8/14/2019 03 - OWJ200103 WCDMA Handover Algorithm and Parameters RAN10 ISSUE2.00 http://slidepdf.com/reader/full/03-owj200103-wcdma-handover-algorithm-and-parameters-ran10-issue200 1/197 WCDMA Handover Algorithm and Parameters Confidential Information of Huawei. No Spreading Without Permission 1
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03 - OWJ200103 WCDMA Handover Algorithm and Parameters RAN10 ISSUE2.00
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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.
Intra-frequency soft handover is more commonly used than intra-frequency hardhandover. Intra-frequency hard handover is used only in some special scenarios, for
example, when there is no Iur interface between two RNCs.
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Content: This parameter specifies the intra-frequency measurement L3 filtercoefficient. The greater this value is set, the greater the smoothing effect and thehigher the anti-fast fading capability are, but the lower the signal change tracingcapability is.
The default value of this parameter is 3
Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
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MNew is the measurement value of the cell in the reporting range.
WCDMA Handover Algorithm and Parameters
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.
W represents Weighted factor, used to weight the quality of the active set.
Mi is the measurement value of a cell in the active set.
NA is the number of cells not forbidden to affect the reporting range in the active
set.
MBest is the measurement value of the best cell in the active set.
R1a is the reporting range or the relative threshold of soft handover. The thresholdparameters 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
H1a represents 1A hysteresis, the hysteresis value of event 1A.
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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)Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MODCELLINTRAFREQHO .
VP service 1A event relative THD
Parameter ID: IntraRelThdFor1ACSVP
Value range: 0~14.5; step: 0.5
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..
The default value of this parameter is 6 (3dB)
Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MODCELLINTRAFREQHO .
PS service 1A event relative THD
Parameter ID: IntraRelThdFor1APS
Value range: 0~14.5; step: 0.5
Content: This parameter specifies the PS service relative threshold of event 1A. The smallerthe parameter value is, the more easily event 1A is triggered.
The default value of this parameter is 6 (3dB)
Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MOD
CELLINTRAFREQHO .
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Content: This parameter specifies the hysteresis value of event 1A. It is related to the slow fadingcharacteristic.
The default value of this parameter is 0 (0dB)
Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MODCELLINTRAFREQHO .
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 theslower the response of event reporting, triggered by measured signal changes.
The recommended value of this parameter is D320 ( 320ms )
Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MODCELLINTRAFREQHO .
Weighted factor
Parameter ID: WeightValue range: 0~20,step:0.1
Content: This parameter is used to define the soft handover relative threshold based on the measured
value of each cell in the active set. The greater the parameter value, the higher the soft handoverrelative threshold. When this value is set to 0, the soft handover relative threshold is determined only by
the best cell in the active set. .
The Default Value of this parameter is 0
Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MOD
CELLINTRAFREQHO .
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Parameter ID: Hystfor1CValue range: 0~7.5; step: 0.5Content: This parameter specifies the hysteresis value of event1C. It is related to the slow fading characteristic.The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
1C event trigger delay time Parameter ID: TrigTime1CValue range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320,640, 1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of event1C. It is related to the slow fading characteristic. The greater theparameter value, the smaller the probability of misjudgment, butthe slower the response of event reporting, triggered by measuredsignal changes.The recommended value of this parameter is D640 ( 640ms )Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
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Value range: 0~7.5; step: 0.5Content: This parameter specifies the hysteresis value of event1D. It is related to the slow fading characteristic.
The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
1D event trigger delay time Parameter ID: TrigTime1DValue range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320,640, 1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of event1D. It is related to the slow fading characteristic. The greater theparameter value, the smaller the probability of misjudgment, but
the slower the response of event reporting, triggered by measuredsignal changes.The recommended value of this parameter is D640 ( 640ms )Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
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The first measurement report is sent when primary CPICH D becomes better than primary CPICH
WCDMA Handover Algorithm and Parameters
B. The "cell measurement event result" of the measurement report contains the information of
primary CPICH D and CPICH B.
On the assumption that the E-DCH active set has been updated after the first measurement report
(E-DCH active set is now primary CPICH A and primary CPICH D), the second report is sentwhen primary CPICH C becomes better than primary CPICH A. The "cell measurement event
result" of the second measurement report contains the information of primary CPICH C and
primary CPICH A.
The parameters described in the following need to be set on the RNC LMT:
1J hysteresis
1J event trigger delay time
1J event to periodical rpt number
1J event to periodical rpt period
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Parameter ID: Hystfor1JValue range: 0~7.5; step: 0.5Content: This parameter specifies the hysteresis value of event 1J. It isrelated to the slow fading characteristic.
