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
