3 LTE Interoperability in Connection Mode (LTE-GU).ppt

LTE Interoperability in Connection Mode (LTE->G/U)

Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

www.huawei.com

Contents 1.

LTE Interoperability in Connection Mode

2.

CS Interoperability


Page3

Contents 1.

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


Page4

States of UE at Switch on

*


Related to interoperability which will be discussed in this course

Page5

Mobility Management Overview in Connection Mode UE States

Types Intra-frequency HO

Connection Mode

Inter-frequency HO Inter-RAT HO

Causes/Scenario Frequencypriority-based Coverage-based

SRVCC

UL-qualitybased

CCO/eNACC

Service-based

Redirection

SPID-based HO back to the HPLMN

Not be discussed Discussing

PS HO

Load-based

Distance-based Discussed

Execution

CSFB


Page6

Handover Procedure


Page8

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 neighboringThe cells Max Number of

Types

The Max Number of Ncell

Nfrequency

Intra-frequency Ncell

64

NA

Inter-frequency Ncell

64

8

128(UTRAN)

16(UTRAN)

64(GERAN)

16(GERAN)

Inter-RAT Ncell


Page9

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

UE Capability 

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.

quiry n E ility b a p a UE C

indicates whether the UE is capable of frequency-specific or RAT-specific measurements and handovers. Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page11

Contents 1.



Page12

HO Measurement Configuration Overview 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


Page13

Measurement Configuration 

After UE attachment, eNodeB sends RRC reconfiguration message which includes intra/intrefrequency/IRAT measurement control info which inform UE to perform intra/intre-frequency/IRAT measurement

It contains all intra/intrefrequency/IRAT measurement and report configuration, including A1(optional), A2(optional) and A3(mandatory) event.

Trace from eNodeB Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page14

The Measurement Configuration for InterRAT HORAT HO, the measurement configuration includes: For inter



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


Page15

Inter-RAT Measurement Object Overview 

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.


Page16

Inter-RAT Measurement Object Parameters Parameters

Description

carrierFreq

Indicates the DL EARFCN of the interfrequency E-UTRAN cell

allowedMeas BandWidth

Indicates the measurement bandwidth for inter/intra-frequency neighboring cells

PresenceAnt ennaPort1

Indicates whether all of the inter-frequency neighboring cells are configured with the double-TX antenna.

neighCellCon Indicate whether all the neighbor have the same configuration or not fig offsetFreq

Indicates the frequency offset of the interfrequency neighboring cell


Page18

Data Configuration of Inter-RAT Measurement Object 

UMTS



GERAN


Page19

UTRAN Measurement Object


Page20

GERAN Measurement Object


Page21

Tracing Case – Measurement Object


Page22

Report Configuration 

Reporting configurations consist of the parameters related to specific events.


Page23

Events for Report Event Threshold Configuration

Action

s

interfrequen cy or IRAT intrafrequen cy/interfrequen cy

interfrequen cy

A1

Signal quality in the serving cell is higher than a specified threshold

The eNodeB stops interfrequency or inter-RAT measurements.

A2

Signal quality in the serving cell is lower than a specified threshold

The eNodeB starts interfrequency or inter-RAT measurements

A3

Signal quality in at least one intra-frequency/interfrequency neighboring cell is higher than that in the serving cell

Source eNodeB sends an intrafrequency/inter-frequency handover request.

A4

Signal quality is higher than a specified threshold in at least one inter-frequency neighboring cell

A5

A2 + A4

Source eNodeB sends an interfrequency handover request. Source eNodeB sends an interfrequency handover request.

Signal quality is higher than a specified source eNodeB sends an atLtd. least onereserved. inter-RAT handover Copyright © 2013B1 Huawei threshold Technologies in Co., All rights Page24 inter-RAT neighboring request.

Tracing Case – Event 3 Report Configuration


Page26

Other Parameters Related to Events 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 

Example:

RSRP & RSRQ


Page27

Data Configuration of Reporting Configuration(1/2) 

1.Hysteresis

2.Time-to-trigger

UMTS

GERAN


Page28

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

4

6 3 5


Page29

Other Parameters—Measurement Filtering



A: Measurement value at the physical layer



B: Measurement value obtained after L1 filtering.



C :Measurement value obtained after L3 filtering.

EUTRAN EUTRAN

GERAN UTRAN


Page30

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

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

Contents 1.



