lte interoperability in connection mode (lte-gu)
DESCRIPTION
LTE Operability documentTRANSCRIPT
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Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LTE Interoperability in Connection Mode (LTE->G/U)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page3
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
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Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
States of UE at Switch on
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Idle Mode
Connection Mode
Data Service Continuity
PS HO
CCO/NACC
Redirection
Voice Service Continuity
CS FallBack
SRVCC
States of UE at Switch on
*
*Related to interoperability which will be discussed in this course
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Coverage-based
Connection Mode
Discussing
Frequency-priority-based
Intra-frequency HO
Mobility Management Overview in Connection Mode
Page6
Inter-frequency HO
Inter-RAT HO
Load-based
UL-quality-based
Service-based
Distance-based
SPID-based HO back to the HPLMN
CSFB
PS HO
SRVCC
CCO/eNACC
Redirection
Types Causes/Scenario Execution
Discussed
Not be discussed
UE States
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Handover Procedure
Page8
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Neighbor Relationship Management Overview Neighbor relationships define the relationships between
the serving cell and its neighboring cells, and they play a
fundamental role in handovers.
Neighbor relationships are planned in the network design
stage. They are automatically adjusted by ANR which is
enabled.
There are three types of neighboring cells
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Types The Max Number of NcellThe Max Number of
Nfrequency
Intra-frequency Ncell 64 NA
Inter-frequency Ncell 64 8
Inter-RAT Ncell128(UTRAN) 16(UTRAN)
64(GERAN) 16(GERAN)
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Priority of the Neighboring Cell
For normal handover, if the target system is E-UTRAN or UTRAN, the
eNodeB preferentially selects the cells with parameters
EUTRANINTRAFREQNCELL.CellMeasPriority, EUTRANINTERFREQNCELL.
CellMeasPriority, or UTRANNCELL.CellMeasPriority setted as
HIGH_PRIORITY.
For the blind handover, The candidate cells must be the neighboring cells
with blind-handover priorities ≠ 0.
Page10
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
indicates whether the UE is capable of frequency-specific or RAT-specific measurements and handovers.
UE Capability
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UE
UE Capability InformationIncludes the “UECapabilityInformation” parameter-UE-CapabilityRAT-ContainerList--UE-EUTRA-Capability---featureGroupIndicators--UE-EUTRA-Capability-v9a0---featureGroupIndRel9Add-r9--UE-EUTRA-Capability-v1020---featureGroupIndRel10-r10
eNBUE Capability Enquiry
The MME may inform the eNodeB of UE capabilities.
If the MME does not inform the eNodeB of UE capabilities, the eNodeB
initiates UE capability transfer over the radio interface to a UE, and the
UE informs the eNodeB of the UE capabilities through the UE Capability
Information IE.
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Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
After a UE establishes a radio bearer, the eNodeB delivers the
Measurement Configuration to the UE in an RRC Connection
Reconfiguration message.
The measurement configuration consists of
Measurement Objects
Reporting Configurations
Other Parameters
HO Measurement Configuration Overview
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RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - measObjectToRemoveList- measObjectToAddModList- reportConfigToRemoveList- reportConfigToAddModList- measIdToRemoveList- measIdToAddModList- quantityConfig- measGapConfig- s-Measure
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Measurement Configuration After UE attachment, eNodeB sends RRC
reconfiguration message which includes intra/intre-
frequency/IRAT measurement control info which
inform UE to perform intra/intre-frequency/IRAT
measurement It contains all intra/intre-frequency/IRAT measurement and report configuration, including A1(optional), A2(optional) and A3(mandatory) event.
Trace from eNodeB
Page14
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The Measurement Configuration for Inter-RAT HO For inter- RAT HO, the measurement configuration includes:
Inter-RAT measurement object: UTRAN or GERAN
Reporting configuration
Inter-RAT handover thresholds
Hysteresis
Time-to-trigger
Triggering quantity for handovers to UTRAN
Maximum number of cells to be reported
Interval between reports
The number of periodic measurement reports
Measurement quantity configuration
Measurement gap configuration
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Inter-RAT Measurement Object Overview
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RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - measObjectToAddModList-- measObjectId-- measObject measObjectEUTRA --- carrierFreq --- allowedMeasBandwidth--- presenceAntennaPort1--- neighCellConfig--- offsetFreq --- cellsToAddModList---- cellIndex ---- physCellId---- cellIndividualOffset
Measurement objects are the objects that UEs measure.
Measurement object information includes the target system,
target frequency and target cell for a UE to measure, as well
as the measurement bandwidth and frequency-specific
offset if target system is EUTRAN.
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Inter-RAT Measurement Object Parameters
Parameters Description
carrierFreqIndicates the DL EARFCN of the inter-frequency E-UTRAN cell
allowedMeasBandWidth
Indicates the measurement bandwidth for inter/intra-frequency neighboring cells
PresenceAntennaPort1
Indicates whether all of the inter-frequency neighboring cells are configured with the double-TX antenna.
neighCellConfig
Indicate whether all the neighbor have the same configuration or not
offsetFreqIndicates the frequency offset of the inter-frequency neighboring cell
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Data Configuration of Inter-RAT Measurement Object UMTS
GERAN
Page19
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UTRAN Measurement Object
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RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - measObjectToAddModList-- measObjectId-- measObject measObjectUTRA --- carrierFreq --- offsetFreq--- cellsToRemoveList--- cellsToAddModList---- cellIndex---- physCellId--- cellForWhichToReportCGI
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GERAN Measurement Object
Page21
RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - measObjectToAddModList-- measObjectId-- measObject measObjectGERAN --- carrierFreqs--- offsetFreq--- ncc-Permitted--- cellForWhichToReportCGI
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Tracing Case – Measurement Object
Page22
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Report Configuration
Reporting configurations consist of the parameters
related to specific events.
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RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - reportConfigToAddModList-- reportConfigId-- reportConfig reportConfigEUTRA--- triggerType event---- eventId e.g. eventA1----- a1-Threshold threshold-RSRP---- hysteresis---- timeToTrigger--- triggerQuantity (RSRP)--- reportQuantity--- maxReportCells--- reportInterval--- reportAmount
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Events for Report Configuration
Page24
Events
Threshold Action
inter-frequen
cy or IRAT
A1Signal quality in the serving cell is higher than a specified threshold
The eNodeB stops inter-frequency or inter-RAT measurements.
A2Signal quality in the serving cell is lower than a specified threshold
The eNodeB starts inter-frequency or inter-RAT measurements
intra-frequency/inter-frequen
cy
A3
Signal quality in at least one intra-frequency/inter-frequency neighboring cell is higher than that in the serving cell
Source eNodeB sends an intra-frequency/inter-frequency handover request.
inter-frequen
cy
A4
Signal quality is higher than a specified threshold in at least one inter-frequency neighboring cell
Source eNodeB sends an inter-frequency handover request.
A5 A2 + A4 Source eNodeB sends an inter-frequency handover request.
IRAT
B1
Signal quality is higher than a specified threshold in at least one inter-RAT neighboring cell
source eNodeB sends an inter-RAT handover request.
B2 A2 + B1source eNodeB sends an inter-RAT handover request.
