View
105
Download
0
Category
Tags:
Preview:
Citation preview
1 © Nokia Siemens Networks
Voice over LTE Telephony on the National Public Safety Broadband Network
Brian Kassa Head of Technology – Public Safety Broadband June 5th, 2013
2 © Nokia Siemens Networks
Public Safety Broadband
Agenda
• VoLTE Overview
• What is VoLTE
• VoLTE for FirstNet
3 © Nokia Siemens Networks
Public Safety Broadband Setting the scene for voice in the LTE era
The industry known options for voice are:
• Circuit switched fallback (CSFB)
• IMS based VoLTE (VoLTE)
• Simultaneous voice and data (SV-LTE)
A voice solution is needed for an LTE smartphone to connect to LTE network, otherwise it is connected to 2G/3G only – for voice and data.
LTE
2G/3G
UE
3GPP
3GPP
4 © Nokia Siemens Networks
Public Safety Broadband Foreseen Voice over LTE Technology Evolution
2012 2013
Dual radio terminals for CDMA /LTE operators SV-LTE
VoLTE with QoS
VoLTE with SRVCC
CS Fallback to 2G/3G
Voice over CDMA and data over LTE
Voice over 2G/3G and data over 2G/3G or LTE
Seamless voice continuity
Secured voice quality
2014
SMS over LTE connection Over the air configuration, prepaid information
VoLTE roaming
2015
Smartphone launch on LTE networks means that a voice solution must be
implemented
SVLTE CSFB VoLTE SRVCC
LTE coverage
Network impact
Terminal impact
5 © Nokia Siemens Networks
Public Safety Broadband
Agenda
• VoLTE Overview
• What is VoLTE
• VoLTE for FirstNet
6 © Nokia Siemens Networks
Public Safety Broadband VoLTE system architecture The Obligatory Spaghetti Diagram
MME
S-GW P-GW eNB
HSS
PCRF P-CSCF
I/S-CSCF BGCF
MGW
TAS GERAN/UTRAN MGW
MGCF Call control signalling
User plane traffic
Other control signalling S6a
Gx
Rx
Ma, ISC Sh
Mb S11 S1-MME
S1-U
SGs Sv
Mw
Cx Mi
Mn
D
MSS
LTE-Uu
EPS IMS
CS
7 © Nokia Siemens Networks
What Is Needed for VoLTE 1. Circuit Switched Fallback (CSFB)
2. Single Radio Voice Call Continuity (SRVCC)
3. Rich Communications (RCS)
4. IMS Centralized Services (ICS)
8. Roaming
7. Lawful Intercept (LI)
6. Emergency Call (911)
5. Domain Selection (T-ADS)
Assumed: LTE Network with QoS, Location and Charging
9. Terminals
8 © Nokia Siemens Networks
Public Safety Broadband
Dept. / Author / Date
Main drivers
LTE Voice and Messaging Evolution
VoLTE • QoS for voice • Based on all-IP network
architecture • Provides similar tools to fight OTT • Improved voice spectral efficiency
of LTE, short call setup time, short delays
RCS • Richer service offering to attract users • Alternative service offering to OTT • Works with CSFB and VoLTE
¹ RCS can be introduced at any time, works with both CSFB and VoLTE
CS Fallback • Immediate voice solution for LTE • Roaming before VoLTE roaming • Emergency calls before IMS based
VoLTE in place • SMS over SGs before SMS o IP
(Simplified for clarity, visited network and roaming not shown)
BSC / RNC BSS/NB
PGW eNB
MSS
MME
MGW
SMSC
HLR
SGW
CSFB
SMS
1. CSFB + SMS over SGs 2. VoLTE
RCS
3. SRVCC
Voice
Voice
TAS
SR-‐VCC
Sv SGs
Voice core
LTE packet core LTE radio network
2G/3G radio network IMS
PCRF
HSS
4. RCS¹
IP network
MNO PSTN
9 © Nokia Siemens Networks
Public Safety Broadband SRVCC in 3GPP
• SRVCC has been standardized in 3GPP Release 8 TS 23.216 to provide seamless continuity for UE handovers from E-UTRAN to UTRAN/GERAN. 3GPP Release 10 targets to enhance SRVCC performance in roaming cases. 3GPP Release 10 introduces two new functional entities for SRVCC: ATCF and ATGW.
ATCF Access Transfer Control Function ATGW Access Transfer Gateway
10 © Nokia Siemens Networks
Public Safety Broadband - a simple interoperable extension to voice and SMS . . .
Messages (SMS/MMS)
Voice
Initial ‚joyn‘ Service Set
New services to monetize market trends
Source: operator & GSMA slides presented at the Informa ‘Rich Communication 2011’ conference, Munich, 25+26 Oct 2011
RCS-e
11 © Nokia Siemens Networks
Public Safety Broadband . . . and a basis to continuously deliver innovation
Source: GSMA RCS 5.0 - Services and Client Specification
RCS 5 is completely backward compatible with RCS-e V1.2 specifications and also includes features from RCS 4 and exciting new features such as IP video call, IP voice call and Geo-location exchange.
