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2014-07
VoLTE and SRVCC
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Agenda
Overview of LTE
IMS Network
Standards and Test Requirements
VoLTE, Call Continuity, and IMS Services (RCS) VoLTE vs VoIP and Other Solutions
VoLTE in Detail
Mobility/Call Continuity (SRVCC)
IMS Services (RCS)
Anritsu Solutions for VoLTE and Call Continuity Anritsu Products Supporting New Features and Requirements
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LTE-SAE/EPC System Architecture
E-UTRAN
2G/3G
UTRAN
WiFi 1xEV-DO
EPCOperator
Services
HSSMME
PCRF
SGSN
ePDG
S-GW
P-GW/PCEF
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System Architecture Evolution (SAE)
Synonymous with Evolved Packet Core (EPC)
ALL IP Architecture
Key Features:
Higher data rates and Reduce Latency
Multi-RAT Support
Allows integration of Non-3GPP networks
Optimized for all IP services
http://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-core
http://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-corehttp://www.3gpp.org/technologies/keywords-acronyms/100-the-evolved-packet-core8/12/2019 Volte Srvcc
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LTE-EPC Network Nodes
MME (Mobility Management Entity) UE Mobility Control
Security
Authentication
Bearer path control
HSS (Home Subscriber Server) Master Subscriber Database that stores:
User ID
Numbering and service/subscription profiles
Generates security relation information
MME
HSS
S6a (3Gpp 29.272)
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LTE-SAE/EPC System Architecture
S-GW (Serving Gateway) Routes data packets between the P-GW and E-UTRAN
Buffers downlink data during paging operations
P-GW (Packet Data Network Gateway) Default router to the UE providing IP assignment/PDN
Connectivity Handles mobility between 3GPP/non-3GPP access
systems
QoS/Policy enforcement/charging/lawful interception
PCRF (Policy and Charging Rules
Function) Policy and Charging Enforcement Function
S-GW
P-GW/PCEF
PCRF
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IMS Development & History
Developed by the cellular industry to meet growing needs
across the mobile, fixed and IT/computing networks
Designed to allow ubiquitous access to multimedia
services from an access terminal
IMS Standards were developed by 3G.IP formed in 1999,
which is now taken over by 3GPP
In 2010, GSMA announced at MWC that they were
supporting the One World initiative for carrying Voice
over LTE (VoLTE)
Operators decided to incorporate IMS capabilities
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IMS Network Architecture
MRFP
AS
HSS
S-CSCF
I-CSCF
MRFC
EPC
PGW
PCRFP-CSCF
MGCF
MGWTrGW
BGCF
IBCF
Internet
Media
PSTN
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Call Session Control Functions
Proxy CSCF (P-CSCF)
Provides IMS access tomobiles/Forwards SIP messages
between mobile and a S-CSCF
Emergency Services
Security and QoS
Compression of SIP messages
Interrogating CSCF (I-CSCF) Selects S-CSCF
Provides Load Distribution
Serving CSCF (S-CSCF) Acts as a SIP registrar and theprimary call server for certain
registered UEs
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Additional IMS Functions
Media Gateway Control Function Controls Media Gateways
Translates signaling messages (converts SIP to
ISUP)
Breakout Gateway Control
Function SIP proxy between the S-CSCF and MGCF
Selects MGCF based on destination network
Determines PSTN breakout point
Chooses MGCF in its own network/Routes
requests to BGCF in a different network
Application Servers Local SIP AS, OSA-SCS, and IM-SSF
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Putting it ALL Together
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Voice over LTE (VoLTE)
Why VoLTE?
LTE is seen as IP only system for data Operators chose to carry voice over 2G/3G systems or VoIP in one form or
the other
This would lead to fragmentation and incompatibility not allowing all
phones to communicate with each other
VoLTE Formation The system is based on the IMS MMTel concepts and are specified in the
GSMA IR.92
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Other Options for VoLTE
Circuit Switch Fallback (CSFB/1xeCSFB) Data over LTE and when required voice (CS) services will fallback to
2G/3G
Simultaneous Voice LTE (SVLTE) Requires 2 radios
Data Only over LTE and Voice (CS) services over 1x
Voice over LTE via GAN (VoLGA) Based on existing 3gpp Generic Access Network
Aim to enable LTE users to receive consistent voice/SMS (CS) services
while transitioning between GSM, UMTS and LTE
Dual SIM
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VoLTE Challenges
Meeting end user expectations
Supplementary Services must work as current 2G/3G CS networks Mobility/Roaming Interoperability between LTE and 2G/3G
networks
Regulatory Requirements (Emergency Calls)
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Motivation for VoLTE
VoIP Applications Data streams of these applications are not
differentiated from other IP data traffic
No QoS
VoLTE
Uses LTE prioritization to deliver consistent QoS Enables features users are accustomed to in their
2G/3G devices
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Why VoLTE over VoIP?