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Tracing Case – Event 3 Report Configuration
Page26
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Other Parameters Related to Events
Page27
Example:
Hysteresis
To reduce the number of event reports generated because of radio signal
fluctuation, the hysteresis to the signal quality is used in the entering and
leaving conditions for each event.
Time-to-Trigger
When the entering condition of an
event is met, the UE does not report
the cell measurement result
associated with the event to the
eNodeB until the entering condition is
met throughout a specified period, as
defined by the time-to-trigger
parameter.
Triggering Quantity and
Reporting Quantity
RSRP & RSRQ
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1.Hysteresis 2.Time-to-trigger
Data Configuration of Reporting Configuration(1/2)
Page28
UMTS
GERAN
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Data Configuration of Reporting Configuration(2/2)
3. Triggering quantity for handovers to UTRAN
4. Maximum number of cells to be reported
5. Interval between reports
6. The number of periodic measurement reports
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33
44
55
66
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A: Measurement value at the physical layer
B: Measurement value obtained after L1 filtering.
C :Measurement value obtained after L3 filtering.
Other Parameters—Measurement Filtering
Page30
EUTRAN
UTRAN
GERAN
EUTRAN
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Tracing Case – Filtering Configuration
This filtering is performed by RRC, smoothing
measurement to resist fast fading effect. A larger value
of this parameter indicates a stronger smoothing effect
and higher resistance to fast fading, but it may weaken
the tracing capability towards varying signals
Page32
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Tracing Case - Measurement ID
Based on the object and report configuration, eNodeB
creates one or more measurement ID linked with object ID
and report ID. And this ID should be also included in the UE
report, so eNodeB can differentiate each reports
Page33
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Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT
Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
IRAT HO Scenario
Page35
Inter-RAT HOService-based HO
Coverage-based HO
Load-based HO
UL-quality-based HO
Distance-based HO
SPID-based HO back to the HPLMN
CSFB(it will be introduced in Chapter4)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Coverage-based Handover OverviewMoves to neighbor LTE FDD cell
Moves to neighbor LTE TDD cell
Intra-FrequencyInter-Frequency
Using different event threshold to decide handover target Handover Priority: Intra-frequency > inter-frequency , Intra-RAT > inter-
RAT Handover between TDD/FDD looks as Inter-Frequency of LTE system
Inter-RAT
LTE FDD LTE TDD
UMTS
Threshold of
trigger Inter-freq
HO (IF A2) is
higher than
threshold of
trigger Inter-RAT
HO (IR A2), which
means that inter-
freq HO is
triggered earlier
than inter-RAT
HO.
Moves out of LTE coverage
If UE under UMTS move to LTE coverage, there are two options: Service is still provided by UMTS. When service
ends, UE will camp on LTE network by cell reselection
UMTS triggers Inter-RAT handover to LTE
Moves to LTE
coverage
Page36
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Event Related with Coverage-based HO The eNodeB delivers the measurement configuration
related to event A2 to a UE in connected mode to monitor
the signal quality of the serving cell. The eNodeB may
deliver measurement configurations for two types of
events A2 to the UE
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...•If the signal quality in the serving cell is lower than the
specified threshold
...
•If the signal quality in the serving cell further deteriorates
and the eNodeB does not perform a handover for the UE, the
UE reports event A2 for blind handover.
Event A2 for IRAT measurement
Event A2 for blind handover
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Data Configuration of Coverage-based HO The switches UtranRedirectSwitch and
GeranRedirectSwitch under the ENodeBAlgoSwitch.
HoModeSwitch parameter specify whether coverage-
based handovers to GERAN and UTRAN cells are enabled,
respectively.
Page38
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Measurement Trigger Conditions of IRAT HO by Event A2
Entering condition: Ms + Hys < Threshold
Leaving condition: Ms – Hys > Threshold
A2 Event
LTE
GSM/UMTS Coverage
Intra-LTE Inter-RAT
According to radio link condition (LTE: RSRP/RSRQ)
Moves to neighbor LTE
cell
Moves out of LTE
coverage
Page39
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Data Configuration Of Measurement Trigger Condition of IRAT HO by Event A2
Hysteresis,
threshold and time
to trigger related
with event A2
Page41
RSRP/RSRQ Measurement quantities
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Target-based Setting of Inter-RAT Event A2 For GU, RSRP thresholds can be adjusted via the
offsets.
The offsets do not affect the RSRQ thresholds for
inter-RAT measurement event A2.
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Entering condition: Ms + Hys < Threshold-10
Leaving condition: Ms – Hys > Threshold-10
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Measurement Stopping Condition of IRAT HO by Event A1
The event A1 threshold
must be higher than the
event A2 threshold to
ensure that event A1
can stop inter-RAT
measurements in
coverage-based inter-
RAT handovers.
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Entering condition: Ms - Hys > Thresh
Leaving condition: Ms + Hys < Thresh
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Data Configuration Of Measurement Stopping Condition of IRAT HO by Event A1
Hysteresis,
threshold and time
to trigger related
with event A1
Page46
These parameters are the same to both A1 and A2
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Blind-Handover Triggering by Event A2
In coverage-based IRAT handovers, the eNodeB delivers a measurement
configuration related to event A2 for blind handover if the signal quality of
the serving cell deteriorates to a specified level and the UE has not
been handed over.
Event A2 for blind handover can trigger both inter-frequency and IRAT
blind handovers.
the RSRP threshold and RSRQ threshold of event A2 for blind handover are
the same and specified in the following parameters.
Other parameters related to blind handover events A1 and A2 are
specified by parameters for inter-RAT blind handovers
Page47
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Relationship between IRAT HO and Blind HO The eNodeB delivers event A2 for blind handover but not event A2 for inter-
frequency or inter-RAT measurement if both the following conditions are met:
The UE does not support inter-frequency or inter-RAT measurement.
The threshold of event A2 used for inter-frequency or inter-RAT
measurement is lower than the threshold of event A2 for blind handover.
A coverage-based inter-RAT blind handover can be performed in the form of a
blind redirection.
If the target system is GERAN, it can also be performed in the form of a blind
CCO.
If VoIP services are running on the UE that reports event A2 for blind
handovers, the eNodeB determines an IRAT handover policy(discussed later)
based on the handover policy configuration and UE capability.
Page49
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When high load occurs in LTE but low load in GSM/UMTS,
make some UEs handover to GSM/UMTS
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load transfer
LTE
High load
GSM Low loadUMTS
Load Evaluation
Load Balancing Decision
Inter-RAT HO based
Measurement
Event B1 Triggered
UE eNB
Measure Report
HO Decision
IR-HO Execute
Measurement GAPEvent B1 Parameters
Blind HO
YBlind HO Switch is ON & target cell is in blind HO List?
target cell
N
Blind HO list can be configured according to operator's strategy and networking scenarios
Multiple handover schemes according to the capability of network, and UE e.g. PSHO, CCO/NACC, Redirection
Load based Handover: Inter-RAT
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Data Configuration of Load-based HO
Blind HO
UEs in connected mode are handed over to UTRAN cells
UEs are handed over to GERAN cells
and
and
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UL-Quality-based Handover
X
HO
Scenario:
DL quality is good,
but UL quality is
limited, which result
to poor service
experience.
Principle:
When UL IBLER is
higher than
threshold, trigger
handover to a better
neighbor cell.
