03 - OWJ200103 WCDMA Handover Algorithm and Parameters RAN10 ISSUE2.00

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WCDMA Handover Algorithm and Parameters

Confidential Information of Huawei. No Spreading Without Permission 1



Handover is a basic function of a cellular mobile network. The purpose of handover is to


ensure that a UE in CELL_DCH state is served continuously when it moves.

HCS: hierarchical cell structure




Handover types supported by UMTS





Handover types supported by UMTS can be classified as:


Intra-frequency handover

Inter-frequency handover

Inter-RAT handover




Active set : Cells, which belong to the active set. User information is sent from all these cells. In


FDD, the cells in the active set are involved in soft handover. The UE shall only consider active

set cells included in the variable CELL_INFO_LIST for measurement; i.e. active set cells not

included in the CELL_INFO_LIST shall not be considered in any event evaluation and

measurement reporting.

Monitored set :Cells, which are not included in the active set, but are included in the

CELL_INFO_LIST belong to the monitored set.

Detected set : Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the

active set belong to the detected set. Reporting of measurements of the detected set is only

applicable to intra-frequency measurements made by UEs in CELL_DCH state.

RL: Radio link between NodeB and UE.

RLS: Radio link set. The RLs from same NodeB.

Combination way: For soft handover, the uplink signals are combined in RNC. The RNC will

select one best signal to process. We call this selective combination. For softer handover, the

uplink signals are combined in the RAKE receiver of NodeB. It is maximum ratio combination.

Soft handover gain: We have introduced in Coverage Planning.

CPICH: Common Pilot Channel. UE measure the signal strength of CPICH for handover decision.




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.

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.




The maximum number of RL is 3. This value can be changed. But this function need the


UE to support. Normally, the active set supported by UE is fixed 3 and can not be

changed.




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.

During soft handover, a UE is in the overlapping cell coverage area of two sectors

belonging to different base stations. The communications between UE and base station

take place concurrently via two air interface channels from each base station separately.

During softer handover, a UE is in the overlapping cell coverage area of two adjacent

sectors of a base station. The communications between UE and base station take place

concurrently via two air interface channels, one for each sector separately.




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

Compare to later one, the maximum ratio combination can get

more gain. So the performance of maximum ratio combinationis better

Since softer handover is completed in NodeB, it do not

consume transport resource of Iub




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.

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

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

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

There is a high-speed Best Effort (BE) service.

Compared with soft handover, intra-frequency hard handover is used to savedownlink bandwidth for a high-speed BE service.

The intra-frequency soft handover fails and intra-frequency hard handoveris allowed.

When intra-frequency soft handover fails because of a congestion problem of the target

cell, the RNC tries an intra-frequency hard handover with a lower service bit rate.

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.




Intra-frequency handover procedure is divided into three phases: handover


measurement, handover decision, and handover execution.

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 event results.

Upon receiving an event report from the UE, the RNC makes a handover decision and

performs the corresponding handover




The measurement control message carries the following information:


Event trigger threshold

Hysteresis value

Event trigger delay time

Neighboring cell list




The purpose of the measurement reporting procedure is to transfer


.

Based on the algorithm in measurement control, the UE will measure the signal

strength or quality and check if it meet the requirement of all event. If it meet the

requirement of any event, UE will send the measurement report to UTRAN to

trigger the handover. The most important information in the measurement are the

PSC , the CPICH Ec/No of the target cell, and the triggered event.




A is measurement value at the physical layer


B is the measurement value after layer 1 filtering at physical layer. The value goes from the

physical layer to high layer

C is measurement after processing in the layer3 filter

C’ is another measurement value

D is measurement report information sent on the radio interface or Iub interface




The measurement quantity of intra-frequency handover can be Common PilotChannel CPICH Ec/No or CPICH Received Si nal Code Power RSCP . It can be


used in all the measurement events of intra-frequency handover

Intra-freq Measure Quantity

Parameter ID: IntraFreqMeasQuantity

Value range: CPICH_Ec/No, CPICH_RSCPContent: This parameter specifies the measurement quantity used in intra-frequency measurement.

The default value of this parameter is CPICH_Ec/No

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

Before judging a measurement event and sending the measurement report, theUE performs L3 filtering for the measurement value.

Intra-freq meas L3 filter coeff

Parameter ID: FilterCoef

Value range: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19

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 .




Event Description

1A The PCPICH quality or strength of the cells in the monitored set enters

the reporting range . This indicates that the cell is close to the best cell .

A relative high combined gain can be achieved when the cell is added to

the active set

1B The PCPICH quality or strength of the cells in the active set leaves the

reporting range . This indicates that a cell is much worse than the quality

of the best cell. The cell should not stay in the active set

1C A non-active PCPICH becomes better than an active PCPICH. This

indicates that the quality or strength of a cell is close to the best cell. In

addition ,the number of cells in the active set has reached the maximum

Intra-Frequency Handover Measurement Events


value. The cell replaces the worst cell in the active set ; thus achieving a

higher combined gain

1D Event of the change of the best cell

1J RAN10.0 provides the solution to the issue of how to add an HSUPA cell in

a DCH active set to an E-DCH active set. Event 1J is added to the 3GPP

protocol. This event is triggered when a non-active E-DCH but active DCH

primary CPICH becomes better than an active E-DCH primary CPICH.




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


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.




If the signal quality of a cell that is not in the active set is higher than Th1A for a period of time


specified by 1A event trigger delay time (that is, Time to trigger in the figure), the UE reports

event 1A




CS non VP service 1A event relative THD


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)Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MODCELLINTRAFREQHO .

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..

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


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


Set this parameter through SET INTRAFREQHO / ADD CELLINTRAFREQHO / MOD

CELLINTRAFREQHO .




