01 GUL Interworking Principal & Solution Introduction V1.1

HUAWEI TECHNOLOGIES CO., LTD.

GUL Interworking Principal & Solution

Introduction

HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

35pt

32pt

) :18pt

1 GUL Interworking Background & Challenges

GUL Idle Mode/Connected Mode/CSFB/MLB 2

GUL Interworking KPI Introduction 3

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Typical Network Deployment Trend

Different RAT used for Coverage & Capacity layer, Increases Network complexity & interworking problems

L2600(FDD-20M)

L700(FDD-10M)

U900(4.2M)

U2100(20M)

L1800(FDD-15M)

L2300(TDD-20M)

G900(4.2M)

2015 L2300(TDD-20M)

Network Deployment Strategy O operation in A Country

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Typical Network Top and Structure

IRAT interworking, especially applied in the LTE early establishment stage,

while the coverage not continues and no voice barer network (IMS).

The typical network structure as follows:

GSM

LTE

UMTS

LTE

UMTS

GSM

LTE

UMTS

LTE

UMTS

The following is typical GUL network coverage : GSM with

widest coverage, UMTS and LTE with hotpot coverage,

solutions needed for UE power on, register, handover

requirement.

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G900/1800 G900/1800

U2100 U2100 U2100

U900 U900

L2600 L2600

L1800 L1800

Which network

to camp？

1. Cell edge coverage not good

enough, which network to camp?

2. How to keep continuous service in

connecting status?

1. How to adjust idle strategies to

balance traffic load when connected.

2. How to raise efficiency of new

network(LTE e.g)?

L800 L800

Heavy load cell

How to balance

cell load,

increase user

experience?

Facing problems

Idle mode

camping

1）In multi mode and multi freq. network,

which network to camp?

2）How to reselect when coverage is not good?

Service

continuity

How to keep service continuity when user is in

cell edge?

Load

balance

When cell load is heavy, how to balance

between cells belonged to different freq/mode.

Traffic layer 1）How to keep voice service continuous from

LTE network?

2）What is the traffic layer strategy within

UMTS network?

3）What is the traffic layer strategy between

GSM and UMTS?

Complicate network situation:

Multi mode, multi freq.

Different coverage with different freq.

New network cannot get a perfect coverage

Cell load is too heavy for hot spot or dense

area L1800

Operator’s Problems

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Broad pipe

Traffic continuity solution

CS&PS service seamless

between different network

LTE coverage solution

UMTS coverage solution

GSM coverage solution

Idle mode solution

Terminal optimized

camping & seamless

reselection between modes

and freq.

inter network camping

intra network camping

Traffic layer solution

Traffic steered to suitable

network, to get better user

experiences & capacity

GU Traffic layer solution

L->U CSFB solution

UMTS intra network Traffic

layer solution

Load balance solution

Raise network inter-

network efficiency

GSM heavy load solution

UMTS heavy load solution

LTE heavy load solution

Basic Solutions

Idle mode solution


Necessary solution for every

network

Option Solutions

Load balance solution

Traffic layer solution

To choose based on terminal

penetration, network load,

operator requirement.

Inter-working Solution Overview(1/2)

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• VoIP through IMS is agreed as target voice solution of LTE

• CSFB is migration solution before VoIP over LTE is available (IMS deployment and

terminal supporting VoIP/SRVCC are available) and CSFB would co-exist with

VoIP when VoIP is deployed.

• SRVCC supports the LTE VoIP handover to UMTS CS Voice when out of LTE

coverage

• If VoIP is implemented over HSPA, only PS handover for LTE to UMTS voice

continuity

LTE/EPC UMTS

Idle mode mobility

PS service mobility

Voice service mobility

Inter-working Solution Overview(2/2)

Step1

Cell Reselection

Blind

Redirection

CSFB over Blind

Redirection

Step 2

+ PSHO

Step2 Step3

Step1

+ Measurement

Base on the SW version and UE ability, 3 stages suggested as follows :

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GU Version Required & UE recommended for Probe Test

System Target RAN ability Required Version Suggested

Version

GSM

GSM to LTE reselection GBSS12.0 GBSS14.0

LTE to GSM PSHO GBSS12.0 GBSS14.0

LTE to GSM CCO/NACC GBSS12.0 GBSS14.0

LTE to GSM SRVCC GBSS12.0 GBSS14.0

UMTS

UMTS to LTE reselection RAN 12 RAN 14

LTE to UMTS PSHO RAN 13 RAN 14

LTE to UMTS SRVCC RAN 15 RAN 15

Page 9

Recommended UE for Probe Test： Samsung S5，G620s-L01/L02/L03


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1.Idle Mode Reselection

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Idle Mode Camping Solution (1/2) Camping solution

LTE camping prior, if no LTE

or bad LTE coverage,

reselect to UMTS;

If no UMTS or weak UMTS

coverage, reselect to GSM.

UMTS prior camping, If no

UMTS or weak UMTS

coverage, reselect to GSM.

