8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
1/20
Event 2D Triggering ParameterSelection Criteria
(Huawei)
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
2/20
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
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
3/20
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
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
4/20
Selection CriteriaFlow Chart & Major Steps
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
5/20
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
Inter Frequency Neighbor Configured
for Converge-Based HO?
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
6/20
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.
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
7/20
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
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
8/20
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.
Parameter Level Description Parameter Value Range MO ID
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
Typical Configuration in Roshan Network
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.
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
9/20
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
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
10/20
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.
Parameter Level Description Parameter Value Range MO ID
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
Typical Configuration in Roshan Network
Inter-Frequency and Inter-RAT Coexist Measure Threshold Choice= Inter-RAT 2D Measurement Threshold Oriented
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
11/20
Typical Scenarios in Roshan Network
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
12/20
Typical Scenarios in Roshan Network -1 (CS conversational call with no inter-frequency HO neighbor)
N
2D Triggering Parameter
= Inter RAT 2D Start Threshold
Y
Inter-RAT
Parameter Oriented
Inter-Frequency
Parameter Oriented
Service Handover
Indicator
Y
HO to GSM Not AllowedHO to GSM Allowed
Event 2D Triggering Threshold Selection Criteria
N
2D Triggering Parameter
= Inter Frequency 2D Start Threshold
Inter-Frequency & Inter-RAT
Coexisting Measurement Choice
Inter Frequency Neighbor Configured
for Converge Based HO?Inter Frequency Neighbor Configured
for Converge Based HO?
No 2D Triggering Parameter
in Measurement Control Massage
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.
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
13/20
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)
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
14/20
N
2D Triggering Parameter
= Inter RAT 2D Start Threshold
Y
Inter-Frequency
Oriented
Service Handover
Indicator
Y
HO to GSM Not AllowedHO to GSM Allowed
Event 2D Triggering Threshold Selection Criteria
N
2D Triggering Parameter
= Inter Frequency 2D Start Threshold
Inter-Frequency & Inter-RAT
Coexisting Measurement Choice
Inter Frequency Neighbor Configured
for Converge Based HO?Inter Frequency Neighbor Configured
for Converge Based HO?
No 2D Triggering Parameter
in Measurement Control Massage
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
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
15/20
-120
-115
-110
-105
-100
-95
-90
-85
-80
-75
-70
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
2014-08-16
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
Priority of Coverage Based Inter-
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.
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
16/20
Typical Scenarios in Roshan Network -3 (CS conversational call with inter-frequency HO neighbors)
N
2D Triggering Parameter
= Inter RAT 2D Start Threshold
Y
Inter-RAT
Parameter Oriented
Inter-Frequency
Parameter Oriented
Service Handover
Indicator
Y
HO to GSM Not AllowedHO to GSM Allowed
Event 2D Triggering Threshold Selection Criteria
N
2D Triggering Parameter
= Inter Frequency 2D Start Threshold
Inter-Frequency & Inter-RAT
Coexisting Measurement Choice
Inter Frequency Neighbor Configured
for Converge Based HO?Inter Frequency Neighbor Configured
for Converge Based HO?
No 2D Triggering Parameter
in Measurement Control Massage
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).
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
17/20
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
Priority of Coverage Based Inter-
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
(Cell 23031 Configuration:
Inter-Frequency 2D Measurement Start CS = -95dBm;
Inter-RAT 2D Measurement Start CS = -105dBm)
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
18/20
Typical Scenarios in Roshan Network -4 (PS background service with inter-frequency HO neighbors)
N
2D Triggering Parameter
= Inter RAT 2D Start Threshold
Y
Inter-Frequency
Oriented
Service Handover
Indicator
Y
HO to GSM Not AllowedHO to GSM Allowed
Event 2D Triggering Threshold Selection Criteria
N
2D Triggering Parameter
= Inter Frequency 2D Start Threshold
Inter-Frequency & Inter-RAT
Coexisting Measurement Choice
Inter Frequency Neighbor Configured
for Converge Based HO?Inter Frequency Neighbor Configured
for Converge Based HO?
No 2D Triggering Parameter
in Measurement Control Massage
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 .
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
19/20
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
Priority of Coverage Based Inter-
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
(Cell 25591 Configuration:
Inter-Frequency 2D Measurement Start PS = -108dBm;
Inter-RAT 2D Measurement Start PS = -110dBm)
EVENT 2D TRIGGERING PARAMETER SELECTION CRITERIA
8/11/2019 Event 2D Triggering Parameter Selection Criteria_V1.0
20/20
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
Top Related