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 default value of this parameter is 0 ( 0dB )

Set this parameter through ADD CELLSETUP / MOD CELLSETUP

Neighboring cell oriented CIO

Parameter ID: CIOOffset


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 default value of this parameter is 0 ( 0dB )

Set this parameter through ADD INTRAFREQNCELL / MOD INTRAFREQNCELL




1A hysteresis

Parameter ID: Hystfor1A



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



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 )


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


CELLINTRAFREQHO .




The report mode of 1A is Event Trigger Report .


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




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


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.

W represents Weighted factor, used to weight the quality of the active set.

Mi is the measurement value of the 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.

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

H1b represents 1B hysteresis, the hysteresis value of event 1B.




If the signal quality of a cell in the active set is lower than Th1B curve for a period of time


specified by 1B event trigger delay time (Time to trigger in the figure), the UE reports

event 1B




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 .



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 .



CELLINTRAFREQHO .

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 .



CELLINTRAFREQHO .




1B hysteresis


Parameter ID: Hystfor1B


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

the slow fading characteristic.



CELLINTRAFREQHO .

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.

The recommended value of this parameter is D640 ( 640ms )


CELLINTRAFREQHO .




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


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.

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

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.

H1c represents 1C hysteresis, the hysteresis value of event 1C.




If the signal quality of a cell not in the active set is higher than Th1C for a period of time


specified by 1C event trigger delay time (Time to trigger in the figure), the UE reports

event 1C




1C hysteresis


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 .




The report mode of 1C is Event Trigger Report .


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




1C event to periodical rpt period


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.

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

Set this parameter through SET INTRAFREQHO / ADD

CELLINTRAFREQHO / MOD CELLINTRAFREQHO .

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






M is the measurement value of a cell that is not in the list of the best


cells.

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

H1d represents 1D hysteresis, the hysteresis value of event 1D.




If the si nal ualit of a cell not in the active set is hi her than Th1D for a eriod


of time specified by 1D event trigger delay time (Time to trigger in the figure),

the UE reports event 1D




1D hysteresis


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 .




Reporting event 1J: A non-active E-DCH but active DCH primary CPICH becomes better than an


active E-DCH primary CPICH

MNew is the measurement result of the cell not included in the E-DCH active set but included in

DCH active set.

CIONew is the individual cell offset for the cell not included in the E-DCH active set but included in

DCH active set becoming better than the cell in the E-DCH active set if an individual cell offset is

stored for that cell. Otherwise, it equals 0.

MInAS is the measurement result of the cell in the E-DCH active set with the lowest measurement

result.

CIOInAS is the individual cell offset for the cell in the E-DCH active set that is becoming worse than

the new cell.

H1J is the hysteresis parameter for event 1J.




The first measurement report is sent when primary CPICH D becomes better than primary CPICH


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




1J hysteresis


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


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 .




The report mode of 1J is Event Trigger Report .


enera y e even s repor e on y once. owever, o avo measuremen

report loss, the event 1J reporting can be turned to periodical reporting.

1J event to periodical rpt period

Set this parameter through SET INTRAFREQHO / ADDCELLINTRAFREQHO / MOD CELLINTRAFREQHO

1J event to periodical rpt number


CELLINTRAFREQHO / MOD CELLINTRAFREQHO




1D

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.

1J

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 re ort 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.




Max 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.




Minimum Quality Threshold for SHO

Parameter ID: SHOQualmin

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

Content: This parameter specifies the minimum quality thresholdfor soft handover..

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






If the RNC receives a 1A, 1C, or 1D measurement re ort, 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.




Estimation Procedure for Rate Reduction





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.


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.




The rate reduction execution rocedure is :

Execution Procedure of Rate Reduction


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.




Period 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.




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.

1,The intra-frequency, inter-frequency and Inter-RAT neighboring cells of each cell in the current active

set are obtained.

2,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.

3,The cells in the active set are added to Sall.

4,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.

5,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 repeatedneighboring cell is recorded.

6,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.




The NCELL_COMBINE_SWITCH of Handover Algorithm Switch parameter

decides the measurement range of neighboring cells


If the switch is set to ON, measurement objects are chosen from the neighboring

cells of all the cells in the active set.

If the switch is set to OFF, measurement objects are chosen from the neighboring

cells of the best cell.

But, limited by the 3GPP, the maximum number of neighboring cells is 32. So if the

NCELL_COMBINE_SWITCH is ON, it very possible that the neighboring cell of

all the cells in the active set may exceed 32.

By the Neighboring Cell Combination Algorithm , RNC will choose 32 neighboring

cell for measurement.

Neighboring Cell Combination Switch

Parameter ID: NCELL_COMBINE_SWITCH

Value range: OFF, ON

Content: If the switch is set to ON, measurement objects are chosen from the

neighboring cells of all the cells in the active set.If the switch is set to OFF,

measurement objects are chosen from the neighboring cells of the best cell.

The default value of this parameter is OFF Set this parameter through SET CORRMALGOSWITCH




The flag of the priority

Parameter ID: NPrioFlag

Value range: FALSE, TRUE

Content:

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


objects than the cells with priority 2 in the neighboring cell combination algorithm.

Set this parameter through

ADD INTRAFREQNCELL/MOD INTRAFREQNCELL / ADD

INTERFREQNCELL/MOD INTERFREQNCELL / ADD GSMNCELL/MOD

GSMNCELL




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

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.




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.

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.




Compressed Mode control is a mechanism whereby certain idle periods are created in


radio frames during which the UE can perform measurements on other frequencies. The

UE can carry out measurements in the neighbouring cell, such as GSM cell and FDD

cell on other frequency. If the UE needs to measure the pilot signal strength of an inter-

frequency WCDMA or GSM cell and has one frequency receiver only, the UE must usethe compressed mode.

Each physical frame can provide 3 to 7 timeslots for the inter-frequency or Inter-RAT cell

measurement, which enhances the transmit capability of physical channels but reduces

the volume of data traffic.

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.

The compressed mode includes two types, spreading factor reduction (SF/2) and high

layer approaches. The usage of type of compressed mode is decided by the RNC,according to spreading factor used in uplink or downlink.