LTE intra system camping

UMTS intra system camping

GSM intra system camping

G900/1800 G900/1800

U2100 U2100 U2100

U900 U900

L2600 L2600

L1800 L1800

Which

network to

camp？

1. Cell edge coverage not good

enough, which network to

camp?

2. How to keep continuous

service in connecting status?

1. How to adjust idle strategies

to balance traffic load when

connected.

2. How to raise efficiency of

new network

L800 L800

Heavy load

cell

How to balance

cell load,

increase user

experience?

L1800

Multi-mode camping strategies

GU dual-mode Camping strategies

Single mode Camping strategies

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Coverage

LTE camping strategies：

High frequency with high priority for camping

The same frequency with the same priority

G900/1800 G900/1800

U2100 U2100 U2100

U900 U900

L2600 L2600

L1800 L1800

L800 L800

Priority1

Priority2

Priority3

Cell reselection

Priority1

Priority2

Priority3

Frequency priority Mode priority

UMTS camping strategies：

Scenario 1: without traffic layer： The UE preferentially camp on the carrier with

contiguous coverage.

If all carriers’ coverage are contiguous, the UE

randomly camp on any cell.

Both U900 and U2100 are contiguous coverage,

choose U2100 for camping or random camping

Scenario 2: traffic layer in UMTS network： Recommend to camp in R99 carrier.

GSM camping strategies：

• The same frequency with the same priority

• High frequency TRX with high priority

High

High

7

L1800

1

2

7

5 6

9

10

4 8 8

Idle Mode Camping Solution (2/2)

Single mode Camping strategies

Priority tip: Different system priority cannot be same.

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No. ID Feature Release Description

1 GBFD-114301 GSM/WCDMA Interoperability GBSS6.0 U2G reselection or handover; G2U reselection or handover

2 GBFD-511301 Cell Reselection Between GSM and LTE GBSS12.0 GL cell reselection based on neighbor level and mode priority.

3 WRFD-010401 System Information Broadcasting RAN 2.0 Support handover between different frequency.

4 WRFD-020303 Inter-RAT Handover Based on

Coverage RAN2.0 Handover Based on Coverage

5 WRFD-020126 Mobility Between UMTS and LTE Phase

1 RAN12.0

Cell selection and reselection between UMTS and LTE ;

LTE to UMTS PS handover

6 LBFD-00201803 Cell Selection and Re-selection eRAN1.0 LTE intra system Cell selection and reselection

7 LOFD-001019 PS Inter-RAT Mobility between E-

UTRAN and UTRAN eRAN1.0 L2U Cell selection and reselection Based on Coverage

8 LOFD-001020 PS Inter-RAT Mobility between E-

UTRAN and GERAN eRAN1.0 L2G Cell selection and reselection Based on Coverage

9 LBFD-00201802

Coverage Based Inter-frequency

Handover eRAN2.0 LTE intra system Cell selection and reselection Based on Coverage

10 WRFD-020302 Inter Frequency Hard Handover Based

on Coverage RAN2.0 UMTS intra system Cell selection and reselection Based on Coverage

Inter-working Key Features

1

2

7

5

6

4

8

3

9

10

*The features above comply with the protocols, can interconnect with networks by other

vendors.

So as the features below, except features with special remarks.

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Low Prio.

eNodeB/BTS

High Prio.

eNodeB

SservingCell is worse than Thresh_serving.low &

SNonservingCell is better than Thresh_x.low

SNonservingCell is better than Thresh_x.high

Cell Reselection From Low > High

Cell Reselection

Cell Reselection Principle for absolute priority

Cell Reselection From High -> Low

GSM (Low)

UMTS

(Medium)

LTE

(High)

SIB

SIB

SIB

Suggested RAT Priority:

LTE(High)

UMTS(Medium)

GSM(Low)

Measure：Srxlev<=SnonIntraSearchP or Squal<=SnonIntraSearchQ

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Camping - Cell Reselection between LTE and GSM/UMTS

Threshold

Threshx,high: threshold of reselecting to High Priority Cell

Threshx,low: threshold of reselecting to Low Priority Cell

Measurement parameter

SServingCell: Signal quality of serving cell

SNonServingCell: Signal quality of target reselection cell

Threshold and Measurement

LTE GSM/UMTS

Cell Reselection from GSM/UMTS to LTE

network when UE enters the LTE coverage area

Cell Reselection from LTE to GSM/UMTS

network

only when UE is out of LTE coverage area

Cell Reselection Strategy

LTE->GSM/UMTS (High to Low)

SServingCell <Threshserving,low & SNonServingCell >Threshx,low

Length of camping on serving cell > 1 sec

GSM/UMTS->LTE (Low to High)

SNonServingCell > Threshx,high

Length of camping on serving cell > 1 sec

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Camping - Cell Reselection between GSM and UMTS

