03 OWJ200103 WCDMA Handover Algorithm and Relevant Parameters (1)

OWJ200103_WCDMA Handover Algorithm and Relevant Parameters

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Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA Handover Algorithm and Relevant Parameters



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Page1Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved.

Objectives

z Upon completion of this course, you will be able to:

Know the features of handover

Know the algorithms of handover

Know the handover procedure

Know the parameters of handover

z Handover types supported by UMTS can be classified as:

Intra-frequency handover

Inter-frequency handover

Inter-RAT handover



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Contents

1. Intra-Frequency Handover

2. Inter-Frequency Handover

3. Inter-RAT Handover



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Contents


1. Intra-Frequency Handover Overview

2. Intra-Frequency Handover Procedure



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Intra-Frequency Handover Overview

z Characters of Intra-Frequency Handover:

z The carrier frequencies of the current cell and target cell are the

same

Intra-frequency soft handover

Soft Handover

Softer Handover

Intra-frequency hard handover

z Intra-frequency handover consists of two types,

Intra-frequency soft handover: more than one radio link are set up for the UE.

Intra-frequency hard handover: only one radio link is set up for the UE.

z Intra-frequency soft handover is more commonly used than intra-frequency hard handover. Intra-frequency hard handover is used only in some special scenarios, for instance, when there is no Iurinterface between two RNCs.

z Intra-Frequency soft handover is a function in which the UE is connected to several cells at the same time. Addition or release of radio links are controlled by the ACTIVE SET UPDATE procedure.

z During soft handover, a UE is in the overlapping cell coverage area of two sectors belonging to different NodeBs. The communications between UE and NodeB take place concurrently via two channels from each NodeB separately.

z During softer handover, a UE is in the overlapping cell coverage area of two adjacent sectors of a NodeB. The communications between UE and NodeB take place concurrently via two channels, one for each sector separately.



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z Comparison between soft handover and hard handover:

z Comparison between soft handover and softer handover :

z During softer handover, the uplink signaling are combined in NodeB by maximum ratio combination, but during soft handover they are combined in RNC by selective combination

z Compare to later one, the maximum ratio combination can get more gain. So the performance of maximum ratio combination is better

z Since softer handover is completed in NodeB, it does not consume transport resource of Iub



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z Intra-Frequency Hard Handover :

No Iur interface

Iur interface is congested

High-speed Best Effort (BE) service Handover

Admission fails for soft handover

z Intra-frequency hard handover refers to a handover where all the old radio links are released before the new radio links are established. Compared with soft handover, intra-frequency hard handover uses fewer resources.

z The scenarios of intra-frequency hard handover are as follows:

The UE needs to perform the intra-frequency handover between two cells configured in different RNCs. No Iur interface is present between RNCs.

The UE needs to perform the intra-frequency handover between two cells configured in different RNCs. The Iur interface is congested between RNCs.

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

The intra-frequency soft handover admission fails and intra-frequency hard handover is allowed. When intra-frequency soft handover admission fails because of a congestion problem of the target cell, the RNC tries an intra-frequency hard handover with a lower service bit rate.

z The INTRA_FREQUENCY_HARD_HANDOVER_SWITCH parameter in the SET CORRMALGOSWITCH command is used to determine whether to enable intra-frequency hard handover. By default, this switch is ON.



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Contents






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Intra-Frequency Handover Procedure

z The following figure shows handover procedure

Decision

Execution

Measurement

Decision phase

Execution phase

Measurement phase

Yes

NoAre handover criteria satisfied?

Perform a handover and update relative parameters

Measure the CPICH Ec/N0 of the serving cell andits neighboring cells as well as the relative timedifference between the cells

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

z After the UE transits to CELL_DCH state in connected mode during a call, the RNC sends a measurement control message to instruct the UE to take measurements and report the measurement results.

z Upon receiving measurement report from the UE, the RNC makes a handover decision and performs the corresponding handover.



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Contents




1. Intra-Frequency Handover Measurement

2. Intra-Frequency Handover Decision and Execution

3. Neighboring Cell Combination Algorithm

4. Rate Reduction after Admission Failure of SHO



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Intra-Frequency Handover Measurement

z MEASUREMENT CONTROL for HO includes

Measurement ID

Neighboring cell list

Measurement Quantity

Measurement Report Quantity

Report Criteria

z The example for intra-frequency HO measurement control



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z MEASUREMENT REPORT

The purpose of the measurement reporting procedure is to transfer

measurement results from the UE to UTRAN

Based on the algorithm in measurement

control, the UE will measure the signal

strength or quality and check if it meet the

requirement

If measurement results meet the

requirement, UE will send the measurement

report to UTRAN to trigger handover

z The example for intra-frequency HO measurement report



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Parameters of Intra-Frequency Handover

z Intra-freq Measure Quantity

Parameter ID: IntraFreqMeasQuantity

The default value of this parameter is CPICH_Ec/No

z Max number of cell in active set

Parameter ID: MaxCellInActiveSet

The default value of this parameter is 3

z The measurement quantity of intra-frequency handover can be Common Pilot Channel (CPICH) Ec/No or CPICH Received Signal Code Power (RSCP). It can be used in all the measurement events of intra-frequency handover

z Intra-freq Measure Quantity

Parameter ID: IntraFreqMeasQuantity

Value range: CPICH_Ec/No, CPICH_RSCP

Content: This parameter specifies the measurement quantity used in intra-frequency measurement.

The default value of this parameter is CPICH_Ec/No

z Max number of cell in active set

Parameter ID: MaxCellInActiveSet

Value range: 1~6

Contents: This parameter specifies the maximum number of cells in the active set.


z Set above parameters through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO



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z Measurement events for intra-frequency handover

z Actually ,we can consider the Events are the suggestions from the UE:

1A means UE suggests to add a radio link into active set

1B means UE suggests to remove a radio link from active set

1C means UE suggests to exchange a radio link

1D means UE suggests to best cell change



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z 1A Event

Event 1A is triggered on the basis of the following formula

)2/( 11 aaBestNewNew HRMCIOM +

z MNew is the measurement value of the cell in the reporting range.

z CIONew is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.

z MBest is the measurement value of the best cell in the active set.

z R1A is the reporting range or the relative threshold of soft handover. The threshold parameters of the CS non-VP service, VP service, and PS service are as follows:

CS non VP service 1A event relative THD

VP service 1A event relative THD

PS service 1A event relative threshold

z H1A represents 1A hysteresis, the hysteresis value of event 1A.

z The case for 1A event report



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Parameters of 1A Eventz CS non VP service 1A event relative THD

Parameter ID: IntraRelThdFor1ACSNVP

Value range: 0~14.5; step: 0.5

Content: This parameter specifies the relative threshold of event 1A for the CS non-VP service. The larger the parameter value is, the more easily event 1A is triggered..

