Support of Voice in LTE. Global Service Delivery Unit

Transcription

1 Support of Voice in LTE Global Service Delivery Unit

2 Contents 1 LTE Environment 2 Methods to provide Voice in LTE 3 Services & Technology in VoLTE 4 KT s IMS Implementation Strategy

3 1 LTE Environment 2 Methods to provide Voice in LTE 3 Services & Technology in VoLTE 4 KT s IMS Implementation Strategy

4 1. LTE Environment KT s Data Explosion

5 1. LTE Environment 3 Factors of Mobile Data Explosion Network Infrastructure - High Speed Wireless Networks Terminal - Diverse Smart Devices ( Smart Phones, Tablets, etc. ) Contents - Emerging Data Services ( Smart TV, VoD, SNS, UCC, Cloud Services )

6 1. LTE Environment Korea s Mobile Traffic Status WiFi and WiMax used as data offloading of 3G, and after LTE Deployment mobile data traffic has surpass 3G data traffic. 40% of LTE users has exceeded 3G data traffic Source by Korea Information Society

7 1. LTE Environment Why Voice in LTE? - Voice is still dominant source of the revenue - To provide better experiment of service - Competing with OTT Players Main Factors behind the decision to implement Voice in LTE - Existing Mobile Technology - LTE Spectrum and Coverage Available - Local Market and competitive Conditions Source by infornetics Research 2012

8 1 LTE Environment 2 Methods to provide Voice in LTE 3 Services & Technology in VoLTE 4 KT s IMS Implementation Strategy

9 2. Method to provide Voice in LTE CSFB : Fallback to CS domain when voice service is requested MSC/VLR SGs MME Pros - Origination Voice Call - Terminating (Page Resp) Voice Call - Location Update via SGs - Page via SGs - MO/MT SMS via SGs - Service Consistency - Using existing CS Infrastructure 2G/3G LTE Cons - Call setup delay - Heavy signalling - MSC Upgrade( for SGs interface) - No LTE during voice Switch LTE to 3G

10 2. Method to provide Voice in LTE The Consideration point for CSFB in KT What KT has faced with the CSFB - 4 times heavy signalling due to CSFB - Longer Call Setup times - Call completion ratio dropped slightly at the boarder of the cell KT s Considerations for the CSFB - Signalling Increment : Considered implementing of ISR technology by upgrading SGSN to S4-SGSN - Call Setup delay : Try to reduce the call set-up time by using pre-paging technology. - Call Completion ratio Improvement of call completion ratio by MT roaming forward.

11 2. Method to provide Voice in LTE SV-LTE : Allows UE to access both to LTE and WCDMA/GSM/CDMA simultaneously 2G/3G Core EPC Voice Call Data 2G/3G LTE Simultaneous access Pros - No new modification is required - Using existing CS Infrastructure - Simultaneous service available between voice and data Cons - Cost of Handset increase due to dual modem chip - High battery utilization

12 2. Method to provide Voice in LTE Korea Voice in LTE Deployment before VoLTE. Parameter CSFB SVLTE Standard 3GPP 3GPP2 Operator KT, SKT LGU+ Voice WCDMA 1xCDMA Data LTE LTE Voice calls while Data Traffic LTE Drops while voice call ( Data Traffic is connected to WCDMA) LTE Data and Voice Call Simultaneously Battery Usage of UE Lower than SVLTE More than CSFB

13 2. Method to provide Voice in LTE SR-VCC : Allows UE with active call to switch to CS network when LTE Coverage is lost emsc 2G/3G HandOver LTE to 3G Sv IMS (SCC-AS) Session HandOver MME LTE Pros - Service Consistency - Lower Call Setup times than CSFB Cons - Requirement of an IMS core network ( SCC-AS ). - Session transfer and remote UE update need time - MSC Upgrade ( for Sv interface )

14 2. Method to provide Voice in LTE CSFB Vs SRVCC Parameter SRVCC CSFB Terminal customization Less complex Complex IMS anchoring Mandatory Optional Switching network/ mobility to CS network Only when the terminal roams out of LTE coverage area For every mobile originating and mobile terminating voice call Voice call setup time Less. as time is required only when the terminal moves out of LTE coverage area More. as the terminal needs to establish the voice call session with CS network for every access to call

15 2. Method to provide Voice in LTE VoLTE : IMS based voice over LTE services IMS Core CSCF HSS AS/ MS Pros - Provide Rich Communication Suite - Fast call setup time - Fixed and Mobile Convergence EPC MME SGW PGW Cons - Need Eco system to support inter operation with legacy services and roaming. LTE enb

16 2. Method to provide Voice in LTE Big Picture of KT Network Architecture Migrated from PSTN