Threshold FDDQOFF：the differ between UMTS candidate cell signal and GSM

target cell signal

FDDQMIN：Ec/No UTRAN FDD cell reselection minimum threshold

FDD RSCP threshold

FDDRSCPMIN：UMTS cell reselection minimum threshold

Measurement parameter RLA_C: GSM service cell average receive level

CPICH RSCP：UMTS neighbor cell RSCP measurement value

CPICH Ec/No：UMTS neighbor cell Ec/No measurement value

Threshold and Measurement

UMTS GSM

Cell Reselection from GSM to UMTS network

when UE enters the UMTS coverage area

Cell Reselection from UMTS to GSM network

only when UE is out of UMTS coverage area

Cell Reselection Strategy

UMTS->GSM

Squal ≤ SsearchRATm

Rn > Rs

GSM->UMTS

CPICH RSCP>RLA_C+FDDQOFF

CPICH Ec/No≥FDDQMIN - FDDQMINOFFSET

CPICH RSCP≥FDD RSCP threshold

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LTE Reselection to GU Signaling

2G接入网信令 3G接入网信令

GSM Side LTE Side UMTS Side

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2.Connected Mode-Redirection/PS HO

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How to keep continuous service in connecting status, especially at the edge of different mode network?

LTE bad Coverage

UMTS bad Coverage

GSM bad Coverage

Three scenarios:

Choose coverage based

handover to other system.

Adjacent cell priority: inter

freq. >UMTS>GSM

First handover to inter freq.

If no proper cell, then

handover or steer to GSM

First handover to inter freq.

If no proper cell, then

handover or steer to UMTS.

In U900 discontinuously covered network, it is recommended to handover

to U2100 based on coverage.

In U900 continuously covered network, it is NOT recommended to

handover to U2100 based on coverage.

Coverage

G900/1800 G900/1800

U2100 U2100 U2100

U900 U900

L2600 L2600

L1800 L1800

L800 L800

L2U PS handover based on

coverage

L2G PS handover based on

coverage

LTE handover based on

coverage

8 8

7

4

L1800

7

9

10

7

8

U2G handover based on

coverage UMTS PS handover based on

coverage

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• Support cell reselection between eUTRAN &

GERAN/UTRAN

• LTE to GSM/UMTS Redirection/PS handover

based on coverage in initial phase

• Guarantee users’ data service quality when

handover occurs

• Keep network performance stable and

service continuity

Data Service Mobility Solution

GSM/UMTS Coverage

LTE

Coverage

Data service handover (LTE->GSM/UMTS):

1. Ongoing data service is beared by LTE

2. UE handovers to GSM/UMTS

3. PS service will be on G/U PS domain

Data service handover (GSM/UMTS->LTE):

1. Ongoing data service is beared by G/U

2. UE moves into LTE coverage area, two options for data continuity:

i. Service handover to LTE directly

ii. Service provided by G/U, after service ends, UE camp on LTE by

cell reselection

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Inter RAT Handover Strategy based on different Scenarios

Coverage

• Coverage based is recommended by default at initial stage

• Load based is useful when LTE traffic significantly increased

• Service based is for better utilization of each radio

technologies

Based on the radio link quality (LTE: RSRP/RSRQ)

Load

Based on the RB utilization (cell load)

Service

Based on the service

Based on UL Quality

√

X

UL Quality

Intra-LTE

Moves to neighbor LTE cell Moves out of LTE coverage

LTE UMTS

Overload, offload to

neighbor LTE cell

Overload, offload to

neighbor G/U cells

Intra-LTE Inter-RAT

LTE UMTS

LTE UMTS

Inter-RAT

LTE UMTS

Distance

Based on the distance bet. eNodeB & UE

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LTE To UMTS/GSM Handover Based On Coverage

LTE

Coverage LTE

Coverage

UMTS/GSM Coverage

L2U/G PS HO based on coverage

Description:

• When the LTE signal quality is poor and the UMTS or GSM signal

quality is good, UE with active PS service can be handover or

redirection to the UMTS or GSM network based on UE capability, to

ensure the continuity of PS services and avoid service drops.

• Compared with PS redirection, PS handover shortens the service

interruption duration, improving user experience.

Benefits:

• Improves end user’s PS service experience when UE is moving out of

LTE coverage

Dependency:

• Redirection: UE should support 3GPP R8 & UL or GL dual mode.

• PS Handover: The UE should support 3GPP R8, L2U PS handovers & LTE

measurements. UMTS or GSM CN and LTE CN should support LTE to

UMTS or GSM PS handover

Difference between B1 & B2: B2 event requires the serving cell RSRP <

A2Thresh(ERAN 8.0 support setting separately )

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Coverage-Based PS Handover/Redirection from UMTS to LTE

UMTS

LTE

PS Service Handover/Redirection

Description:

• When the UMTS signal quality is poor and the LTE signal

quality is good, UE with active PS service can be handover

or redirection to the LTE network based on UE capability,

to ensure the continuity of PS services and avoid service

drops.

• Compared with PS redirection, PS handover shortens the

service interruption duration, improving user experience.