Page34

IRAT HO Scenario Coverage-based HO Load-based HO UL-quality-based HO

Inter-RAT HO

Service-based HO Distance-based HO SPID-based HO back to the HPLMN CSFB (it will be introduced in Chapter4)


Page35

Coverage-based Handover Overview Moves to neighbor LTE TDD cell

Moves to neighbor LTE FDD cell LTE FDD

Threshold of trigger Inter-freq HO (IF A2) is

LTE TDD

Inter-Frequency Intra-Frequency

Moves out of LTE coverage InterRAT

higher than threshold of trigger Inter-RAT HO (IR A2), which means that interfreq HO is

UMTS

triggered earlier

Moves to LTE coverage

than inter-RAT If UE under UMTS move to LTE coverage, there are HO. 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 to decide handover target

Using different event threshold  Handover Priority: Intra-frequency > inter-frequency , Intra-RAT > interRAT  Handover between TDD/FDD looks as Inter-Frequency of LTE system 


Page36

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 Event A2 for IRAT... measurement

Event A2 for ... blind handover

•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.


Page37

Data Configuration of Coveragebased HO 

The switches UtranRedirectSwitch and GeranRedirectSwitch under the ENodeBAlgoSwitch. HoModeSwitch parameter specify whether coveragebased handovers to GERAN and UTRAN cells are enabled, respectively.


Page38

Measurement Trigger Conditions of IRAT HO by Event A2 A2 Event Moves to neighbor LTE cell

Moves out of LTE coverage

LTE GSM/UMTS Coverage

Intra-LTE

Inter-RAT

According to radio link condition (LTE: RSRP/RSRQ)



Entering condition: Ms + Hys < Threshold



Leaving condition: Ms – Hys > Threshold


Page39

Data Configuration Of Measurement Trigger Condition of IRAT HO by Event A2 RSRP/RSRQ Measurement quantities

Hysteresis, threshold and time to trigger related with event A2


Page41

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.



Entering condition: Ms + Hys < Threshold-10



Leaving condition: Ms – Hys > Threshold-10


Page42

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-



Entering condition: Ms - Hys > Thresh RAT handovers.



Leaving condition: Ms + Hys < Thresh


Page44

Data Configuration Of Measurement Stopping Condition of IRAT HO by Event A1 These parameters are the same to both A1 and A2

Hysteresis, threshold and time to trigger related with event A1


Page46

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

Relationship between IRAT HO and Blind HO 

The eNodeB delivers event A2 for blind handover but not event A2 for interfrequency 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

Load based Handover: Inter-RAT 

When high load occurs in LTE but low load in GSM/UMTS, make some UEs handover to GSM/UMTS

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


Page50

Data Configuration of Load-based HO UEs in connected mode are handed over to UTRAN cells and

UEs are handed over to GERAN cells

and

Blind HO Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

UL-Quality-based Handover Scenario: DL

quality is good,

but UL quality is √ X

limited, which result to poor service experience.

Principle: HO

When

UL IBLER is

higher than threshold, trigger handover to a better neighbor cell.

Improve Edge User Experience in Interference or UL-Limited Scenario Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page52

UL-Quality-based Inter-RAT Handover LTE(F1)

UL Quality threshold are set by the system. 1. UL Quality > threshold 2. Sends target cell and instructs UE 2G/3G to initiate GAP/B1 measurement or LTE(F2)

2

1

4 3

3. Sends GAP/B1 measurement report to the eNodeB 4. Instruct UE to HO

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


Page 53

Service-based Handover: InterRAT Handover voice service when E-RAB 

UE

established to UMTS/GSM 

UE initiate service

To improve efficiency and capacity of E-RAB Initial

whole system 

eNB

To save the investment at the

Only Voip E-RAB Y

beginning of LTE

HO Measurement

Handover to 3G/2G according to service

Measurement Configuration Event B1 trigger Measure Report

LTE coverage

HO Decision

3G/2G coverage

HO Execute


Page54

Data Configuration of Service-based HO


Page55

Distance-based HO Overview


Page57

Data Configuration of Distance-based HO


Page59

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

Data Configuration of Inter-PLMN HO(1/2)


Page61

Data Configuration of Inter-PLMN HO(2/2)

MAPPING


Page62

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.