The default value of this parameter is 6 (3dB)

z VP service 1A event relative THD

Parameter ID: IntraRelThdFor1ACSVP


Content: This parameter specifies the relative threshold of event 1A for the VP service. The larger the parameter value is, the more easily event 1A is triggered..


z PS service 1A event relative THD

Parameter ID: IntraRelThdFor1APS


Content: This parameter specifies the PS service relative threshold of event 1A. The smaller the parameter value is, the more easily event 1A is triggered.


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

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

z 1A hysteresis

Parameter ID: Hystfor1A


Content: This parameter specifies the hysteresis value of event 1A. It is related to the slow fading characteristic.


z 1A event trigger delay time

Parameter ID: TrigTime1A

Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms

Content: This parameter specifies the trigger delay time of event 1A. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes.

The recommended value of this parameter is D320 ( 320ms )

z Set above parameters through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MOD CELLINTRAFREQHO



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Parameters of Intra-Frequency Handoverz Cell oriented Cell Individual Offset

Parameter ID: CIO

Value range: -10 to +10

Content: This parameter is used together with Neighboring cell oriented CIO. The sum of the two parameter values is added to the measurement quantity before the UE evaluates whether an event occurred. In handover algorithms, this parameter is used for moving the border of a cell.

The recommended value of this parameter is 0 ( 0dB )

Set this parameter through ADD CELLSETUP / MOD CELLSETUP

z Neighboring cell oriented CIO

Parameter ID: CIOOffset Value range: -10 to +10

Content: This parameter is used together with Cell oriented Cell Individual Offset. The sum of the two parameter values is added to the measurement quantity before the UE evaluates whether an event has occurred. In handover algorithms, this parameter is used for moving the border of 2 neighbors.

The recommended value of this parameter is 0 ( 0dB )

Set this parameter through ADD INTRAFREQNCELL / MOD INTRAFREQNCELL



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z 1A Event Report Mode:

Event Trigger Report

Event to Periodical Report

The parameters for 1A Event to Periodical Report

1A event to periodical rpt period

1A event to periodical rpt number

z The report mode of 1A is Event Trigger Report .

z Generally the event 1A is reported only once. However, to avoid measurement report loss, the event 1A reporting can be turned to periodical reporting.

z 1A event to periodical rpt period

Parameter ID: ReportIntervalfor1A

Value range: NON_PERIODIC_REPORT, D250, D500, D1000, D2000, D4000, D8000, D16000

Content: The reporting period for the event 1A. Generally the event 1A is reported only once. However, to avoid measurement report loss, the event 1A reporting can be turned to periodical reporting.

The default value of this parameter is D4000 (4000 ms)

z 1A event to periodical rpt number

Parameter ID: PeriodMRReportNumfor1A

Value range: D1, D2, D4, D8, D16, D32, D64, infinity

Content: The periodical reporting times for the event 1A. When the actual times exceed this parameter, the periodical reporting comes to an end.

The recommended value of this parameter is D16




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z 1B EVENT

Event 1B is triggered on the basis of the following formula

)2/( 11 bbBestOldOld HRLogMCIOM ++

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

z CIOOld is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.

z R1B is the reporting range or the relative threshold of soft handover. The threshold parameters of the CS non-VP service, VP service, and PS services are as follows:

CS non VP service 1B event relative THD

VP service 1B event relative THD

PS service 1B event relative threshold

z H1B represents 1B hysteresis, the hysteresis value of event 1B.

z The case for 1B event report



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Parameters of 1B Eventz CS non VP service 1B event relative THD

Parameter ID: IntraRelThdFor1BCSNVP


Content: This parameter specifies the relative threshold of event 1B for the CS non-VP service. The smaller the parameter value is, the more easily event 1B is triggered .


z VP service 1B event relative THD

Parameter ID: IntraRelThdFor1BCSVP


Content: This parameter specifies the relative threshold of event 1A for the VP service. The smaller the parameter value is, the more easily event 1B is triggered .


z PS service 1A event relative THD

Parameter ID: IntraRelThdFor1APS


Content: This parameter specifies the PS service relative threshold of event 1A. The smaller the parameter value is, the more easily event 1B is triggered .


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

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

z 1B hysteresis

Parameter ID: Hystfor1B


Content: This parameter specifies the hysteresis value of event 1B. It is related to the slow fading characteristic.


z 1B event trigger delay time

Parameter ID: TrigTime1B

Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms

Content: This parameter specifies the trigger delay time of event 1B. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes.





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z 1C Event

Event 1C is triggered on the basis of the following formula

2/1cInASInASNewNew HCIOMCIOM +++

z MNew is the measurement value of the cell in the reporting range.

z CIONew is the cell individual offset value of the cell in the reporting range. It is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.

z MInAS is the measurement value of the worst cell in the active set.

z CIOInAS is the cell individual offset value of the worst cell in the active set. It is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO.

z H1C represents 1C hysteresis, the hysteresis value of event 1C.

z The case for 1C event report



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Parameters of 1C Eventz 1C hysteresis

Parameter ID: Hystfor1C


Content: This parameter specifies the hysteresis value of event 1C. It is related to the slow fading characteristic.


z 1C event trigger delay time

Parameter ID: TrigTime1C

Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms

Content: This parameter specifies the trigger delay time of event 1C. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes.





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z 1C Event Report Mode:

Event Trigger Report

Event to Periodical Report

1C event to periodical rpt period

1C event to periodical rpt number

z The report mode of 1C is Event Trigger Report .

z Generally the event 1C is reported only once. However, to avoid measurement report loss, the event 1C reporting can be turned to periodical reporting.

z 1C event to periodical rpt period

Parameter ID: ReportIntervalfor1C

Value range: NON_PERIODIC_REPORT, D250, D500, D1000, D2000, D4000, D8000, D16000

Content: The reporting period for the event 1C. Generally the event 1C is reported only once. However, to avoid measurement report loss, the event 1C reporting can be turned to periodical reporting.


z 1C event to periodical rpt number

Parameter ID: PeriodMRReportNumfor1C

Value range: D1, D2, D4, D8, D16, D32, D64, infinity

Content: The periodical reporting times for the event 1C. When the actual times exceed this parameter, the periodical reporting comes to an end.

The recommended value of this parameter is D16




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z 1D Event

Event 1D is triggered on the basis of the following formula

2/1dBestBestNotbestNotbest HCIOMCIOM +++

z MNotBest is the measurement value of a cell that is not in the list of the best cells.

z CIONotBest is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.

z MBest is the measurement value of the best cell in the active set.

z H1D represents 1D hysteresis, the hysteresis value of event 1D.

z The case for 1D event report



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Parameters of 1D Eventz 1D hysteresis

Parameter ID: Hystfor1D


Content: This parameter specifies the hysteresis value of event 1D. It is related to the slow fading characteristic.


z 1D event trigger delay time

Parameter ID: TrigTime1D

Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms

Content: This parameter specifies the trigger delay time of event 1D. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes.


z Min quality THD for SHO [dB]

Parameter ID: SHOQualmin

Value range: -24~0

Content: When the RNC receives events 1A, 1C and 1D, the target cell can be added to the active set only when CPICH Ec/No of the target cell is higher than this absolute threshold.

