koshimizu takashi- ntt docomo- voip over lte
TRANSCRIPT
Voice over LTE and the Migration Path
(the standardization and development)
Next Generation Core Networks Summit 2010
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
KOSHIMIZU, Takashi
Core Network Development Strategy GroupCore Network Development Department
Research and Development Center
NTT DOCOMO, INC.
19 May 2010
Introduction• Our (as an operator) goal is designing a network which enable to offer
rich service platform* in economical and timely manner, considering available alternatives** with the migration path from conventional system.
• This presentation focuses following focal points as the presentation topics.
ServiceService--EnablerEnabler NetworkNetworkServiceService--EnablerEnabler NetworkNetwork
Image
ProcessVoIP ASPresence
IMS CoreIMS CoreIMS CoreIMS Core
IMContents
Sharing
…
NW Value added functions
This Presentation Contains
Migration
・・・・Access Migration Plan
・・・・Voice Migration Plan
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
EPC EPC (Evolved Packet Core)(Evolved Packet Core)
LTE AccessLTE Access3G Access
IMS CoreIMS CoreIMS CoreIMS CoreMigration
From
Conventional
Systems
・・・・Voice Migration Plan
・・・・Complexities in Migration
Alternatives
・・・・IMS Migration Plan
・・・・NW Value Added
Mechanism with Migration
Through our i.e., NTT DOCOMO’s standardization and development activities
LTE Area Expansion and Voice Service Migration in DOCOMO
・・・・ LTE is introduced as an overlay on the full-nation-covered existing 3G areas⇒⇒⇒⇒ Start form Data Card, then LTE/3G Dual-Handset-UE is planned to migrate existing 3G
services. In outside LTE areas, service is plan to be provided via 3G access NW.⇒⇒⇒⇒ LTE expansion to nationwide is step wise, it’ll take time till full covered LTE access.
・・・・Our Goal is to offer a set of Multimedia Telephony service (VoIP) via LTE /IMS
⇒⇒⇒⇒ Yet initially, “voice” service plan to be provided by the existing 3G system using CS fallback till all system functionalities and service migration plan get prepared.
⇒⇒⇒⇒ Eventually VoIP/LTE (VoLTE) is introduced, all voice services will be provided via LTE.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved. - 3 -- 3 -
PDC
3G
LTE
4GPSPSservicesservices
CS&PSCS&PSservicesservices
CS&PS ServicesCS&PS Servicesover packet networksover packet networks
3G UE
LTE UE
LTE/4GUE
LTE/4GUE
Noaccess
2GUE
3G(HSPA)
(R99)
Simple network that provides all services
Access Area Expansion PlanAccess Area Expansion Plan
2001 2010s 2015s From 2020s onwards
LTELTE
4G
CSFB Basic Mechanism and the Advantages
Basic Mechanism• When a voice service is needed, the UE switch RAT from LTE to 2G/3G
then offer voice services in 2G/3G RAT domain.
Key Advantages• It enables to offer Handset (Voice) UE early-stage of LTE rollout.• CSFB enables to offer all existing 3G services, no service de-grade.
Prerequisites• Nation wide coverage of 2/3G, and 2/3G with LTE dual terminal.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
• Nation wide coverage of 2/3G, and 2/3G with LTE dual terminal.• CSFB capable network enhancements.
This technology have been proposed aiming a migration step toward MMTel(VoIP)/IMS
EPC/3GCore Network
２/３G
①Voice Call Request
③Voice Call Resp.
④Voice Call Voice Call U-Plane Path
C-Plane Path
LTLTLTLTEEEE
②Fallback to2G/3G RAT
CSFB key support functions
Evolved Packet Core NWMME
HSSHSSS6a
①Voice Call Request
TA LA MSC/VLR
TA1 LA1 MSC/VLR#1
TA2 LA2 MSC/VLR#2
TA3 LA2 MSC/VLR#2
Example: UE Originated and Terminated Call
(assumption with LTE is “default” RAT)
•MME holds mapping information of TA and corresponding LA+MSC/VLR#, this enable to select an appropriate MSC at a location update.
•Combine Location update enables 3G location update from LTE side, by using the relation of MME and MSC/VLR.