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 A’s subscriber allowed to roam in B’s network

Operator B

Operator B‘s eNB needs to know the

Operator A

subscriber’s home PLMN to decide whether a handover towards A‘s network shall be triggered.

Inter-PLMN Handover to A’s home PLMN


Page63

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. Parameter and Setting UE Spid

HoBackToHPLMNSwitch

1

1

FALSE(FALSE)

2 3 4 5 ... ...

2 3 4 5 ... 256

TRUE(TRUE) TRUE(TRUE) FALSE(FALSE) ... ... ...


Page64

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: High frequency priorities and different PLMN • Comparing with serving cell, a Switch related neighbour cell should to InterPlmnHo has higher frequency is enable priorities and a • The parameter • ENodeBAlgoSwitch.H different PLMN SpidCfg.HoBackT oAlgoSwitch.InterP oHPLMNSwitch lmnHoSwitch is selected. parameter is set to TRUE(TRUE) SPID-based HO Back to the HPLMN

Switch related to SpidCfg is enable


Page65

Example of SPID-based HO Back to the HPLMN PLMN B

PLMN A CN

2. eNB/RNC get SPID of

this UE from B’s MME

1. A’s UE access to B’s network 1

2

3

3. eNB check the neighbor cell list by HO to HPLMN this PLMN when UE HO to it, if happens in this cell find Handover to HPLMN based SPIDcell, can facilitate roaming matched ask the UE to HOuser back to its network to save the cost. Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page66

Contents 1.



Page67

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

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

Contents 1.



Page71

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

Comparison between Blind HO and Normal HO Measurement report (A2) intra/inter-frequency/IRAT measurement activate Measurement report (A4) Handover command

Measurement based HO

Measurement report (A2) Handover command

Blind Ho



Measurement based handover: HO must be trigged by intra/interfrequency/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


Page73

The Target Selection Procedure of the Blind HO Star

Attention: Firstly select a cell in the intraRAT system and then a inter-RAT system, for the priority of EUTRAN is higher than that of an inter-RAT system.

The eNodeB selects the system with the highest priority

Are valid Ncells available for the blind-HO?

No

Yes

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 ? Yes

No

The eNodeB randomly selects target cells or frequency

The eNodeB performs a blind-HO Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page74

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

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

Data Configuration of Neighbor Cell Blind HO Priority 2. The eNodeB selects a neighboring cell for the blind handover. 

Within EUTRAN system

EUTRAN


Page78

Data Configuration of Neighbor Cell Blind HO Priority 2. The eNodeB selects a neighboring cell for the blind handover. 

In IRAT system

UTRAN

GERAN


Page79

Data Configuration of the Neighbor Frequency Priority

…

UTRAN

GERAN


Page80

Data Configuration of Filtering the Target Frequencies 3.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

Data Configuration of Filtering the Target Frequencies

UTRAN

GERAN


Page82

Contents 1.



Page83

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

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

IRAT Report Configuration - Event B1 

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.


Page86

Event B1 Triggering Mechanism

UTRAN Cell

EUTRAN Cell



Entering condition: Mn + Ofn - Hys > Thresh



Leaving condition: Mn + Ofn + Hys < Thresh


Page87

Data Configuration Related to Event B1 Ofn

URAN Thresh

Hys

time-to-trigger Thresh

GERAN Hys Thresh time-to-trigger


Page88

IRAT Report Configuration - Event B2 

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.


Page89

Event B2 Triggering Mechanism

•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.

Page90

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 Triggering Quantity The same as the triggering quantity of event A2



QuantityB2 Thresh Measurement 2 for event

UTRAN GERAN

RSCP Ec/No RSSI

Thresh 1 RSRP InterRatHoCommGroup.InterRatHoA2ThdRSRP RSRQ InterRatHoCommGroup.InterRatHoA2ThdRSRQ

Thresh 2

InterRatHoUtranGroup.InterRATHoUtranB1ThdRSCP InterRatHoUtranGroup.InterRATHoUtranB1ThdEcN0 InterRatHoGeranGroup.InterRATHoGeranB1Thd


Page91

Measurement GAP 

Measurement gaps are applicable to inter-frequency and inter-RAT measurements.



During the measurement gaps the UE: 

not transmit any data



is not expected to tune its receiver on the EUTRAN serving carrier frequency.


Page92

Data Configuration of IRAT Measurement Priorities This is only available to IRAT measurements on the 

UTRAN.