The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO .
1J event trigger delay time Parameter ID: TrigTime1JValue range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640,1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of event 1D. Itis related to the slow fading characteristic.The recommended value of this parameter is D640 ( 640ms )Set this parameter through SET INTRAFREQHO / ADD
CELLINTRAFREQHO / MOD CELLINTRAFREQHO .
Max number of cell in edch active cell
Parameter ID: MAXEDCHCELLINACTIVESETValue range: 1 to 4Content: This parameter specifies the maximum number of cells in theE-DCH active set.The recommended value of this parameter is 3Set this parameter through SET HOCOMM .
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The estimation procedure after the cell fails to admit the UE is described as follows:
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.
The condition of rate reduction is as follows:
Mnew > Mbest_cell - RelThdForDwnGrd
where
Mnew is the CPICH Ec/No measurement value of the cell failing to be admitted. Mbest_cell is 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.
WCDMA Handover Algorithm and Parameters
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 failurecounter by one.
Before the SHO failure evaluation timer expires, no action is takenand the RNC waits for the next measurement report period.
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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Step1:The RNC performs a rate reduction process for the
access service.
Step2:After the rate reduction succeeds, the RNC immediatelyattempts to add this cell to the active set without measurement:
If the cell succeeds in admitting the UE, the RNCadds the radio link and sets the SHO failurecounter of the cell to 0 and ends the execution.
If the cell fails to admit the UE, the RNC starts thePeriod of penalty timer for SHO failure afterdown rate to avoid an increase in the ratetriggered by DCCC within the period. Also in this
period, the RNC sets the SHO failure counter ofthe 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.
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FALSE: The priority of the neighboring cell is invalid. The neighboringcells whose priority flag is FALSE are the last ones to be considered asthe measurement objects in the neighboring cell combination algorithm.
TRUE: The priority of the neighboring cell is valid in the neighboring cellcombination algorithm. .
The default value of this parameter is FALSE
Set this parameter through ADD INTRAFREQNCELL/MOD INTRAFREQNCELL
/ ADD INTERFREQNCELL/MOD INTERFREQNCELL / ADD
GSMNCELL/MOD GSMNCELL
The priority of neighbor cell
Parameter ID: NPrio
Value range: 0 to 30 The default value of this parameter is None
Content:
When The flag of the priority is TRUE, The priority of neighbor cell specifies the
priority of neighboring cells. The smaller the parameter value is, the higher the
priority is and the more easily the neighboring cell is chosen as a measurement
object in the neighboring cell combination algorithm. For example, the
neighboring cells with priority 1 are more easily chosen as the measurement
WCDMA Handover Algorithm and Parameters
objects than the cells with priority 2 in the neighboring cell combination algorithm.
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
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.
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.
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 anda 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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Q Used is the measured quality of the used frequency.
WCDMA Handover Algorithm and Parameters
T Used2d 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
H 2d is the event 2D hysteresis value 2D hysteresis.
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.
Note:
Any of the Ec/No and RSCP measurement result can trigger the 2D event.
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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.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV .
Inter-freq R99 PS measure start Ec/No THD
Parameter ID : InterFreqR99PsThd2DEcNo
Value range: –24 to 0 ,step :1dB.The default value of this parameter is -14dBContent: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE reports event 2D when themeasurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to startthe inter-frequency measurement.Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV
Inter-freq H measure start Ec/No THD
Parameter ID : InterFreqHThd2DEcN0Value range: –24 to 0 ,step :1dB.The default value of this parameter is -14dBContent: For PS domain HSPA services, when Ec/No is used as the measurement quantity for inter-frequencymeasurement, the RNC sends the signaling to activate compressed mode and start inter-frequency measurement, if theUE reports the event 2D when the measured value is smaller than the value of this parameter.Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV
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Content: If the CS service uses RSCP as a measurement quantity, the UE reports event 2Dwhen 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..
Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV .
Inter-freq R99 PS measure start RSCP THD
Parameter ID : InterFreqR99PsThd2DEcNoValue range: –115 to -25 dBm ,step :1dB.
The default value of this parameter is -95dBm
Content: If the PS domain R99 service uses RSCP as a measurement quantity, the UE reportsevent 2D when the measurement value is lower than the threshold. The RNC sends a messageto enable the compressed mode and to start the inter-frequency measurement.Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
Inter-freq H measure start RSCP THD
Parameter ID : InterFreqHThd2DRSCPValue range: –115 to -25 dBm ,step :1dB.