The recommended value of this parameter is -24 ( -24dB )




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Contents










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Intra-Frequency Handover Decision and Executionz RNC will make decision and execute handover depends on the

Events that RNC receives

1A Event : add the target cell into active set

1B Event : remove the target cell from active set

1C Event : replace the worst with the target cell

1D Event : best cell change

new neighbor list or hard handover



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Algorithm Switch for intra-frequency Handoverz SOFT_HANDOVER_SWITCH

When the switch is selected, the cells on the RNC can active the soft handover. When the RNC receives reports on the events 1A, 1B, 1C, or 1D, associated addition, removal, and replacement of handover cell of the soft handover are initiated.Content: switches of the handover algorithms.

z INTRA_FREQUENCY_HARD_HANDOVER_SWITCH

When the switch is selected, the RNC is allowed to initiate the intra-frequency hard handover. The RNC initiates the intra-frequency hard handover in the following cases:1. When a BE service is carried over the DCH and the rate of the BE service or combined service exceeds the DL rate threshold for soft handover2. When the switch of soft handover is OFF and the UE reports the event 1D

z DETSET_ADD_TO_ACTSET_SWITCH

When the switch is selected, the cells in the detected set from which the RNC receives their valid event reports can be added to the active set. The cells allowed to be added to the active set must be the neighboring cells of the cells in the active set.

z DETSET_RPRT_SWITCH

When the switch is selected, statistics on the intra-frequency measurement reports of the detected set are taken.

z SIGNAL_IUR_INTRA_HO_SWITCH

If the RRC connection has been setup but the RB has NOT, whether a cross-Iur soft handover can be executed is determined by SIGNAL_IUR_INTRA_HO_SWITCH . The parameter is set by MML: SET CORRMALGOSWITCH. Only the SIGNAL_IUR_INTRA_HO_SWITCH is ON, the cross-Iur soft handover for RRC connection can be executed.

z Set above parameters through SET CORRMALGOSWITCH



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Contents


1. Intra-Frequency handover Overview








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Neighboring Cell Combination Algorithm

z When the UE is in handover state

Intra-frequency neighboring cells

Inter-frequency neighboring cells

Inter-RAT neighboring cells



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z The combined neighboring cell list is affect by :

Repeat times

Serving cell signal quality (Ec/No) order

Neighboring cell priority

z After obtaining the intra-frequency neighboring cells of each cell in the active set, the RNC calculates the union neighboring cell set of the intra-frequency cells, which is also referred as Sall, by using the following method. This method can also be used to generate the Sall of inter-frequency or inter-RAT cells. The intra-frequency, inter-frequency and inter-RAT neighboring cells of each cell in the current active set are obtained. The RNC sequences the cells in the active set in descending order of CPICH Ec/No according to the latest measurement report (event 1A, 1B, 1C, or 1D) from the UE. The best cell is based on event 1D, whereas other cells are based on the latest measurement report.

The cells in the active set are added to Sall.

The neighboring cells of the best cell in the active set are added to Sall. The priority of neighbor cell, which are set for each neighboring cell, are used to change the order of adding the neighboring cells to Sall.

The neighboring cells of other cells in the active set are added to Sall in descending order by CPICH Ec/No values of these cells in the active set. The neighboring cells of the same cell in the active set are added according to The priority of neighbor cell and repeated number of repeated neighboring cell is recorded.

If there are more than 32 neighboring cells in Sall, delete the neighboring cells whose repeat number in Sall is less. The top 32 neighboring cells are grouped into the final Sall.

If The flag of the priority is switched to FALSE, The priority of neighbor cell is cleared.

If The flag of the priority is switched to TRUE, The priority of neighbor cell is set simultaneously.



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z Parameters of Neighboring Cell Combination Algorithm

NCELL_COMBINE_SWITCH

NPrioFlag

NPrio

z Neighboring Cell Combination Switch

Parameter ID: NCELL_COMBINE_SWITCH

Value range: OFF, ON

Content: When it is checked, measurement object is chosen from neighbour cells of all the cell in the Active Set and limited by 32. Otherwise, measurement object is chosen from neighbor cells of the Best Cell and limited by 32.

The default value of this parameter is ON

z Set this parameter through SET CORRMALGOSWITCH

z The flag of the priority

Parameter ID: NPrioFlag

Value range: FALSE, TRUE

Content: TRUE indicates that the neighboring cell priority is valid in the algorithm of neighboring cell combination. FALSE indicates that the neighboring cell priority is invalid.

z The priority of neighbor cell

Parameter ID: NPrio

Value range: 0 to 30

Content: The priority that corresponds to the neighboring cell is valid only when the this parameter is set to TRUE. The value is lower, it is easier for add the cell into measurement control. For instance, it is easier for a neighboring cell with priority 1 than a neighbor with priority 2 to be add into measurement control.

z Set above parameters through ADD INTRAFREQNCELL / MOD INTRAFREQNCELL; ADD INTERFREQNCELL / MOD INTERFREQNCELL;ADD GSMNCELL / MOD GSMNCELL



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Contents


1. Intra-Frequency handover Overview








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Rate Reduction after Admission Failure of SHOz If the RL addition (e.g. 1A,1C) for SHO fails, the rate reduction

is trigger for R99 NRT (Non_Real_Time) service to increase the

probability of a successful SHO



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z The following figure illustrate estimation procedure for admission failures of SHO

z If the RNC receives 1A or 1C event measurement report, the target cell tries to admit the UE. If the admission of target cell fails, the RNC perform the evolution procedure for rate reduction

z Step1:The RNC evaluates whether the signal quantity of the target cell (admission failure cell) to be meet the condition of rate reduction

Condition of rate reduction: Mnew>Mbest_cellRelThdForDwnGrd Mnew is the PCPICH EcIo of the target cell (admission failure cell)

Mbest_cell is the PCPICH EcIo of best cell in active set

RelThdForDwnGrd is parameter in RNC side

z If the condition of rate reduction is met, the RNC perform rate reduction for this service

z If the condition is NOT met, the RNC perform Step2



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z Step2: The RNC evaluate whether the times of SHO admission failures in target cell exceed SHOFailNumForDWnGrd (the threshold times of SHO failure ) during evaluation period

If the times of the times of SHO admission failures in target cell is less than SHOFailNumForDWnGrd (the threshold times of SHO failure ), the RNC determines whether the timer has been started

If the timer of evaluation has NOT been started, the RNC starts it.