Page94

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 eventtriggered periodical reporting.


Page95

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

Contents 1.



Page97

Handover Decision Overview 

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. Check measurement result

Measurement Report Decide target cell Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page98

Filtering Principle of Target Cell 

The eNodeB filters out the following cells from the neighboring cell list:

cell1



Blacklisted neighboring cells



Neighboring cells that have a different PLMN

cell2

from the serving cell if the inter-PLMN handover

cell3

switch is disabled. Refer to the section InterPLMN Handovers

cell4 cell5



cell5

Neighboring cells with a handover prohibition flag.

cell6 

Neighboring cells in the areas indicated by the IE Handover Restriction List in the INITIAL CONTEXT SETUP REQUEST message sent from the MME.


cell3

Page99

Contents 1.



Page100

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.

In the case of IRAT HO, the eNodeB sends a handover request and forwards data over the S1 interface.


Page101

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

Data Forwarding Procedure Source eNodeB Buffering

DL data

Step1:RRC connection Break

S-GW

Source eNodeB

Step2: source eNodeB implement DL data buffering Target eNodeB Source eNodeB

Data forwarding

Target eNodeB Step3: Buffer forwarding to target cell

Step4: Random access to target cell

Attention: There are several scenario introduced in the notes


Page104

IRAT Handover Execution •IRAT Handover Execution Policy Priority: Policy PS handover > SRVCC > CCO(GSM ONLY) > Redirection

LTE PS

2G/3G PS

PS handover

LTE VOIP

2G/3G CS LTE PS

SRVCC

CCO/NACC

RRC Connection Release LTE Connection Mode

Access Procedure

2G/3G

Redirection Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

GSM Idle Mode

Page105

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 mobileterminated CS service, the UE will be moved to another RAT by means of CSFB.


Page106

Contents

1.



Page107

Contents 1.9 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.

Page108

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 HO Trigger, Measurement and Decision continuity of PS services.

SGW

①

② ⑥

③

LTE eNodeB

② MME sends relocation to target SGSN Target GU network establish access connection

⑥

MME ③ ②

PGW

① HO decision: LTE to GU eNodeB sends HO request

⑤

③ HO command is sent to UE

⑤ ④ MS detected by target GU network

⑤

④

BSC/RNC

② ⑤

SGSN

GGSN

GSM / UMTS BTS


⑤ Target network finish relocation. Context exchange with source PGW ⑥ Release source network resources

Page109

MS

Source eNodeB

Target RNC

Old MME

Serving GW

New Gn/Gp SGSN

P-GW

1. Decision to perform handover to UTRAN 2. Handover Required

3. Forward Relocation Request

4. Relocation Request Establishment of Radio Access Bearers

PS HO(LTE>UMTS) – Gn/Gp SGSN

4. Relocation Request Acknowledge 5. Forward Relocation Response 6. Create Indirect Data Forwarding Tunnel Request 8. Handover Command

7. Create Indirect Data Forwarding Tunnel Response

9. Forwarding of data 10. HO from E-UTRAN Command

MS detected by target RNC 13. RRC message

12. Relocation Detect 14. Relocation Complete 15. Forward Relocation Complete 15. Forward Relocation Complete Acknowledge 16. Update PDP Context Request 16. Update PDP Context Response

17. Routeing Area Update

C2 C3

18. Delete Session Request 18b. Release Resources 18a. Delete Session Response


Page110

PS HO(LTE->GERAN) – Gn/Gp SGSN Preparation phase (Almost the same with that of LTE->UMTS except for



some signaling message name ) UE

Source eNodeB

Target BSS

Source MME

New SGSN

Serving GW

Uplink and Downlink User Plane PDUs 1. Handover Initiation 2. Handover Required 3. Forward Relocation Request 4. PS Handover Request 5. Reservation of radio resources in target BSS 6. Target BSS creates the Target BSS to Source BSS Transparent Container 7. PS Handover Request Acknowledge

8. Forward Relocation Response


Page112

PDN GW

HSS

PS HO(LTE> GERAN) – Gn/Gp SGSN 

Execution phase (Almost the

same with that of LTE->UMTS except for some signaling message name )


Page113

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

PS HO(UTRAN ->LTE) – Gn/Gp SGSN


Page115

PS HO(GERAN->LTE) – Gn/Gp SGSN 

Preparation phase


Page117

PS HO(GERAN->LTE) – Gn/Gp SGSN 

Execution phase


Page118



Page119

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

LTE->G/U RRC Release & Redirection Procedure SGW

PGW

③ ②

MME

③ ①

LTE eNodeB

③

BSC GSM /UMTS BTS

③

HO Trigger, Measurement and Decision 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.