TA&LA Mapping @ MME
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
S4
S1-UP-GWS-GW
3G Core NW
SGs
Iu-cs
Iu-ps
S11
S5
S3
SGSN
DS1-MME
U-Plane Interface
C-Plane Interface
MSC/VLR
LTE
3G GGSN
②HO Command
TA#1
LA#1
④④④④Voice Call Initiation
③Handover＋RAT Change
①UE Terminated
CS Voice Case
VoLGA (Voice over LTE via Generic Access)
Basic Mechanism• Virtually use LTE access as
transport pipe and mimic LTE as Legacy access.
• VANC work for the intimidator.
Key Advantages• It enables to offer Handset (Voice)
UE early-stage of LTE rollout.
Circuit Services(Voice, SMS, VMS..)
Packet Services(MMS, WAP, RCS..)
BSC RNCVANC
Evolved Packet Core
•VoLGA technical solution used to be discussed in 3GPP, yet faded out now
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
• It enables to offer Handset (Voice) UE early-stage of LTE rollout.
• It enables to offer all existing 3G services, even in LTE access.
Prerequisites• Not fully required nation wide
coverage of 2/3G.• UE should be 2/3G with LTE dual
terminal with VoLGA capable.• VoLGA capable network
enhancements, need VANC.
GSM/EDGE UMTS/HSPA LTE
VANC (VoLGA Access NW Controller)
This enables to support circuit-switched servicesover LTE access. Originally, proposed in 3GPP as GAN
Controller (GANC), now specified in VoLGA Forum.
VoLGA Mechanism Shown in 3GPP-TR 23.879
VANC (IWF)• Behave like a BSC or RNC towards the UE, and behave like an Application
Function (AF) towards the EPS, as SGi IF.
• Translation between the UE-IWF protocol and BSSAP/RANAP. This includes the mapping of information between the UE and the MSC communication paths.
UE• CS domain registration and CS signalling using IP transport over LTE access.
• Communication with the IWF using a “UE-IWF ” protocol (shown as New Protocol); e.g., for carrying CS NAS messages and paging the UE.
CC/SS/SMS CC/SS/SMS
Z1 Iu_CSSGi
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
PDCP
IP
MM
Ethernet
IP
“New Protocol” RANAP RANAP
MM
UE IWF MSC/VLR
Signalling
Transport
Layers
(TS 25.412)
TCP TCP
Signalling
Transport
Layers
(TS 25.412)
“New Protocol”
RLC
MAC
PHY
EPS
IP
Ethernet
PDCP
RLC
MAC
PHY
IPSec functions
(see Note 1)
IPSec functions
(see Note 1)
3GPP TR23.879 Figure 5.2.1.5-1: Protocol stack for control plane over Z1 (Iu-cs IF)
VANC
VoLTE (Voice over LTE / IMS) and VoLGA
• Call Control is performed in IMSCall Control is performed in IMSCall Control is performed in IMSCall Control is performed in IMS• Call Control Protocol is SIP based.Call Control Protocol is SIP based.Call Control Protocol is SIP based.Call Control Protocol is SIP based.• The Terminal speaks SIP.The Terminal speaks SIP.The Terminal speaks SIP.The Terminal speaks SIP.• This is the Target SolutionThis is the Target SolutionThis is the Target SolutionThis is the Target Solution
VoLGA・・・・ Uses LTE access but Call control performed Uses LTE access but Call control performed Uses LTE access but Call control performed Uses LTE access but Call control performed
Interwork.Interwork.Interwork.Interwork.
・・・・ Uses LTE access but Call control performed Uses LTE access but Call control performed Uses LTE access but Call control performed Uses LTE access but Call control performed at conventional MSC by interworking via at conventional MSC by interworking via at conventional MSC by interworking via at conventional MSC by interworking via VANC.VANC.VANC.VANC.
• Call Control protocol uses same as 3G CS.Call Control protocol uses same as 3G CS.Call Control protocol uses same as 3G CS.Call Control protocol uses same as 3G CS.• VANC is the VoLGA specific node for VANC is the VoLGA specific node for VANC is the VoLGA specific node for VANC is the VoLGA specific node for
Interwork.Interwork.Interwork.Interwork.
VoLTE
PS Core NW
CS Core NWIMS
GMSC
Call
Control
PS Core NW
CSコアNWIMS
GMSC
Call
Control
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
MSC
RNC
BTS
EPC
eNB
PCRF
Iu-CS
SIP Protocol
MSC
RNC
BTS
EPC
eNB
PCRF
Iu-CS
VANC
Iu IF conversio
n
Legacy 3G Protocol over LTE Physical Layer
Issues Under Multiple Migratory Solutions
• Roaming complexity– Need to prepare some fallback
solution if the NW and Terminal are not fully ready in roaming.