17 2. Method to provide Voice in LTE KT Migration Scenario for Voice in LTE Voice Implementation KT Case Voice Over LTE SRVCC - Fully IMS based VoLTE - Roaming and Compatibility with Legacy services issue Circuit Switch Fall Back - Migrate subscriber to IMS equipment - SRVCC required when users is outside the LTE coverage - Intermediate solution - CS service used for telephony and SMS LTE Coverage

18 1 LTE Environment 2 Methods to provide Voice in LTE 3 Services & Technology in VoLTE 4 KT s IMS Implementation Strategy

19 3. Services & Technology in VoLTE HD Voice & Video Calls X times wider bandwidth for voice signal - Bandwidth for 3G : 300 ~ 3,400Hz Bandwidth for VoLTE : 50 ~ 7,000Hz X20 - Up to 20 times faster call setup time - Call Setup time in 3G : 5 sec Call Setup time in VoLTE : 0.25 ~ 2.5 sec X12-12 times improved resolution for video call - Resolution in 3G Video call : QCIF 176 x 144 Resolution in VoLTE Video call : VGA 640 x 480

20 3. Services in VoLTE QoS ( Quality of Service ) Support Provide Quality of Service by separating default bearer channel and dedicated bearer channel in priority Service differentiation with OTT Players UE enb S - GW P - GW PDN PDN Connectio (EPS Session) UE IP address APN Application Default EPS Bearer: QCI5: IMS signal QCI9: OTT mvoip Dedicated EPS Bearer: QCI1: VoLTE Call SDF1 QoS Policy SDF2 QoS Policy SDF3 QoS Policy Filtering IP flow 1 IP flow 2 IP flow 3 IP flow 4 SDF4 QoS Policy IP flow 5

21 3. Services in VoLTE VoLTE vs OTT Service and Network Comparison Packet Core Network Parameter VoLTE OTT mvoip(skype, Viber, KaKaoTalk...) Provider Network Operator Application Provider Core Network IMS Non IMS Interoperability Available to interoperate with legacy network QoS QoS supported QoS not supported Interoperability not supported for all legacy network Quality HD Voice Depends on network environment Battery Consumption Many technology exist Do not care Handover Solution for HO and Roaming Do not care

22 3. Technology in VoLTE Seamless Voice Call Improve the reliability of VoLTE packet transmission through TTI(Transmission Time Interval) Bundling in poor radio conditions. TTI Bundling OFF TTI Bundling On Nack Retransmission Nack Retransmission Ack RV0 RV1 RV2 Ack RV0 RV1 RV2 Same set of bits in consecutive TTI

23 3. Technology in VoLTE Efficient management of Radio Resources Reducing the overhead at air interface by Robust header compression : RTP/UDP/IP header of 40 bytes(ipv4)/60 bytes(ipv6) are compressed 1 to 3 bytes EPC Payload S1 interface Header enb Air interface UE Payload Header

24 3. Technology in VoLTE Through the technology with CoMP(Coordinated MultiPoint), we could reduce Inter-Cell Interference A B VoLTE Data VoLTE resource Adjacent cell interference cancellation A B Case 1 Case 2 Data resource considering interference by VoLTE Resource un-allocation

25 1 LTE Environment 2 Methods to provide Voice in LTE 3 Technology in VoLTE 4 KT s IMS Implementation Strategy

26 KT s IMS Implementation Strategy Ready for Action 2004 Co-developed CSCF with Samsung Electronics 2007 Developed 18 item services on CSCF and Pilot Test ( Video, Conference, MMRB, MMS ) 2008 Developed IMS Equipment for Residential Services ( Voice/Video/Life Convenience Services, FMC ) H Tested and deployed Unified IMS Equipment for Fixed(Residential/Enterprise/Centrex) Services H Tested and deployed Unified IMS Equipment for Mobile(VoLTE/PSVT/RCS)

27 KT s IMS Implementation Strategy Big Challenges for KT IMS - Excessive investment from Service Signaling Load, Dual Homing adoption and Private IP Address Usages - Tuning Interoperability : NGN vs. Fixed, 3G mobile vs. VoLTE - New equipment for New Services : MRF for HD media transformation, Presence server for RCS - Access network QoS : WiFi/WiMAX AP technology vs. Mobile antenna technology

28 KT s Strategy for the Voice in LTE IMS Infrastructure Transformation IMS Platform Improvement Cloud based IMS Configuration CUDB Call Control UE Attach Eq For short Term : - Dual homing for the stability of the service - Integrating Fixed and Mobile CSCF - Integrating HLR and HSS by CUDB For Mid/Long Term : - Cloud Based IMS Platform under CCP ( Cloud based Common Platform ) - TCO Reduction by Lightening IMS Platform

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30 [ Appendix 1 ] The Consideration point for CSFB in KT Signalling Increment - Considered implementing ISR technology by upgrading SGSN to S4-SGSN

31 [ Appendix 2 ] MT Roaming Forward Improvement of call complete Ratio