Intra-Frequency Handover Decision and Execution- 123docz.net

3. Signaling Procedures for Intra-Frequency Handover

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Intra-Frequency Handover Decision and Execution

RNC will make decision and execute handover depends on the Events the RNC receives.

z 1A Event

z 1B Event

z 1C Event

z 1D Event

z 1J Event

When receiving an event 1C report, the RNC decides whether to change the worst cell.

For event 1C, the UE reports a list that contains good cells and the cells to be replaced, and sequences the cells in descending order by

measurement quantity.

After receiving the list from the UE, the RNC replaces the bad cells in the active set with the good cells in the list.

When receiving an event 1B report, the RNC determines whether to delete a cell.

When receiving an event 1A report, the RNC decides whether to add a cell.

For event 1A, the UE can report more than one cell in the event list in one measurement report. These cells are in the list of the Measurement Control message, and they are sequenced in descending order by measurement quantity.

For the cells in the list, the RNC adds the radio link to the active set only if the number of cells in the active set does not reach the maximum value.

Decision and Execution Event

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When receiving an event 1J report with information about the good cells and the cells to be replaced, the RNC proceeds as follows:

•If the current number of cells in the E-DCH active set is less than the value of Max number of cell in edch active set, the uplink of the cell where event 1J is triggered is reconfigured to E-DCH.

•If the current number of cells in the E-DCH active set is equal to the value of Max number of cell in edch active set, the RNC searches the

measurement report for the non-serving Cell_EDCH with the lowest measured quality in the E-DCH active set. Then, the uplink of the cell where event 1J is triggered is reconfigured from DCH to E-DCH, and the uplink of CELL-EDCH is reconfigured from E-DCH to DCH.

When receiving an event 1D report, which includes information about only one cell, the RNC learns that the quality of this cell is better than that of the serving cell and takes one of the following actions:

•If the reported cell is in the active set, the RNC decides whether to change the best cell or reconfigure measurement control.

•If the reported cell is in the monitored set,

•If the number of cells in the active set has not reached the maximum value, the RNC decides a soft handover and adds the cell to the active set.

•If the number of cells in the active set has reached the maximum value, the RNC decides a soft handover and replaces the worst cell in the active set with the reported cell.

•The RNC determines whether the intra-frequency hard handover scenarios are applicable. For detailed information, see 3.1 Intra-Frequency Handover Types. If any scenario is applicable, the RNC performs an intra-frequency hard handover.

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z Max number of cell in active set

Parameter ID: MaxCellInActiveSet

The default value of this parameter is 3

z Minimum Quality Threshold for SHO

Parameter ID: SHOQualmin

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

Parameters of Intra-Frequency Handover

When make decision, RNC must follow these restrictions

zMax number of cell in active set

Parameter ID: MaxCellInActiveSet

Value range: 1~6;

Content: This parameter specifies the Max number of cell in active set.

The default value of this parameter is 3

Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .

zMinimum Quality Threshold for SHO

Parameter ID: SHOQualmin

Value range: -24~0,step:1dB

Content: This parameter specifies the minimum quality threshold for soft handover..

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

Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .

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z For R99 NRT services to increase the probability of a successful soft handover, the rate reduction is triggered after a admission failure

Rate Reduction After an SHO Failure

1A,1C,1D is received by RNC

Execute admission control in target cell

Admission succeed?

Execute Handover

Rate Reduction

If the RNC receives a 1A, 1C, or 1D measurement report, the corresponding cell tries to admit the UE. If the cell fails to admit the UE, the RNC performs the estimation procedure for rate reduction.

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z procedure for rate reduction

Estimation

Execution

Rate Reduction After an SHO Failure

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z Estimation Procedure for Rate Reduction

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The estimation procedure after the cell fails to admit the UE is described as follows:

z Step 1 : The RNC evaluates whether the measurement quantity of the cell failing to be admitted meets the condition of rate reduction.

If the condition is met, the RNC performs a rate reduction process for the handover service immediately.

If the condition is not met, the RNC performs Step2.

z The condition of rate reduction is as follows:

z Mnew> Mbest_cell- RelThdForDwnGrd

z where

Mnew is the CPICH Ec/No measurement value of the cell failing to be admitted.

