Voice in LTE - HTE

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Evolution into Voice over LTE. GSMA VoLTE family. PRD IR.92. PRD IR.65. UNI. IMS Roaming. & interconnect. PRD IR.94. PRD IR.58. Video call additions.
Voice in LTE András Gerhát Ericsson

Why Telephony in LTE ? Imagine LTE without it ... Textmessage: „Hi Sue, it‘s Bob. I‘ve got a cool new phone. It‘s LTE. It‘s superfast. It‘s pretty cool!“ Textmessage: „Hi Bob, sounds great! But I tried to call you, I didn‘t get through ...?“ Textmessage: „It‘s Internet only. One cannot make calls with it ....“ Textmessage: „You can‘t call me with it? That‘s weired.“

Textmessage: „Why don‘t you try with Google or Skype?“

People want to make phone calls. If operators do not offer it, subscribers will seek alternatives! Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 2

Telephony in LTE GSM

GSM

Circuit switched CORE IMS Telephony

3G

WCDMA

HSPA

Packet Core LTE

LTE

INTERNET

LTE is PS-only, no CS. Telephony over LTE is VoIP! Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 3

Evolution into Voice over LTE GSMA VoLTE family

PRD IR.58

PRD IR.94

PRD IR.64

PRD IR.65

IMS voice on HSPA

Video call additions

SR-VCC

IMS Roaming & interconnect

Version 3.0

Version 3.0

Version 4.0

& ICS

PRD IR.92

Version 10.0

UNI Version 6.0

Note: version numbers as of Sept 15, 2012 Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 4

GSMA VOLTE IR.92 UNI profile Telephony Service UNI

MMTel

UNI IMS UNI

– MMTel Supplementary Services – OIP, OIR,TIP, TIR – CDIV (CFU, CFNL, CFB, CFNRc, CFNR) – CB (ICB, OCB, ICB-R, OCB-IC) – HOLD – MWI – Comm. Waiting – Conf – Supplementary service management using Ut with XCAP procedures

IMS feature part EPC

UNI

LTE

– – –

ISIM based authentication (USIM fallback). IPSec protection of signaling. Both Tel-URI and SIP URI GBA (recommended) or http digest authentication for Ut – Early dialogues – IMS Emergency

LTE radio capabilities

Bearer management

IMS media

– GBR EPS bearer (QCI1) for voice – Non-GBR EPS bearers for SIP and XCAP – RoHC in PDCP

– Well known “IMS APN” with local PDN GW – The IMS APN with signaling bearer (QCI=5) established at initial attach – P-CSCF Discovery

– – – –

Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 5

AMR NB and WB Codec & payload format RTP profile / Data transport RTCP usage Jitter buffer management

VoLTE Architecture 3GPP R10 S6a Sh

MME S11

S1-MME

HSS MMTel AS

PCRF Gx

Rx

ISC Cx

e-Uu

S1-U

SGi

Mw

IR.92

S&P GW

eNodeB

P-CSCF IMS AGW

I-/SCSCF

LTE Gm Mb

Ut

E-UTRAN

EPC, Evolved Packet Core

EPS, Evolved Packet System VoLTE, Voice over LTE Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 6

IMS

What to do when? CS Voice => VoLTE Evolution IMS-MMTel, SR-VCC, ICS VoLTE VoLTE

MSC or MSS CS

CS

CS Voice

CS Voice

PS VoIP

PS VoIP

CSFB

SRVCC

(SRVCC)

(CSFB)

(CSFB)

Circuit Switched Voice Service

(CSFB)

CSFB LTE

LTE

LTE

LTE

LTE

CS CS LTE

LTE

SRVCC

LTE

LTE

LTE

LTE

LTE

LTE

LTE

LTE

LTE

LTE

LTE LTE

LTE

LTE

LTE

LTE LTE LTE

LTE LTE

3G / HSPA LTE LTE

LTE

LTE LTE LTE

LTE LTE LTE LTE

LTE LTE LTE LTE LTE LTE LTE

CS = Circuit Switched; PS = Packet Switched CSFB = Circuit Switched Fallback SRVCC = Single Radio Voice Call Continuity VoLTE = Voice over LTE (VoIP) ICS = IMS Centralized Services Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 7

LTE LTE LTE LTE LTE LTE LTE LTE

LTE LTE LTE LTE LTE LTE LTE

Circuit Switch FallBack CSFB LTE



CSFB subscribers attach with preference on LTE access, and also registers in CS core



Fallback triggered to overlapping CS domain (GSM / WCDMA) whenever voice services are requested



Resumed LTE access for PS services after call completion LTE island

PS

PS LTE

LTE

GSM / WCDMA CS (+PS) LTE

Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 8

LTE

LTE

CS LTE

LTE

LTE

CSFB LTE Attach 3. The Ue is CSFB Attached in the LA via the MME

BSC RNC

BTS NodeB

Nc / Nb

A / IuCS

Abis / Iub

MSS

GSM / WCDMA SGs Location Update (LA)

4.

