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VoLTE Device Interoperability Challenges
Thomas EyringDirector of Engineering MNO Test Solutions
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 2
Introduction Voice over LTEWhat are the challenges today?
l LTE provides all over IP network, discontinuing the CS-based voice of legacy wireless standards
l No straight forward path to introduce Voice over LTE for MNOs
l OTT application already support Voice in LTE today
l Network operators have the opportunity to differentiate with fully integrated voice service based on IMS/VoLTE and additional rich communication services
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 3
Introduction Voice over LTEFrom IMS to VoLTE
IMS
One Voice
IR.92(VoLTE)
l IMS standardization laid the ground work with an all-over-IP service network architecture already in 3GPP Rel5
l Network roll-out hampered by “IMS complexity trap”
l One Voice Industry Initiative specified a particular profile for voice & SMS over IMS to reduce complexity and specify a minimum feature set
l Includes Single Radio Voice Call Continuity (SRVCC)
l GSMA VoLTE Initiative has adopted One Voice specificationl Focus on entire end-to-end voice & SMS service and
emphasize on roaming and interconnect interfacesl Promoting CSFBl VoLTE is common standard for Voice in LTE
l Now industry standard but is this sufficient?
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 4
VoLTE ChallengesInteroperability of VoLTE deployments
l Goal of VoLTE was to narrow down IMS options for voicel Most MNO roll-outs of VoLTE are not interoperable. Issues
arel different EPS bearer configurationl proprietary simplification of SIP call flowsl operator specific introduction of SIP headersl different security configuration (AKA, IPsec, …)
None interoperable roll-out of VoLTE hampers national as well as international roaming and leads to fragmentation in the market
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 5
GCF / PTCRBStatus IMS / VoLTE related Work Items
IMS Call Controll P-CSCF discovery, registration, authentication, subscription
About 50% validated in GCF and PTCRB by R&S
SMSl MO / MT SMS (3GPP TS 34.229-1 section 18)
100% validated in GCF and PTCRB by R&S
MTSI (Multimedia Telephony Services in IMS)l SIP session handling and supplementary servicesl 50% validation in PTCRB (GCF started) by R&S
Emergency l IMS Emergency + IMS Emergency IPl Test case verification has started, no validations so far
RCSel OMA based protocol conformance tests for RCSel TTCN-3 under development in OMA
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 6
VoLTE ChallengesService Parity and Standardisation
l Customers expect at least same user experience in VoLTE as they know from CS-Voice.
l CS-Voice is tightly specified based on 3GPP NAS protocols CC/MM includesl State machines & timers l Error and failure case specification
Implementation of IMS/VOLTE is much more proprietary and varies from device to device, e.g. • Device behavior when receiving SIP error message• Device behavior when LTE connection is lost
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 7
Technique Description Use Case
Dual Stand-by Independent radios for Voice (GSM, 3G, CDMA2000) and Data (LTE)
Useful to provide voice over legacy network
Circuit Switched Fallback (CSFB)
HO to legacy technology to establish common CS callLTE connection suspended
Required for roaming support
Single Radio Voice Call Continuity (SRVCC)
During VoLTE Call HO to legacy technology and establish common CS callCS voice handled as IMS service
Maintain speech connection when running out of LTE coverage
Interworking of VoLTE with CS-Voice
• CSFB and SRVCC support is necessary to cope with handover and roaming scenarios
• Dual Stand-by is required in selected markets
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 8
VoLTE Emergency Call Statusl VoLTE Emergency attach request is specified in 3GPP Rel9l In addition regulatory requirements required support of
Location based Servicesl US FCC E911: requires that location information is automatically
reported by UE to identify the closest PSAP (Public Safety Answering Point)
l In Europe, mobile operators have to supply the „best location information available“ per requirement of the EU directive E112
l Location Based Service (LBS) can be achieved by various combination of different techniques and protocolsl Based on satellite (GPS, GLONASS) or network (OTDOA, eCID) l Based on C-Plane protocol or SUPL 2.0
Different combinations of VoLTE Emergency Call and LBS services needs to be considered to cope with local regulatory requirements
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 9
Functional
Testing
Performance
Testing
Quality
Testing
IMS Device Testing OverviewAreas of Testing LTE attach procedure IMS registration Session Initiation Protocol (SIP) Audio: echo verification in
loopback mode
Verify audio quality using PESQ® and POLQA® algorithm Acoustic analysis: 3GPP TS 26.132
R&S®CMW500 LTE Call-box
R&S®UPV Audio Analyzer
R&S®CMW500 LTE Protocol Tester
end-to-end performance Impact of noise and fading IP traffic impairment (Jitter, Packet loss, Delay)
R&S®CMW-PQA
R&S®VTE Video Analyzer
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 10
Summary
l Deployment of VoLTE is ongoing and already >30 MNOs have launched VoLTE Services.
l UICC interoperability is not given in most cases due to VoLTE “dialects”
l Support of VoLTE / CSFB / SRVCC / VoLTE Emergency Call remains a challenging target for some time
l Required activities to avoid further fragmentation of the market and lay foundation for VoLTE roamingl VoLTE implementation guidelines as propose by GSMAl and extend to GCF/PTCRB
l Lessons learned from IR.92 should be considered for IR.94 (Video over VoLTE), VoLTE over WiFi and RCS
ITU Workshop “Voice and Video over LTE”
1st December 2015 | 11
Thank you for your attention