– Having 4 alternatives, need to resolve 6 roaming patterns.
– Having 3 alternatives, the pattern has been greatly minimized.
• Industry Fragmentation
3G
CS-Fallback
VoLTE
VoLGA
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
• Industry Fragmentation– Causes Terminals, network nodes,
interface variations. It leads impacts on the economies of scale.
• Test complexity– UE and the network components
also has to be validated conformance test, etc.
– This makes additional complexity for the service role out.
3G
CS-Fallback
VoLTE
• Key role for the cellular •An cellular operators forum • Aiming for global roaming
LTE Voice Related Standardization Activities (overall)
Genera
l Role
•NGMN took the role of decision of migratory voice solution, intensive discussion held Dec 2009 to February 2010 in the NGMN-TF for selection of single migratory solution.
•GSMA dedicated to the work on target voice solution, i.e., VoIP/IMS.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
• Key role for the cellular
system standardization.
• Service definition, and
technical feasibility.
•An cellular operators forum
targeting near future topics.
•Consensus formation
among operators.
• Aiming for global roaming
realization.
• Roaming specification and
Testing rules.
• IMS Platform is ready.
• CSFB has been completed in Rel 9.
• VoLGA has been dropped out from Rel9.
• VCC improvements are in
Rel10.
• Discussed migratory voice
solution among operators.
• Asked to select single
solution for the migratory
voice solution.
• Alternatives were CSFB,
VoLGA, and DualRadio.
• LTE roaming technical
document, PRD.
• GSMA concentrated Target
Solution, i.e., VoIP/IMS
technical documentation
(VoLTE Profile)
Genera
l Role
VoIP
Specific
Role
NGMN VoIP-TF Discussion on Voice Migratory Solution
Standards
situation
Industry
supports
(operators)
Roaming Impacts on
network
Impacts on
terminalsPerformance
•Following criteria are the part of discussion in NGMN Voice Task force in the discussion.
•From tough and intensive discussion, it is concluded CSFB shall be implemented as a minimum requirement as the voice migratory solution by complying 3GPP specification.
•Also members are firmly committed to IMS Voice as the target solution for Voice/LTE
•DOCOMO took the role of convener of this NGMN Task force, thanks to all participants.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
Any migratory solution to be recommended by NGMN must be fully standardized by 3GPP.
(Major findings)
・Asked
operators view on each alternatives.
・Majority
supported CSFB.
・Impacts on, or
undesirable behaviors of a visited network.
・Impacts on, or
undesirable behaviors of roaming-in terminals.
Evaluated and analized how network be affected from the alternative.
Evaluated and analized how UE be affected from the alternative.
・Call setup time
・ HO to 2G/3G
・Voice quality
From tough and intensive discussion, finally reached the outcome and announced it in the GSM Mobile World Congress in Feb 2010. NGMN Press
Release
GSMA IREG activity on LTE Roaming Guidelines
1. LTE Data Roaming- LTE-only Data Roaming
- LTE +2G/3G Data Roaming
2. Voice over LTE (VoLTE)- “VoLTE Profile” defines a minimal IMS feature
set for voice interworking
- Started as “One Voice Initiative” in mid 2009
voluntarily by major operators / MNC vendors
- The output was officially transferred to GSMA
as “VoLTE Profile”
•GSMA IREG RiLTE have been taken the major role of LTE roaming discussion
RiLTE(Roaming in LTE)BARG
TADIG
LTE Roaming Steering Committee
IREG
PACKET
-LTE Data RoamingInter-RAT roaming
-VoLTE Profile
-IMS NNI
-IPX/GRX
SIGNAL, HUBBING,GRXWP
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
as “VoLTE Profile”
2009
4Q3Q2Q1Q4Q3Q2Q
2010
LTE-only Data Roaming in RILTE
LTE+2G/3G Data Roaming in RILTE
One Voice InitiativeGS
MA
IR
EG
RIL
TE
-Technical guidelines (Diameter, GTP and PMIP)
-IPX aspects
-Test spec
-Operator information database -Roaming scenarios
-Inter-RAT handover
-Test spec
- Creation of One Voice Profile
VoLTE Profile / IMS Roaming
-VoLTE Profile update
-VoLTE Roaming
Establishment of
LTE Roaming Steering CommitteeEstablished in 2Q 2009
Transfer
of work
Used to be out side of work of GSMA
GRXWP
IMS migration for 3G voice services in DOCOMO
•Migration from the 3G Circuit-Switched NW to IP-based/ IMS controlled NW.
