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
Page 2
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
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
Page 3
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
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.
Page 4
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
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
Page 5
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
Page 6
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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32pt
) :18pt
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
Traffic continuity 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)
Page 7
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
• 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 :
Page 8
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
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
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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1.Idle Mode Reselection
Page 10
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 11
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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.
Page 12
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
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.
Page 13
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 14
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 15
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 16
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 17
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2.Connected Mode-Redirection/PS HO
Page 18
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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Traffic continuity solution
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
Page 19
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 20
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
Page 21
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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 )
Page 22
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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
Page 23
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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
Page 24
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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.
Page 25
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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
Page 27
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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.
Page 28
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Case: Performance for Service Continuity Solution
(K Country V Operator)
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3.Voice Solution-CSFB
Page 30
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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
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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
Page 33
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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)
Page 34
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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
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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Basic Concept- CSFB flow
Page 39
CSFB to UMTS Based on Redirection CSFB to UMTS Based on PS Handover
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
4.IRAT MLB
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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LTE High Load
UMTS High Load
GSM High Load
First to balance inter-
frequency, then balance to
UMTS or GSM
First to balance inter-
frequency, then balance to
LTE or GSM
First to balance inter-
frequency, then balance to
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
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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.
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :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
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :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
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :18pt
1 GUL Interworking Background & Challenges
GUL Idle Mode/Connected Mode/CSFB/MLB 2
GUL Interworking KPI Introduction 3
Page 47
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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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
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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) :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
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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KPI-IRAT redirection & CSFB counters
Counter ID Counter Name Counter Description
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
Counter ID Counter Name Counter Description
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
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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
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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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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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DT KPI
Recorded and analyzed by Probe/Assistant
Page 53
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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.