Q Used is the measured quality of the used frequency.


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.




Inter-freq CS measure start Ec/No THD


Parameter ID: InterFreqCSThd2DEcNo

Value range: –24 to 0 ,step :1dB.

The default value of this parameter is -14dB

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




Inter-freq CS measure start RSCP THD


Parameter ID: InterFreqCSThd2DEcNo

Value range: –115 to -25 dBm ,step :1dB.

The default value of this parameter is -95dBm

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.


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.


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




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.

Set this parameter through ADD CELLINTERFREQHOCOV / MOD

CELLINTERFREQHOCOV / SET INTERFREQHOCOV .

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 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




Q Used is the measured quality of the used frequency.


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.




Inter-freq CS measure stop Ec/No THD


Parameter ID: InterFreqCSThd2FEcNo

Value range: –24 to 0 ,step :1dB.

The default value of this parameter is -12dB

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.


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 .





Inter-freq CS measure stop RSCP THD


Parameter ID: InterFreqCSThd2FRSCP

Value range: –115 to -25 dBm ,step :1dB.

The default value of this parameter is -92 dBm

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




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.

Set this parameter through ADD CELLINTERFREQHOCOV / MOD


2F 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 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





The measurement report mode of inter-frequency handover is configured through the


parameter Inter-frequency measure report mode. By default ,periodically reporting is

recommended.

The advantage of periodical measurement report is that if the handover fails, 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.

Based on the measurement control message received from the RNC, the UE periodically

reports the measurement quality of the target cell. Then, based on the measurement

report, the RNC makes the handover decision and performs handover.




Inter-frequency measure report mode

Parameter ID: InterFreqReportMode


Value range :Periodical reporting, Event trigger

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


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




Q Noused is the measured quality of the cell that uses the other frequencies.


T Noused2b 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




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

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 throughthe 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

TUsed2b of event 2B with the CPICH Ec/No value is configured as the maximum value 0 dB

according to 3GPP specification.

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 be：

Inter-freq CS Used frequency trigger Ec/No THD

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

TUsed2b of event 2B with the CPICH RSCP value is configured as the maximum value -

25 dB according to 3GPP specification.

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







Parameter ID: TargetFreqCsThdEcN0

Value range :–24 to 0, step 1dB

The default value of this parameter is –12 dB

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


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.




2B hysteresis


Parameter ID: Hystfor2B

Value range :0 to 29 , step 0.5dB


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.



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


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.






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.




RNC process the report by following procedure:


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.




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 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 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.




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.

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

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.






Parameter ID: CIO


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


Value range :–20 to +20 , step:0.5dB


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


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.





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




InterFreq Handover Switch based on Uplink/Downlink Traffic AMR


Parameter ID : UlQoSAmrInterFreqHoSwitch/ DlQoSAmrInterFreqHoSwitch

Value range NO, YES

The default value of this parameter is NO

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.

Set this parameter through SET QOSACT




InterFreq Handover Switch based on Uplink/Downlink Traffic VP


Parameter ID : UlQoSVPInterFreqHoSwitch/ DlQoSVPInterFreqHoSwitch

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 VP services.





Down Link QoS Measure timer length

Parameter ID : DLQoSMcTimerLen


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 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


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. .





Procedure of Load-based inter-frequency

handover :


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.


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.


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.


The RNC performs the blind handover according to the decision result.






Parameter ID : BlindHOFlag

Value range FALSE, TRUE

The default value of this parameter is FALSE

Content: This parameter indicates whether the neighboring cell is the target

cell for blind handovers. If the value is TRUE, blind handovers can be

performed to the neighboring cell.

Set this parameter through ADD INTERFREQNCELL/MOD

INTERFREQNCELL




After the RNC determines to trigger an inter-frequency blind handover ,according to the


parameter Blind handover condition, the RNC executes:

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 anintra-frequency measurement for conditional blind handover.

Note:

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




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


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.




Procedure of Speed-based inter-frequency handover :


The handover procedure is divided into four phases: handover triggering, handover measurement handover decision, and handoverexecution


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.


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


For handover from a macro cell to a micro cell, after the UE reports event 2C, the RNC performs the handover decision.


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.




Event 2C is only used in Speed-based inter-frequency handover.


After RNC believe the UE is in low-speed state, RNC will start handover from the macro cell

to the micro cell.

RNC triggers compressed mode firstly, then sends an inter-frequency measurement control

message for 2C event to start the inter-frequency measurement procedure.




Q is the measured ualit of the cell that uses the other fre uencies.


TNoused2c is the absolute quality threshold of the cell that uses the other

frequencies, namely, Inter-freq measure target frequency trigger Ec/No THD.

H2c is the event 2C hysteresis value 2C hysteresis.

2C event trigger delay time is reached, the UE reports the event 2C measurement

report message.

2C Event only takes the Ec/No as the measurement quantity.




Inter-freq measure target frequency trigger Ec/No THD

Parameter ID : InterFreqNCovHOThdEcN0


Value range -24 to 0, step:1dB

The default value of this parameter is -16 (-16dB),

Content: When the Ec/No value of the target frequency is higher than the threshold, event 2C

can be triggered

Set this parameter through ADD CELLINTERFREQHONCOV/MODCELLINTERFREQHONCOV/SET INTERFREQHONCOV

2C hysteresis

Parameter ID: Hystfor2C

Value range 0 to 29

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

Content: This parameter specifies the event 2C 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 CELLINTERFREQHONCOV/MOD

CELLINTERFREQHONCOV/SET INTERFREQHONCOV

2C event trigger delay time

Parameter ID: TrigTime2C

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 2C 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 CELLINTERFREQHONCOV/MOD

CELLINTERFREQHONCOV/SET INTERFREQHONCOV




Blind handover is a special handover, means :before the handover, the UE needn’t


report the target cell signal quality, RNC just select a target inter-frequency or inter-rat

neighbor for the UE ,then force the UE handover to the target, the compressed mode

and inter-frequency measurement can be overleaped

The precondition of blind handover is :the blind handover neighbors are configured to a

cell (Blind handover flag ), which is discussed in the forenamed slides.