√
Improve Edge User Experience in Interference or UL-Limited Scenario
Page52
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UL Quality threshold are set by the system.
Description•Due to the UL interference, the coverage in UL is limited compared to DL•The UE has limited power•The HO algorithms are implemented for DL HO
Benefit•Guarantee Service Continuity in UL limited LTE networks
2. Sends target cell and instructs UE to initiate GAP/B1 measurement
3. Sends GAP/B1 measurement report to the eNodeB
1. UL Quality > threshold
4. Instruct UE to HO
12
3
4
LTE(F1)
2G/3G or LTE(F2)
UL-Quality-based Inter-RAT Handover
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Service-based Handover: Inter-RAT Handover voice service when E-RAB
established to UMTS/GSM
To improve efficiency and capacity of
whole system
To save the investment at the
beginning of LTE
Page54
3G/2G coverage
LTE coverage
Handover to 3G/2G according to service
UE eNB
UE initiate service
Only Voip E-RAB
E-RAB Initial
HOMeasurement
Measurement Configuration
Event B1 trigger
Measure Report
HO Decision
HO Execute
Y
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Data Configuration of Service-based HO
Page55
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Distance-based HO Overview
Page57
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Data Configuration of Distance-based HO
Page59
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Background of Inter-PLMN Handover Besides handover between PLMNs which belong
to different operators, there is another scenario
where an operator may own multiple PLMNs
which are respectively used to provide coverage
for different RATs.
To enable UE handovers between PLMNs owned
by the same operator, inter-PLMN handovers are
introduced.
Page60
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Data Configuration of Inter-PLMN HO(1/2)
Page61
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Data Configuration of Inter-PLMN HO(2/2)
Page62
MAPPING
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SPID-based HO Back to the HPLMN Overview(1/2) A handover back to the HPLMN policy defines whether a UE can
be handed over from another PLMN to its HPLMN when it moves
back to an E-UTRAN of its HPLMN.
The SpidCfg.HoBackToHPLMNSwitch parameter specifies
whether handover back to the HPLMN is allowed for UEs with a
specific SPID.
Page63
Operator A
Operator B
Inter-PLMN Handover to A’s home PLMN
Scenario:
Operator A's coverage is embedded in
Operator B's coverage, i.e. a UE does not
lose coverage from operator B when
entering coverage of operator A.
Operator B‘s eNB needs to know the
subscriber’s home PLMN to decide
whether a handover towards A‘s network
shall be triggered.
Operator A’s subscriber allowed to
roam in B’s network
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UE
Parameter and Setting
Spid HoBackToHPLMNSwitch
1 1 FALSE(FALSE)
2 2 TRUE(TRUE)
3 3 TRUE(TRUE)
4 4 FALSE(FALSE)
5 5 ...... ... ...... 256 ...
SPID-based HO Back to the HPLMN Overview(2/2) For roaming subscribers, HPLMN cell will be more suitable to be
selected than roaming cell when entering HPLMN coverage area
through connected mode handover.
This kind of handover is also an inter-PLMN handover. Before
using this policy, ensure that the HPLMN has the frequency with
the highest priority in the cell reselection policy, and inter-PLMN
handover.
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Conditions of SPID-based HO Back to the HPLMN Handover back to the HPLMN takes effect for a UE
only when all the following conditions are met:
Page65
• Comparing with serving cell, a neighbour cell should has higher frequency priorities and a different PLMN• The parameter
SpidCfg.HoBackToHPLMNSwitch
parameter is set
to TRUE(TRUE)
• ENodeBAlgoSwitch.HoAlgoSwitch.InterPlmnHoSwitch is selected.
Switch related to SpidCfg is enable
High frequency priorities and different PLMN
Switch related to InterPlmnHo is enable
SPID-based HO Back to the HPLMN
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Example of SPID-based HO Back to the HPLMN
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PLMN B PLMN A
CN
1. A’s UE access to B’s network
2. eNB/RNC get SPID of this UE from B’s MME
3. eNB check the neighbor cell list by
this PLMN when UE HO to it, if find
matched cell, ask the UE to HO
HO to HPLMN happens in this cell
1
2
3
Handover to HPLMN based SPID can facilitate roaming user back to its network to save the cost.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page67
Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Redirection Definition Redirection is a method of transferring UEs between cells and is a type
of handover when "handover" is used as a generic term.
When a handover cannot be performed in an emergency or due to
equipment limitations, the eNodeB sends the UE an RRC Connection
Release message, which contains information about a neighboring
frequency in the LTE system or in another RAT system. Using this
message, the eNodeB instructs the UE to initiate a random access
procedure towards an inter-frequency or inter-RAT neighboring cell so
that the UE can resume its services.
Compared with handovers, redirections do not include a
procedure for initiating a handover request towards a
neighboring cell. Therefore, redirections have lower requirements for
equipment capabilities and can be rapidly performed. The two
methods differ in the way to transfer UEs.Page68
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Redirection Data Configuration The 2G/3G network are generally mature, and may not support IRAT
handovers from the E-UTRAN. In this situation, redirections instead of
inter-RAT handovers can be performed on UEs. Therefore, network
capabilities must be collected to determine whether to enable handovers
or redirections for UE transfer.
If both handovers and redirections are enabled, the eNodeB
preferentially uses handovers to transfer UEs.
Page69
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Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Blind Handovers Overview To reduce delay, the eNodeB may select a target cell for handover in
the absence of the measurement information. This type of handover is
called a blind handover, which is a generic term.
Blind handover consists of
The handover without neighboring cell measurements
CCO
Redirection
If eNodeBs decide to perform blind handovers, they will not deliver the
GAP measurement and related measurement control order but directly
deliver handover commands, CCO indicators, or redirection indicators
to the UEs.
Page72
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Comparison between Blind HO and Normal HO
Measurement based handover: HO must be trigged by intra/inter-frequency/IRAT measurement report
Blind handover: Skip intra/inter-frequency/IRAT measurement, directly execute HO based on priority configuration
Once blind HO is activated, eNodeB directly decide the HO target based on the priority configuration of each neighbor
Measurement report (A2)
intra/inter-frequency/IRAT measurement activate
Measurement report (A4)
Handover command
Measurement based HO
Measurement report (A2)
Handover command
Blind Ho
Page73
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The eNodeB randomly selects target cells or frequency
The Target Selection Procedure of the Blind HO
Page74
Star The eNodeB selects the system with the highest priority
Are valid Ncells available for the blind-HO?
The eNodeB selects the Ncells with the highest blind-HO priority
The eNodeB selects a frequency based on the frequency priority
The eNodeB filters the target cells or frequencies
Is only one target cell or frequency available ?
The eNodeB performs a blind-HO
No
Yes
Yes
No
Attention: Firstly select a cell in the intra-RAT system and then a inter-RAT system, for the priority of EUTRAN is higher than
that of an inter-RAT system.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration of IRAT Priority
1. The eNodeB selects the system with the highest
priority as the target system.
The priorities of EUTRAN systems
Page76
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Data Configuration of IRAT Priority
1. The eNodeB selects the system with the highest priority
as the target system.
The priorities of IRAT systems
Page77
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Data Configuration of Neighbor Cell Blind HO Priority
2. The eNodeB selects a neighboring cell for the blind
handover.