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

The evaluation period is set through the parameter SHOFailPeriod (Max evaluation period of SHO failure)

z if the times of SHO failures in target cell is greater/equal than SHOFailNumForDWnGrd, the RNC performs a rate reduction for the service directly.

z The procedure for rate reduction execution

z After the rate reduction succeeds, the RNC immediately attempts to add this cell into the active set without measurement

If the target cell fails to admit the UE, the RNC starts the DCCCSHoPenaltyTime to avoid an increase in the rate triggered by DCCC within the period

z if the RNC fails to perform a soft handover again, it performs evaluation and execution, as previously described



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z The Parameters of Rate Reduction after Admission Failure of SHO

z Max evaluation period of SHO failure [s]

Parameter ID: ShoFailPeriod

Value range: 0~120s

Content: This parameter specifies the maximum evaluation period of the soft handover failure. When the rate reduction evaluation is performed on a cell that fails to join the active set, the evaluation timer is started. If the cell cannot fulfill the condition of rate reduction before the timer expires, the evaluation and rate reduction retry on the cell will not be performed.

The default value of this parameter is 60s

z Threshold number of SHO failure

Parameter ID: ShoFailNumForDwnGrd

Value range: 0~63

Content: This parameter specifies the threshold number of the soft handover failures. This parameter determines the reporting times of the events from the cell that fails to join the active set in soft handover, to trigger the rate reduction of the active set and the attempt to join the active set.


z Relative threshold of SHO failure [dB]

Parameter ID: RelThdForDwnGrd

Value range: -14.5~14.5, Step:0.5

Content: This parameter specifies the threshold of immediate rate reduction after the soft handover failure. The rate reduction of the active set and the SHO retry procedure can be triggered without the intra-frequency reporting event reported, when the quality of the cellin the active set fulfills the following conditions.The formula of direct SHO rate reduction isMnew > Mbest_cell - RelThdForDwnGrdwhereMnew: the CPICH Ec/No measurement value of the failed cell1Mbest_cell: the CPICH Ec/No measurement value in the latest measurement report of the best cell identified by the RNC according to 1DRelThdForDwnGrd: the relative threshold for direct rate reduction.


z Period of penalty timer for SHO failure after down rate [s]

Parameter ID: DcccShoPenaltyTime

Value range: 0~255

Content: This parameter specifies the length of penalty timer for SHO failure after rate reduction in the active set.When the rate reduction in the active set is performed which triggers the increase of SHOsin the target cell, if the target cell fails to join the active again, the RNC starts the penalty timer for SHO failure This parameter determines the length of the penalty timer. Before the timer expires, the rate increasing in the active set is prohibited, but rate reduction is not prohibited.


z Set above parameters through SET INTRAFREQHO



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Rate Reduction after Admission Failure of SHOz The RNC could trigger rate reduction if admission failure of target cell

admission failure due to ENU

GBR

admission failure due to power

GBR

admission failure due to code resource

Max. date rate that the rest code support

admission failure due to Iub bandwidth

Max. date rate that the rest Iub bandwidth support

admission failure due to CE resource

Max. date rate that the rest CE support



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Contents



3. Inter-RAT Handover



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Contents


1 Inter-Frequency Handover Overview

2 Inter-Frequency Handover Procedure



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Inter-Frequency Overview

z Characters of Inter-Frequency Handover:

z The carrier frequency of the current cell and target cell are different

z Based on the triggering causes of handover, inter-frequency handover

can be categorized into four types

Coverage-based

QoS-based

Load-based

Speed-based

z Coverage-based inter-frequency handover

If a moving UE leaves the coverage of the current frequency, the RNC needs to trigger the coverage-based inter-frequency handover to avoid call drops

z QoS-based inter-frequency handover

According to the Link Stability Control Algorithm, the RNC needs to trigger the QoS-based inter-frequency handover to avoid call drops.

z Load-based inter-frequency blind handover

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

z Speed-based inter-frequency handover

When the Hierarchical Cell Structure (HCS) applies, the cells are divided into different layers according to coverage. The macro cell has a larger coverage and a lower priority, whereas the micro cell has a smaller coverage and a higher priority. Inter-frequency handover can be triggered by the UE speed estimation algorithm of the HCS. To reduce the frequencies of handover, the UE at a higher speed is handed over to a cell under a larger coverage, whereas the UE at a lower speed is handed over to a cell under a smaller coverage.



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Contents


1. Inter-Frequency Handover Overview

2. Inter-Frequency Handover Procedure

1. Coverage-based Inter-Frequency Handover

2. QoS-based Inter-Frequency Handover

3. Load-based Inter-Frequency Handover

4. Blind handover Based on Event 1F

5. Inter-frequency anti-PingPong Algorithm

6. Inter-frequency Handover Retry Algorithm



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z The handover procedure is divided into four phases: handover triggering, handover measurement, handover decision, and handover execution.

z In the triggering phase: The RNC notifies the UE to measure through an inter-frequency measurement control message. If the quality of the pilot signal in the current cell deteriorates, the CPICH Ec/No or CPICH RSCP of the UMTS cell that the UE accesses is lower than the corresponding threshold, and the UE reports event 2D.

z In the measurement phase :If the RNC receives a report of event 2D, the RNC requests the NodeB and UE to start the compressed mode to measure the qualities of inter-frequency neighboring cells, and the RNC sends an inter-frequency measurement control message.In the measurement phase, the method of either periodical measurement report or event-triggered measurement report can be used.

z In the decision phase :After the UE reports event 2B, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, and the RNC makes a decision after evaluation.

z In the execution phase :The RNC executes the handover procedure.

Procedure of Coverage-based inter-frequency handover



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Coverage-based Inter-Frequency Handover

z Measurement events for inter-frequency Handover

z When the estimated quality or strength of the currently used frequency is below a certain threshold,2D Event will be triggered, Then RNC will initiate the compress Mode to start inter-frequency or inter-RAT handover measurement.

z During compress mode, if the the estimated quality of the currently used frequency is above a certain threshold, 2F Event will be triggered, Then RNC will stop the compress Mode.



44


Coverage-based inter-frequency handover

z Compress Mode

The purpose for compress mode: Measure the inter-frequency cell or Inter-RAT cell under

FDD mode during the gap that generated by compress mode

The categories for compress mode:

Downlink compressed mode

Uplink compressed mode

In DL, during compressed mode ,UE receiver can test signal from other frequency. In order to avoid

the effect cause by UE transmitter, compress mode is also used in UL

compress mode approaches

SF/2

Higher layer scheduling

z CMCF_DL_HLS_SWITCH: When the switch is selected, the compressed mode supports DL higher-layer scheduling.

z CMCF_UL_HLS_SWITCH: When the switch is selected, the compressed mode supports UL higher-layer scheduling.

z Set above parameters through SET CORRMALGOSWITCH

z Dl SF threshold / Ul SF threshold

Parameter ID: DlSFTurnPoint / UlSFTurnPoint

Value range: 8, 16, 32, 64, 128, 256

Content: CM implementation approach selection basis. When the downlink/uplink spreading factor is greater than or equal to this parameter value, the approach of spreading factor halving (SF/2) will be preferred. Otherwise, the high layer scheduling will be preferred.


z Set above parameters through SET CMCF / ADD CELLCMCF / MOD CELLCMCF



45



z 2D Event

Event 2D is triggered on the basis of the following formula

2/22 DDUsedUsed HTQ

z QUsed is the measured quality of the used frequency.

z TUsed2D is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service, or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through one of the following parameters:

Inter-freq CS measure start Ec/No THD

Inter-freq R99 PS measure start Ec/No THD

Inter-freq H measure start Ec/No THD

Inter-freq CS measure start RSCP THD

Inter-freq R99 PS measure start RSCP THD

Inter-freq H measure start RSCP THD

H2d is the event 2D hysteresis value 2D hysteresis.

z After the conditions of event 2D are fulfilled and maintained until the parameter 2D event trigger delay time is reached, the UE reports the event 2D measurement report message.

z Note: Any of the Ec/No and RSCP measurement result can trigger the 2D event if the measurement quantity.