Blind handover may be triggered by load, UE speed.and also the 1F event




1F Event is a intra-frequency measurement event, like 1A,1B,1C,1D.


Events 1A,1B,1C,1D are used to trigger intra-frequency handover, Event 1F only trigger

inter-frequency or Inter-RAT blind handover.




M is the measurement value of the cell that becomes worse.


T1f is an absolute threshold. It is set to 1F event absolute EcNo threshold or 1F

event absolute RSCP threshold respectively, depending on the measurement

quantity.

H1f is the event 1F hysteresis value 1F hysteresis.

After the conditions of event 1F are fulfilled and maintained until the 1F event trigger

delay time is reached, the UE reports the event 1F measurement report message.




1F event absolute EcNo threshold


Parameter ID : IntraAblThdFor1FEcNo

Value range -24 to 0, step:1dB

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

Content: This parameter specifies the absolute EcNo threshold of event 1F. The

greater the parameter value is, the more easily event 1F is triggered. The smaller the

parameter value is, the harder event 1F is triggered.

Set this parameter through SET INTRAFREQHO/ADD

CELLINTRAFREQHO/MOD CELLINTRAFREQHO

1F event absolute RSCP threshold

•Parameter ID: IntraAblThdFor1FRSCP

Value range -115 to -25 step:1dB

The default value of this parameter is -115(-115dBm)

Content: This parameter specifies the absolute RSCP threshold of event 1F. The

greater the parameter value is, the more easily event 1F is triggered. The smaller the

parameter value is, the harder event 1F is triggered.

Set this parameter through SET INTRAFREQHO/ADD

CELLINTRAFREQHO/MOD CELLINTRAFREQHO




N-121WCDMA Handover Algorithm and Parameters

Confidential Information of Huawei. No Spreading Without Permission



If an inter-frequency handover based

on event-triggered measurement

report mode fails, the RNC initiatesthe inter-frequency handover attempt

according to an inter-frequency retry

algorithm

After the inter-frequency handover

fails, the retry timer for the cell is

started. After the retry timer expires,

the RNC makes a handover retry to

the cell again until the retry number

exceeds the maximum allowed

number. If the handover succeeds or

two new event 2B reports are

received, the periodical retry is

stopped.

Handoveris failed

Retry conditionis satisfied?

2B event? Start timer

Trigger

handover

END Timer isexpired

Inter-frequency handover retry


For the inter-frequency handover based on coverage or QoS, the following two parameters

determine the retry period and the maximum number of retry times:

2B event retry period

2B event retry max times

For the inter-frequency handover based on speed, the following two parameters determine the

retry period and the maximum number of retry times:

2C event retry period

2C event retry max times

2B measurement

control isre-transmitted

implementation




2B event retry period


2B event retry max times

Set above parameters through SET INTRERFREQHOCOV / ADD

CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV



Set above parameters through SET INTRERFREQHONCOV / ADD

CELLINTERFREQHONCOV / MOD CELLINTERFREQHONCOV




Intra-RNC Inter-Frequency Handover





Inter-RNC Inter-Frequency Handover





Inter-RAT handover provides coverage expansion, load sharing, and layered services. It


saves cost by utilizing the existing GSM network resources.

Inter-RAT handover refers to the handover between UMTS and GSM. The reason for the

handover can be coverage limitation, link stability control or load limitation of the 3G

system.

Inter-RAT handover can be UMTS-to-GSM or GSM-to-UMTS handover.

Strategy of 2G and 3G cooperation is shown in the picture:

Based on coverage, QoS , Service, load and speed, RNC can trigger UE

handover from 3G to 2G; When UE return back to Idle Mode, trigger UE Cell

reselect to 3G.

In this handover, however, GSM and UMTS dual-mode UEs (MSs) are required, and

both the GSM MSC and the GSM BSS must be upgraded.




Coverage-based inter-frequency handover


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.




Before handover, the RNC checks whether the preconditions meet the triggering requirements of


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.




Before handover, the RNC checks service handover indicator, This parameter is indicated in the


Radio Access Bearer (RAB) assignment signaling assigned by the CNThe service handover

indicators are as follows:

HO_TO_GSM_SHOULD_BE_PERFORM: means that the handover to the 2G network is

performed when 2G signals are available.

HO_TO_GSM_SHOULD_NOT_BE_PERFORM: means that the handover to the 2G

network is performed when 3G signals are weak but 2G signals are strong.

HO_TO_GSM_SHALL_NOT_BE_PERFORM: means that the handover to the 2G

network is not performed even when 3G signals are weak but 2G signals are strong.




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”





The rules for enabling UMTS-to-GSM handover are based on the parameter Service Handover


n cator an t e t ree types o capa ty parameters. e ru es vary w t erent types o nter-

RAT handover , that is , the 4 factors will decide if the Inter-RAT handover is allowed.

The rules are:

Coverage-based and QoS-based UMTS-to-GSM handover

when Service Handover Indicator is set as follows:

HO_TO_GSM_SHOULD_BE_PERFORM

HO_TO_GSM_SHOULD_NOT_BE_PERFORM

In addition, the RNC initiates Inter-RAT handover based on the following capabilities:

GSM cell capability (can be set on RNC)

Service required capability (can be set on RNC)

UE capability (reported from UE “RRC setup complete” message )




GSM neighboring cell with EDGE capability

UE Capability

Service capability (required by 2G)

EDGE GPRS GSM

EDGE Allowed Allowed Allowed

GPRS Allowed Allowed Allowed

GSM Not allowed Not allowed Allowed

Not supported by 2G Not allowed Not allowed Not allowed

GSM neighboring cell with GPRS capability

UE Capability


EDGE GPRS GSM

EDGE Allowed Allowed Allowed


owe owe owe



GSM neighboring cell with GSM capability

UE Capability


EDGE GPRS GSM

EDGE Not allowed Not allowed Allowed

GPRS Not allowed Not allowed Allowed



If the capability of all the GSM neighboring cells is "No capability",the Inter-RAT handover cannot be started.




