Voice over LTE General Overview

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2. LTE: An IP Packet Only Network. ▫ LTE: Long Term Evolution. • Wireless network beyond 3G. • Enhanced UTRAN (E-UTRAN). • System Architecture Evolution ...
Voice over LTE Overview James Ni 03/17/2010

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LTE: An IP Packet Only Network 

LTE: Long Term Evolution • Wireless network beyond 3G • Enhanced UTRAN (E-UTRAN) • System Architecture Evolution (SAE)

E-UTRAN

SAE EPC 2

LTE: Interoperability with 2G and 3G

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LTE: Voice and Interoperability with 3G  

LTE: No native voice and SMS Three solutions • All VoIP Solution -- IP only signaling and bearer – VoIP LTE – VoIP UMTS – Both IMS oriented



VoIP in LTE and SRVCC in UMTS – SRVCC  CS voice and PS signaling  Compatible with UMTS/GPRS/GSM

– VoLGA – Voice over LTE via Generic Access  CS core and PS access  GAN access: GSM + WiFi + …  VoLGA Access Network Controller (VANC) connect MSC and LTE core  In LTE: VANC = external IP node  In GSM/UMTS VANC = BSC / RNC



Circuit Switched Fallback (CSFB) – No VoIP – Only CS voice – Fallback to 2G or 3G for voice services

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LTE Voice: IMS based all IP Voice Service

    

IP Signaling (SIP, H.248, Diameter etc.) IP Bearer IMS to control the services delivery IMS to interwork with 2G / 3G CS AS to provide services and features Circuit Circuit Switch Switch Network Network

IMS

E-UTRAN E-UTRAN E-UTRAN E-UTRAN

EPC EPC

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GSM GSM/ / UMTS UMTS

LTE Voice: VoLGA 

Voice Over LTE via Generic Access • Access gateway (VANC) to bridge 2G/3G with LTE – To LTE, VANC is an external IP node – To GSM / UMTS, VANC is an BSC / RNC



UE registration: – – – –



UE register with MME MME retrieve subscriber information from HLR/HSS Establish security tunnel between UE and VANC over LTE UE register with MSC through security tunnel and VANC

Voice calls are established using 2G / 3G procedures via security tunnel – VANC does TDM/ATM  IP translation for bearer traffic



Handoff – MME initiates the handoff – VANC executes the handoff – Invokes standard GSM/UMTS handoff procedure – SRVCC assists (?)

VoLGA Architecture 6

LTE Voice: Circuit Switched Fallback (CSFB) 

CSFB • No VoIP • Pure CS voice services • Registration – UE register with MSC via MME

• Calls – Originates MO calls via 2G / 3G CS network – Pages UE via MME/eNB for MT calls, calls are setup via 2G /3G CS network

SGs

MSC

BSC/RNC

NB Registration Calls

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