46

Parameters of 2D Eventz Inter-freq CS measure start Ec/No THD

Parameter ID: InterFreqCSThd2DEcNo Value range: -24 to 0 ,step :1dB. Content: If the CS service uses Ec/No as a measurement quantity, the UE reports event 2D

when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.

The default value of this parameter is -14dBz Inter-freq R99 PS measure start Ec/No THD

Parameter ID : InterFreqR99PsThd2DEcNo Value range: -24 to 0 ,step :1dB. Content: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE

reports event 2D when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.

The default value of this parameter is -14dB z Inter-freq H measure start Ec/No THD

Parameter ID : InterFreqHThd2DEcN0 Value range: -24 to 0 ,step :1dB. Content: For PS domain HSPA services, when Ec/No is used as the measurement quantity

for inter-frequency measurement, the RNC sends the signaling to activate compressed mode and start inter-frequency measurement, if the UE reports the event 2D when the measured value is smaller than the value of this parameter.

The default value of this parameter is -14dB z Inter-freq CS measure start RSCP THD

Parameter ID: InterFreqCSThd2DRSCP Value range: -115 to -25 dBm ,step :1dB. Content: If the CS service uses RSCP as a measurement quantity, the UE reports event 2D

when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.

The default value of this parameter is -95dBmz Inter-freq R99 PS measure start RSCP THD

Parameter ID : InterFreqR99PsThd2DRSCP Value range: -115 to -25 dBm ,step :1dB. Content: If the PS domain R99 service uses RSCP as a measurement quantity, the UE

reports event 2D when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.

The default value of this parameter is -95dBmz Inter-freq H measure start RSCP THD

Parameter ID : InterFreqHThd2DRSCP Value range: -115 to -25 dBm ,step :1dB. Content: For PS domain HSPA services, when RSCP is used as the measurement quantity for

inter-frequency measurement, the RNC sends the signaling to activate compressed mode and start inter-frequency measurement, if the UE reports the event 2D when the measured value is smaller than the value of this parameter.

The default value of this parameter is -95dBmz Set above parameters through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV /

SET INTERFREQHOCOV



47

Parameters of 2D Eventz 2D hysteresis

Parameter ID: Hystfor2D

Value range: 0 to 29 step :0.5dB.

Content: This parameter specifies the event 2D trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.


z 2D event trigger delay time

Parameter ID : TimeToTrig2D

Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000

Content: This parameter specifies the time of event 2D trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed.


z Set above parameters through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV



48



z 2F EVENT

Event 2F is triggered on the basis of the following formula

2/22 FFUsedUsed HTQ +

z QUsed is the measured quality of the used frequency.

z TUsed2F is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:

Inter-freq CS measure stop Ec/No THD

Inter-freq R99 PS measure stop Ec/No THD

Inter-freq H measure stop Ec/No THD

Inter-freq CS measure stop RSCP THD

Inter-freq R99 PS measure stop RSCP THD

Inter-freq H measure stop RSCP THD

H2F is the event 2F hysteresis value 2F hysteresis.

z After the conditions of event 2F are fulfilled and maintained until the parameter 2F event trigger delay time is reached, the UE reports the event 2F measurement report message.



49

Parameters of 2F Eventz Inter-freq CS measure stop Ec/No THD

Parameter ID: InterFreqCSThd2FEcNo Value range: -24 to 0 ,step :1dB. Content: If the CS service uses Ec/No as a measurement quantity, the UE reports event 2F

when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement.

The default value of this parameter is -12dBz Inter-freq R99 PS measure stop Ec/No THD

Parameter ID : InterFreqR99PsThd2FEcNo Value range: -24 to 0 ,step :1dB. Content: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE reports

event 2F when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement.

The default value of this parameter is -12dBz Inter-freq H measure stop Ec/No THD

Parameter ID : InterFreqHThd2FEcN0 Value range: -24 to 0 ,step :1dB. Content: For PS domain HSPA services, when Ec/No is used as the measurement quantity for

inter-frequency measurement, the RNC sends the signaling to deactivate compressed mode and stop inter-frequency measurement, if the UE reports the event 2F when the measured value is larger than the value of this parameter

The default value of this parameter is -12dBz Inter-freq CS measure stop RSCP THD

Parameter ID: InterFreqCSThd2FRSCP Value range: -115 to -25 dBm ,step :1dB. Content: If the CS service uses RSCP as a measurement quantity, the UE reports event 2F when

the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement.

The default value of this parameter is -92 dBmz Inter-freq R99 PS measure stop RSCP THD

Parameter ID : InterFreqR99PsThd2FRSCP Value range: -115 to -25 dBm ,step :1dB. Content: If the PS domain R99 service uses RSCP as a measurement quantity, the UE reports

event 2F when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement.

The default value of this parameter is -92dBmz Inter-freq H measure stop RSCP THD

Parameter ID : InterFreqHThd2FRSCP Value range: -115 to -25 dBm ,step :1dB. Content: For PS domain HSPA services, when RSCP is used as the measurement quantity for

inter-frequency measurement, the RNC sends the signaling to deactivate compressed mode and stop inter-frequency measurement, if the UE reports the event 2F when the measured value is larger than the value of this parameter

The default value of this parameter is -92dBmz Set above parameters through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV /

SET INTERFREQHOCOV



50

Parameters of 2F Eventz 2F hysteresis

Parameter ID: Hystfor2F

Value range: 0 to 29 step :0.5dB.

Content: This parameter specifies the event 2F trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.


z 2F event trigger delay time

Parameter ID : TimeToTrig2F

Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000

Content: This parameter specifies the time of event 2F trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed.





51



z The measurement procedure for inter-frequency handover due to

coverage

z When the UE starts the compress mode, RNC will trigger the inter-frequency handover measurement by two additional measurement control signaling , so as to request UE measure inter-frequency neighbors.

z In this Measurement control message, RNC should inform the UE inter-frequency measurement parameter (Neighbor list, reporting mode)



52



z The measurement procedure for inter-frequency handover due to

coverage

Measurement Report Mode

Periodical reportingEvent report

z The measurement report mode of inter-frequency handover is configured through the parameter in RNC. By default ,periodically reporting is recommended. The advantage of periodical measurement report is that if the handover failure due to capacity shortage for example , the RNC reattempts the handover to the same cell after receiving the periodical measurement report from the UE. This increases the probability of the success of inter-frequency handover.