Page121

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

G/U->LTE RRC Release & Redirection Procedure UTRAN->LTE

GERAN->LTE


Page123



Page124

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

eNACC LTE -> GERAN

SGW

PGW

⑥ ②

③ ①

MME ⑥

LTE eNodeB

②

④ BSC

⑤

② ⑤

⑤

⑤

SGSN

GGSN

GSM BTS HO Trigger, Measurement and Decision 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 ⑤ Target network finish relocation. Context exchange with source PGW ⑥ MME release source network resources


Page126



Page127

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

CCO from the GERAN to the LTE


Page129

Contents 1.


2.

CS Interoperability


Page130

LTE Voice Solution 

From a technological perspective, there are two standard solutions to provide CS services for EUTRAN UEs:


Page131

Network Architecture & Functionality for CSFB to UTRAN/GERAN •Need to be R8 ready •Maintaining SGs association with MME

A Gb

GERAN

for the mobility management and paging procedures between EPS and CS domain.

MSC/VLR

Gs SGSN

Iu-cs

Gr

HSS/HLR

SGs

Iu-ps

UTRAN

C/D

S3

S6a

•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

S12 •Multi-mode G/U/L •CSFB capable •Support of procedures: Combined EPS/IMSI Attach, Update, Detach.

PCRF

S4

MME S11

S7

S1-MME S5

SGi

S1-U E-UTRAN G/U/L handset

S-GW

Rx Internet / intranet / Operators & 3rd Party Applications

PDN-GW

•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).


Page132

Contents 1.


2.

CS Interoperability 2.1 CSFB at the eNodeB

2.2 End-to-End Procedures for CSFB 2.3 SRVCC Procedure


Page133

CSFB Procedure at the eNodeB 

Star

CSFB mechanisms include PS

The eNodeB receives a CSFB Indicator from the MME

redirection, PS handover, and CCO/NACC. No

Triggering phase

matter which CSFB mechanism is adopted, both

Yes

The eNodeB delivers measurement Measurement phase configurations to the UE

measurementbased handover

Are the conditions for initiating a blind HO met?

Decision phase

The eNodeB makes a CSFB decision

Execution phase

The eNodeB exectes a CSFB decision

and blind handover are applicable.

End Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.

Page134

No

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

CSFB Triggering Principle(2/3) 

Choosing Between a Blind HO and a Measurement-based HO

Star ENodeBAlgoSwitch. BlindHoSwitch is enabled ?

Yes

The UE supports certain RAT measurement ?

No

No

Yes

Triggering the RAT measurement

Blind Redirection


Blind CSFB

Page136

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

Data Configuration of Blind CSFB 1. The eNodeB selects a RAT with the highest blind-handover priority.


Page138

Data Configuration of Blind CSFB(1/2) 2.

The eNodeB selects a cell with the highest blind-handover priority in this RAT

UTRAN 0~32

GERAN 0~32


Page139

Measurement Phase – Measurement Based CSFB Overview 

In case of measurement based CS Fallback, eNodeB sends the UE the measurement configuration, include :

The measurement configuration related with both should be that the UE is capable of measuring



RAT type



Frequencies



CSFB B1 parameters


Page140

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

Measurement Phase – Event B1 Threshold 

Configuration of CSFB event B1 threshold:


Page142

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

LAI based CSFB (R10) LTE Core TA1/LA1 MME

GUL

TAI/LAI

CSFB to LA1

Select same LA to CSFB

GUL

TA3/LA1

TA2/LA2

GUL



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

Execution Phase - CSFB to GERAN Star

The eNodeB receives a CSFB indicator from MME Yes

ENodeBAlgoSwitch. BlindHoSwitch is enabled ? No No

Does the UE support B1 measurement ? Yes The eNodeB delivers B1 measurement configuration to the UE The UE sends measurement reports to the eNodeB Is PS handover enabled?

No

Yes Does the UE support No PS HO? Yes PS HO based CSFB

CCO/NACC Switch=ON ? Yes

No

No Does the UE support PS HO? Yes CCO/NACC based CSFB

Flash CSFB Switch=ON ?