The default value of this parameter is -95dBm
Content: For PS domain HSPA services, when RSCP is used as the measurement quantity forinter-frequency measurement, the RNC sends the signaling to activate compressed mode andstart inter-frequency measurement, if the UE reports the event 2D when the measured value issmaller than the value of this parameter .Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
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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.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD
The default value of this parameter is D320 (320 ms)
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 ofmisjudgment. In this case, however, the event responds to the changes of measuredsignals at a lower speed.Set this parameter through ADD CELLINTERFREQHOCOV / MOD
CELLINTERFREQHOCOV / SET INTERFREQHOCOV
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Q Used is the measured quality of the used frequency.
WCDMA Handover Algorithm and Parameters
T Used2f 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
H 2f is the event 2F hysteresis value 2F hysteresis .
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.
Note:
Any of Ec/No and RSCP measurement result can trigger the 2F event.
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Content: If the CS service uses Ec/No as a measurement quantity, the UE reports event 2F when themeasurement value is higher than the threshold. The RNC sends a message to disable the compressed
mode and to stop the inter-frequency measurement.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SETINTERFREQHOCOV
Inter-freq R99 PS measure stop Ec/No THD
Parameter ID : InterFreqR99PsThd2FEcNoValue range: –24 to 0 ,step :1dB.
The default value of this parameter is -12dBContent: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE reports event 2Fwhen the measurement value is higher than the threshold. The RNC sends a message to disable thecompressed mode and to stop the inter-frequency measurement.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SETINTERFREQHOCOV
Inter-freq H measure stop Ec/No THD
Parameter ID : InterFreqHThd2FEcN0Value range: –24 to 0 ,step :1dB.
The default value of this parameter is -12dBContent: 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 ofthis parameter .
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SETINTERFREQHOCOV
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Content: If the CS service uses RSCP as a measurement quantity, the UE reports event 2Fwhen 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.
Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV .
Inter-freq R99 PS measure stop RSCP THD
Parameter ID : InterFreqR99PsThd2FRSCPValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -92dBm
Content: If the PS domain R99 service uses RSCP as a measurement quantity, the UE reportsevent 2F when the measurement value is higher than the threshold. The RNC sends a messageto disable the compressed mode and to stop the inter-frequency measurement.Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
Inter-freq H measure stop RSCP THD
Parameter ID : InterFreqHThd2FRSCPValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -92dBm
Content: For PS domain HSPA services, when RSCP is used as the measurement quantity forinter-frequency measurement, the RNC sends the signaling to deactivate compressed mode andstop inter-frequency measurement, if the UE reports the event 2F when the measured value islarger than the value of this parameter .Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
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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.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD
The default value of this parameter is D1280 (1280 ms)
Content: This parameter specifies the time of event 2F trigger delay, which is related toslow 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 measuredsignals at a lower speed.Set this parameter through ADD CELLINTERFREQHOCOV / MOD
CELLINTERFREQHOCOV / SET INTERFREQHOCOV
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The default value of this parameter is Periodical reporting
Content: This parameter specifies the inter-frequency measurement report mode.
Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
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
The default value of this parameter is D500 (500ms)
Content: This parameter specifies the interval of the inter-frequency measurement report.
Set this parameter through ADD CELLINTERFREQHOCOV / MODCELLINTERFREQHOCOV / SET INTERFREQHOCOV
Inter-freq measure timer length
Parameter ID: PeriodReportInterval
Value range : 0 to 512 ,step 1s
The default value of this parameter is 60 ( 60s)
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-frequencymeasurement and disables the compressed mode.
If this parameter is set to 0, the RNC does not start the inter-frequencymeasurement timer. .
Set this parameter for handover based on coverage through ADDCELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET INTERFREQHOCOV
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Content: If the CS service inter-frequency handover uses the event-triggered measurementreport mode, event 2B may be triggered when the Ec/No value of the target frequency is higher
than the threshold. In periodical measurement report mode, this parameter is used for handover
evaluation on the RNC side.
Set this parameter through ADD CELLINTERFREQHOCOV/MODCELLINTERFREQHOCOV/SET INTERFREQHOCOV
Inter-freq CS Used frequency trigger Ec/No THD
Parameter ID: UsedFreqCSThdEcN0
Value range :–24 to 0, step 1dB
The default value of this parameter is –12 dBContent: If the CS service inter-frequency handover uses the event-triggered measurement
report mode, event 2B may be triggered when the Ec/No value of the used frequency is lower
than the threshold.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
Event 2B is triggered only when the two necessary conditions are met at the same time.