53

Parameters of inter-frequency Handoverz Inter-frequency measure report mode

Parameter ID: InterFreqReportMode

Value range :Periodical reporting, Event trigger

Content: This parameter specifies the inter-frequency measurement report mode.

The default value of this parameter is Periodical reporting

z Inter-frequency measure periodical rpt period

Parameter ID: PeriodReportInterval

Value range : NON_PERIODIC_REPORT, 250, 500, 1000, 2000, 3000, 4000, 6000, 8000, 12000, 16000, 20000, 24000, 28000, 32000, 64000

Content: This parameter specifies the interval of the inter-frequency measurement report.

The default value of this parameter is D500 (500ms)

z Inter-freq measure timer length

Parameter ID: InterFreqMeasTime

Value range : 0 to 512 ,step 1s

Content: This parameter specifies the inter-frequency measurement timer length of the inter-frequency handover based on coverage or speed. This parameter has no effect on the inter-frequency measurement based on QoS. If no such type of inter-frequency handover occurs upon expiry of the inter-frequency measurement timer, the system stops the inter-frequency measurement and disables the compressed mode. This parameter is used to prevent the long inter-frequency measurement state (compressed mode) due to unavailablemeasurement of the target cells that meet the handover requirements. If this parameter is set to 0, the RNC does not start the inter-frequency measurement timer.

The default value of this parameter is 60 ( 60s)

z Set above parameters for handover based on coverage through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV



54



z 2B Event

Event 2B is triggered on the basis of the following formula

2/22

2/22

BBUsedUsed

BBNousedNoused

HTQHTQ

+

z QNoused is the measured quality of the cell that uses the other frequencies.

z TNoused2b is the absolute quality threshold of the cell that uses the other frequencies. Based on the service type (CS , PS domain) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:

Inter-freq CS target frequency trigger Ec/No THD

Inter-freq R99 PS target frequency trigger Ec/No THD

Inter-freq CS target frequency trigger RSCP THD

Inter-freq R99 PS target frequency trigger RSCP THD

z QUsed is the measured quality of the cell that uses the current frequency.

z TUsed2b is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS service, PS domain service) and the measurement quantity (CPICH Ec/No or RSCP) in the coverage-based handover, TUsed2b can be configured through the following parameters.

If the event 2D with the CPICH RSCP value is received by the RNC,

TUsed2b of event 2B with the CPICH RSCP value can be:

Inter-freq CS Used frequency trigger RSCP THD

Inter-freq R99 PS Used frequency trigger RSCP THD

If the event 2D with the CPICH Ec/No value is received by the RNC,

TUsed2b of event 2B with the CPICH Ec/No value can beInter-freq CS Used frequency trigger Ec/No THD

Inter-freq R99 PS Used frequency trigger Ec/No THD

z H2b is the event 2B hysteresis value 2B hysteresis.




55


Parameters of Inter-Frequency Handover

z The Parameters of 2B Event

TargetFreqCsThdEcN0

TargetFreqR99PsThdEcN0

TargetFreqHThdEcN0

TargetFreqCsThdRSCP

TargetFreqR99PsThdRSCP

TargetFreqHThdRSCP

TimeToTrig2B

HystFor2B

InterFreqMeasTime

UsedFreqCSThdEcN0

UsedFreqR99PsThdEcN0

UsedFreqHThdEcN0

UsedFreqCSThdRSCP

UsedFreqR99PsThdRSCP

UsedFreqHThdRSCP

PeriodFor2B

AmntOfRpt2B

z Inter-freq CS target frequency trigger Ec/No THD ; Inter-freq R99 PS target frequency trigger Ec/No THD ; Inter-freq H target frequency trigger Ec/No THD

Parameter ID:TargetFreqCsThdEcN0 ; TargetFreqR99PsThdEcN0 ;TargetFreqHThdEcN0

Value range:-24~0 dB

Content: If the value of [Inter-frequency measure report mode] is set to EVENT_TRIGGER, this parameter is used to set the measurement control of event 2B. One of the necessary conditions for triggering event 2B can be met only when the quality of the target frequency is higher than this threshold. If the value of [Inter-frequency measure report mode] is set to PERIODICAL_REPORTING, this parameter is used to evaluate inter-frequency handovers at the RNC.

The default value of this parameter is -12dB

z Inter-freq CS target frequency trigger RSCP THD ; Inter-freq R99 PS target frequency trigger RSCP THD ; Inter-freq H target frequency trigger RSCP THD

Parameter ID: TargetFreqCsThdRSCP ; TargetFreqR99PsThdRSCP ; TargetFreqHThdRSCP

Value range:-115~-25 dBm

Content: if the value of [Inter-frequency measure report mode] is set to EVENT_TRIGGER, this parameter is used to set the measurement control of event 2B. One of the necessary conditions for triggering event 2B can be met only when the quality of the target frequency is higher than this threshold. If the value of [Inter-frequency measure report mode] is set to PERIODICAL_REPORTING, this parameter is used to evaluate inter-frequency handovers at the RNC.

The default value of this parameter is -92dBm




56

Parameters of 2B Eventz Inter-freq CS Used frequency trigger Ec/No THD ; Inter-freq R99 PS Used frequency trigger Ec/No

THD ; Inter-freq H Used frequency trigger Ec/No THD

Parameter ID: UsedFreqCSThdEcN0 ; UsedFreqR99PsThdEcN0 ; UsedFreqHThdEcN0

Value range:-24~0 dB

Content: if the value of [Inter-frequency measure report mode] is set to EVENT_TRIGGER, this parameter is used to set the measurement control of event 2B. One of the necessary conditions can be met only when the quality of the used frequency is lower than this threshold (Event 2B can be triggered only when both conditions are met.)

The default value of this parameter is -12dB

z Inter-freq CS Used frequency trigger RSCP THD ; Inter-freq R99 PS Used frequency trigger RSCP THD ; Inter-freq H Used frequency trigger RSCP THD

Parameter ID: Inter-freq CS Used frequency trigger RSCP THD ; UsedFreqR99PsThdRSCP ; UsedFreqHThdRSCP

Value range:-115~-25 dBm

Content: if the value of [Inter-frequency measure report mode] is set to EVENT_TRIGGER, this parameter is used to set the measurement control of event 2B. One of the necessary conditions can be met only when the quality of the used frequency is lower than this threshold (Event 2B can be triggered only when both conditions are met.)