No

The UE supports Rel.9 RRC No with SIB & eNodB has stored target cells’ SI ? Redirection Flash CSFB based CSFB


Page145

Execution Phase - CSFB to

UTRAN

Star

The eNodeB receives a CSFB indicator from MME Yes

ENodeBAlgoSwitch. BlindHoSwitch is enabled ? No No

Does the UE support B1 measurement ? Yes The eNodeB delivers B1 measurement configuration to the UE The UE sends measurement reports to the eNodeB Is PS handover enabled?

No

Yes Does the UE support No PS HO? Yes PS HO based CSFB

No

Flash CSFB Switch=ON ?

The UE supports Rel.9 RRC No with SIB & eNodB has stored target cells’ SI ? Redirection Flash CSFB based CSFB


Page146

Flash CSFB (Redirection Based on R9) 

GSM/UMTS Core

LTE Core

To support Flash CS Fallback, eNodeB requires exchange information between E-

SGSN

UTRAN and GERAN/UTRAN RIM Request

RIM Response

MME

through the core networks. 

Saving 1s for UMTS compare with R8 CSFB



Saving 2s for GSM compare with R8 CSFB

UTRAN/GERAN

EUTRAN


Page147

RIM Configuration


Contents 1.


2.

CS Interoperability 2.1 CSFB at the eNodeB 2.2 End-to-End Procedures for CSFB 2.3 SRVCC Procedure


Page149

Mechanisms of CSFB Mechanism

Supported RAT

Impact on Network

CS Access Delay

Based on PS handover

UTRAN/GERA N

Complex

Short

Based on Redirection

UTRAN/GERA N/CDMA2000

Simple

Long

Flash CSFB (Redirection with RIM)

UTRAN/GERA N

Medium

Short

CSFB based on CCO/NACC

GERAN

Medium

Medium


Page150

Combined EPS/IMSI Attach Procedure


Page151

Contents 1.


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


Page153

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)


(Flash)CSFB to UTRAN based on PS Redirection for MOC

For flash CSFB: RRC Connection Release with UTRAN frequency/cell IDs/cell system information


Page155

S1 Message Tracing


Page156

CSFB to UTRAN Procedure for MTC 

PS redirection and PS handover are the same for MTO.


Page160

CSFB to UTRAN based on PS HO for MOC 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.


Page161

Contents 1.


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


Page162

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


(Flash)CSFB to GERAN based on PS Redirection for MOC

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


Page164

CSFB to GERAN based on PS HO for MOC 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.


Page165

CSFB Based on CCO/NACC(GERAN)


Page166

Contents 1.


2.

CS Interoperability 2.1 CSFB at the eNodeB 2.2 End-to-End Procedures for CSFB 2.3 SRVCC Procedure


Page167

LTE – GSM/UMTS SRVCC Flow


Page168

Summary 

GUL Interoperability procedure



GUL Interoperability scenarios



GUL Interoperability algorithm principles and data configuration related


Page170

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

Appendix 1: Mapping from a GUTI to an RAI, and P-TMSI Signature GUTI-to-RAI mappings RAI Component Mapping Data Source MCC MCC in the GUTI MNC MNC in the GUTI LAC MME Group ID RAC MME Code GUTI-to-P-TMSI mappings P-TMSI Component 31 to 30 Bits 29 to 24 Bits 23 to 16 Bits 15 to 0 P-TMSI Signature

Mapping Data Source 11 Bits 29 to the M-TMSI MME CODE Bits 15 to the M-TMSI Bits 23 to the M-TMSI


Page172

Appendix 1: Mapping from P-TMSI/RAI to GUTI Mapping of P-TMSI/RAI to GUTI GUTI Component Mapping Data Source MCC MCC in the RAI MNC MNC in the RAI MME Group ID LAC in the RAI Bits 23 to 16 of the P-TMSI, namely higher-order 8 bits of the NRI M-TMSI (bits 31 to 30) 11 M-TMSI (bits 29 to 24) Bits 29 to the P-TMSI M-TMSI (bits 23 to 16) RAC in the RAI M-TMSI (bits 15 to 0) Bits 15 to the P-TMSI MME Code


Page173

Thank you www.huawei.com

3 LTE Interoperability in Connection Mode (LTE-GU).ppt

Recommend Documents