CSFB subscriber Ue is attached via Combined Attach

2. MME handles the combined PS and CS Attach. For the CS Attach it maps TA->LA and makes a Location Update over SGs

MME S11

S1-MME

e-Uu Internet

CSFB phone

eNodeB

S1-U

A LTE

1. CSFB subscriber Ue initiates attach procedures to LTE using Combined Attach Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 9

S&P GW

SGi

CSFB MT call 5. Page response and call setup over GSM or WCDMA A / IuCS

Abis / Iub

B

Nc / Nb

Um / Uu

BSC RNC

BTS NodeB

MSS

Paging

GSM / WCDMA

4. UE fall back to GSM or WCDMA

RAT change

SGs

1. Incoming call to the subscriber currently attached over LTE. Paging in LTE via SGs.

MME

2. MME orders the UE to release from LTE and execute CSFB

S11 S1-MME e-Uu

Internet

eNodeB

S1-U

A LTE

S&P GW

SGi

3. eNodeB orders the UE to release from LTE to a target frequency and RAT

6. UE reselects an LTE cell after call completion, time staying in GSM/WCDMA is implementation dependent Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 10

Single Radio Voice Call Continuity LTE

LTE

CS LTE

SRVCC

Prepare Handover GERAN UTRAN GSM / WCDMA

LTE

SCC AS

MSS

Sv SRVCC handover

Access transfer

LTE

LTE

LTE

LTE

LTE

B

MMTel IMS

A LTE

EPC

LTE

Moving UE

› IMS Telephony Voice to CS handover – Handover triggered by LTE RAN – Handover signaling from MME to MSC (via Sv interface) – MSC prepares handover and connects CS leg to IMS – SCC AS executes access transfer Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 11

LTE

SRVCC handover CS coverage

LTE

LTE LTE

LTE

LTE

LTE LTE

SR-VCC Architecture – 3GPP R10 SRVCC

SRVCC

Um / Uu BTS NodeB

A

Abis / Iub

BSC RNC

A / IuCS

SRVCC

GSM / WCDMA

MMTel & SCC AS

Sv

SRVCC

ISC I2

Mw / Mg / Mx

SRVCC

S1-MME

SRVCC handover

HLR / HSS

MSS

Mw

MME

Gm P-CSCF ATCF

B

I-/SCSCF

Iq

S11

Mb Mb

SRVCC

e-Uu SRVCC

A

SRVCC

S1-U eNodeB LTE

S&P GW

ATGw SGi

Mb

Serving Network Home Network

Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 12

SRVCC

New functionality

IMS Centralized services (ICS) Rationale and use cases LTE

IMS Centralized Services

MMTel / SRVCC phone GSM WCDMA

Mobile Softswitch

LTE LTE

LTE

MMTel IMS

MMTel Telephony Service

LTE LTE LTE

› ICS enables IMS services also when an IMS user is accessing via CS › Single Service Engine – All service execution in IMS and MMTel, no service execution in CS domain – Enables consistent service experience

› No synchronization needed between service data in CS and IMS domain › Relevant use cases – LTE/IMS user when out of LTE coverage or during SR-VCC – LTE/IMS user roaming abroad via CS (LTE + CSFB or only CS service offered) – Service to a user with an advanced new service e.g. IP Centrex (also in a CS only network) Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 13

LTE LTE

LTE LTE LTE

3G / HSPA LTE LTE

CS access Legacy phone

LTE

LTE

LTE

LTE LTE LTE

LTE LTE LTE

LTE LTE LTE LTE LTE LTE LTE LTE

LTE LTE LTE LTE LTE LTE LTE

ICS - Main solution alternatives ICS

ICS

ICS with eMSC and I2

HLR / HSS

MMTel & SCC AS

Ut

ISC Mw / Mg / Mx

I2 ICS

MMTel / SRVCC phone

Um / Uu Abis / Iub BTS NodeB GSM / WCDMA

A

BSC RNC

A / IuCS

B

CSCF

eMSS

Mb

ICS

ICS with legacy MSC using CAMEL/ISUP/Mg

ICS

MMTel & SCC AS

Ut

HLR / HSS

CAMEL ISC ISUP

MMTel / SRVCC phone

Mw / Mg / Mx

Mg

Um / Uu A

Abis / Iub BTS NodeB GSM / WCDMA

BSC RNC

A / IuCS

MSS

MGCF IM-MGW

CSCF

CS voice

Mb

Serving Network Commercial in confidence | © Ericsson AB 2012 | 2012-10-09 | Page 14

Home Network

B