event 2d triggering parameter selection criteria_v1.0

8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0

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Event 2D Triggering ParameterSelection Criteria

(Huawei)


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EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA

Overview (1)

When active sets RSCP (Ec/No) degrades, coverage-based inter-frequency/inter-RAT HO tends to be conducted. As a

precondition, UE has to first report Event 2D to RNC and start compressed mode for inter-frequency/RAT neighbor measuring.

Event 2D is triggered based on 2D Triggering Threshold parameter, which is sent by RNC in Measurement Control Message. The

triggering threshold can be variable when condition changed, and it has significant impact on UEs behavior and HO performance.

Note: The discussion in this report is also applicable to Event 2F.

CPICH RSCP

(or Ec/No)

2D Measurement

Triggering Threshold

2D Measurement

Stopped Threshold

CPICH RSCP of the best cell

within Active Set

TimeEvent 2D Event 2F Event 2D

t1 t2 t1

UE starts compress mode forinter-frequency/inter-RAT

measurement

UE stops compress mode

UE starts compress mode for

inter-frequency/inter-RAT

measurement


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Overview (2)

When RSCP (Ec/No) is below 2D Triggering Threshold, UE triggers Event 2D and it is reported to RNC. On receiving this

message, RNC reconfigures UEs physical channel and make it into compressed mode for inter-frequency/inter-RAT neighbor

measuring. Measurement results are then feedback to RNC for HO decision and execution.

2. RADIO LINK RECONFIGURATION

PREPARE

3. RADIO LINK RECONFIGURATION

READY

4. PHYSICAL CH RECFG

5. RADIO LINK

RECONFIGURATION COMMIT

UE NodeB SRNC

NBAP

NBAP

NBAP

NBAP

RRC

RRC

NBAP

RRC

NBAP

RRC6. PHYSICAL CH RECFG COMPLETE

1.MEASUREMENT REPORT2D EventRRC RRC

RRC RRC

8. COMPRESS MODE COMMAND

NBAP NBAP

7.MEASUREMENT CONTROL

MR processing

Compression

parameter

configuration

Activate ompression

process

MEASUREMENT REPORT

MEASUREMENT CONTROL



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Selection CriteriaFlow Chart & Major Steps


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Selection Criteria Flow Chart

Different parameters can be effective for UE triggering Event 2D, which depends on conditions such as traffic class, neighboring

cell configurationand etc. The threshold can also be variable when condition is changed during the connection. Huaweis criteria

for selecting 2D triggering parameter is explained in above flow chart. The algorithm is divided into three major steps and can be

applied in different scenarios.

N

2D Trigge

ring Parameter

= Inter RAT 2D Start Threshold

Y

Inter-Frequency & Inter-RAT

Coexisting Measurement Choice

Inter-RAT

Parameter Oriented

Inter-Frequency

Parameter Oriented

Service Handover

Indicator

Inter Frequency Neighbor Configured

for Converge-Based HO?

Y

No 2D Triggering Parameter

in Measurement Control Massage

HO to GSM Not AllowedHO to GSM Allowed

Event 2D Triggering Threshold Selection Criteria

N

2D Triggering Parameter

= Inter Frequency 2D Start Threshold

Step-1

Step-2

Step-3


for Converge-Based HO?



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Step-1 : Service HO Indicator

Setp-1 is to judge whether 3G to 2G HO is allowed based on traffic class and maximum bit rate granted to UE.

Parameter Level Description Parameter Value Range MO ID

Service HO

IndicatorRNC

This parameter specifies

whether HO to 2G network is

allowed based on traffic

class and MBR

HO_TO_GSM_SHOULD_BE_PERFORM: Handover to 2G network isperformed whenever 2G signal is available.

HO_TO_GSM_SHOULD_NOT_BE_PERFORM: Handover to 2G network

is performed only when 3G signal is weak.

HO_TO_GSM_SHALL_NOT_BE_PERFORM: Handover to 2G network is

Not allowed

UTYPRAB

BASICSHInd

Typical Configuration in Roshan Network

Domain Traffic Class Maximum Bit Rate Service HO Indicator

CS Conversational 12.2kbps HO from 3G to 2G Allowed

PSBackground

(both direction)

8/16/32/64/128/

144/256/384 kbpsHO from 3G to 2G Allowed

PSBackground

(both direction)8640 kbps HO from 3G to 2G Not Allowed

Note:

If Service HO Indicator information is carried in RAB_ASSIGNMENT_REQ message from CN during RAB setup

procedure, then the actual setting is following CN configuration while RNC one is not taking into effect.

For PS service, if in one of directions (downlink or uplink) HO to 2G is Not allowed, then for both directions (downlink &

uplink) HO is Not allowed.



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For CS 12.2kbps conversational service, SHIND in RNC is set as HO_TO_GSM_SHALL_NOT_BE_PERFORM, indicting HO to

2G is Not allowed. However, as the same parameter is carried from CN during RAB setup procedure with configurationHO_TO_GSM_SHOULD_NOT_BE_PERFORM (HO to 2G allowed), the actual effective value is following the CN one and HO to

2G is allowed in this case.