Benefits:

• Improves end user’s PS service experience when UE is

moving out of UMTS coverage

Dependency:

• Redirection: UE should support 3GPP R8 & UMTS/LTE dual

mode.

• PS Handover: The UE should support 3GPP R8, UMTS-to-

LTE PS handovers & LTE measurements. UMTS/LTE CN

should support UMTS to LTE PS handover

*The feature comply with the protocols, can interconnect with networks by other vendors. It is recommended the whole network use Huawei products to avoid Ping-pong effect.

Event Trigger:

QUsed <= TUsed - H3a/2 & MOtherRAT >= TOtherRAT + H3a/2

Periodic report:

MOtherRAT ≥ TOtherRAT + HystforPeriodLTE/2

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LTE Cell

UMTS Cell1

UMTS Cell2

(1)

(2)

Congestion

Target UMTS cell congestion

may cause access failure

LTE Cell

UMTS Cell1

UMTS Cell2

(1) Congestion

Select a

suitable cell

Description:

• UMTS cell load information are transferred to LTE by

RIM procedure

• In the L->U CSFB or L->U PS handover based on load,

when choosing UMTS target cells, congestion cells

have the lowest priority

Benefits:

• Increases the success rate of redirection & handover

from LTE to UMTS, reduces inter-RAT ping-pong

handover.

Dependency:

• UE should support flash CSFB in 3GPP R9

• CN should support RIM procedure defined in 3GPP

Release 9.

RIM Based UMTS Target Cell Selection for LTE

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Inter-RAT Handover Trigger Phases

• Coverage based: Event A2 : Serving cell signal

quality lower than Specified threshold

• Load based: MLB algorithm • Service based: UE service type. InterRatHoState to set

MUST_HO, NO_HO, & PERMIT_HO.

• UL Quality based: UL signal quality • Distance based: distance between eNodeB & UE

• GAP-Assisted Measurement

• Event Triggered Periodical

Reporting A4/B1

• A4: Inter-frequency

• B1: Inter-RAT

• Apply for Resource (Admission)

• Signalling Procedure Execution

• Retry Mechanism If Admission

or Handover Fail

• Update Parameters to UE

• LTE: RSRP/ RSRQ

• GSM: RSSI

• UMTS: RSCP/ECNO

Note:

Coverage, Load, Service, UL-quality & Distance based inter-RAT hand

over uses same procedure except for Measurement triggering phase.

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Basic Concept- Redirection

Redirection is performed as RRC release with redirection

indicator, making UE choose and access target cell( Realized

by inter RAT measurement, or blind HO cell configured ).

Redirection is controlled by RAN system, and Core Network not

involved.

UE eNB RNC MME SGSN S/P-GW

1. Measurement Report

2.Handover decision

3. RRC CONNECTION

RELEASE

4. UE reselect the target UTRAN cell and launch RAU procedure

Trigger Redirection reason: Coverage, MLB, off load, uplink power

restrict, S1 interface down, CSFB….

Redirection flow similar as reselection, but the target cell frequency,

system information included in RRC release message. (Based on

R9)

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PS Handover is with

measurement , need

neighbor relation

configured, making PS

service continuity.

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

Basic Concept- PS Handover

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Basic Concept- PS Handover VS Redirection

PS Handover Redirection

RAN Need all equipment software support PS handover

(LTE eRAN , UMTS/GSM RAN, Core

Network) ,usually need software upgrade

No need UMTS/GSM support and upgrade, but

after redirection to GU, Core network should

support IP context transfer , RAU procedure, and

Authentication

UE Most of UE cannot support GUL PS handover,

some UE support L->U PS handover. Currently no

commercial UE support GUL PS handover.

Most of UE support GUL redirection

User

Experien

ce

User- plane latency less than Redirection and Cell

Change Order, especially for voice service

User- plane latency worse, but acceptable for PS

service on user experience , and optimized in R9

with RIM.

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Case: Performance for Service Continuity Solution

（K Country V Operator)

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3.Voice Solution-CSFB

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LTE Voice Solution Options

IMS/SR-VCC: Voice over IMS over LTE;

handover & roaming to 2G/3G is

supported

Data on LTE

Voice on 2G/3G

Voice & Data

on LTE

LTE Voice

Solution

OTT Mode: To rely on OTT

applications for voice service offering

CS Fallback: UE is attached on LTE,

and fallback to 2G/3G for voice calls

(MTC and MOC)

SVLTE (Dual Standby): Dual

simultaneously radio access running

on the same UE allowing data on LTE

and voice on 2G/3G CS in parallel Samsung Craft LTE smart-

phone, USA MetroPCS,

Verizon since Q4-2010

LG Optimus, Samsung

Galaxy SII HD, SK Telecom

South Korea since 10-2011

IMS only*, E2012

IMS-SRVCC, 2013

Not standardized

Project specific

Page 31

http://www.engadget.com/2011/10/04/lg-optimus-lte-now-official-high-speed-data-alongside-a-high-de/


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Network Strategies for Delivering Voice to LTE Subscribers