RCS 5
= new features (not part of RCS-e 1.2)
12 © Nokia Siemens Networks
Public Safety Broadband
• 3GPP VoLTE/IMS Roaming Alternatives – the alternatives differ in:
– Architecture: different network elements (P-CSCF, PCRF, PGW) are located in home- and visited networks. – Regulatory Service Support: ability to provide local support for IMS Emergency Calls and Lawful Interception. – Bearer Support: ability to support an optimized routing for the bearer.
– today, operators typically have the GGSN/PDN-GW in the Home Network (= Alternative 3) – GSMA IR.92 “One Voice” recommends Alternative 1:
– due to the flexibility to serve regulatory needs (LI, Emergency Calls) and to support optimized routing. – the roaming architecture however always also depends on the abilities of the roaming partners (who might not have an IMS at
all).
IMS Roaming / LTE Roaming Support and Evolution
Visited Network (of the A-Party)
Home Network (of the A-Party)
Terminating Network (Home of the B-Party)
V-PCRF
H-PCRF
PDN -PGW
I-/S-CSCF
V-PCRF
H-PCRF
PCRF
VoLTE/ IMS Alternative 1 VoLTE/IMS Alternative 2 VoLTE/IMS Alternative 3
PDN-PGW
PDN-PGW
P-/E-CSCF I-/S-CSCF
P-/E-CSCF SIP Signaling SIP Signaling
SIP Signaling
VoIP Bearer
VoIP Bearer
VoIP Bearer
Serving-GW
Visited Network (of the A-Party)
Home Network (of the A-Party)
Visited Network (of the A-Party)
Home Network (of the A-Party)
Terminating Network (Home of the B-Party)
Terminating Network (Home of the B-Party)
P-/E-CSCF I-/S-CSCF
UE (A-Party)
UE (A-Party)
UE (A-Party)
S8
Gm Gm
S9 S9
Ic/Mw
13 © Nokia Siemens Networks
Public Safety Broadband
1. Routing of media for Voice & video over IMS when call originator is Roaming should be at least as optimal as that of current Circuit Switched (CS) domain. 2. The charging model for roaming used in CS domain shall be maintained in VoIMS. 3. Allow the HPMN to decide, based on service and commercial considerations & regulatory obligations, to enforce the routing of the traffic to itself (home routing).
GSMA IR.65 Operational Requirements for IMS Voice and Conversational Services
14 © Nokia Siemens Networks
Public Safety Broadband VoLTE (IR.92) in terminals
VoLTE (IR.92)
Terminal industry trend is that VoIP (VoLTE IR.92) client will be integrated in a chipset
– not in a terminal as an separate application
2G/3G CS
voice
CSFB
IMS VoIP LTE
CSFB and CS
2G/3G CS voice
CSFB VoLTE client (GSMA IR.92) run on the modem processor while the application processor can enter sleep mode. The same approach is used for CS voice.
Today VoIP (application) runs on top of OS in the application processor which is power hungry.
VoLTE (GSMA IR.92) calls are invisible to end user as those will be done same way as CS call – press the green button. Voice clients (CS, CSFB, VoLTE, SRVCC)
integrated in chipset.
15 © Nokia Siemens Networks
Public Safety Broadband
Agenda
• VoLTE Overview
• What is VoLTE
• VoLTE for FirstNet
16 © Nokia Siemens Networks
Public Safety Broadband LTE Voice implementation depends on operator conditions
Coverage evolution VoLTE implementation Market situation
Capacity demand
LTE spectrum
Carrier Relations
Existing network
17 © Nokia Siemens Networks
Public Safety Broadband
What Is Needed for VoLTE for FirstNet 1. Circuit Switched Fallback (CSFB)
2. Single Radio Voice Call Continuity (SRVCC)
3. Rich Communications (RCS)
4. IMS Centralized Services (ICS)
8. Roaming
7. Lawful Intercept (LI)
6. Emergency Call (911)
5. Domain Selction (T-ADS)
2G/3G Network Partner
2G/3G Network Partner
2G/3G Network Partner
Assumed: LTE Network with QoS, Location and Charging
9. Terminals
18 © Nokia Siemens Networks
Public Safety Broadband IMS Roaming / LTE Roaming Support and Evolution
• Key Outbound Roaming Scenarios for a Firstnet VoLTE Subscriber (with an 1xCS, LTE, 2G/3G UE) roaming in a visited network:
1. visited network that supports: 1xCS 2. visited network that supports: 1xCS, LTE Data 3. visited network that supports: 1xCS, VoLTE/IMS 4. visited network that supports: 2G/3G CS/PS 5. visited network that supports: 2G/3G CS/PS, LTE Data 6. visited network that supports: 2G/3G CS/PS, VoLTE/IMS
SCC-AS
MME SGSN 1xMSC MSC
MME
1xMSC
IS41-MAP MAP S6a
P-CSCF
CSCF
1xHLR
HLR HSS
Terminating Call
2G/3G Network 1xCS Network LTE/EPC Network
Mw
(Visited) IMS Network
Firs
tNet
(H
ome)
N
etw
ork
Visi
ted
Net
wor
k
IMS
UE PDN-GW
PDN-GW
UE (outbound
1xCS roamer)
UE (outbound
2G/3G roamer)
UE (outbound
VoLTE roamer)
TAS
UE (FirstNet VoLTE subscriber)
19 © Nokia Siemens Networks
Public Safety Broadband
FirstNet LTE with CSFB to partner’s 2/3G Partner’s 2/3G network
Firstnet LTE
Roa
min
g in
terfa
ces
LTE GSM/WCDMA
To PSTN
BSC RNC
2/3G MSC/VLR
A
Iu-cs
HSS/ HLR MAP
MME
S6a
SGs
2/3G SGSN
S3
Gs
S3 and Gs are used for ISR. S3 is also needed if PS-HO for CSFB is used. Legacy SGSN requires MME to support Gn/Gp interface. PLMN ID in LTE (PS) and 2/3G (CS) can be different.