Mbest_cellis the CPICH Ec/No measurement value of the best cell in the active set.

RelThdForDwnGrd is configured through the parameter Relative threshold of SHO failure.

z Step 2 :The RNC evaluates whether the number of SHO failures in the cell exceeds the Threshold number of SHO failure.

If the number of SHO failures in the cell is smaller than the Threshold number of SHO failure, the RNC determines whether the SHO failure evaluation timer has been started:

If the timer has not been started, the RNC starts it.

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

Before the SHO failure evaluation timer expires, no action is taken and the RNC waits for the next measurement report period.

z When the SHO failure evaluation timer expires, the RNC sets the SHO failure counter of the corresponding cell to 0 and ends the evaluation.

If the number of SHO failures in the cell is larger than or equal to the Threshold number of SHO failure, the RNC performs a rate reduction process for the access service and sets the SHO failure counter of the corresponding cell to 0.

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z Relative threshold of SHO failure

Parameter ID: RelThdForDwnGrd

The default value of this parameter is 2 ( 1dB )

z Max evaluation period of SHO failure

Parameter ID: ShoFailPeriod

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

z Threshold number of SHO failure

Parameter ID: ShoFailNumForDwnGrd

The default value of this parameter is 3

Parameters of Intra-Frequency Handover

zRelative threshold of SHO failure

Parameter ID: RelThdForDwnGrd

Value range: -29 to +29 ; step: 0.5 dB

Content: This parameter specifies the relative threshold for direct rate reduction after an SHO failure. If the difference between the signal quality of the target cell to which an SHO fails and that of the best cell is lower than this relative threshold, the RNC directly initiates a rate reduction process in the active set, regardless of the limitation on the number of SHO failures.

The default value of this parameter is 2 (1dB)

Set this parameter through SET INTRAFREQHO.

Max evaluation period of SHO failure

Parameter ID: ShoFailPeriod

Value range: 0~120s

Content: This parameter specifies the maximum evaluation period of SHO failures for rate reduction. During the evaluation period, the RNC records the number of SHO failures in at most three cells for each UE. After the evaluation period, the RNC clears this record.

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

Set this parameter through SET INTRAFREQHO

zThreshold number of SHO failure

Parameter ID: ShoFailNumForDwnGrd

Value range: 0~63

Content: This parameter specifies the threshold number of SHO failures for rate reduction. If the number of SHO failures in a cell reaches or exceeds this threshold during the period specified by Max evaluation period of SHO failure, the RNC performs a rate reduction process in the active set. After the rate reduction succeeds, the RNC initiates an SHO in the cell.

The recommended value of this parameter is 3

Set this parameter through SET INTRAFREQHO

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The rate reduction execution procedure is :

z Step1：The RNC performs a rate reduction process for the access service.

z Step2：After the rate reduction succeeds, the RNC immediately attempts to add this cell to the active set without measurement:

If the cell succeeds in admitting the UE, the RNC adds the radio link and sets the SHO failure counter of the cell to 0 and ends the execution.

If the cell fails to admit the UE, the RNC starts the Period of penalty timer for SHO failure after down rate to avoid an increase in the rate triggered by DCCC within the period. Also in this period, the RNC sets the SHO failure counter of the cell to 0 and ends the execution.

If fails to perform a soft handover again, RNC performs the estimation procedure and the execution procedure, as previously described.

z Execution Procedure of Rate Reduction

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z Period of penalty timer for SHO failure after down rate

Parameter ID: DcccShoPenaltyTime

The default value of this parameter is 30 ( 30s )

Parameters of Rate Reduction Execution

zPeriod of penalty timer for SHO failure after down rate

Parameter ID: DcccShoPenaltyTime

Value range: 0 to 255 ; step: 1 s

Content: If an SHO fails again after the rate reduction, the RNC is forbidden to increase the rate during the period specified by this parameter.

The default value of this parameter is 30 ( 30s)

Set this parameter through SET INTRAFREQHO.

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Contents

1. Intra-Frequency Handover

1. Intra-Frequency handover Overview 2. Intra-Frequency Handover Procedure

1. Intra-Frequency Handover Measurement