load-based UMTS-to-GSM handover



HO_TO_GSM_SHOULD_NOT_BE_PERFORM

service-based UMTS-to-GSM handover



The following switch are on:

Inter-RAT CS handover switch (service based)

Inter-RAT PS handover switch (service based)

In addition, the RNC initiates Inter-RAT handover based on the following capabilities:

GSM cell capability (can be set on RNC)

Service required capability (can be set on RNC)

“ ”


capa y repor e rom se up comp e e message

GSM neighboring cell with EDGE capability

UE Capability


EDGE GPRS GSM

EDGEAllowed Allowed Allowed

GPRSNot allowed Allowed Allowed

GSMNot allowed Not allowed Allowed

Not supported by 2GNot allowed Not allowed Not allowed




GSM neighboring cell with GPRS capability

GSM neighboring cell with GSM capability

UE Capability


EDGE GPRS GSM

EDGE Not allowed Allowed Allowed

GPRS Not allowed Allowed Allowed



UE Capability


EDGE GPRS GSM


If the capability of all the GSM neighboring cells is "No capability",the Inter-RAT handover cannot be started.

EDGE Not allowed Not allowed Allowed

GPRS Not allowed Not allowed Allowed






Inter-RAT cell type


Parameter ID : RatCellType

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




The handover procedure is divided into four phases: handover triggering, handover measurement, handover


decision, and handover execution.


The RNC sends a MEASUREEMNT CONTROL message to the UE, notifying the UE to measure the current

carrier quality. This message defines the reporting rules and thresholds of events 2D and 2F. 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.


If the RNC receives a report of event 2D, the RNC may request the NodeB and UE to start the compressed

mode to measure the qualities of GSM cells. Then, the RNC may send an Inter-RAT measurement control

message that defines the neighboring cell information, reporting period, and reporting rule.

In the measurement phase, either periodical measurement report mode or event-triggered measurement

report mode can be used.


After the UE reports event 3A, the RNC makes a handover decision. Or, after the UE periodically sends the

measurement reports, the RNC evaluates the reports first and then makes a handover decision.






The parameters for Inter-RAT handover 2D are similar with inter-frequency handover.


Set above parameters through ADD CELLINTERRATHOCOV / MOD

CELLINTERRATHOCOV / SET INTERRATHOCOV




QUsed is the measured quality of the used frequency.


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-RAT CS measure stop Ec/No THD

Inter-RAT R99 PS measure stop Ec/No THD

Inter-RAT H measure stop Ec/No THD

Inter-RAT CS measure stop RSCP THD

Inter-RAT R99 PS measure stop RSCP THD

Inter-RAT H measure stop RSCP THD

H2f 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 the Ec/No and RSCP measurement result can trigger the 2F event.




During the coverage-based and QoS-based UMTS-to-GSM handover, the measurements on


both inter-frequency and Inter-RAT neighboring cells can be made, which enables the cells to

provide continuous coverage and high quality.

The preconditions for the measurements are as follows:

Both inter-frequency and Inter-RAT neighboring cells are available.

Inter-freq and Inter-RAT coexist switch is set to SIMINTERFREQRAT.

If Inter-freq and Inter-RAT coexist switch is set as follows:

Inter-frequency measurement, which means that the RNC allows the UE to perform only this

type of measurement.

Inter-RAT measurement, which means that the RNC allows the UE to perform only this type of

measurement.

Concurrent inter-frequency and Inter-RAT measurement, which means that the RNC allows the

UE to perform both types of measurement in compressed mode at the same time.




Inter-freq and Inter-RAT coexist switch


Value range INTERFREQ, INTERRAT, SIMINTERFREQRAT

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.

InterFreq & InterRat coexist measure threshold choice

•Parameter ID: CoexistMeasThdChoiceValue range COEXIST_MEAS_THD_CHOICE_INTERFREQ, COEXIST_MEAS_THD_CHOICE_INTERRAT

The default value of this parameter is COEXIST_MEAS_THD_CHOICE_INTERFREQ

Content: This parameter specifies the type of event 2D/2F measurement thresholds when inter-frequency and Inter-RAT adjacent cells coexist.

COEXIST_MEAS_THD_CHOICE_INTERFREQ: represents the event 2D/2F measurement threshold for the inter-frequency measurement.

COEXIST_MEAS_THD_CHOICE_INTERRAT: represents the event 2D/2F measurement threshold for the Inter-RATmeasurement.

Set this parameter through SET HOCOMM/ADD CELLHOCOMM/MOD CELLHOCOMM




When the UE enters the compress mode, RNC will trigger the Inter-RAT handover measurement by


one additional measurement control signaling , so as to request UE test Inter-RAT neighbor cell.

In this Measurement control message, RNC should inform the UE Inter-RAT measurement

parameter (Neighbor list, reporting mode…)




Inter-RAT report mode


Parameter ID: InterRATReportMode

Value range :Periodical reporting, Event trigger

The default value of this parameter is Periodical reporting

Content: This parameter specifies the Inter-RAT measurement report mode.Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET

INTERRATHOCOV

Inter-RAT period report interval

Parameter ID: InterRATPeriodReportInterval

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 1000 (500ms)

Content: This parameter specifies the interval of the Inter-RAT measurement report.

Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SETINTERRATHOCOV





Inter-RAT measure timer length

Parameter ID: InterRATMeasTime

Value range : 0 to 512 ,step 1s


Content: If no Inter-RAT handover occurs upon expiry of the Inter-RAT measurement timer, the system

stops the Inter-RAT measurement and disables the compressed mode. If this parameter is 0, the system

does not start the Inter-RAT measurement timer.