•Without making changes the existing radio interface and 3G radio access network,
by converting them to IP-based protocols via CS-GW, same concept as ICS.
•Perform unified Call control／／／／Service control in IMS ���� preparation to LTE VoIP IMS.
HLR Bill details
MPN
ATMNW
MPNHLR/HSS
AS
Bill details
Service controlService controlMGW
PLMN gatePLMN gate
IMSCall controlService control
POIPOI
Router Router Router Router networknetworknetworknetwork
TMSC
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GMSC
GGSN/SGSN
RNC RNC
MSC
GMSC
3G packet3G packet
POIPOIPLMN gatePLMN gate
GuidanceGuidance
GGSN/SGSN
CSCF
Call controlCall control
IP-based protocols(SIP, RTP)
MRF
3G 3G packetpacket
Migration
TMSC
CS-GW
Accommodate Accommodate
3G3G--CSCS
accessesaccessesProtocolconversion
Existing radiointerface
RNC RNC
Use as it is
DOCOMO’s SEN (Service Enabler Network) Concept
ServiceService--EnablerEnabler NetworkNetworkServiceService--EnablerEnabler NetworkNetwork
VoIP ASIMPresence
IMS CoreIMS CoreIMS CoreIMS Core
Contents
Sharing
…
NW Value added functions
•Provide enriched communication services to satisfy various user needs with timely manner via Service Enabler Network
Enabler
RCS•SEN (Service Enabler Network) is service provision platform on top of IMS.
•Enabler is the piece of service function that can be commonly used by multiple services.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
(Reference 1)
RCS (Services provided by mutually connecting the IMS among operators in different
countries: First release can realize instant messaging, presence and contents sharing
by using part of SEN)
EPC EPC (Evolved Packet Core)(Evolved Packet Core)
LTE AccessLTE Access3G Access
IMS CoreIMS CoreIMS CoreIMS Coreused by multiple services.
•By combining multiple enablers, realize various services (corporate, consumer , etc.) within reasonable time period and cost.
(Reference 2)
Enabler is a service function part that can be commonly used by multiple services.
Combination of standardized enablers and operator-specific enablers, realizes the specialized services for operator.Standardization of the mechanism to offer NW value-added services is developed as the GSMA RCS release 3. DOCOMO is also leading this study group.
Network value-added services
RCS Standard Enablers (Release 1)
PresencePresenceContentContentsharingsharing
Media Media Processing Processing
AA
Media Media Processing Processing
BB
Operator-specific Enablers
Instant Instant messagingmessaging
. . .. . .. . .. . .
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Realization of NW Value-Added Services
Service Service CompositionComposition
IMSIMS
位置情報シェア Here
Location Location Info. SharingInfo. Sharing
Voice callVoice call
I guess you are close now.
I’m already here.
Where are you ? I’m at this point now!
I’m getting closer to you!
Conclusion
This presentation explained;– Access Migration Plan in DOCOMO
• Step by step LTE access rollout over legacy accessand the deployments are on schedule in DOCOMO.
– Voice Solution in the Migration path• CSFB has been identified as the solution in NGMN
– Roaming complexities and Migration Alternatives• GSMA IREG RiLTE working on LTS roaming aspect with the PRDs
(Permanent Reference Documents) and it’s on the way.
(c) 2010 NTT DOCOMO, INC. All Rights Reserved.
(Permanent Reference Documents) and it’s on the way.
– IMS Migration Path• NW migration toward IMS based control which same concept as
ICS (IMS Centralized Service) are ongoing in DOCOMO.
– NW Value Added Mechanism with the Migration• DOCOMO proposed SEN concept which provides service rich
platform in an economical and timely manner are also on going.
• This supported various standardization activities and the efforts in global place• The standardization and our deployments are on going having such background• DOCOMO also expect all necessary function provided from vendors in economical and timely manner, hopefully. Now, our goal is on the horizon.