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Content: This parameter specifies the event 2B trigger hysteresis, which is related toslow 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.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
2B event trigger delay time
Parameter ID: TimeToTrig2B
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320,
D640, D1280, D2560, D5000
The default value of this parameter is D0 (0ms)
Content: This parameter specifies the time of event 2B 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.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Add all the pilot cells that trigger event 2B to a cell set and arrange the cellsaccording to the measurement quality of CPICH_Ec/No in descending order.
Select the cells in turn from the cell set to perform inter-frequency handover.
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Mother_Freq is the CPICH Ec/No or CPICH RSCP measurement value of the
WCDMA Handover Algorithm and Parameters
target cell reported by the UE. Both of the two measurement values of theinter-frequency cell must satisfy the formula.
CIOother_Freq is the cell individual offset value of the target cell. It is equal to thesum of Cell oriented Cell Individual Offset and Neigbhoring cell oriented
CIO. 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
NOTE:
These thresholds are the same as the quality threshold of event 2B.
H is the inter-frequency hard handover hysteresis value HHO hysteresis.
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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 default value of this parameter is 0 ( 0dB )
Set this parameter through ADD CELLSETUP / MOD CELLSETUP
Neigbhoring cell oriented CIO
Parameter ID: CIOOffset
Value range :–20 to +20 , step:0.5dB
The default value of this parameter is 0 (0dB)
Content: The sum of the value of this parameter and the Cell oriented Cell Individual Offset specifies theoffset of the cell CPICH measurement value. In handover algorithms, this parameter is used for moving theborder of a cell.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SET
INTERFREQHOCOV
HHO hysteresis
Parameter ID: HystForPrdInterFreq
Value range 0 to 29 , step:0.5dB
The default value of this parameter is 0 (0dB)
Content: This parameter is used to evaluate the inter-frequency handover on the RNC side. The greater thevalue of the parameter, the smaller the probability of the ping-pong effect and misjudgment. In this case,however, the speed of response to handover is lower.
Set this parameter through ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV / SETINTERFREQHOCOV
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The handover procedure is divided into four phases: handover triggering, handover measurement, handover
Procedure of QoS-based inter-frequency handover :WCDMA Handover Algorithm and Parameters
, .
Besides the triggering step, the rest 3 steps are the same with Coverage-based inter-frequency handover
In the triggering phase
If the service quality of the current cell deteriorates, the Link Stability Control Algorithm makes a handovermeasurement decision.
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 measurementreport can be used.
In the decision phase
After receiving the event 2B measurement reports of CPICH RSCP and CPICH Ec/No of the inter-frequencycell, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, andthe RNC makes a decision after evaluation.
In the execution phase
The RNC executes the handover procedure.
Note :
About “Link Stability Control Algorithm” :
When the uplink transmit power of the UE or downlink transmitted code power of the NodeB exceeds theassociated threshold :
For AMR, a fixed sequence of rate downsizing, inter-frequency handover, and then Inter-RAT handover areperformed,
for VP ,Inter-handover handover are performed,
For BE service, rate downsizing, inter-frequency handover, and then Inter-RAT handover are performedaccording to the configured sequence
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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 downlinkinter-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.
Set this parameter through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
Down Link QoS Measure timer length
Parameter ID : UpQoSMcTimerLen
Value range 0 to 512 ,step 1s
The default value of this parameter is 20 (20s)
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 uplinkinter-frequency measurement timer, the RNC stops the inter-frequencymeasurement and disables the compressed mode.
If this parameter is set to 0, the RNC does not start the inter-frequency QoS-based measurement timer. .
Set this parameter through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
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The handover procedure is divided into three phases: handover triggering, handover decision, and
handover execution
There is no measurement of the target cell, so we call it blind handover.
In the triggering phase
The Load Reshuffling (LDR) module directly determines whether the current cell is overloaded
and whether an inter-frequency handover needs to be performed. The LDR module provides thetarget cell information for the current cell, and the RNC performs the handover procedure.
In the decision phase
The RNC decides to trigger an inter-frequency blind handover if If the blind handoverneighbors are configured :
After the inter-frequency handover is triggered, the RNC chooses a decision algorithmaccording to whether the conditions “Blind handover condition” of direct blind
handover are met.
If the value of the parameter of a cell is -115, the RNC performs direct blindhandover 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.
In the execution phase
The RNC performs the blind handover according to the decision result.
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The intra-frequency measurement for conditional blind handover is described as follows:
WCDMA Handover Algorithm and Parameters
1.The RNC initializes the timer of intra-frequency measurement for blind handover. The timer is
specified by internal algorithm and needn't to be configured.
2. The RNC modifies the measurement mode:
The measurement reporting mode is changed to periodic reporting by a newmeasurement control . The reporting period is Intrafrequency measurement reportinterval of blind handover. The measurement reporting number is Intrafrequencymeasurement report amount of blind handover.The intra-frequency measurementquantity is CPICH RSCP.