Set this parameter for handover based on coverage through ADD CELLINTERRATHOCOV / MODCELLINTERRATHOCOV / SET INTERRATHOCOV

3A Measure Quantity

Parameter ID: MeasQuantityOf3A

Value range : CPICH_Ec/No, CPICH_RSCP, Auto

The default value of this parameter is Auto (based on the 2D)

Content: This parameter indicates the measurement value of the coverage-based Inter-RAT measurement

in event-triggered measurement report mode.

When 3A Measure Quantity is set to Auto, the measure quantity of the used UTRAN frequency is chosen

the same as the measure quantity of the reporting 2D event that triggered this Inter-RAT measurement.

Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERFREQHOCOV/SETINTERRATHOCOV

This parameter can be configured only when Inter-RAT report mode is set to EVENT_TRIGGER.




QUsed is the measurement value of the cell at the currently used frequency.


TUsed is the absolute quality threshold of the cell that uses the current frequency.




Inter-RAT CS Used frequency trigger Ec/No THD


Parameter ID: UsedFreqCsThdEcN0


The default value of this parameter is –12 dB

Content: If CS service Inter-RAT handover uses the event-triggered measurement report mode,

event 3A is triggered only when the Ec/No value of the used frequency is lower than this

threshold.

Set this parameter through ADD CELLINTERRATHOCOV / MOD CELLINTERRATHOCOV / SETINTERRATHOCOV

Inter-RAT CS handover decision THD

Parameter ID: TargetRatCsThd

Value range :0 to 63, step 1dB

The default value of this parameter is 16 (-95 dBm)

Content: This parameter indicates the requirement of CS service Inter-RAT handover for thequality of Inter-RAT cells.

If the event-triggered measurement report mode is used, event 3A may be triggered when the

quality of the target frequency is higher than this threshold. In periodical measurement report

mode, this parameter is used to evaluate the coverage-based Inter-RAT handover on the RNC

side.

The value 0 means that the physical value is smaller than –110 dBm. .

Set this parameter through ADD CELLINTERRATHOCOV / MOD CELLINTERRATHOCOV / SET

INTERRATHOCOV




3A hysteresis


Parameter ID: Hystfor3A

Value range 0 to 15 , step 0.5dB

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

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





Cell Individual Offset


Parameter ID: CIO

Value range –50 to 50 , step 1dB

The default value of this parameter is 0 dB

Content: This parameter cooperates with the Neighboring cell oriented CIO in

Inter-RAT handover decision. The larger the sum, the higher the handover

priority of the GSM cell. The smaller the sum, the lower the handover priority of

the GSM cell.

Set this parameter through ADD GSMCELL/MOD GSMCELL

Neigbhoring cell oriented CIO


Value range : –50 to 50 , step 1dB

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

Content: This parameter is used in Inter-RAT handover decision. The larger the

parameter, the higher the handover priority of the GSM cell. The smaller the

parameter, the lower the handover priority of the GSM cell .

Set this parameter through ADD GSMNCELL / MOD GSMNCELL




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.




Mother_RAT is the measurement result of Inter-RAT handover received by the RNC.


CIOother_RAT 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. Neigbhoring cell oriented CIO indicates

the offset of the measurement cell relative to the best cell.

Tother_RAT is the decision threshold of Inter-RAT hard handover.

Based on the service type (CS or PS service) and measurement quantity (CPICH Ec/No or RSCP),

this threshold can be configured through the following parameters:


Inter-RAT R99 PS handover decision THD

Inter-RAT H handover decision THD

NOTE:

These thresholds are the same as the quality threshold of event 3A.

For H is the Inter-RAT handover hysteresis value Inter-RAT hysteresis.

Select the cells in sequence, that is, from high quality cells to low quality ones, to initiate UMTS-to-

GSM handover in the cells where the handover time-to-trigger timer expires.

The length of the time-to-trigger timer is configured through the parameter Time to trigger for verified

GSM cell (with BSIC acknowledged) or the parameter Time to trigger for non-verified GSM cell

(with BSIC unacknowledged).




Time to trigger for verified GSM cell

Parameter ID : TimeToTri ForVerif


Value range 0 to 64000, step:1ms

The default value of this parameter is 0 (0 ms)

Content: This parameter specifies the delay time for triggering a GSM cell with BSIC acknowledged.

In the period specified by this parameter, if the signal quality of an adjacent GSM cell meets the requirement of

Inter-RAT handover, and this cell is acknowledged, the network will start Inter-RAT handover.

Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET

INTERRATHOCOV

Time to trigger for non-verified GSM cell

Parameter ID: TimeToTrigForNonVerify

Value range 0 to 64000 , 65535 , step:1ms


Content: This parameter specifies the delay time for triggering a GSM cell with BSIC unacknowledged.

In the period specified by this parameter, if the signal quality of an adjacent GSM cell meets the requirement of

Inter-RAT handover, and this cell is unacknowledged, the network will start Inter-RAT handover.

The value 65535 means that the RNC does not perform handover to an unacknowledged GSM cell. .


INTERRATHOCOV

Inter-RAT hysteresis

Parameter ID: HystforInterRAT

Value range 0 to 15 , step:0.5dB


Content: This parameter determines whether to trigger Inter-RAT handover decision together with the quality

threshold. The smaller the shadow fading, the smaller the value of this parameter.


INTERRATHOCOV




After receiving the event 3A measurement report of GSM cells, the RNC performs the following


decision and execution procedures:

Put all the GSM cells that trigger event 3A into a cell set and arrange the cells according to

the measurement quality in descending order.

Select the cells in sequence from the cell set to perform Inter-RAT handover.




InterRAT Handover Switch based on Uplink/Downlink Traffic AMR


Parameter ID : UlQoSAmrInterRATHoSwitch/ DlQoSAmrInterRATHoSwitch

Value range NO, YES


Content: If the value of this parameter is YES, Inter-RAT handover can be

executed on the basis of the downlink/uplink QoS of AMR services.