Within EUTRAN system
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EUTRAN
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Data Configuration of Neighbor Cell Blind HO Priority
2. The eNodeB selects a neighboring cell for the blind
handover.
In IRAT system
Page79
UTRAN
GERAN
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Data Configuration of the Neighbor Frequency Priority
Page80
…UTRAN
GERAN
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Data Configuration of Filtering the Target Frequencies3.The eNodeB filters the blind-handover targets to prevent a blind
handover to an inappropriate target.
For cell: The filtering of the target neighboring cells is the
same as that in Handover Decision.
For frequency: When filtering the target frequencies, the
eNodeB filters out the frequencies whose PLMN is different
from the PLMN of the serving cell.
Page81
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration of Filtering the Target Frequencies
Page82
UTRAN
GERAN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page83
Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
IRAT HO Measurement Overview Step1: When inter-RAT measurements are required, the
eNodeB delivers to the UE a Measurement Configuration
message containing the inter-RAT measurement
configuration, instructing the UE to perform inter-RAT
measurements.
Step2: If the triggering condition of inter-RAT handover event
B1 or B2 are met, event B1 or B2 will be reported. Basing on
the reported inter-RAT measurement result, the eNodeB
makes an inter-RAT handover decision.
The measurement phase of the inter-RAT handover consists of
inter-RAT measurement configuration, setup of measurement
gaps, and triggering of event B1 or B2.
Page84
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Event B1/B2 Triggering Scenario Coverage-based inter-RAT handovers
can be triggered by event B1 or B2
The type of event used to trigger coverage-based inter-RAT
handovers is specified by the InterRatHoComm.
InterRatHoEventType parameter.
Other types of inter-RAT handover
can be triggered only by event B1. If event B2 is used to
trigger non-coverage-based inter-RAT handovers, cell center
users (CCUs) do not report event B2.
Page85
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
IRAT Report Configuration - Event B1
Page86
RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - reportConfigToAddModList-- reportConfigId-- reportConfig ReportConfigInterRAT--- triggerType event---- eventB1----- b1-ThresholdUTRA or----- b1-ThresholdGERAN---- hysteresis---- timeToTrigger --- maxReportCells --- reportInterval --- reportAmount
Event B1 indicates that the signal quality is higher than a
specified threshold in at least one inter-RAT neighboring cell.
When the information about the cells that meet the triggering
condition is reported, the source eNodeB sends an inter-RAT
handover request.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Event B1 Triggering Mechanism
Page87
EUTRAN Cell
UTRAN Cell
Entering condition: Mn + Ofn - Hys > Thresh
Leaving condition: Mn + Ofn + Hys < Thresh
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration Related to Event B1
Page88
Ofn
Hys
Thresh
time-to-trigger
Hys
time-to-trigger
Thresh
URAN
GERAN
Thresh
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
IRAT Report Configuration - Event B2
Page89
RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - reportConfigToAddModList-- reportConfigId-- reportConfig ReportConfigInterRAT---triggerType event---- eventB2----- b2-Threshold1----- b2-Threshold2------ b2-Threshold2UTRA or------ b2-Threshold2GERAN---- hysteresis---- timeToTrigger --- maxReportCells --- reportInterval --- reportAmount
Event B2 indicates that the signal quality in the serving cell is
lower than a threshold and that the signal quality in at least one
inter-RAT neighboring cell is higher than another threshold.
When the information about the cells that meet the triggering
condition is reported, the source eNodeB sends an inter-RAT
handover request.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Event B2 Triggering Mechanism
Page90
TTT
B2-1
Threshold 2
Threshold 1
EUTRA Cell
UTRACell Hys
Ofn-Hys
Mn
Mp
B2-2 B2 Triggered
•Entering condition: Ms + Hys < Thresh 1 and Mn + Ofn - Hys > Thresh 2 •Leaving condition: Ms - Hys > Thresh 1 or Mn + Ofn + Hys < Thresh 2
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration Related to Event B1
Event B2 uses the same set of parameters as event B1
except four parameters: the triggering quantity related to
Thresh 1, the measurement quantity related to Thresh 2,
Thresh 1, and Thresh 2. For details about the four
parameters, see the following Tables.
Thresh 1 for event B2
Thresh 2 for event B2
Page91
Triggering Quantity Thresh 1
The same as the triggering quantity of event A2
RSRPInterRatHoCommGroup.InterRatHoA2ThdRSRP
RSRQInterRatHoCommGroup.InterRatHoA2ThdRSRQ
Measurement Quantity Thresh 2
UTRANRSCP
InterRatHoUtranGroup.InterRATHoUtranB1ThdRSCP
Ec/NoInterRatHoUtranGroup.InterRATHoUtranB1ThdEcN0
GERAN RSSI InterRatHoGeranGroup.InterRATHoGeranB1Thd
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Measurement gaps are applicable to inter-frequency and
inter-RAT measurements.
Measurement GAP
Page92
During the measurement
gaps the UE:
not transmit any data
is not expected to tune
its receiver on the E-
UTRAN serving carrier
frequency.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration of IRAT Measurement Priorities
This is only available to IRAT measurements on the
UTRAN.
Page94
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Event-Triggered Periodical Reporting
After an event is reported at the first time, the
measurement results associated with the event are
reported periodically by UE, which is called event-
triggered periodical reporting.
Page95
eNB
UE
eNB
Periodical Reporting
Report Interval (ms120, ms240, ms480, ms640, ms1024, ms2048, ms5120, ms10240,
min1, min6, min12, min30, min60)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
The Purpose of IRAT Periodical Reporting
There are three purposes defined for periodical reporting:
Report Strongest Cells.
Report Strongest Cells For SON.
Report CGI.
Page96
RRC Connection Reconfiguration Request
eNBUE
RRC Connection Reconfiguration Complete
RRC Connection Reconfiguration RequestMeasurement Configuration - reportConfigToAddModList-- reportConfigId-- reportConfig ReportConfigInterRAT---triggerType periodical ---- purpose--- maxReportCells --- reportInterval --- reportAmount
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page97
Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Handover Decision Overview
Measurement ReportCheck measurement result
Decide target cell
Page98
In this phase, the eNodeB checks the measurement result reported by
the UE and decides whether to perform an inter-RAT handover for a
UE or the blind-handover priorities and judges to triger a handover.
The eNodeB derives a list of candidate cells from the measurement
report sent by the UE.
For normal handover, the list is based on the signaling strength, while
for a blind handover, it is based on the blind-handover priorities.
If the eNodeB receives measurement reports about different RATs, it
processes the reports in a First In First Out (FIFO) manner.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Filtering Principle of Target Cell The eNodeB filters out the following cells from the
neighboring cell list:
Page99
cell1
cell2
cell3
cell4
cell5
cell6
cell3
cell5
Blacklisted neighboring cells
Neighboring cells that have a different PLMN
from the serving cell if the inter-PLMN handover
switch is disabled. Refer to the section Inter-
PLMN Handovers
Neighboring cells with a handover prohibition
flag.
Neighboring cells in the areas indicated by the
IE Handover Restriction List in the INITIAL
CONTEXT SETUP REQUEST message sent from
the MME.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page100
Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Handover Execution Overview In this phase, the UE and the eNodeB exchange signaling over
the radio interface according to the protocol.
