    Direct Retry Algorithm

    Application scenarios and Trigger Conditions

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    Internal Use 82

    RRC direct retry During the initial signaling establishment, the RRC connection is

    refused. RRC redirection

    The initial signaling is already established, but the requestedcell refused and RRC direct retry is failed.

    RAB direct retry The signaling is established successfully, but the service

    establishment is failed. Blind handover

    Load balanced between inter-frequency cells RRC direct retry RAB direct retry

    RRC Direct Retry (I)

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    Internal Use 83

    Application scenarios (I)

    Same sector covered by different frequencies

    cell1

    cell2

    1 2

    3

    RRC Direct Retry (II)

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    Internal Use 84

    Application scenarios (II)

    The soft handover area

    cell1 cell2

    1

    2

    3

    UE camp ing

    cel l1 first

    RRC Retry Key Parameters

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    Internal Use 85

    DRMaxNumber The maximum allowed retry times for the direct retry module

    after the initial failure CsThreshold.

    When the signal quality of a cell is higher than this threshold,this cell will be included in the direct retry candidate set.

    MinSignalRequired

    The basic access threshold described in Section 2.2.8,namely the minimum requirement of the UE form the receivingCPICH Ec/No density during normal demodulation.

    MaxRelatingTime The maximum time that the RACH measurement report can

    continue to be used for the direct retry candidate set.

    RRC Redirection

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    Internal Use 86

    Application scenarios

    The signaling connection is failed, and RRC retry is also failed.

    Inter-freq cell

    cell1

    1

    2

    1

    GSM cell

    1

    RRC Direct Retry and Direction

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    Internal Use 87

    The trigger condition should be the signaling permitting failure

    if congestion happed, the RRC connection signaling is refused. Advantages and disadvantages:

    RRC direct retry can ensure the time delay. RRC direction is more flexible, and can select to GSM cell. But

    the time delay is longer.

    RAB Direct Retry

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    Internal Use 88

    Application scenarios

    UTRAN CELL

    GSM CELL

    1 3

    4

    Signaling process

    1 RAB Assignment (from CN)2 SRNS relocation (to CN)

    3 Handover from UTRAN ( Inform UE

    access to GSM system)

    4 Handover Complete (GSM message)

    2

    CN

    Questions

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    Internal Use 89

    What is the difference of RRC direct retry and RRCredirection?

    What are the trigger conditions for RRC direct retry and RRC

    direction?

    Summary

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    Internal Use 90

    This chapter focus on RRC direct retry, RRC redirection, the

    application scenarios of RAB direct retry and blind handover.

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