The default value of this parameter is -92dBm




57

Parameters of 2B Eventz 2B hysteresis

Parameter ID: HystFor2B

Value range:0~14.5 ; step:0.5dB

The default value of this parameter is 4 (i.e. 2dB)

z 2B event trigger delay time

Parameter ID:TimeToTrig2B

Value range:0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000, unit: ms

The default value of this parameter is 0ms

z Inter-freq measure timer length

Parameter ID: InterFreqMeasTime

Value range:0~512 ; unit:s

Content: After inter-frequency measurement starts, if no inter-frequency handover is performed when this timer expires, the inter-frequency measurement and the compressed mode (if started) are stopped. The value 0 indicates the timer is not to be enabled.


z 2B event retry period

Parameter ID: PeriodFor2B

Value range: 1 ~ 64 ; unit:0.5s

Content: This parameter defines the length of the event 2B retry period. The smaller the value of this parameter, the more frequent the handover retry due to inter-frequency handover failure, and the faster the UE to be successfully handed over to the target cell whose load is restored, thus lowering the probability of call drops. In this case, however, frequent handover retry brings more load to the RNC system.

The default value of this parameter is 1(i.e. 0.5s)

z 2B event retry max times

Parameter ID: AmntOfRpt2B

Value range:0 ~ 62 times, 63: Infinity

Content: This parameter defines the number of times for event 2B retry when the measurement control is valid. The larger the value of this parameter, the larger the number of times for inter-frequency handover retry, and the higher probability for the UE to be successfully handed over to the target cell whose load is restored. After the maximum number of times for event 2B retry, the RNC sends the inter-frequency measurement control message again to hand over the UEs to the other cells of this frequency.If the measurement control message is released, the retry will be immediately stopped.





58



z Handover Decision and Execution

Event-Triggered Measurement Report Mode

Based on the event 2B measurement reports of CPICH RSCP and event

2B CPICH Ec/No of the inter-frequency cell

Periodical Measurement Report Mode

Both the CPICH Ec/No value and CPICH RSCP value of the pilot signal of

the target cell must meet the requirement

NOTE: No consideration of the current cell

2/HTCIOM OtherFreqOtherFreqOtherFreq ++

z The coverage-based handover decision is categorized into two types according to the following two measurement report modes: periodical measurement report mode and event-triggered measurement report mode. Each mode corresponds to a different decision and execution procedure.

z The RNC decision and execution procedure for periodical measurement reporting mode

z Mother_Freq is the CPICH Ec/No or CPICH RSCP measurement value of the target cell reported by the UE. Both of the two measurement values of the inter-frequency cell must satisfy the formula.

z CIOother_Freq is the cell individual offset value of the target cell. It is equal to the sum of Cell oriented Cell Individual Offset and Neigbhoring cell oriented CIO.

z Tother_Freq is the decision threshold of inter-frequency hard handover.

Based on the service type (CS or PS service) and measurement quantity (CPICH Ec/No or CPICH RSCP), this threshold can be configured through the following parameters

Inter-freq CS target frequency trigger Ec/No THD

Inter-freq R99 PS target frequency trigger Ec/No THD

Inter-freq H target frequency trigger Ec/No THD

Inter-freq CS target frequency trigger RSCP THD

Inter-freq R99 PS target frequency trigger RSCP THD

Inter-freq H target frequency trigger RSCP THD

z NOTE: These thresholds are the same as the quality threshold of event 2B. H is the inter-frequency hard handover hysteresis value HHO hysteresis.



59


Parameters of Inter-Frequency Handover

z The Parameters of inter-frequency handover due to coverage if

periodical report is used

Cell oriented Cell Individual Offset

Neighboring cell oriented CIO

Hysteresis for inter-frequency hard handover in periodical reporting mod

Inter-frequency measure periodical rpt period

z Cell oriented Cell Individual Offset

Parameter ID :CIO

Value range :-20 to +20 , step:0.5dB


Set this parameter through ADD CELLSETUP/MOD CELLSETUP

z Neighboring cell oriented CIO

Parameter ID: CIOOffset Value range :-20 to +20 , step:0.5dB


Set this parameter through ADD INTERFREQNCELL / MOD INTERFREQNCELL

z Hysteresis for inter-frequency hard handover in periodical reporting mod

Parameter ID: HystForPrdInterFreq

Value range 0 to 29 , step:0.5dB


Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV

z Inter-frequency measure periodical rpt period

Parameter ID : PrdReportInterval

Value range : 250, 500, 1000, 2000.3000, 3000, 4000, 6000, 8000, 12000, 16000, 20000, 24000, 28000, 32000, 64000, unit: ms

The default value of this parameter is 500ms

Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV



60



z Handover Decision and Execution for Periodical Measurement Report

Mode

z Decide whether both the CPICH Ec/No value and CPICH RSCP value of the pilot signal of the target cell meet the requirement of inter-frequency handover.

z Start the hard handover time-to-trigger timer, which is configured through the parameter HHO period trigger delay time.

z Select the cells in sequence, that is, from high quality cells to low quality ones, to initiate inter-frequency handover in the cells where the hard handover time-to-trigger timer expires.



61


Contents












62

z The handover procedure is divided into 4 phases: handover triggering, handover measurement, handover decision, and handover execution.

z Besides the triggering step, the rest 3 steps are the same with coverage-based inter-frequency handover

z In the triggering phase: If the service quality of the current cell deteriorates, the Link Stability Control Algorithm makes a handover measurement decision.

z In the measurement phase: The RNC requests the NodeB and the UE to start the compressed mode to measure the qualities of inter-frequency neighboring cells. Then, the RNC sends inter-frequency measurement control messages. In the measurement phase, the method of periodical measurement report or event-triggered measurement report can be used.

z In the decision phase: After receiving the event 2B measurement reports of CPICH RSCP and CPICH Ec/No of the inter-frequency cell, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, and the RNC makes a decision after evaluation.

z In the execution phase: The RNC executes the handover procedure.

z Note : About Link Stability Control Algorithm : When the uplink transmit power of the UE or downlink transmitted code power of the NodeB exceeds the associated threshold :

For AMR, a fixed sequence of rate downsizing, inter-frequency handover, and then inter-RAT handover are performed

For VP, inter-frequency handover are performed

For BE service, rate downsizing, inter-frequency handover, and then inter-RAT handover are performed according to the configured sequence

Procedure of QoS-based inter-frequency handover



63


Parameters of QoS-based Inter-Frequency Handoverz The parameters for inter-frequency handover due to QoS

QOS Switch For AMR Traffic

InterFreq Handover Switch Based On Uplink Traffic AMR

QOS Switch For VP Traffic

InterFreq Handover Switch Based On Uplink Traffic VP

QOS Switch For BE Traffic

First / Second / Third Uplink QOS Enhancement Action for Traffic BE

First / Second / Third Downlink QOS Enhancement Action for Traffic BE

z QOS Switch For AMR Traffic ; QOS Switch For VP Traffic ; QOS Switch For BE Traffic Parameter ID : AMRQosPerform ; VPQosPerform ; BEQosPerform Value range NO, YES Content: When the parameter is set to YES, the QOS control algorithm is used for

AMR/VP/BE services. When the parameter is set to NO, the QOS control algorithm is not used for AMR/VP/BE services.