The LTE system uses hard handovers, that is, only one radio link
is connected to a UE at a time.
The source and target eNodeBs exchange signaling and data
through X2/S1 adaptation.
Page101
In the case of IRAT HO, the eNodeB sends a handover request and forwards data over the S1 interface.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Forwarding Overview
Definition: After the source eNodeB sends a handover
command to the UE, the UE detaches the connection from
the source eNodeB. The source eNodeB then forwards the
uplink (UL) data that is received out of order and the DL
data to be transmitted, to the target eNodeB.
Data forwarding prevents a decrease in the data transfer
ratio and an increase in the data transfer delay that are
caused by user data loss during the handover.
Page103
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Forwarding Procedure
Step1:RRC connection Break
Source eNodeB
Step2: source eNodeB implement DL data buffering
Source eNodeBS-GW
Buffering
Step3: Buffer forwarding to target cell
Source eNodeB
Target eNodeB
Data forwarding
Step4: Random access to target cell
Target eNodeB
DL data
Page104
Attention: There are several scenario introduced in the notes
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
IRAT Handover Execution Policy
LTE PS 2G/3G PS
PS handover
LTE VOIP 2G/3G CS
SRVCC
LTE PS
CCO/NACC
GSM Idle Mode
•IRAT Handover Execution Policy Priority:
PS handover > SRVCC > CCO(GSM ONLY) > Redirection
Page105
LTE Connection Mode
Redirection
2G/3G
RRC Connection Release
Access Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration of Handover Execution Policy The LTE system is incapable of carrying CS services. If an E-
UTRAN UE needs to start a mobile-originated or mobile-
terminated CS service, the UE will be moved to another RAT by
means of CSFB.
Page106
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page107
Contents1. LTE Interoperability in Connection Mode
1.1 Technical Overview and Basic Concepts
1.2 Measurement Configuration
1.3 Measurement Triggering/Stopping Phase of an IRAT Handover
1.4 Redirection
1.5 Blind Handover
1.6 Measurement Phase of an IRAT Handover
1.7 Decision Phase of an IRAT Handover
1.8 Execution Phase of an IRAT Handover
1.9 IRAT Signaling Procedure in Connection Mode
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page108
Contents1.9 IRAT Signaling Procedure in Connection
Mode
1.9.1 PS Handover for LTE <->G/U
1.9.2 RRC Release & Redirection for LTE <->G/U
1.9.3 eNACC for LTE->GERAN
1.9.4 CCO for GERAN->LTE
Mainly focus on the Gn/Gp SGSN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS Handover LTE->GERAN/UTRAN Overview The UE in connected mode is handed over to a
GERAN/UTRAN cell after the UE moves from the area
covered by both the LTE network and GERAN/UTRAN to
the area covered only by the GERAN/UTRAN to ensure the
continuity of PS services.
Page109
SGW PGW
MMELTE
eNodeB
GSM /UMTS BTS
BSC/RNC SGSN GGSN
① HO decision: LTE to GU
eNodeB sends HO request
② MME sends relocation to target SGSN
Target GU network establish access connection
③ HO command is sent to UE
④ MS detected by target GU network
⑥ Release source network resources
⑤ Target network finish relocation.
Context exchange with source PGW
①
②
②
②
③③
④⑤
⑤
⑤
⑤⑥
⑥
HO Trigger, Measurement and Decision
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Target RNC
Source eNodeB Old MME
New Gn/Gp SGSN
P-GW
3. Forward Relocation Request
4. Relocation Request
2. Handover Required
8. Handover Command
5. Forward Relocation Response
4. Relocation Request Acknowledge
12. Relocation Detect
MS
13. RRC message
1. Decision to perform handover to UTRAN
MS detected by target RNC
Establishment of Radio Access Bearers
9. Forwarding of data
14. Relocation Complete
15. Forward Relocation Complete
17. Routeing Area Update
16. Update PDP Context Request
18b. Release Resources
16. Update PDP Context Response
15. Forward Relocation Complete Acknowledge
C3
C2
10. HO from E-UTRAN Command
Serving GW
18. Delete Session Request
18a. Delete Session Response
6. Create Indirect Data Forwarding Tunnel Request
7. Create Indirect Data Forwarding Tunnel Response
PS HO(LTE->UMTS) – Gn/Gp SGSN
Page110
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS HO(LTE->GERAN) – Gn/Gp SGSN Preparation phase (Almost the same with that of LTE->UMTS except for
some signaling message name )
Page112
UE
Source eNodeB Target BSS Source MME New SGSN Serving GW HSS
1. Handover Initiation 2. Handover Required
3. Forward Relocation Request
4. PS Handover Request
7. PS Handover Request Acknowledge
8. Forward Relocation Response
PDN GW
Uplink and Downlink User Plane PDUs
5. Reservation of radio resources in target BSS
6. Target BSS creates the Target BSS to Source BSS Transparent Container
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
UE
Source eNodeB Target BSS Source MME New SGSN Serving GW HSS
PDN GW
Uplink and Downlink User Plane PDUs
1. Handover Command
2. HO from E-UTRAN Command
Sending of uplink data possible
4. GERAN A/Gb Access Procedures
5. XID Response
6. PS Handover Complete
8. Forward Relocation Complete
8a. Forward Relocation Complete Acknowledge
9. Update PDP Context Request
11. Update PDP Context Response
Uplink and Downlink User Plane PDUs
7. XID Response
12. XID Negotioation for LLC ADM
12a. SABM UA exchange re-establishment and XID negotiation for LLC ABM)
Downlink User Plane PDUs
Forwarding of data
13. Routing Area Update procedure
14b. Release Resource 14. Delete Session Request
14a. Delete Session Response
PS HO(LTE-> GERAN) – Gn/Gp SGSN
Page113
Execution phase (Almost the same
with that of LTE->UMTS except for
some signaling message name )
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS HO(GERAN/UTRAN->LTE) – Gn/Gp SGSN The UE in connected mode is handed over to an LTE
cell after the UE moves from the area covered only
by the GERAN/UTRAN to the area covered by both
the LTE network and GERAN/UTRAN to ensure the
continuity of PS services.