Initial: Data Only Intermediate Solution: Voice CS Fall Back

Option 1a: To start using CSFB voice solution as an intermediate step

Option 1b: To migrate to IMS/SRVCC as the target solution when it is available and mature

Option 2: To straight forward move to IMS/SRVCC (SRVCC supports the LTE+IMS VoIP handover to 2G/3G CS voice when out of

LTE coverage)

Target Solution: VoIP + SRVCC

LTE PS Data VoIP

2G/3G PS Data CS Voice

LTE Access LTE Access 2G/3G Access

EPC Core EPC Core 2G/3G

PS Core

CSFB Voice

2G/3G

CS Core

LTE Access 2G/3G Access

EPC Core 2G/3G

PS Core

OUT of LTE

2G/3G

CS Core

1a 1b

2

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Scenario:

• LTE initial phase for data services, IMS is not deployed

CSFB Principles:

• Handover to G/U voice service in the overlay coverage area

between LTE and G/U

• If CSFB voice service is triggered, there are 2 options for the

pre-existing LTE data services:

• Data services are hand-over to GSM/UMTS networks (DTM

supported by G/U network)

• Data services are suspended in LTE until voice call is released

(e.g. DTM not supported)

• SMS services do not need to fall back GSM/UMTS

Dependency:

• No addition Core equipment, Reuse traditional GU Core

network

• Multimode G/U/L Terminals to support CSFB

CS Fallback (CSFB) Introduction

LTE Access

LTE Core GSM/UMTS

PS Core

2G/3G Access

GSM/UMTS

CS Core

Internet

Voice fall back to GU

PS data PS data

PS data Voice

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Conclusion:

• Both PS handover and R9 Redirection w/ SIB (Flash

CSFB) are better realization mechanism for CSFB to

UTRAN considering latency and impact for UTRAN

and UE.

• 3GPP Rel9 Terminal is needed to support R9

Redirection w/ SIB.

• CSFB with PS HO requires UMTS PS/CS software

upgrade to support PS HO function

Call Setup Latency

Impact on LTE

Impact on UTRAN

Terminal Requirement

New Signaling

Success Rate

R8 Redirection

PS Handover

R9 Redirection w/ SIB

4.4 ~ 5.04s

5.62 ~ 6.26s

6.58 ~ 7.22s

CS Fallback: Performance and E2E Impact (UTRAN)

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Conclusion:

• R9 Redirection w/ SIB (Flash CSFB) is a better

realization mechanism for CSFB to GERAN

considering small change to legacy network and

good success rate.

• 3GPP Rel9 Terminal is needed to support R9

Redirection w/ SIB

• Current Device chipsets do not support LTE to GERAN

PS handover

Call Setup Latency

Impact on LTE

Impact on GERAN

Terminal Requirement

New Signaling

Success Rate

R8 Redirection

PS Handover

R9 Redirection w/ SIB

5.4 ~ 8.04s

6.8 ~ 9.44s

8.8 ~ 11.44s

CS Fallback: Performance and E2E Impact (GERAN)

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Principle:

1. eNB request system information from BSC/RNC

2. Request is sent toward core network

3. BSC/RNC processes RIM

4. BSC/RNC replies with updated system information

5. Core Network does not handle the message and

directly forwards it to eUTRAN

6. eNodeB does not translate the message from BSC/RNC

and directly sends it to UE

7. eNodeB extracts the target frequency and related

neighboring cell information

Dependency:

• Both GSM/UMTS and LTE core network support R9 RIM

procedure

• Terminal support R9 redirection with SIB

Flash CSFB:

• Saving 1-1.5s for UMTS compare with R8 CSFB

• Saving 2s for GSM compare with R8 CSFB

Flash CSFB to UTRAN/GERAN (R9 PS Redirection with SIBs)

2G/3G Access LTE Access

2. RIM :

RAN Information

Mgt Exchange

SGSN

GSM/UMTS Core

MME

EPC Core

BSC/RNC

3. R

AN

Info

rmati

on R

Q

1. R

AN

info

rmati

on

request

4. 2

G/3

G R

AN

Info

rma

tion

5. 2G/3G RAN Information

6. M

ME

Direct

Info

rmation T

ransfe

r

7. Frequency and target

cell system information

*The feature comply with the protocols, can interconnect with networks by other vendors. The network need support RIM protocol.

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Terminal

Core Network

MME

MSC

eNodeB/

UTRAN/GERAN

•The MSC server and MME need to support

the SGs interface.

• MSCs need to support Rel.8

• MME and SGSN need to support RIM due

to flash CSFB.

Blind/With measurement:

Recommended to use blind when LTE

share same site with G/U. (0.3s saving on

call setup time)

PS HO/Redirection

RIM procedure

•L to G with PS HO: None terminal support

•L to U with PS HO: main stream terminal

•L to G/U with Redirection: main stream

terminal

SGSN

Deployment requirement:

•GUL networks support CSFB function.

•Data preparation: neighbor cell, frequency, CSFB

way, etc.