3. 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 >= Blind handover condition
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. When the counter reaches the value of Intrafrequency measurement report
amount of blind handover, the RNC initiates a blind handover to the cell that triggersLDR.
If the counter does not reach this value, the RNC waits for the next intra-frequencymeasurement report from the UE.
If the timer of intra-frequency measurement for blind handover expires, the RNC doesnot perform a blind handover to the cell that triggers LDR and stops intra-frequencyhandover for blind handover.
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Procedure of Speed-based inter-frequency handover :
WCDMA Handover Algorithm and Parameters
The handover procedure is divided into four phases: handover triggering, handover measurement handover decision, and handoverexecution
In the triggering phase
The RNC receives the internal handover request according to the HCS speed estimation. The handover based on HCSspeed estimation is of two types:
When the UE is in low-speed state, RNC will trigger handover from the macro cell to the micro cell.
When the UE is in high-speed state, RNC will trigger handover from the micro cell to the macro cell.
For different types of handover, the RNC acts differently.
In the measurement phase
If the handover is performed from a macro cell to a micro cell, the RNC triggers compressed mode ,then sends an inter-frequency measurement control message for 2C event to start the inter-frequency measurement procedure
If the handover is performed from a micro cell to a macro cell, the RNC directly performs blind handover, withoutmeasurement procedure. only if the handover fails, the RNC triggers compressed mode ,then sends an inter-frequencymeasurement control message for 2C event to start the inter-frequency measurement procedure
In the decision phase
For handover from a macro cell to a micro cell, after the UE reports event 2C, the RNC performs the handover decision.
In the execution phase
The RNC initiates a handover procedure.
If the handover is performed from a micro cell to a macro cell and the target cell of blind handover is configured, the RNCperforms blind handover to the target cell.
If the blind handover fails or the handover is performed from a macro cell to a micro cell, the RNC performs the inter-frequency handover procedure to the cell with the best quality after receiving event 2C from the UE.
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The coverage of the UMTS is incontinuous at the initial stage of the 3G network. On theborder of the coverage, the poor signal quality of UMTS triggers the UMTS-to-GSMmeasurement. If the signal quality of GSM is good enough and all the services of the UEare supported by the GSM, the coverage-based UMTS-to-GSM handover is triggered.
QoS-based inter-frequency handover According to the Link Stability Control Algorithm, the RNC needs to trigger the QoS-based
UMTS-to-GSM handover to avoid call drops.
Load-based inter-frequency blind handover
If the load of the UMTS is heavy and all the RAB of a UE are supported by the GSM, theload-based UMTS-to-GSM handover is triggered.
Service-based UMTS-to-GSM handover
Based on layered services, the traffic of different classes is handed over to differentsystems. For example, when an Adaptive Multi Rate (AMR) speech service is requested,this service can be handed over to the GSM.
Speed-based inter-frequency handover
When the Hierarchical Cell Structure (HCS) is used, the cells are divided into differentlayers on the basis of coverage. Typically, a marco cell has large coverage and lowpriority, whereas a micro cell has small coverage and high priority.UMTS-to-GSMhandover can be triggered by the UE speed estimation algorithm of the HCS. A UEmoving at high speed is handed over to a cell with larger coverage to reduce the times ofhandover, whereas a UE moving at low speed is handed over to a cell with smallercoverage.
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Before handover, the RNC checks whether the preconditions meet the triggering requirements of
WCDMA Handover Algorithm and Parameters
the UMTS-to-GSM handover. The preconditions include the service handover indicator, GSM cell
capability, service capability, and UE capability.
The parameter Service handover indicator indicates the CN policy for the service handover to
the GSM. This parameter is indicated in the Radio Access Bearer (RAB) assignment signalingassigned by the CN, or can be configured on the RNC side by ADD/MOD TYPRABBASIC .
Before deciding UMTS-to-GSM handover, the RNC considers GSM cell capability, service
capability and UE capability.
GSM cell capability could be “GSM”,”GPRS”,”EDGE”, it should be the real capability of
the GSM neighbor, and configured in RNC data base by LMT correctly
Service capability could be “GSM”,”GPRS”,”EDGE” also, it should be properly configured
in RNC data base by LMT
UE capability is reported by the UE itself in “RRC Setup Complete” message.
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For the UE accessing combined services (with CS services), the RNC sets the service
handover indicator of the UE to that of the CS service, because the CS service has the
highest QoS priority.