z InterFreq Handover Switch based on Uplink/Downlink Traffic AMR Parameter ID : UlQoSAmrInterFreqHoSwitch / DlQoSAmrInterFreqHoSwitch Value range NO, YES Content: If the value of this parameter is YES, inter-frequency handover can be executed on

the basis of the downlink/uplink QoS of AMR services. The default value of this parameter is NO

z InterFreq Handover Switch based on Uplink/Downlink Traffic VP Parameter ID : UlQoSVPInterFreqHoSwitch / DlQoSVPInterFreqHoSwitch Value range NO, YES The default value of this parameter is NO

z First / Second / Third Uplink QOS Enhancement Action for Traffic BE Parameter ID : BeUlAct1/ BeUlAct2/ BeUlAct3 Value range None, RateDegrade, InterFreqHO, InterRatHO Content: This parameter defines the action sequence to enhance the Uplink QoS of BE

services . The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO

z First / Second / Third Downlink QOS Enhancement Action for Traffic BE Parameter ID : BeDlAct1/ BeDlAct2/ BeDlAct3 Value range None, RateDegrade, InterFreqHO, InterRatHO The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO

z Set above parameters through SET QOSACT



64


Parameters of QoS-based Inter-Frequency Handoverz The parameters for inter-frequency handover due to QoS

Down Link QoS Measure timer length

Up Link QoS Measure timer length

z Down Link QoS Measure timer length

Parameter ID : DLQoSMcTimerLen

Value range 0 to 512 ,step 1s

Content: This parameter specifies the inter-frequency measurement timer length of the inter-frequency handover based on downlink QoS. This parameter has no effect on the inter-frequency measurement based on coverage. If no QoS-based inter-frequency handover occurs upon expiry of the downlink inter-frequency measurement timer, the RNC stops the QoS-based inter-frequency measurement. If this parameter is set to 0, the RNC does not start the inter-frequency QoS-based measurement timer.

The default value of this parameter is 20 (20s)

z Down Link QoS Measure timer length

Parameter ID : UpQoSMcTimerLen

Value range 0 to 512 ,step 1s

Content: This parameter specifies the inter-frequency measurement timer length of the inter-frequency handover based on uplink QoS. This parameter has no effect on the inter-frequency measurement based on coverage. If no QoS-based inter-frequency handover occurs upon expiry of the uplink inter-frequency measurement timer, the RNC stops the inter-frequency measurement and disables the compressed mode. If this parameter is set to 0, the RNC does not start the inter-frequency QoS-based measurement timer.

The default value of this parameter is 20 (20s)

z Set above parameters through ADD CELLQOSHO / MOD CELLQOSHO / SET QOSHO



65


Contents












66

z The handover procedure is divided into three phases: handover triggering, handover decision, and handover execution. Because no measurement for the target cell, so we call it blind handover.

z In the triggering phase: The Load Reshuffling (LDR) algorithm directly determines whether the current cell is LDR state (i.e. basic congestion state) and whether an inter-frequency handover needs to be performed. The RNC performs the handover procedure.

z In the decision phase: The RNC decides to trigger an inter-frequency blind handover if the blind handover neighbors are configured, the RNC chooses a decision algorithm according to whether the conditions Blind handover condition of direct blind handover are met.

If BlindHOQualityCondition value of the blind handover neighbor cell is -115( i.e. blind handover neighbor coverage area is greater than the serving cell in LDR state), the RNC performs direct blind handover to this cell.

If there is no such cell with the parameter value -115, the RNC initiates an intra-frequency measurement for conditional blind handover.

z In the execution phase: The RNC performs the blind handover according to the decision result.

Procedure of Load-based inter-frequency handover



67

Procedure of Load-based inter-frequency handoverLoad-Based Inter-Frequency Handover Decision

Step1: The LDR algorithm learns that a cell is overloaded and provides target cells and the UE with lowest priority for handover.

Step2: The RNC will determines whether to trigger inter-frequency blind handover

1. The RNC determines to trigger an inter-frequency blind handover through parameter LDR_HO_ALLOW_SHO_SWITCH of Handover Algorithm Switch parameter if the selected UE (with the lowest priority) is in SHO state.

1. If LDR_HO_ALLOW_SHO_SWITCH is set to ON, the UE in soft handover supports an inter-frequency blind handover. The RNC determines whether the cell that triggers LDR is the best cell.

1. If this cell is the best cell, the RNC initiates intra-frequency measurement for inter-frequency blind handover.

2. If this cell is not the best cell, the RNC does not initiate an inter-frequency blind handover.

2. If LDR_HO_ALLOW_SHO_SWITCH is set to OFF, The RNC determines whether the UE has multiple RLs.

1. If the UE has multiple RLs, the RNC does not initiate an inter-frequency blind handover.

2. If the UE does not have multiple RLs, the RNC initiates inter-frequency measurement.

Step3: According to the parameter Blind handover condition, the RNC executes:

If BlindHOQualityCondition value of the blind handover neighbor cell is -115( i.e. blind handover neighbor coverage area is greater than the serving cell in LDR state), the RNC performs direct blind handover to this cell.

If there is no such cell with the parameter value -115, the RNC initiates an intra-frequency measurement for conditional blind handover. For detailed information, see Intra-Frequency Handover Measurement Based on Conditional Blind Handover.

If the neighboring cells have the same Blind handover condition value, the RNC chooses any one of them.



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Procedure of Load-based inter-frequency handoverIntra-Frequency Handover Measurement Based on Conditional Blind Handover

The inter-frequency cells with the same coverage area have the same PCPICH RSCP values.

By measuring the PCPICH RSCP of the cell, the quality of the cells with the same coverage

area can be determined, which increases the probability of successful blind handover.

The intra-frequency measurement for conditional blind handover is described as follows:

Step1: The RNC initializes the timer of intra-frequency measurement for blind handover.

Step2: The measurement reporting mode is set to periodic reporting by RNC. The reporting period is set by the parameter BlindHoIntrafreqMRInterval. The measurement reporting number is set by BlindHOIntrafreqMRAMount.The intra-frequency measurement quantity is PCPICH RSCP. The list of cells to be measured just includes the cell that triggers LDR.

Step3: After receiving from the UE the intra-frequency measurement reports for conditional blind handover, the RNC checks whether the following condition is met: CPICH RSCP of the cell in the measurement report BlindHOQualityCondition

If the condition is met, the RNC increments the counter of the number of intra-frequency measurement reports for blind handover by 1.

If the condition is not met, the RNC does not perform a blind handover to the cell that triggers LDR and stops intra-frequency measurement for blind handover.

Step4: When the counter reaches the value of Intra-frequency measurement report amount for blind handover (i.e. BlindHOIntrafreqMRAMount), the RNC initiates a blind handover to the cell that triggers LDR. If the counter does not reach this value, the RNC waits for the next intra-frequency measurement report from the U

03 OWJ200103 WCDMA Handover Algorithm and Relevant Parameters (1)

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