•For incumbent vendors, it is easy to deploy

without complex IOT.

1. Voice

service

request

LTE

MME

BSC/

RNC

3. Fallback to GSM/UMTS with

PS handover, PS redirection

or flash CSFB G/U

2.resource allocation

4. Initiate CS

service

MSC/

SGSN

RIM Based CS Fallback

Page 37


35pt

32pt

) :18pt

CSFB

“Fast Return”

Channel release with

LTE frequencies

GSM/UMTS

LTE

Without

Fast Return

With

Fast Return

Search Cycle and

Cell Re-selection

U->L Fast Return by

PS redirection

Camp in LTE Camp in LTE

CS call on UMTS

Camp in LTE Camp in LTE

CS call on UMTS

8s after UE idle

500ms after CS call

GSM/UMTS Fast Return to LTE

UMTS Fast Return to LTE

GSM Fast Return to LTE

• When a Multimode UE terminates a call in

GSM/UMTS network, the frequency

information of LTE cell is sent in RRC

Connection Release message in order to

instruct the UE to camp on the LTE cell

instead of cell re-selection to LTE

Cell reselection time from GSM to LTE in idle mode reduced to

480ms

Page 38


35pt

32pt

) :18pt

Basic Concept- CSFB flow

Page 39

CSFB to UMTS Based on Redirection CSFB to UMTS Based on PS Handover


35pt

32pt

) :18pt

P3 test latency and success rate reach NO.1

Case: Performance for LTE Voice Solution

G900/1800 G900/1800

U2100 U2100

L1800 L1800 L1800

U2100

Priority in idle state

First to camp

U2100 U2100 U2100

Second to camp

Third to camp

Fast return

after CS call

CSFB Success rate(P3 DT): +99.6%

CSFB M2M delay(P3 DT): 6.0~6.5s

Compared to other vendors in the same city: NO.1

1. Measured CSFB to U

2. Blind CSFB to G if no U coverage

CSFB of Operator X in Europe

U2100 U2100 U2100

Page 40


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32pt

) :18pt

4.IRAT MLB

Page 41


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32pt

) :18pt

LTE High Load

UMTS High Load

GSM High Load

First to balance inter-

frequency, then balance to

UMTS or GSM



LTE or GSM



UMTS or LTE

G900/1800 G900/1800

U2100 F1 U2100 F1

U900

L2600

L1800

L800

U2100 F2

L2600

U900 U900

U2100 F1

U2100 F2

L800

L1800

11

12 13 14 15

16

Load Balance Solution

Avoid cell overload, get the highest efficiency of resource utility.

Raise user experiences through balancing between different mode or frequency cells

Page 42


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32pt

) :18pt

No. ID Feature Release

LOFD-001032 Intra-LTE Load Balancing eRAN2.0

LOFD-001044 Inter-RAT Load Sharing to UTRAN eRAN2.0

LOFD-001045 Inter-RAT Load Sharing to GERAN eRAN2.0

WRFD-020120 Service Steering and Load Sharing in RRC Connection

Setup RAN11.0

WRFD-02040004 Traffic Steering and Load Sharing During RAB Setup RAN10.0

WRFD-020103 Inter Frequency Load Balance RAN3.0

WRFD-150217 Load Based PS Handover from UMTS to LTE RAN15.0

WRFD-020120 Service Steering and Load Sharing in RRC Connection

Setup RAN11.0

WRFD-020306 Inter-RAT Handover Based on Load RAN3.0

WRFD-020310 3G/2G Common Load Management RAN10.0

WRFD-070004* Load Based GSM and UMTS Handover Enhancement

Based on Iur-g RAN11.1

WRFD-070006* GSM and UMTS Load Balancing Based on Iur-g RAN12.0

Inter-working Key Features

11

12

13

14

15

16

* These two features use Huawei private protocol.

Page 43


35pt

32pt

) :18pt

Inter-RAT Load Balance Between LTE and UMTS

Threshold

Before After

Lo

ad

LTE

UMTS

LTE

UMTS

15% UL Network Throughput Increase

eNodeB

GU RAN

SGSN

MME

load measurement and evaluation

RIM includes cell load status

(overload, congestion, normal).

RIM includes GU cell load status

(overload, congestion, normal).

Perform Inter-RAT MLB

Interoperation: eNodeB and GU RAN Criteria vary based

on different vendors policy

OSS introduced to coordinate eNodeB and

GBSS&UMTS and further improve GUL

network performance

balance Load and reduce call drop & handover failure rate

eNodeB

RNC

NodeB

Cell load

Info.

MME

SGSN

Page 44


35pt

32pt

) :18pt

Load-Based PS Handover/Redirection from UMTS to LTE

Description: • In some scenarios, such as after a CSFB call or moving at the edge of LTE

coverage, although LTE coverage is available, UE still use UMTS to do PS

service.

• In case of UMTS load is high, those UEs can be pushed back to LTE cells

by PS handover or redirection based on the UE’s capability.