Step-1 : Service HO Indicator (CS 12.2kbps Case)

HO to 2G is allowed in

RAB_ASS_REQ message from CN



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Step-2 : Inter-Frequency Neighbor for Coverage-Based HO

Setp-2 is to judge whether inter-frequency neighbor relationship is existing and whether it is allowed for coverage-based HO.


Priority of

Coverage Based

Inter-Frequency

HO

Cell

Assuming inter-frequency

neighbors are existing, this

parameter specifies if it is

supporting coverage-based inter-

frequency handover and specifieseach neighbor's priority.

0: indicates that the coverage-based inter-frequency

handover is Not supported.

1: indicates that the inter-frequency neighbor cell is

assigned with the highest priority for handover.

2: indicates that the inter-frequency neighbor cell is

assigned with the medium priority for handover.

"3":indicates that the inter-frequency neighbor cell is

assigned with the lowest priority for handover.

UINTERFRE

QNCELLHOCovPrio


Scenario Inter-Frequency NB Configuration Priority of Coverage Based Inter-Frequency HO

Macro sites onlyF1 & F2 of same direction sector configured as

inter-frequency NB0 (Coverage based inter-frequency HO is Not allowed)

Macro/Micro

Coexistence

1. F1 & F2 of macro site of same direction

sector configured as inter-frequency NB

2. Macro & micro sites configured as inter-

frequency NB

0 for F1&F2 of macro (Coverage based inter-frequency HO is Not allowed)

2 for macro-micro (Coverage based inter-frequency HO is allowed)

Note: In case there are more than one cell within active set and if anyone (not necessarily the best cell) is configured with inter-

frequency neighbors & coverage-based HO flag is ON, then coverage-based inter-frequency HO is considered enabled for this

connection.



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In case there are more than one cell within active set and if anyone (not necessarily the best cell) is configured with inter-

frequency neighbors & coverage-based HO is allowed, then coverage-based inter-frequency HO is considered enabled for thisconnection. Judgment is renewed each time when active set is updated.

Step-2 : Inter-Frequency Neighbor for Coverage-Based HO (Active Set Case)

Active Set Update



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Step-3 : Inter-Frequency & Inter-RAT Coexist Measurement Threshold Choice

Setp-3 is to judge which set of parameters should be applied for Event 2D triggering when both inter-frequency and inter-RAT

neighbors coexist for coverage-based HO.


Inter-Frequency

and Inter-RAT

Coexist Measure

ThresholdChoice

RNC

This parameter specifies the event

2D measurement threshold of

which measurement type

(inter-frequency or inter-RAT

measurements) will be used, wheninter-frequency and inter-RAT HO

neighbors coexist.

COEXIST_MEAS_THD_CHOICE_INTERFREQ: Event 2D

measurement thresholds oriented towards inter-frequency

configuration are selected

COEXIST_MEAS_THD_CHOICE_INTERRAT: Event 2Dmeasurement thresholds oriented towards inter-RAT

configuration are selected

UHOCOMMCoexistMea

sThdChoice


Inter-Frequency and Inter-RAT Coexist Measure Threshold Choice= Inter-RAT 2D Measurement Threshold Oriented



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Typical Scenarios in Roshan Network


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Typical Scenarios in Roshan Network -1 (CS conversational call with no inter-frequency HO neighbor)

N



Y

Inter-RAT

Parameter Oriented

Inter-Frequency

Parameter Oriented

Service Handover

Indicator

Y



N






for Converge Based HO?Inter Frequency Neighbor Configured

for Converge Based HO?



For CS 12.2kbps conversational service when there is no inter-frequency neighbor configured for coverage-based HO, 2D

triggering parameter is selected as Inter-RAT 2D Start Thresholdaccording to the selection criteria.



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In Roshan 3G network coverage-based inter-frequency HO is Not allowed between F1 & F2 layers in macro sites. So in scenario

where only macro sites exist and UE initiates a 12.2kbps conversational service, 2D Triggering Parameter= Inter-RAT 2Dthresholdaccording to the selection criteria.

Related Parameter Configuration Value Remark

Service Handover IndicatorHO_TO_GSM_SHOULD_NOT_BE_PERFORM

(Domain=CS, Traffic Class= Conversational, MBR=12.2kbps)

HO to 2G allowed for CS 12.2k call

(Following CN setting)

Priority of Coverage Based Inter-

Frequency HO0

Coverage based inter-frequency HO Not

allowed between F1 & F2

Typical Scenarios in Roshan Network -1 (CS conversational call with no inter-frequency HO neighbor)

Example:

Inter-RAT 2D Start Threshold is selected for triggering Event

2D in measurement control message

(Cell 23393 Configuration:

Inter-Frequency 2D Measurement Start CS = -95dBm;

Inter-RAT 2D Measurement Start CS = -97dBm)



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N



Y

Inter-Frequency

Oriented

Service Handover

Indicator

Y



N










Typical Scenarios in Roshan Network -2 (PS background service with no inter-frequency HO neighbor)

For PS 8.64Mbbps background service when there is no inter-frequency neighbor configured for coverage-based HO, 2D

triggering parameter is Not contained in Measurement Control Message sent to UE according to the selection criteria. Thus Event

2D will Not be triggered and inter-frequency or inter-RAT HO will Not take place.