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


Parameter ID : BeUlAct1/ BeUlAct2/ BeUlAct3

Value range None, RateDegrade, InterFreqHO, InterRatHO

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

Content: This parameter defines the action sequence to enhance the Uplink QoS of BE

services .


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

Content: This parameter defines the action sequence to enhance the downlink QoS of

BE services .





These two parameters are shared by QoS based inter-frequency and QoS based Inter-


an over:


Up Link QoS Measure timer length

Set these parameters through ADD CELLQOSHO / MOD CELLQOSHO / SET QOSHO3A Used-Freq Measure Quantity for QoS

Parameter ID : UsedFreqMeasQuantityForQoS3A

Value range CPICH_Ec/No, CPICH_RSCP

The default value of this parameter is CPICH_RSCP

Content: This parameter indicates the measurement quantity used in QoS-based

UMTS-to-GSM measurement in event-triggered reporting mode.

If the coverage and QoS-based UMTS-to-GSM handovers are triggered

simultaneously, the RNC distributes QoS-based measurement parameters.





The handover procedure is divided into three phases: handover triggering, handover decision, and

Procedure of Load-based Inter-RAT handover :


handover execution


When the load of the UMTS cell that the UE accesses is higher than the related threshold, the Load

Reshuffling (LDR) algorithm makes a handover decision.


The RNC enables the compressed mode and starts the Inter-RAT handover measurement.


After the UE reports event 3C, the RNC makes a handover decision.



Based on the service ARP, Traffic class, Channel type(R99, HSDPA), RNC will choose the users

with lower priority to execute handover .




Inter-RAT measure timer length


Parameter ID : InterRATMeasTime

Value range 0 to 512

The default value of this parameter is 60 s

Content: If no Inter-RAT handover occurs upon expiry of the Inter-RAT measurement

timer, the system stops the Inter-RAT measurement and disables the compressed

mode. If this parameter is 0, the system does not start the Inter-RAT measurement

timer.

Set this parameter through ADD CELLINTERRATHONCOV/MODCELLINTERRATHOCOV/SET INTERRATHONCOV




MOtherRAT is the measurement value of the cell (in another RAT) in the reporting range.


CIOOtherRAT is the cell individual offset value of the cell (in another RAT) in the reporting range,

which is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell

oriented CIO.

TOtherRAT is the absolute Inter-RAT handover threshold. Based on the service type (CS , PS

domain R99 service, or PS domain HSPA service), this threshold can be configured through

the following parameters:


Inter-RAT R99 PS handover decision THD

H3c is 3C hysteresis, the hysteresis value of event 3C.

For the PS and CS combined services, the threshold(s) for CS services is (are) used.

When the conditions for event 3C are met and the delay requirement specified by the 3C event

trigger delay time parameter can be satisfied, the UE sends the measurement report of event

3C.






Parameter ID : InterRATNCovHOCSTh

Value range 0 to 63 ,step:1dB

The default value of this parameter is 21 (-90dBm)

Content: This parameter is used to set measurement control on the event 3C. The

event 3C is triggered when the quality of the target frequency is higher than this

threshold. Note that the value 0 means the physical value is smaller than -110 dBm .


Inter-RAT PS handover decision THD

Parameter ID : InterRATNCovHOPSTh

Value range 0 to 63 ,step:1dB

The default value of this parameter is 21 (-90dBm)

Content: This parameter is used to set measurement control on the event 3C. The

event 3C is triggered when the quality of the target frequency is higher than this

threshold. Note that the value 0 means the physical value is smaller than -110 dBm .





3C hysteresis


Parameter ID : Hystfor3C

Value range 0 to 15 ,step:0.5 dB

The default value of this parameter is 0 dB

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


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




After receiving the event 3C measurement report of GSM cells, the RNC performs the


following handover decision and execution procedure:

Put all the GSM cells that trigger event 3C into a cell set and arrange the cells

according to the measurement quality in descending order.

Select the cells in sequence from the cell set.

The load status between the source cell and the target cell can be acquired by

interchanging load information between a UMTS cell and a GSM cell during the load-

based and service-based UMTS-to-GSM handover. Thus, whether to further conduct

the handover can be determined to avoid the 2G cell overload and possible handover

to the congested cell.




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


- .




Send Load Info to GSM Ind

Parameter ID : SndLdInfo2GsmInd


Value range ON, OFF

The default value of this parameter is ON

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

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.





CS domain Reloc GSM load THD


Parameter ID : CSHOOut2GLoadThd

Value range 0 to 100 ,step:1%

The default value of this parameter is 80 (80%)

Content:




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:







Inter-RAT handover max attempt times


Parameter ID : InterRATHOAttempts

Value range 1 to 16


Content: This parameter specifies the maximum number of attempts of load-based and

service-based Inter-RAT handover.

Set this parameter through ADD CELLINTERRATHONCOV / MOD

CELLINTERRATHONCOV / SET INTERRATHONCOV




The handover procedure is divided into four phases: handover triggering, handover measurement handover

Procedure of Service-based Inter-RAT handover :


ec s on, an an over execu on


When a service is established (RAB Assignment ), If the Service Handover Indicator is set to

HO_TO_GSM_SHOULD_BE_PERFORM, the RNC requests the handover to the GSM


The RNC enables the compressed mode and starts the Inter-RAT handover measurement.


After the UE reports event 3C, the RNC makes a handover decision.



service type is defined by parameters on cell level:

Inter-RAT CS handover switch and Inter-RAT PS handover switch

When a single CS service is initially set up by the UE, the RNC allows the UMTS-to-GSM service-

based handover if Inter-RAT CS handover switch is set to ON.

When a single PS service is initially set up by the UE, the RNC allows the UMTS-to-GSM service-

based handover if Inter-RAT PS handover switch is set to ON.