Trigger : • service cell Load_Value > Thresh_Load

• Neighbor cell Qual_N>Thresh_Qual, and neighbor load <Thresh_Load.

(In which the neighbor load can be get through private interface or RIM

flow.)

Benefits: • Reduces the possibility of UMTS congestion by allowing more UEs in the

UMTS to handover/redirection to LTE.

• Improves the LTE network resource utilization at the early stage of LTE

network deployment.

Dependency: • Redirection: UE should support 3GPP R8 & UMTS/LTE dual mode.

• PS Handover: The UE should support 3GPP R8, UMTS-to-LTE PS

handovers & LTE measurements. UMTS/LTE CN should support UMTS to

LTE PS handover

UMTS

LTE

LDR triggered

UMTS

LTE

Handover/Redirection

triggered

Serving

Cell

Target

Cell

Page 45


35pt

32pt

) :18pt

Case：Performance for Load Balance Solution(K Country V Operator)

Background：The LTE network is high load as half ratio UE

type is dongle and the UE DL throughput is lower in the peak

time. The UMTS network load is not very high and. The load

can be balanced between UMTS and LTE network.

L2U MLB of Operator X in middle east Asia

UMTS2100UMTS2100

UMTS2100 UMTS2100 UMTS2100

UMTS2100 UMTS2100

LTE1800 LTE1800

F1

F2

F3

UMTS2100

L2U Mobility Load Balance

UMTS Inter band LDR

L2U coverage based PS HO

UMTS Coverage based HO

UMTS Intra band HO

The L2U Handover success rate is above 99% after on

IRAT HO

On IRAT HO

Page 46


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32pt

) :18pt




Page 47


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32pt

) :18pt

KPI-IRAT PS HO

Counter ID Counter Name Counter Description 1526726986 L.IRATHO.E2C.PrepAttOut Number of Outgoing Handover Attempts from E-UTRAN to CDMA2000

1526726987 L.IRATHO.E2C.ExecAttOut Number of Performed Outgoing Handovers from E-UTRAN to CDMA2000

1526726988 L.IRATHO.E2C.ExecSuccOut Number of Successful Outgoing Handovers from E-UTRAN to CDMA2000

1526726989 L.IRATHO.E2W.PrepAttOut Number of Outgoing Handover Attempts from E-UTRAN to UTRAN

1526726990 L.IRATHO.E2W.ExecAttOut Number of Performed Outgoing Handovers from E-UTRAN to UTRAN

1526726991 L.IRATHO.E2W.ExecSuccOut Number of Successful Outgoing Handovers from E-UTRAN to UTRAN

1526726992 L.IRATHO.E2G.PrepAttOut Number of Outgoing Handover Attempts from E-UTRAN to GERAN

1526726993 L.IRATHO.E2G.ExecAttOut Number of Performed Outgoing Handovers from E-UTRAN to GERAN

1526726994 L.IRATHO.E2G.ExecSuccOut Number of Successful Outgoing Handovers from E-UTRAN to GERAN

1526727226 L.IRATHO.E2T.PrepAttOut Number of Outgoing Handover Attempts from E-UTRAN to TD-SCDMA

1526727227 L.IRATHO.E2T.ExecAttOut Number of Performed Outgoing Handovers from E-UTRAN to TD-SCDMA

1526727228 L.IRATHO.E2T.ExecSuccOut Number of Successful Outgoing Handovers from E-UTRAN to TD-SCDMA

KPI Formula LTE->WCDMA L2W Handover Success Rate exec [L.IRATHO.E2W.ExecSuccOut]/[L.IRATHO.E2W.ExecAttOut]*{100}

LTE->GSM L2G Handover Success Rate exec [L.IRATHO.E2G.ExecSuccOut]/[L.IRATHO.E2G.ExecAttOut]*{100}

LTE->CDMA2000 L2C Handover Success Rate exec [L.IRATHO.E2C.ExecSuccOut]/[L.IRATHO.E2C.ExecAttOut]*{100}

LTE->TD-SCDMA L2T Handover Success Rate exec [L.IRATHO.E2T.ExecSuccOut]/[L.IRATHO.E2T.ExecAttOut]*{100}

PS HO Statistic

Page 48


35pt

32pt

) :18pt

KPI-IRAT PS HO failures

IRAT counters for PS HO different failure reasons

Counter ID Counter Name Counter Description

1526728306 L.IRATHO.E2G.Prep.FailOut.MME Number of handover prepare failure from LTE to GERAN for MME reason

1526728307 L.IRATHO.E2G.Prep.FailOut.NoReply Number of handover prepare failure from LTE to GERAN for no reply with GERAN

1526728308 L.IRATHO.E2G.Prep.FailOut.PrepFailure Number of handover prepare failure from LTE to GERAN for prepare failure indication from

GERAN

1526728309 L.IRATHO.E2T.Prep.FailOut.MME Number of handover prepare failure from LTE to TD-SCDMA for MME reason

1526728310 L.IRATHO.E2T.Prep.FailOut.NoReply Number of handover prepare failure from LTE to TD-SCDMA for no reply with TD-SCDMA