For the UE accessing combined services (with only PS services), the RNC sets theservice handover indicator of the UE to that of the PS service, which has the highest
QoS priority.
If service handover indicators are not configured by the CN, each indictor can be set to
Service parameter index of a service on the RNC.
Based on different service handover indicators .RNC may initiate different action, for
example, handover based on service are not not performed for the services whose
handover indicator is “HO_TO_GSM_SHOULD_NOT_BE_PERFORM” or
“HO_TO_GSM_SHALL_NOT_BE_PERFORM”
WCDMA Handover Algorithm and Parameters
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Content: Identifying the type of the inter-RAT cell NO_CAPABILITY indicates thatthe capacity of the GSM cell remains unknown. It is not recommended to set thecell type to NO_CAPABILITY. If the cell type is NO_CAPABILITY, the inter-RAT
handover cannot be triggered. Set this parameter through ADD GSMCELL
Handover algorithm switch is set in the command SET CORRMALGOSWITCH.
INTER_RAT_PS_OUT_SWITCH
The switch decides whether the RNC will initiate Inter-RATmeasurement to trigger Inter-RAT handover of the PS domain fromthe UTRAN.
INTER_RAT_CS_OUT_SWITCH
The switch decides whether the RNC will initiate Inter-RATmeasurement to trigger Inter-RAT handover of the CS domain fromthe UTRAN.
Set this parameter through SET CORRMALGOSWITCH
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The default value of this parameter is SIMINTERFREQRAT
Content: This parameter specifies the type of cells to be measured when inter-frequency and Inter-RAT adjacent cellscoexist:
InterFreq: means that only the inter-frequency cells are measured and inter-frequency handover is performed.
InterRAT: means that only the GSM cells are measured and Inter-RAT handover is performed.
SimInterFreqRAT: means that both inter-frequency and Inter-RAT cells are measured and inter-frequency or Inter-RAThandover is performed according to the type of the cell that first meets the condition for handover decision. If only theinter-frequency cells or Inter-RAT cells exist, the value of this parameter is invalid
Set this parameter through ADD CELLHOCOMM/MOD CELLHOCOMM
During the concurrent inter-frequency and Inter-RAT measurement, the values of the parameter InterFreq & InterRatcoexist measure threshold choice for events 2D and 2F are chosen as follows:
When the value COEXIST_MEAS_THD_CHOICE_INTERFREQ is chosen, the inter-frequency measurementthreshold for event 2D is used.
When the value COEXIST_MEAS_THD_CHOICE_INTERRAT is chosen, the Inter-RAT measurement threshold forevent 2D is used.
Content: This parameter specifies the event 3A trigger hysteresis, which is related toslow 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 .
Set this parameter through ADD CELLINTERRATHOCOV/MOD
CELLINTERRATHOCOV/SET INTERRATHOCOV
3A event trigger delay time
Parameter ID: TrigTime3A
Value range :D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320,D640, D1280, D2560, D5000
The default value of this parameter is 0 ( 0ms )
Content: This parameter specifies the time of event 3A 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.
Set this parameter through ADD CELLINTERRATHOCOV / MOD
CELLINTERRATHOCOV / SET INTERRATHOCOV
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Content: This parameter specifies the event 3C trigger hysteresis, which is related to slowfading . The larger the value of this parameter, the smaller the probability of ping-pong effect and
decision mistakes. In this case, however, event 3C cannot be triggered in time .
Set this parameter through ADD CELLINTERRATHONCOV/MOD
CELLINTERRATHOCOV/SET INTERRATHONCOV
3C event trigger delay time
Parameter ID : TrigTime3C
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640,
D1280, D2560, D5000
The default value of this parameter is D640 (640 ms)
Content: This parameter specifies the time of event 3C trigger delay, which is related to slow
fading. The larger the value of this parameter, the smaller the probability of decision mistakes. In
this case, however, event 3C responds to the changes of measured signals more slowly.
Set this parameter through ADD CELLINTERRATHONCOV/MOD
CELLINTERRATHOCOV/SET INTERRATHONCOV
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The procedure of load information interchanging between the 3G source cell and 2G target cell is
described as follows:
When the RNC sends a RELOCATION REQUIRED message to the 3G CN,
If the switch Send Load Info to GSM Ind is set to ON, the RELOCATIONREQUIRED message includes the load information of the 3G source cell.
If the switch Send Load Info to GSM Ind is set to OFF, then the RELOCATIONREQUIRED message does not include the Information
When the RNC receives the RELOCATION COMMAND message from the 2G CN,
If the switch NCOV Reloc Ind based on GSM cell load is set to ON, the RNC obtains
the load information of the 2G target cell by reading the RELOCATION COMMANDmessage.