For the CS and PS combined services, no service-based handover is trigged

service handover indicator assigned by the Core Network. Only the services with the indicator

“HO_TO_GSM_SHOULD_BE_PERFORM” can trigger Service-based Inter-RAT handover




Inter-RAT CS handover switch


Inter-RAT PS handover switch

Parameter ID :

CSServiceHOSwitchPSServiceHOSwitch

Value range ON, OFF


Content:

This parameter indicates whether the cell allows the service-based

Inter-RAT handover for the CS or PS services

Set this parameter through ADD CELLHOCOMM/MOD CELLHOCOMM




Compared with the traditional speech service of the GSM, the VP service of the UMTS can


transmit not only speech services but also the images and videos captured by both

parties

For the UMTS-to-GSM handover, network-initiated multimedia fallback on the following

occasions:

The RNC decides to send an Inter-RAT handover request after receiving periodical

measurement reports or event 1F, 3A, or 3C.

The service is combined with a VP, and the "Alternative RAB Para" in the RAB

ASSIGNMENT message is a valid AMR speech format.




The procedure for the fallback service is described as follows:

Procedure of Multimedia Fallback


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.




Normal PS is realized by cell reselection, the time delay can not be guaranteed. But


Some PS services have requirements for the delay. If the handover takes too long,

TCP may start slowly or data transmission of the stream service may be interrupted

due to the overflow of the UE buffer.

The introduction of NACC enables the system information exchange between BSS and

RAN , Thus the inter-system delay in PS domains, can be reduced.

With NACC, the RNC sends the cell change order to the UE, which contains the GSM

EDGE Radio Access Network (GERAN) system information, when the UMTS-to-GSM

handover in the PS domain is triggered.




After the SRNC receives a measurement report from the UE, the UE is reselected to

Procedure of NACC


the GERAN cell according to the decision.

The SRNC sends a RAN INFORMATION REQUEST message to the SGSN.

The SGSN forwards the message to the corresponding BSS.

The BSS sends a GERAN SI/PSI message to the SRNC via the SGSN. RAN

INFORMATION message can either be On-demand (single report) or On-modification

(multiple reports).

The SGSN forwards the report message to the SRNC through Iu interface.

If there are several report messages, the SRNC terminates reporting by the

TERMINATION/END message.

To enable the NACC function, do as follows:

Run the SET CORRMALGOSWITCH command to set

PS_3G2G_CELLCHG_NACC_SWITCH to ON.

Run the ADD GSMCELL / MOD GSMCELL command to set Inter-RAT cell support

RIM indicator to TRUE.




PS 3G to 2G Cell change order NACC Switch


Parameter ID : PS_3G2G_CELLCHG_NACC_SWITCH

Value range OFF, ON


Content: When it is checked, and Inter-RAT handover of the PS domain from

UTRAN use cell change order method, Inter-RAT handover support

NACC(Network Assisted Cell Change) function.

Set this parameter through SET CORRMALGOSWITCH

Inter-RAT cell support RIM indicator

Parameter ID: SuppRIMFlag

Value range FALSE, TRUEThe default value of this parameter FALSE

Content: The parameter indicates whether the Inter-RAT cell supports RIM.

Set this parameter through ADD GSMCELL/MOD GSMCELL




3A event retry period


3A event retry max times

Set this parameter through ADD CELLINTERRATHOCOV / MOD




Set this parameter through ADD CELLINTERRATHONCOV / MOD

CELLINTERRATHONCOV / SET INTERRATHONCOV




UMTS-to-GSM Handover in CS Domain






1. The SRNC sends the 3G MSC a RANAP message RELOCATION REQUIRED if the

condition of Inter-RAT outgoing handover is met.

2. As indicated in the received message, the 3G MSC forwards this request to the 2G

MSC on the MAP/E interface through a MAP message PREPARE HANDOVER.

3. The 2G MSC forwards the request to the BSC. The message shown in the figure is for

reference only and is subject to the actual condition of the GSM.

4. The BSC responds to this request. The message shown in the figure is for reference

only and is subject to the actual condition of the GSM.

5. Once the initial procedures are completed in the 2G MSC/BSS, the 2G MSC returns a

MAP/E message PREPARE HANDOVER RESPONSE.

6. The 3G MSC sends the SRNC a RANAP message RELOCATION COMMAND.

7. The SRNC sends the UE an RRC message HANDOVER FROM UTRAN through the

existing RRC connection. This message may include information from one or several

other systems.


8. The BSC performs handover detection. The figure does not show such procedures as

GSM BSS synchronization. The message shown in the figure is for reference only and

is subject to the actual condition of the GSM.

9. The UE sends the BSC a HANDOVER COMPLETE message.

10. The BSC sends the MSC a HANDOVER COMPLETE message. The message shown

in the figure is for reference only and is subject to the actual condition of the GSM.

11. After detecting the UE in the coverage area of the GSM, the MSC sends the CN a

MAP/E message SEND END SIGNAL REQUEST.

12. The CN sends the former SRNC an IU RELEASE COMMAND message, requesting

the former SRNC to release the allocated resource.

13. After the bearer resource is released in the UMTS, the former SRNC sends the CN an

IU RELEASE COMPLETE message.

14. After the call ends, the CN sends the MSC a MAP/E message SEND END SIGNAL

RESPONSE.




UMTS-to-GSM Handover in PS Domain


The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of

the serving cell is heavy.

When the UE is in CELL_DCH state, the UTRAN sends a CELL CHANGE ORDER message to theUE to perform a handover to GSM by cell reselection.

The NodeB sends a RADIO LINK FAILURE INDICATION message, because the UE shuts down

transmission towards the WCDMA cell after cell reselection to a GSM cell.

After the UE accesses a GSM cell, the SGSN directly sends an IU RELEASE COMMAND message

to the SRNC, if the Packet Data Protocol (PDP) context does not need to be transferred.





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.


.

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.





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.


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.


03 - OWJ200103 WCDMA Handover Algorithm and Parameters RAN10 ISSUE2.00

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Transcript of 03 - OWJ200103 WCDMA Handover Algorithm and Parameters RAN10 ISSUE2.00