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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-core


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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



IMS Network Architecture

MRFP

AS

HSS

S-CSCF

I-CSCF

MRFC

EPC

PGW

PCRFP-CSCF

MGCF

MGWTrGW

BGCF

IBCF

Internet

Media

PSTN



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



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



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
http://www.3gpp.org/http://www.gsma.com/http://www.gsma.com/http://www.3gpp.org/


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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


PRACK

AMR


200 OK

AMR


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


IP Video Call (IR.94) (*7, 8) (*7, 8) (*7) Support only IR.94 base


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

Documents

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