Inter-RAT

Parameter Oriented



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-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

-70

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UE RSCP (dBm)

Example:

No event 2D triggered even at

very poor coverage level

Typical Scenarios in Roshan Network -2 (PS background service with no inter-frequency HO neighbor)

Related Parameter Configuration Value Remark

Service Handover IndicatorHO_TO_GSM_SHALL_NOT_BE_PERFORM

(Domain=PS, Traffic Class= Background, MBR=8.64Mbps)

HO to 2G Not allowed for 8.64Mbps

background service


Frequency HO0

Coverage based inter-frequency HO Not

allowed between F1 & F2

In Roshan 3G network coverage-based inter-frequency HO is Not allowed between F1 & F2 layers in macro sites. So in scenario

where only macro sites exist and UE initiates a PS 8.64Mbps background service, 2D Triggering Parameter is Not contained inMeasurement Control Message. Thus Event 2D will Not be triggered by UE in this case.



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Typical Scenarios in Roshan Network -3 (CS conversational call with inter-frequency HO neighbors)

N



Y

Inter-RAT

Parameter Oriented

Inter-Frequency

Parameter Oriented

Service Handover

Indicator

Y



N










For CS 12.2kbps conversational service when there is inter-frequency neighbor configured for coverage-based HO, 2D triggering

parameter is selected as Inter-RAT 2D Start Thresholdaccording to the selection criteria (Coexist Measure Threshold Choice is

oriented to Inter-RAT parameter).



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Typical Scenarios in Roshan Network -3 (CS conversational call with inter-frequency HO neighbors)

Parameter Configuration Value Remark

Service Handover IndicatorHO_TO_GSM_SHOULD_NOT_BE_PERFORM

(Domain=CS, Traffic Class= Conversational, MBR=12.2kbps)HO to 2G allowed for CS 12.2k call


Frequency HO

2

(Between macro & micro)

Coverage based inter-frequency HO

allowed between macro & micro

Inter-Frequency and Inter-RAT

Coexist Measure Threshold Choice

COEXIST_MEAS_THD_CHOICE_INTERRAT Inter-RAT 2D threshold to be applied

In Roshan 3G network coverage-based inter-frequency HO is allowed between macro & micro sites. So in scenario where macro

& micro coexist and UE initiates a 12.2kbps conversational service, 2D Triggering Parameter= Inter-RAT 2D thresholdaccording to the selection criteria (Coexist Measure Threshold Choice is oriented to Inter-RAT parameter).

Example:

Inter-RAT 2D Start Threshold is selected for triggering Event

2D in measurement control message


Inter-Frequency 2D Measurement Start CS = -95dBm;

Inter-RAT 2D Measurement Start CS = -105dBm)



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Typical Scenarios in Roshan Network -4 (PS background service with inter-frequency HO neighbors)

N



Y

Inter-Frequency

Oriented

Service Handover

Indicator

Y



N










For PS 8.64Mbps background service when there is inter-frequency neighbor configured for coverage-based HO, 2D triggering

parameter is selected as Inter-Frequency 2D Start Thresholdaccording to the selection criteria .



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Typical Scenarios in Roshan Network -4 (PS background service with inter-frequency HO neighbors)

Parameter Configuration Value Remark

Service Handover IndicatorHO_TO_GSM_SHALL_NOT_BE_PERFORM

(Domain=PS, Traffic Class= Background, MBR=8.64Mbps)

HO to 2G Not allowed for 8.64Mbps

background service


Frequency HO

2

(Between macro & micro)

Coverage based inter-frequency HO

allowed between macro & micro

In Roshan 3G network coverage-based inter-frequency HO is allowed between macro & micro sites. So in scenario where macro

& micro coexist and UE initiates a PS 8.64Mbps background service, 2D Triggering Parameter= Inter-Frequency 2D thresholdaccording to the selection criteria.

Example:

Inter-Frequency 2D Start Threshold is selected for triggering

Event 2D in measurement control message


Inter-Frequency 2D Measurement Start PS = -108dBm;

Inter-RAT 2D Measurement Start PS = -110dBm)



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Summary

The Event 2D is triggered based on 2D Triggering Threshold parameter.

Huaweis criteria for selecting 2D triggering parameter is described in page-9 based on three major steps of judgment, which canbe applied in different scenarios.

Based on current network design and configuration, below are the parameters selected for triggering Event 2D in typical scenarios

in Roshan 3G network:

# Scenario Domain Traffic Class Parameter selected for triggering Event 2D

1 Macro sites only CS 12.2kbps conversational Call Inter-RAT 2D Start Threshold (CS)

2 Macro sites only PS 8.64Mbps Background serviceNo 2D Triggering Parameter contained in

Measurement Control Message3 Macro/micro coexist CS 12.2k conversational Call Inter-RAT 2D Start Threshold (CS)

4 Macro/micro coexist PS 8.64Mbps Background service Inter-Frequency 2D Start Threshold (PS)


event 2d triggering parameter selection criteria_v1.0

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