1526728311 L.IRATHO.E2T.Prep.FailOut.PrepFailure Number of handover prepare failure from LTE to TD-SCDMA for prepare failure indication from

TD-SCDMA

1526728316 L.IRATHO.E2W.Prep.FailOut.MME Number of handover prepare failure from LTE to WCDMA for MME reason

1526728317 L.IRATHO.E2W.Prep.FailOut.PrepFailure Number of handover prepare failure from LTE to WCDMA for prepare failure indication from

WCDMA

1526728318 L.IRATHO.E2C.Prep.FailOut.NoReply Number of handover prepare failure from LTE to WCDMA for no reply with WCDMA

Page 49


35pt

32pt

) :18pt

KPI-IRAT redirection & CSFB counters


1526728326 L.RRCRedirection.E2W Number of Redirction to WCDMA

1526728327 L.RRCRedirection.E2G Number of Redirction to GERAN

1526728330 L.RRCRedirection.E2W.PrepAtt Number of attempt Redirction to WCDMA

1526728331 L.RRCRedirection.E2G.PrepAtt Number of attempt Redirection to GERAN


1526728321 L.CSFB.PrepAtt Number of CS fallback indicators received by the eNodeB

1526728323 L.CSFB.E2W Number of CS fallback procedures to UTRAN

1526728324 L.CSFB.E2G Number of CS fallback procedures to GERAN

1526728322 L.CSFB.PrepSucc Number of successful CS fallback responses from the eNodeB

Redirection Counters

CSFB Counters

Page 50


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32pt

) :18pt

Level Counter name Counter Description

Cell L.RRCRel.DedicatePri.UMTS.High Dedicated Priority (UMTS highest) RRC Release Time

Cell L.IRATHO.E2W.PrepAttOut Number of Inter-RAT Handover Attempts from E-UTRAN to WCDMA Network

Cell L.IRATHO.E2W.ExecAttOut Number of inter-RAT handover executions from E-UTRAN to WCDMA network

Cell L.IRATHO.E2W.ExecSuccOut Number of inter-RAT handover success from E-UTRAN to WCDMA network

Cell L.Thrp.Time.DL Transmit duration of downlink PDCP SDUs

Cell L.ChMeas.PRB.DL.Used.Avg Average number of used PDSCH PRBs

Cell L.Thrp.bits.DL Total downlink traffic volume for PDCP SDUs

Cell L.HHO.IntereNB.InterFreq.PrepAttOut Number of inter-eNodeB inter-frequency outgoing handover attempts

Cell L.HHO.IntereNB.InterFreq.ExecAttOut Number of inter-eNodeB inter-frequency outgoing handover executions

Cell L.HHO.IntereNB.InterFreq.ExecSuccOut Number of inter-eNodeB inter-frequency outgoing handover success

KPI-MLB Performance 1/2

Page 51


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32pt

) :18pt

Level Counter name Counter Description

Cell L.HHO.InterFreq.UeNumLoad.PrepAttOut Number of user-number-load-based inter-frequency handover preparation attempts

Cell L.HHO.InterFreq.UeNumLoad.ExecAttOut Number of user-number-load-based inter-frequency handover executions

Cell L.HHO.InterFreq.UeNumLoad.ExecSuccOut Number of successful user-number-load-based inter-frequency handover executions

Cell L.Traffic.User.Ulsync.Avg Average number of UL synchronized users in a cell

Cell L.Thrp.bits.DL Total downlink traffic volume for PDCP SDUs

Cell L.Thrp.Time.DL Transmit duration of downlink PDCP SDUs

Cell L.InterFreq.UeNumLoad.Dur.Cell Total duration of inter frequency user high load status

Cell L.IRATHO.E2W.Load.PrepAttOut Number of Handover Preparation Attempts from E-UTRAN to WCDMA Network

Triggered Because of High Load

Cell L.IRATHO.E2W.Load.ExecAttOut Number of inter-RAT handover execution attempts from E-UTRAN to WCDMA network

triggered because of high load

Cell L.IRATHO.E2W.Load.ExecSuccOut Number of successful inter-RAT handover executions from E-UTRAN to WCDMA

network triggered because of high load

Cell L.RRCRedirection.E2W.Load Number of redirections from E-UTRAN to WCDMA network triggered because of high

load

Cell L.RRCRel.DedicatedPri.WCDMA.High Number of times that the WCDMA network is configured as the highest frequency

priority in an IMMCI IE

KPI-MLB Performance 1/2

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32pt

) :18pt

DT KPI

Recorded and analyzed by Probe/Assistant

Page 53

Thank you www.huawei.com

Copyright©2009 Huawei Technologies Co., Ltd. All Rights Reserved.

The information contained in this document is for reference purpose only, and is subject to

change or withdrawal according to specific customer requirements and conditions.

Documents

01 GUL Interworking Principal & Solution Introduction V1.1