If the 2G load is lower than CS domain Reloc GSM load THD (for CS service),
or if the 2G load is lower than PS domain Reloc GSM load THD (for PSservice), the RNC continues the Inter-RAT handover procedure; otherwise,
the RNC returns the RELOCATION CANCEL message to the CN to cancelthis Inter-RAT handover and makes another handover attempt to the nextcandidate cell generated in the cell list based on Inter-RAT measurement.
If the load information of the 2G target cell is not included in the RELOCATION
COMMAND message, the load information of the 2G target cell is notconsidered and this Inter-RAT handover is continued.
If the switch NCOV Reloc Ind based on GSM cell load is set to OFF, the RNC
WCDMA Handover Algorithm and Parameters
- .
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When the parameter is set to ON, the RNC sends UMTS cell load informationto the GSM CN during the non-coverage based system relocation in or outprocess.
When the parameter is set to OFF, the RNC does not send UMTS cell loadinformation to the GSM during the system relocation in or out process.
Set this parameter through SET INTERRATHONCOV
NCOV Reloc Ind based on GSM cell load
Parameter ID : NcovHoOn2GldInd
Value range ON, OFF
The default value of this parameter is ON
Content:
When the parameter is set to ON, the RNC stops the non-coveragebased system relocation out process if the GSM cell load exceeds the CSdormain Reloc GSM load THD or PS dormain Reloc GSM load THD.
When the parameter is set to OFF, the RNC continues the systemrelocation out process without considering the thresholds. This parameterspecifies the time of event 3C trigger delay, which is related to slowfading. The larger the value of this parameter, the smaller the probabilityof decision mistakes. In this case, however, event 3C responds to thechanges of measured signals more slowly.
Set this parameter through SET INTERRATHONCOV
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When the parameter is set to ON, the RNC sends UMTS cell load informationto the GSM CN during the non-coverage based system relocation in or outprocess.
When the parameter is set to OFF, the RNC does not send UMTS cell loadinformation to the GSM during the system relocation in or out process.
Set this parameter through SET INTERRATHONCOV
PS domain Reloc GSM load THD
Parameter ID : PSHOOut2GLoadThd
Value range 0 to 100 ,step:1%
The default value of this parameter is OFF
Content:
When the parameter is set to ON, the RNC sends UMTS cell load informationto the GSM CN during the non-coverage based system relocation in or outprocess.
When the parameter is set to OFF, the RNC does not send UMTS cell loadinformation to the GSM during the system relocation in or out process.
Set this parameter through SET INTERRATHONCOV
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The procedure for the fallback service is described as follows:
Procedure of Multimedia Fallback
WCDMA Handover Algorithm and Parameters
In the service set up stage, the CN sends the SRNC a RANAP RAB ASSIGNMENT
REQUIREMENT message to set up the VP service. The message includes the "Alternative RAB
Para" that has QoS parameters required for setting up the speech service.
During UMTS-to-GSM handover, the SRNC sends a RANAP MODIFY REQUEST message to
change the VP service to the AMR speech service. In the 3GPP R6 protocol, the AlternativeRAB Configuration is also added to the RAB MODIFY REQUEST message, which enables the
RNC to request the CN to change the VP service to the AMR speech service.
The MSC initiates the Bearer Capability (BC) negotiation with the UE.
After the negotiation is modified, the RNC is informed of performing service change. The
multimedia fallback ends when the service change is completed.
When the multimedia fallback ends, the RNC decides whether to perform the UMTS-to-GSM
handover according to the current measurements reported by the UE.
At the beginning of the service setup, the RNC saves the RAB Para and "Alternative RAB Para" in
the RAB ASSIGNMENT or REQUEST RELOCATION REQUEST message. This makes
preparations for notifying the CN of changing the VP service to the AMR speech service.
The CN initiates the RAB reconfiguration to inform the two calling parties of performing the
multimedia fallback. The multimedia fallback of the calling party is consistent with that of the
called party. The single VP service falls back to the single AMR speech service. The multi-RAB
service combined with VP falls back to the multi-RAB service combined with AMR. If the
multimedia fallback succeeds, that is, the video phone in the service falls back to speech
successfully, the Inter-RAT handover is initiated. Otherwise, the Inter-RAT handover fails.
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1. The UE in CELL_DCH state or the UTRAN (when the UE is in CELL_FACH state) decides to
initiate an Inter-RAT handover in the PS domain to hand over the UE to a new GSM cell and
stop the data transmission between the UE and the network.
