This document provides an overview of Voice over LTE (VoLTE) including its history, requirements, architecture, and advantages. It discusses how VoLTE allows voice calls to be carried over the LTE network rather than traditional circuit-switched networks. Key points covered include VoLTE's improved voice quality and capacity compared to 2G and 3G, its use of quality of service mechanisms to prioritize real-time voice, and fallback options when LTE coverage is unavailable like Circuit Switched Fallback. The document also reviews the end-to-end network architecture and call handling process to enable VoLTE.

2. Contents
• Introduction
• LTE
• The New Conservation Experience
• History
• Requirements for Voice over LTE
• Architecture
• QoS & bearers
• Voice for the 4G LTE subscriber
• Circuit Switched Fallback (CSFB)
• Network Architecture End-to-End

3. Continue……
• Call Handling
• Applications
• Advantages
• Conclusion
• References

4. Introduction
• Voice over Long-Term Evolution (VoLTE) is a standard for high-speed
wireless communication for mobile phones and data terminals.
• VoLTE has up to three times more voice and data capacity than 3G UMTS
and up to six times more than 2G GSM.
• Designed to carry both voice and data.
• Supports voice as well as data transmission.
• Voice quality remains excellent even if the data connection is on.

5. LTE
• LTE stands for Long Term Evolution.
• Primarily designed to be a data-only technology.
• Does not natively support voice transmission.
• Quality of voice reduces if data connection is left on.

6. The New Conservation
Experience
• A better user experience: Gained by making video and messaging as easy as
voice.
• Connected communities: Users can easily contact friends and family over
social network.
Figure 1: Conservation Experience

7. History Of Mobile Communication
• 1G ~1980
• analog signal
• 2G ~1990 (Global system for mobile communication: GSM)
• SMS, circuit switched data transfer 9,6kbps
• 2.5 ~ 2000 (General packet radio service: GPRS, Enhanced data for GSM
evolution :EDGE)
• Packet switched data transfer 50-150 kbps
• 3G ~2000 ( Universal Mobile Telecommunication System: UMTS )
• 2 Mbps
• 4G ~2010 (LTE)
• ~100Mbps

9. Requirements for Voice over LTE
Subscriber Requirements
• Telephony
• Quality
• Battery
Carrier Requirements
• Cost
• Complexity
• Efficiency

10. • The 4G VoLTE network is composed of the evolved universal terrestrial
radio access network (e-UTRAN) and the Evolved Packet Core (EPC).
Figure 2 : VoLTE network architecture
Architecture

11. QoS & bearers
• Typically multiple bearers are running on a UE at the same time, for
example, covering the default bearer, streaming video and an in-
progress VoLTE call.
• Unlike 2G and 3G packet data services, which treat everything on a first-
come, first-served basis.
• A real-time voice session (such as VoLTE) can tolerate more missed bits
because the ear does not notice it as quickly as the eye.
• In this priority is set for all functions.

12. Voice for the 4G LTE subscriber
Voice Options
• Voice over LTE (VoLTE)
• Circuit switched fallback (CSFB)
• Simultaneous voice and LTE (SV-LTE)
• VoLGA, Voice over LTE via GAN

13. Circuit switched fallback (CSFB)
• The Circuit Switched Fallback technique is the widely accepted solution for
voice and messaging services within LTE.
• To prevent a VoLTE call from being dropped in such cases, a handover
mechanism allows the call to continue as a CS call.
• This process is enabled by the Single Radio Voice Call Continuity (SRVCC)
mechanism.
Figure 3 : Handover from packet-switched voice to circuit-switched voice

14. Simultaneous voice and LTE (SV-LTE)
• Simultaneous Voice and LTE (SV-LTE) is implemented by some device
manufacturers for CDMA operators.
• An SV-LTE smartphone actually has two simultaneously active radios.
• One radio provides CDMA 1xRTT(single-carrier radio transmission technology) for
circuit voice, and a second radio provides 4G LTE for IP data.
• In this way, an SV-LTE handset equips the CDMA operator with the clear
subscriber value of simultaneous legacy voice and 4G LTE data.
• However, such a handset might be larger or heavier due to the need for two
simultaneously used antennas plus a larger battery.

15. Voice over LTE via generic access
(VoLGA)
• Another fallback technique suitable for LTE is called the Voice over LTE via
Generic Access method (i.e. VoLGA) an industry based initiative
introduced in 2009.
• Voice over LTE via generic access (VoLGA) is a true voice-over-LTE
solution which enables LTE mobile devices to access legacy systems and
services without having to leave the LTE domain.
• Generic Access Network architecture (GAN) which was developed to
support circuit switched services such as SMS messaging in an IP-based
network it quickly gained attention and became one possible candidate for
LTE's voice and messaging requirements.

16. • VoLTE includes voice in full duplex, either in a one-to-one or one-to-many
communication format.
• For end-to-end Full-HD Voice calls to succeed however both the caller and
recipient's handsets as well as networks have to support the feature.
Figure 4 : VoLTE end-to-end (simplified view).
Network Architecture End-to-End

17. Call Handling
• The LTE radio network uses admission control to ensure that there are
sufficient resources and capacity for the network-requested voice bearer.
• End-to-end voice latency is on par with or even better than 2G/3G CS.
Figure 5 : Signaling bearer and a dedicated bearer for voice

18. APPLICATIONS
• Near/far noise cancellation.
• Call continuity across networks, push-to-talk over cellular, group calling.
• Video telephony.
• Enhanced address book features such as status, location, communication
capabilities and pictures.

19. ADVANTAGES
• HD Voice.
• More Capacity with good quality.
• Video Calling.
• Power saving of 30%.
• Provides rapid call establishment time.

20. CONCLUSION
• The increasing demand and increased number of users has forced the
communication industry to modify technology from 1G to 4G.
• Operators can use VoLTE to innovate and extend mobile voice beyond a
traditional call.
• Voice can become a feature of other services, such as navigation, e-
commerce, social networking, status updates and augmented reality
applications.
• VoLTE time is now.

21. REFERENCES
• Alcatel-Lucent, Service Consistency for Today’s VoLTE Subscribers,
2011,M201110952,www.alcatel-lucent.com/4g-consumer-communications.
• GSMA, April 2014, IR.92 IMS Profile for Voice and SMS v. 8.0, available
at:http://www.gsma.com/newsroom/wp content/uploads/2014/06/ IR92v8-
0.pdf.
• F.Alomary and I. Kostanic, “Evaluation of Quality of Service in 4th
Generation (4G) Long Term Evolution (LTE) Cellular Data Networks”,
Universal Journal of Communications and Network ,Vol. 1, pp. 110-117,
2013.