Page114
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS HO(UTRAN->LTE) – Gn/Gp SGSN
Page115
Target eNodeB
Source RNC
Old Gn/Gp SGSN
New MME S-GW
3. Forward Relocation Request
6. Handover Request
2. Relocation Required
11. Relocation Command
10. Forward Relocation Response
7. Handover Request Acknowledge
MS
14. Forward SRNS Context 14. Forward SRNS Context
13. RRC message
15. HO to EUTRAN Complete
MS detected by target RNC
Establishment of Radio Access Bearers
C1
12. Forwarding of data
14. Forward SRNS Context Acknowledge
15. Handover Notify
16. Forward Relocation Complete
17. Modify Bearer Request 20 Iu Release Command
20a. Iu Release Complete
19. Modify Bearer Response
16a. Forward Relocation Complete Acknowledge
18. Modify Bearer Request/Response
P-GW
4. Create Session Request
5. Create Session Response
1. Decision to handover
HSS
22. Procedure as in TS 23.401, steps 2 to 7 of Figure 5.4.2.2-1
21. Tracking Area Update procedure
8. Create Indirect Data Forwarding Tunnel Request
9. Create Indirect Data Forwarding Tunnel Response
23. Delete Indirect Data Forwarding Tunnel Request
23a. Delete Indirect Data Forwarding Tunnel Response
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS HO(GERAN->LTE) – Gn/Gp SGSN
Preparation phase
Page117
UE
Source BSS
Target eNodeB Old
SGSN Target MME Serving GW HSS
1. Handover Initiation
2. PS Handover Required
3. Forward Relocation Request
5. Handover Request
5a. Handover Request Acknowledge
6. Forward Relocation Response
PDN GW
Uplink and Downlink User Plane PDUs
4. Create Session Request
4a. Create Session Response
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Serving GW UE Source BSS
Target eNodeB Old SGSN Target MME HSS
PDN GW
Uplink and Downlink User Plane PDUs
1. PS HO Required Acknowledge
2. PS Handover Command
Sending of uplink data possible
4. E-UTRAN Access Procedures
3. Forward SRNS Context
3a. Forward SRNS Context Ack
5. HO to E-UTRAN Complete 6. Handover Notify
7. Forward Relocation Complete
7a. Forward Relocation Complete Acknowledge
11. BSS Packet Flow Delete Procedure
Uplink and Downlink User Plane PDUs
Forwarding of data
8 . Modify Bearer Request
10. Modify Bearer Response
(A)
9. Modify Bearer Request
9a. Modify Bearer Response
12. Tracking Area Update procedure
13. Procedure as in TS 23.401, steps 2 to 7 of Figure 5.4.2.2-1
PS HO(GERAN->LTE) – Gn/Gp SGSN Execution phase
Page118
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page119
Contents1.9 IRAT Signaling Procedure in Connection
Mode
1.9.1 PS Handover for LTE <->G/U
1.9.2 RRC Release & Redirection for LTE <->G/U
1.9.3 eNACC for LTE->GERAN
1.9.4 CCO for GERAN->LTE
Mainly focus on the Gn/Gp SGSN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LTE->G/U RRC Release & Redirection Overview
When the UE in connected mode moves from the area
covered by both the LTE network and UTRAN(or GERAN)
to the area covered by only the UTRAN, the UE needs to
be handed over to the UTRAN to ensure the continuity
of PS services. . The eNodeB obtains the UE
capability and knows that the UE does not
support either PS handover or CCO(for GERAN).
The eNodeB instructs the UE to reselect the target cell
in RRC release & redirection mode.
Page120
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LTE->G/U RRC Release & Redirection Procedure
Page121
SGW PGW
MMELTE
eNodeB
GSM /UMTS BTS
BSC SGSN GGSN ① UE send target cell measurement to
eNodeB. eNodeB makes HO decision
② eNodeB send RRC Release message to UE, carrying RedirectedCarrierInfo that specifies the frequency of the target GERAN/UTRAN cell.
③ UE in RRC IDLE state, reselect the GERAN/UTRAN cell with the specified frequency according to redirection information.
eNodeB requests MME release LTE RRC_Connect.
UE initiates an RAU procedure.
②
③ ③
③
③
①
HO Trigger, Measurement and Decision
UE eNB RNC MME SGSN S/P-GW
2.Handover decision
4. UE reselect the target GERAN/UTRAN cell and launch RAU procedure
1. Measurement Report
3. RRC Connection Release
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
G/U->LTE RRC Release & Redirection Overview GERAN->LTE
The UE initiates a CSFB voice call in the area covered by both LTE and
GERAN and camps on the GERAN network. When the BSC releases the air
interface connection after the voice call is terminated, the released message
carries the Cell selection indicator after release of all TCH and SDCCH
parameter, which contains the information about the E-UTRAN cell (EARFCN
and PCI), instructing the UE to reselect to the LTE network.
UTRAN->LTE
The UE in connected mode is handed over to an LTE cell after the UE moves
from the area covered only by the UTRAN to the area covered by both the
LTE network and UTRAN to ensure the continuity of PS services. The RNC
obtains the UE capability and knows that the UE does not support the PS
handover. The eNodeB decides to instruct the UE to reselect the target cell in
RRC release + redirection mode.
Page122
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
G/U->LTE RRC Release & Redirection Procedure
Page123
UE RNC eNB MME SGSN S/P-GW
2.Handover decision
4. UE reselect the target E-UTRAN cell and launch TAU procedure
1. Measurement Report
3. RRC Connection Release
UE BSC eNB MME SGSN S/P-GW
1. CS call terminated
3. UE reselect the target E-UTRAN cell and launch TAU procedure
2. Channel Release
UTRAN->LTE
GERAN->LTE
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page124
Contents1.9 IRAT Signaling Procedure in Connection
Mode
1.9.1 PS Handover for LTE <->G/U
1.9.2 RRC Release & Redirection for LTE <->G/U
1.9.3 eNACC for LTE->GERAN
1.9.4 CCO for GERAN->LTE
Mainly focus on the Gn/Gp SGSN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
eNACC from the LTE to the GERAN Overview When the UE in connected mode moves out of the
area covered by both the LTE network and the
GERAN, if the target GERAN or UE does not support
the PS handover, the system message of the target
GERAN cell is sent to the UE on the source LTE
network. In this case, the duration of the UE
accessing the target GERAN cell is shortened to
reduce the service interruption duration.
Page125
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
eNACC LTE -> GERAN
Page126
10. Routing Area Update Procedure
UEServing
GWSource MME
Target SGSN
HSSPDN GW
Target BSS
Source-eNB
2.Handover decision
1. Measurement Report
3. ENB Direct Information Transfer
4. RAN Information Request
5. RAN Information Request
6. RAN Information
7. RAN Information
8. MME Direct Information Transfer
9. Mobility From EUTRA Command
SGW PGW
MMELTE
eNodeB
GSM BTS
BSC SGSN GGSN
① UE send target cell measurement to eNodeB. eNodeB makes HO decision
② eNodeB gets target cell info. by RIM procedure
③ eNodeB sends HO command to UE
④ MS detected by target GSM network
⑥ MME release source network resources
⑤ Target network finish relocation.
Context exchange with source PGW
②
②
②③
④
⑤⑤
⑤
⑤⑥
⑥
①
HO Trigger, Measurement and Decision
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page127
Contents1.9 IRAT Signaling Procedure in Connection
Mode
1.9.1 PS Handover for LTE <->G/U
1.9.2 RRC Release & Redirection for LTE <->G/U
1.9.3 eNACC for LTE->GERAN
1.9.4 CCO for GERAN->LTE
Mainly focus on the Gn/Gp SGSN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CCO from the GERAN to the LTE Overview After the UE in connected mode moves from the area
covered by only the GERAN to the area covered by
both the LTE network and the GERAN, if the GERAN or
UE does not support the PS handover, the BSC
initiates the NACC procedure to obtain the system
message of the target E-UTRAN and informs the UE
about the message. In this case, the duration of the
UE accessing the target E-UTRAN cell is shortened to
reduce the interruption duration is reduced.