Gb/Iu-ps
20 © Nokia Siemens Networks
Public Safety Broadband MOC call flow from LTE to GERAN/UTRAN with redirection
UE/MS eNB BSS/RNS MME MSC RRC Connection Request
RRC Connection Setup Complete with Extended Service Request (MO CSFB)
S1-AP message with CSFB Indicator
RRC Connection Setup
Optional Measurement Report Solicitation
Location Area Update or Combined RA/LA Update (if LAI from radio is different than the one stored by the UE
CS MO Call Establishment
RRC Connection and Extended Service messages
UE makes IRAT measurements from GERAN/UTRAN cells
Redirection procedure
CS Call Setup
RRC Connection Release to GERAN or UTRAN
Location Update procedure
21 © Nokia Siemens Networks
Public Safety Broadband MT call flow from LTE to GERAN/UTRAN with redirection UE/MS eNB BSS/RNS MME MSC
RRC Connection Request
RRC Connection Setup Complete with Extended Service Request (MO CSFB)
S1-AP message with CSFB and Emergency Indicators
RRC Connection Setup
Optional Measurement Report Solicitation
RRC Connection and Extended Service messages
UE makes IRAT measurements from GERAN cells
Redirection procedure RRC Connection Release to GERAN or UTRAN
CS Paging CS Paging
CS Paging
Location Area Update or Combined RA/LA Update
CS MT Call Establishment
Location Update procedure CS Call Setup
Paging Response A/Iu-cs message with paging response Paging Response
22 © Nokia Siemens Networks
Public Safety Broadband
FirstNet LTE with eSRVCC to partner’s 2/3G Partner’s 2/3G network
Firstnet LTE
Roa
min
g in
terfa
ces
LTE GSM/WCDMA
To PSTN
BSC RNC
2/3G MSC/VLR
A
Iu-cs
HSS/ HLR MAP
MME
S6a
Sv
2/3G SGSN
2/3G SGSN
S3
S3 is used for eSRVCC with PS HO procedure (optional). Legacy SGSN requires MME to support Gn/Gp interface.
Gb/Iu-ps
Other VoLte functional elements: PCC/S/P-GW/P-CSCF/ATCF…
S1-U
S5
23 © Nokia Siemens Networks
Public Safety Broadband
UE E-UTRAN MME MSC Server Target UTRAN/GERAN
MeasurementReports
SRVCC Handover to UTRAN/GERAN required (CS or CS+PS)
3GPP IMS
Initiates SRVCC for voice component
CS handover preparationIMS Service Continuity ProcedureHandles PS-PS HO for
non-voice if needed
P S-CS HO response to MME(CS resources)
To eUTRANCoordinates SRVCC and PS HO response Handover CMD
Handoverexecution
SRVCC indicationSRVCC possible indication
VoLTE session ongoing
High level flow for E-UTRAN SRVCC
Request to partner’s 2/3G network via Sv interface
24 © Nokia Siemens Networks
Public Safety Broadband
E/I/S-CSCF BGCF
P-CSCF. BCF, ATCF
A-BGF ATGW MRFP
TAS
S/P-GW
CSFB/SRVCC/MGCF/GMSC
PCRF
eNB
ISC/SIP
Gx
Rx
Iq H.248
Gm/ SIP
CS/IMS-MGW 2G/3G CS/IMS-MGW
Example FirstNet VoLTE Solution Architecture
CS MSS
Mw/SIP
SIP HLR
HSS
SDM MME
Sv,SGs
Mc
Nc (ISUP/BICC/SIP-I)
E (MAP)
SMSC C (MAP)
E (MAP) FirstNet 2G/3G Partner
SGSN
E (MAP)
Recommended