VoLTE
Guaranteed QoS
IMS
RAN Features Semi Persistent Scheduling (SPS)
Transmission Time Interval (TTI)
Discontinuous Transmission (DRx)
Robust Header Compression
(RoHC)
VoIP
Best- Effort
Generic IP Network
Carrier
Grade!
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Key VoLTE/IMS Specifications
3GPP TS 23.216SRVCC Stage 2
TS 23.228 IMS Stage 2
TS 23.237 IMS Service
Continuity Stage 2 TS 23.292 IMS Centralized
Services Stage 2
TS 24.237 IMS Service
Continuity
TS 26.132 PESQ/POLQA
http://www.3gpp.org
GSMA IR.92IMS Profile for Voice
and SMS
IR.64IMS Service
Centralization and ContinuityGuidelines
IR.94Video Call Support
IR.65IMS Roaming and
Interworking Guidelines
IR.88LTE Roaming
Guidelines
http://www.gsma.com
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GSMA PRD IR.92
IMS Profile for Voice and SMS Aprofile as opposed to a technical specification Defines how the facilities already defined by 3GPP should be used to
ensure interoperability across various operators networks
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GSMA IR.92 v7.0 Focus Areas
IMS Feature Set SIP Registration Procedures
Authentication
Call Establishment and Termination
Forking
Signaling Compression
SMS over IP
Supplementary Services
Multi Party Conference
Communication Waiting
Message Waiting Indication
Communication Diversion
Communication Barring
IMS Media Codecs
RTP Profile and SDP Considerations
RTCP Usage
AMR Payload Format Considerations
Jitter Buffer Management Considerations
DTMF Events
Radio and Packet Core Feature Set
Robust Header Compression
Radio Bearer and RLC configurations
DRX Mode of Operation
GBR and NGBR Services and Monitoring
EPS Bearer Considerations for
SIP Signaling
XCAP
Voice
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GSMA PRD IR.64 v6.0
IMS Service Centralization and Continuity Guidelines
Centralization / Anchoring of services in the IMS Core Continuity of service for single radio devices when access network
changes
Adds to the guidelines defined in IR.92
Focus Areas
Network basedsolution
SRVCC from
LTE/HSPA to
GERAN/UTRAN
UE-based solutionand other service
continuity scenarios
are out of scope
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SIP and SDP
Session Initiation Protocol (SIP) Signaling protocol used for controlling multimedia communication
sessions in IP networks
Defined in RFC 3261
Application protocol designed to be independent of the underlying
transport layer
Session Description Protocol (SDP) Responsible for session description
Transported in SIP message
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VoLTE Pre-Call
IMS PDN Connection Provides connection to one or more IP networks for services
For VoLTE UE will require connection to operators IMS-based services
network (PDN_ID/APN for the IMS network would be in the subscription
information in the HSS)
IMS PDNEPS
PGW
SIP Signaling and
Voice Packets
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Initial VoLTE Registration
visited.net S-CSCF
I-CSCF
P-CSCF
HOME.net
1. Proxy CSCF Discovery
9. Service Control
7. Profile Retrieval
6. Subscriber Authentication
5. S-CSCF Selection
3. I-CSCF Discovery2. REGISTER
8. 200 OK (Register Successful)
4. REGISTER
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VoLTE Basic CallFlow
User1User2INVITE
AMR, AMR-WB
Local QoS unsatisfied
183 Session Progress
AMR-WB, AMR
Local QoS unsatisfied
PRACK
AMR
Local QoS unsatisfied
200 OK
AMR
Local QoS unsatisfied
Final Decision
(AMR)
Request Resources Request Resourses
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EPS Bearers for IMS VoIP
Default EPS Bearer
Default Connectivity for IMS Signaling
Dedicated EPS Bearer
Additional Bearer for
VoIP or Video Traffic
EPS
IMS PDN
One PDN connection for IMS VoIP calls with more than
one EPS bearer
One IP address is used for PDN Connection
Each EPS bearer will have defined QoS Characteristics
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VoLTE Mobility
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IMS Service Continuity
Allows user to transfer media sessions across different access networks or UEs
Example: transfer ongoing media session from mobile device to TV
Sessions can be transferred as a whole (for example voice and video) or in part
User can add/delete sessions on multiple devices, controlled from a single device
Even control of a collaborative session can transfer from one user to another
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IMS Centralized Services (ICS)
Provides the same servicesregardless of access network:
CS or PS
Users get new IMS services
while still using CS domain for
the media bearer
IMS sessions on CS bearers
treated like any other full IMS
session
All services provided by IMS
application servers and
controlled by IMS service controlarchitecture
Adds supplementary services to
VCC
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SRVCC For VoLTE
Single Radio Voice Call Continuity (SRVCC)
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IMS Services - RCS
Rich Communication Services Designed to offer richer yet simpler communication
services supported by a strong ecosystem and avariety of architecture implementation options
Main Features: Enhanced Phonebook: service capabilities and
enhanced contacts informations such as presence andservice discovery
Enhanced Messaging: enables a large variety ofmessaging options including chat, emoticons, locationshare and file sharing
Enriched Calls: enables multimedia content sharing
during a voice call, video call and video sharing
Reference: http://en.wikipedia.org/wiki/Rich_Communication_Services
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RCS v5.1 Feature Set
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Anritsu MD8430/8480 Solution
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Addresses Technology Challenges
IMS Signaling over LTE Transport Test IMS protocols over the LTE radio interface
CSFB and SRVCC
Built in test cases Over 100 example tests
IR.92, IR.94, PRS, XDM, AMR, H.264, etc
Rich Communication Services Presence, Instant messaging, file transfer
Address book, XML Document Management (XDM)
XCAP server simulation
IMS Emergency Calls
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Media Quality Testing
Voice/Audio Quality MOS PESQ
Video No-Reference (online)
Full Reference
Audio VideoNo-Reference
Offline
ITU G.107 ITU G.107
ITU-R BT.500.9
Full-Reference
Offline
PESQ
ITU P.862 (also
available online)
ITU J.247 (unique
synchronization
algorithm)
No-Reference
Online
ITU G.107 ITU G.107
ITU-R BT.500.9
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Anritsu MD8475 Solution
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Tests Performed On MD8475
IMS registration IMS security procedures
Device (SIP) addressing
Call processing including
abnormal call handling
Call conferencing
and supplementary services
such as call forwarding
Call drop and reestablishment
Emergency calls SRVCC
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RCS On MD8475
IMS Core
Presence serverXDM server IM server
RCS server component
3GGP
Network
MX847570A-083 RCS Basic Option
Configuration/registration
Social Presence
1-to-1 chat
Capability discovery
MX847570A SmartStudio - IMS Services
CSCF
XCAP
* New MX847570A-083 RCS Basic Option required
Key Value for CustomerUsers can test each service RCS 5.1 which needs
some servers with one box.
Target customer is leading-edge UE vendor which
develops for special operators.
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RCS 5.1 Service Support
Item Support Future Comment
Configuration & Registration (*1) (*1) (*1) Support only HTTP(S) base
Capability discovery
Standalone messaging
1-to-1 Chat (*2, 3) (*2) Support only IM. Not support CPM.
(*3) Interaction with other RCS service is not supported.
Group Chat
File Transfer
Content sharing
Social Presence Information (*4) (*4) Not supported geolocation service.
IP Voice Call (*5, 6) (*5, 6) (*5) Support only IR.92 base
(*6) Interaction with other RCS service is not supported.
IP Video Call (IR.94) (*7, 8) (*7, 8) (*7) Support only IR.94 base
(*8) Interaction with other RCS service is not supported.
Geolocation services (*9) (*9) Interaction with other RCS service is not supported.
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Anritsu ME7834L Solution
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3GPP and CAT
Conformance
36.521-1RF 36.521-3RRM
36.523-1Protocol
37.571-1Emergency Calls
Test suites covering ancillaryfunctionality such as the UICC
Carrier-specific test plans
ATT
T-Mobile Verizon
Others
2G/3G Simulators
LTE Simulators
Test
Controller
*Example configuration
Supporting
Components
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Conclusion
LTE EPC and IMS Networks are Complex
New Specifications and Recommendations Including Signaling; Media; Services
Service Continuity SRVCC
RCS (Rich Communication Services)
Service Continuity is Important
SRVCC (GSMA indicates 3GPP Rel10 for initial rollouts)
Anritsu Products Meet the Challenges
Several different configurations based on needs of customer