2. The UE sends a ROUTING AREA UPDATE REQUEST message to the 2G SGSN. The Update
Type in the message indicates RA update, combined RA/LA update, or combined RA/LA update
with IMSI attach. The BSS adds the CGI including the RAC and LAC of the cell to the received
message before forwarding the message to a new 2G SGSN.
3. The new 2G SGSN sends an SGSN CONTEXT REQUEST message to the old 3G SGSN to
obtain the MM and PDP contexts. The old 3G SGSN validates the old P-TMSI Signature. If the
old P-TMSI Signature is valid, the old 3G SGSN starts a timer. Otherwise, the old 3G SGSN
responds with an error cause.
4. If the UE stays in connected mode before handover, the old 3G SGSN sends an SRNS
CONTEXT REQUEST message. After receiving this message, the SRNS buffers the DPUs,
stops sending the PDUs to the UE, and sends an SRNS CONTEXT RESPONSE message to
the old 3G SGSN.
5. The old 3G SGSN sends an SGSN CONTEXT RESPONSE message to the 2G SGSN,
including the MM and PDP contexts.
6. The securit functions can be executed.
WCDMA Handover Algorithm and Parameters
.
7. The new 2G SGSN sends an SGSN CONTEXT ACKNOWLEDGE message to the old 3G
SGSN. This informs the old 3G SGSN that the new 2G SGSN is ready to receive the PDUs
belonging to the activated PDP contexts.
8. The old 3G SGSN sends a DATA FORWARD COMMAND message to the SRNS. The SRNSstarts a data-forwarding timer and sends the buffered PDUs to the old 3G SGSN.
9. The old 3G SGSN tunnels the GTP PDUs to the new 2G SGSN. In the PDUs, the sequence
numbers in the GTP header remain unchanged.
10. The new 2G SGSN sends an UPDATE PDP CONTEXT REQUEST message to each related
GGSN. Each GGSN sends an UPDATE PDP CONTEXT RESPONSE message after updating
its PDP context fields.
11. The new 2G SGSN sends an UPDATE GPRS LOCATION message, requesting the HLR to
modify the SGSN number.
12. The HLR sends a CANCEL LOCATION message to the old 3G SGSN. The old 3G SGSNresponds with a CANCEL LOCATION ACK message. After the timer expires, the old 3G SGSN
removes the MM and PDP contexts.
13. The old 3G SGSN sends an IU RELEASE COMMAND message to the SRNS. After the data-
forwarding timer expires, the SRNS responds with an IU RELEASE COMPLETE message.
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14. The HLR sends an INSERT SUBSCRIBER DATA message to the new 2G SGSN. The 2G
SGSN constructs an MM context and PDP contexts for the UE and returns an INSERT
SUBSCRIBER DATA ACK message to the HLR.
15. The HLR sends an UPDATE GPRS LOCATION ACK message to the new 2G SGSN.
16. If the association has to be established, the new 2G SGSN sends a LOCATION UPDATE
REQUEST message to the VLR. The VLR stores the SGSN number for creating or updating the
association.
17. If the subscriber data in the VLR is marked as not confirmed by the HLR, the new VLR informs
the HLR. The HLR cancels the old VLR and inserts subscriber data in the new VLR.
1. The new VLR sends an UPDATE LOCATION message to the HLR.
2. The HLR cancels the data in the old VLR by sending a CANCEL LOCATIONmessage to the old VLR.
3. The old VLR acknowledges the message by responding with a CANCELLOCATION ACK message.
4. The HLR sends an INSERT SUBSCRIBER DATA message to the new VLR.
5. The new VLR acknowledges the message by responding with an INSERT
SUBSCRIBER DATA ACK message.
WCDMA Handover Algorithm and Parameters
6. The HLR responds with a UPDATE LOCATION ACK message to the new VLR.
18. The new VLR allocates a new TMSI and responds with a LOCATION UPDATE ACCEPT
message to the 2G SGSN.
19.
The new 2G SGSN checks the presence of the MS in the new RA. If all checks are successful,the new 2G SGSN constructs the MM and PDP contexts for the MS. A logical link is established
between the new 2G SGSN and the UE. The 2G SGSN responds to the UE with a ROUTING
AREA UPDATE ACCEPT message.
20. The UE acknowledges the new P-TMSI by returning a ROUTING AREA UPDATE COMPLETE
message, including all PDUs successfully sent to the UE before the routing area update
procedure.
21. The new 2G SGSN sends a TMSI REALLOCATION COMPLETE message to the new VLR if
the UE confirms the VLR TMSI.
22.
The 2G SGSN and the BSS perform the BSS PACKET FLOW CONTEXT procedure.
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