Page128
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CCO from the GERAN to the LTE
Page129
10.Tracking Area Update Procedure
UE Source SGSN Target MME HSSPDN GWTarget eNB
1. Measurement Report
Source-BSC
9. PACKET CELL CHANGE ORDER
2.Handover decision
3. RAN INFORMATION REQUEST 4. RAN INFORMATION
RELAY
5. MME DIRECT INFORMATION
TRANSFER
6. ENB DIRECT INFORMATION
TRANSFER7. RAN INFORMATION
RELAY8. RAN INFORMATION
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page130
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LTE Voice Solution
From a technological perspective, there are two
standard solutions to provide CS services for E-
UTRAN UEs:
Page131
Voice Solution
Voice over IMS
CSFB
IMS required Rich VoIP service experience Fast connection Required SRVCC handover support
Fast supply voice service for LTE userMake full utilization of inherited CS network, fast deployment Large delay
Copyright © 2011 Huawei Technologies Co., Ltd. All rights reserved.
Network Architecture & Functionality for CSFB to UTRAN/GERAN
Page132
•Deriving a VLR number and LAI from the TAI of the current cell, or using a default VLR number and LAI.•Maintaining SGs association with MSC/VLR for EPS/IMSI Attached UE•Triggering paging to eNodeB (when MSC-S pages the UE)•Initiating IMSI Detach at EPS Detach
S1-MME
S1-U
S11
E-UTRAN
MME
S-GW
S5
SGSN
HSS/HLR
S6a
S4
S3
S12
Iu-ps
Gb
PDN-GW
SGi
S7
MSC/VLR
A
Iu-cs
Gr
SGs
G/U/L handset
•Multi-mode G/U/L•CSFB capable•Support of procedures: Combined EPS/IMSI Attach, Update, Detach.
GERAN
UTRAN
•Need to be R8 ready•Maintaining SGs association with MME
•Forwarding paging request for CS domain to the UE.•Directing the UE to the target CS capable cell. (PS HO/redirection with or without SIBs).
C/D
PCRF
Rx
Internet / intranet / Operators & 3rd
Party Applications
Gs
for the mobility management and paging procedures between EPS and CS domain.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page133
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
2.1 CSFB at the eNodeB
2.2 End-to-End Procedures for CSFB
2.3 SRVCC Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB mechanisms
include PS
redirection, PS
handover, and
CCO/NACC. No
matter which CSFB
mechanism is
adopted, both
measurement-
based handover
and blind handover
are applicable.
CSFB Procedure at the eNodeB
Page134
Star
The eNodeB receives a CSFB Indicator from the MME
Are the conditions for initiating a blind HO met?
The eNodeB delivers measurement configurations to the UE
The eNodeB makes a CSFB decision
No
Yes
The eNodeB exectes a CSFB decision
End
Execution phase
Decision phase
Measurement phase
Triggering phase
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB Triggering Principle(1/3) After a UE initiates a CS service in an E-UTRAN cell, the MME
sends the eNodeB an S1-AP Request message that contains a
CSFB Indicator, notifying the eNodeB that the UE should be
transferred to the target networks which are specified by the
ENodeBAlgoSwitch.HoAlgoSwitch parameter.
Page135
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Choosing Between a Blind HO and a Measurement-based
HO
CSFB Triggering Principle(2/3)
Page136
Star
Triggering the RAT measurement
ENodeBAlgoSwitch.BlindHoSwitch is
enabled ?No
Yes
The UE supports certain RAT measurement ?
No
Yes
Blind Redirection Blind CSFB
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB Triggering Principle(3/3) - Blind CSFB Overview
In case of Blind HO(or redirection) , eNodeB decides
the CSFB target based on:
Blind handover priority of the target RAT:
InterRatHighestPri, InterRatSecondPri, and
InterRatLowestPri
Blind handover priority of the specific cell:
BlindHoPriority
LAI information ( R10 feature)
Page137
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1. The eNodeB selects a RAT with the highest blind-handover
priority.
Data Configuration of Blind CSFB
Page138
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Data Configuration of Blind CSFB(1/2)
2. The eNodeB selects a cell with the highest blind-handover
priority in this RAT
Page139
UTRAN
GERAN
0~32
0~32
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Measurement Phase – Measurement Based CSFB Overview
In case of measurement based CS Fallback, eNodeB
sends the UE the measurement configuration,
include :
RAT type
Frequencies
CSFB B1 parameters
Page140
The measurement configuration related with both should be that the UE is capable of measuring
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Measurement Phase – Measurement Report Configuration
In Measurement, CSFB is triggered by event B1:
Entering condition: Mn + Ofn - Hys > Thresh
Leaving condition: Mn + Ofn + Hys < Thresh
The B1 thresholds are different from those of
handover:
CS FallbackHoUtranB1ThdRscp
CS FallbackHoUtranB1ThdEcn0
CS FallbackHoGeranB1Thd
Page141
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Measurement Phase – Event B1 Threshold
Configuration of CSFB event B1 threshold:
Page142
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Decision Phase – Target Selection
In the decision phase of a measurement-based
handover, the eNodeB determines target cell based
on:
Evaluation of measurement report
LAI priority ( R10 feature)
Page143
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LAI based CSFB (R10)
Priority to select target GU cells with same LAC as UE registered in GU NW during CSFB to avoid LAU (0.5s~3s).
Support national Roaming UE to select suitable fallback RAT/Cell bases on LAI Indicator among multi-PLMNs.
Page144
TA3/LA1
TAI/LAI
MME
LTE CoreLTE Core
GUL
GUL
GUL
TA1/LA1
TA2/LA2
Select same LA to CSFB
CSFB to LA1
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
PS HO based CSFB
The UE sends measurement reports to the eNodeB
The eNodeB delivers B1 measurement configuration to the UE
Execution Phase - CSFB to GERAN
Page145
Star
ENodeBAlgoSwitch.BlindHoSwitch is enabled ?
No
Yes
Does the UE support B1 measurement ?
No
Yes
CCO/NACC based CSFB Flash CSFB
The eNodeB receives a CSFB indicator from MME
Is PS handover enabled?
Does the UE support PS HO?
CCO/NACC Switch=ON ?
Flash CSFB Switch=ON ?
Does the UE support PS HO?No The UE supports Rel.9 RRC
with SIB & eNodB has stored target cells’ SI ?
Redirection based CSFB
No No No
Yes
Yes
Yes
Yes
NoNo
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Execution Phase - CSFB to UTRAN
Page146
PS HO based CSFB
The UE sends measurement reports to the eNodeB
The eNodeB delivers B1 measurement configuration to the UE
Star
ENodeBAlgoSwitch.BlindHoSwitch is enabled ?
No
Yes
Does the UE support B1 measurement ?
No
Yes
Flash CSFB
The eNodeB receives a CSFB indicator from MME
Is PS handover enabled?
Does the UE support PS HO?
Flash CSFB Switch=ON ?
No The UE supports Rel.9 RRC with SIB & eNodB has stored
target cells’ SI ?Redirection based CSFB
No No
Yes
Yes
No
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Flash CSFB (Redirection Based on R9)
To support Flash CS Fallback,
eNodeB requires exchange
information between E-
UTRAN and GERAN/UTRAN
through the core networks.
Saving 1s for UMTS compare
with R8 CSFB
Saving 2s for GSM compare
with R8 CSFB
Page147
UTRAN/GERAN EUTRAN
SGSN
GSM/UMTS Core
MME
LTE Core
RIM
Re
qu
es
t
RIM
Re
sp
on
se
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
RIM Configuration
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page149
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
2.1 CSFB at the eNodeB
2.2 End-to-End Procedures for CSFB
2.3 SRVCC Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Mechanisms of CSFB
Mechanism Supported RAT
Impact on Network
CS Access Delay
Based on PS handover
UTRAN/GERAN
Complex Short
Based on Redirection
UTRAN/GERAN/CDMA2000
Simple Long
Flash CSFB (Redirection with RIM)
UTRAN/GERAN
Medium Short
CSFB based on CCO/NACC
GERAN Medium Medium
Page150
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Combined EPS/IMSI Attach Procedure
Page151
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page153
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
2.1 CSFB at the eNodeB
2.2 End-to-End Procedures for CSFB
2.2.1 CSFB to UTRAN
2.2.2 CSFB to GERAN
2.3 SRVCC Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB to UTRAN
Based on the capabilities of UEs and networks, the
following mechanisms are available for an eNodeB to
perform CSFB to UTRAN
CSFB based on PS redirection for MOC(Mobile-Originated
Calls)
Flash CS Fallback
CSFB based on PS handover for MOC(Mobile-Originated
Calls)
CSFB to UTRAN Procedure for MTC (Mobile-Terminated Calls)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
(Flash)CSFB to UTRAN based on PS Redirection for MOC
Page155
MMERNCeNodeBUE MSC SGSN
2.S1-AP Message with CS Fallback Indicator
1.Extended Service Request (containing a CS Fallback Indicator)
S1-AP Reponse Message
3.Optional measurement report
5. LAU, combined RAU/LAU, or RAU and LAU
6.CS call establishment procedure
S1 UE context release
4. RRC Connection Release with UTRAN frequency
For flash CSFB: RRC Connection Release with
UTRAN frequency/cell IDs/cell system information
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
S1 Message Tracing
Page156
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB to UTRAN Procedure for MTC
PS redirection
and PS handover
are the same for
MTO.
Page160
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
MMERNCeNodeBUE MSC SGSN
Handover Command
1. Extended Service Request (containing a CS Fallback Indicator)
Handover Command
S1-AP Response Message
3. Optional measurement report
4. PS handover preparation phase
5.CS call establishment procedure with LAU or combined RAU/LAU
6.PS handover execution phase
2. S1-AP Message (containing a CS Fallback Indicator)
PS handover procedure
CSFB to UTRAN based on PS HO for MOC
Page161
The eNodeB selects a fallback mechanism and a target cell using the CSFB algorithm. For details, see chapter 4 4.1 CSFB at the eNodeB.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page162
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
2.1 CSFB at the eNodeB
2.2 End-to-End Procedures for CSFB
2.2.1 CSFB to UTRAN
2.2.2 CSFB to GERAN
2.3 SRVCC Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB to GERAN Based on the capabilities of UEs and networks, the following
mechanisms are available for an eNodeB to perform CSFB to
GERAN
CSFB based on PS redirection for MOC
Flash CSFB (New introduced in eRAN3.0)
CSFB based on PS handover for MOC
CSFB based on CCO/NACC for MOC
CCO is short for “cell change order”
NACC is short for “network assistant cell change”
CSFB to GERAN Procedure for MTC is the same to that of CSFB to
UTRAN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
(Flash)CSFB to GERAN based on PS Redirection for MOC
Page164
MMEBSCeNodeBUE MSC SGSN
2.S1-AP Message with CS Fallback Indicator
1.Extended Service Request (containing a CS Fallback Indicator)
S1-AP Reponse Message
3.Optional measurement report
5. LAU, combined RAU/LAU, or RAU and LAU
7.CS call establishment procedure
S1 UE context release
4. RRC Connection Release with GERAN frequency group
6. Suspend
For flash CSFB: RRC Connection Release with
UTRAN frequency/PCIs/cell system information
Completely similar with that of (Flash)CSFB to UTRAN except the points in italic and red with underline
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
MMEBSCeNodeBUE MSC SGSN
Handover Command
1. Extended Service Request (containing a CS Fallback Indicator)
Handover Command
S1-AP Response Message
3. Optional measurement report
4. PS handover preparation phase
5.CS call establishment procedure with LAU or combined RAU/LAU
6.PS handover execution phase
2. S1-AP Message (containing a CS Fallback Indicator)
PS handover procedure
4b. Suspend
SGWPGW
UpdateBearers
CSFB to GERAN based on PS HO for MOC
Page165
The eNodeB selects a fallback mechanism and a target cell using the CSFB algorithm. For details, see chapter 4 4.1 CSFB at the eNodeB.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
CSFB Based on CCO/NACC(GERAN)
Page166
BSC MSC SGSN
4. MobilityFromEUTRACommand (CCO optionally with NACC)
2.S1-AP Message (containing a CS Fallback Indicator)
1.Extended Service Request (containing a CS Fallback Indicator)
S1-AP Response Message
3.Optional measurement report
6.Suspend
5.LAU, combined RAU/LAU, or RAU and LAU
7.CS call establishment procedure
8. S1 UE context release
MMEUE eNodeB
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page167
Contents
1. LTE Interoperability in Connection Mode
2. CS Interoperability
2.1 CSFB at the eNodeB
2.2 End-to-End Procedures for CSFB
2.3 SRVCC Procedure
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
LTE – GSM/UMTS SRVCC Flow
Page168
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Summary
Page170
GUL Interoperability procedure
GUL Interoperability scenarios
GUL Interoperability algorithm principles and data
configuration related
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Appendix 1: Subscriber Identity Mapping The mappings are described briefly as follows slides.
For the details on the mappings between the
Globally Unique Temporary Identity (GUTI), RAI,
PTMSI, and PTMSI signature when the UE performs
GUL interworking, see sections 2.8.2.1 and 2.8.2.1 of
3GPP TS23.003.
Page171
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Appendix 1: Mapping from a GUTI to an RAI, and P-TMSI Signature
RAI Component Mapping Data SourceMCC MCC in the GUTIMNC MNC in the GUTILAC MME Group IDRAC MME Code
Page172
GUTI-to-RAI mappings
P-TMSI Component Mapping Data Source31 to 30 11Bits 29 to 24 Bits 29 to the M-TMSIBits 23 to 16 MME CODEBits 15 to 0 Bits 15 to the M-TMSIP-TMSI Signature Bits 23 to the M-TMSI
GUTI-to-P-TMSI mappings
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
Appendix 1: Mapping from P-TMSI/RAI to GUTI
GUTI Component Mapping Data SourceMCC MCC in the RAIMNC MNC in the RAIMME Group ID LAC in the RAI
MME Code Bits 23 to 16 of the P-TMSI, namely higher-order 8 bits of the NRI
M-TMSI (bits 31 to 30) 11M-TMSI (bits 29 to 24) Bits 29 to the P-TMSIM-TMSI (bits 23 to 16) RAC in the RAIM-TMSI (bits 15 to 0) Bits 15 to the P-TMSI
Page173
Mapping of P-TMSI/RAI to GUTI
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