Follow UP : LTE and Voice

This month it is LTE and Voice!!  In the previous blog we have seen the problems/developments in voice over LTE.  Lets dig deeper into the basics!!
What exactly is Voice over LTE.

As previously said, LTE is an all IP network and voice call in GSM, UMTS and CDMA2000 are circuit switched. Currently all the calls go on 2G/3G systems.

There are several proposed approaches. The chart below shows these.

There are four approaches. Lets discuss them one by one.

1. Circuit Switched Fall Back (CSBF): This is the simplest option. In this case LTE is data only network and whenever there is a voice call to be received/initiated , it will fall back to circuit switched domain(2G/3G).

2. Simultaneous voice LTE (SV-LTE) : This is a handset based solution. The device works simultaneously in the Circuit switched and  LTE(packet switched) 
modes providing voice services and data services respectively. Can you think of the battery life of such a device??

3. Voice over LTE via GAN (VoLGA) :  This concept came up to unable LTE users to receive voice/SMS as they transition between LTE/GSM/UMTS. This was an interim solution.


4. One Voice/Voice Over LTE (VoLTE) : This approach eliminates the dependency on the circuit switched networks. This will facilitate LTE networks to be stand alone networks. It is based on IP Multimedia Subsystem (IMS).

The key technical requirements for VoLTE :
1.  IP Multimedia System (IMS) 
2. SMS over IP
3. Multimedia telephony.
4. Single Radio Voice call continuity 

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LTE and Voice

I was telling my father about LTE the other day, my father is not really a super tech-savvy person. According to him, cellphones are devices invented to make and receive calls. So he asked me a very simple question, what does LTE offer to me , a person who doesn't use any data/Apps. Then I started thinking..I am missing on a big part.. LTE and Voice

Since the beginning, whenever anyone starts talking about LTE everyone starts talking data..Is the "LTE = higher data rates" only valid equation. What about LTE and Voice. Does LTE even support voice? Can the LTE networks be stand alone networks and function without the existing 2G, 3G networks? Some valid and some invalid questions!!

I started searching for articles.This week I read an amazing article on the qualcomm blog by Mr Prakash Sangam , "Evolving your voice – VoLTE, WCDMA+ and more"..And all these questions started occupying my mind..The author starts with a similar question and the best part is he provides us with the list of current and future solutions/developments clarifying the equation between Voice and LTE!!
Do read this article on qualcomm blog page.

After reading this article I actually started reading more about VoLTE. VOIP over LTE. The operators have a BIG say here, they are currently satisfied with the present 2G/3G network for voice telephony and secondly the vendors and devices are not ready yet!!

Another interesting report is from the LTE World summit (May 2012) "4G Voice Still Just a Whisper"!! The title clearly explains the current status of Voice and LTE. So there is still a great deal of efforts needed in VOIP /Voice in LTE. It is predicted that Voice over LTE will not be widely used till 2013-2014..


Now lets see why is Voice over LTE such a big fuss word! As we are fully aware that the LTE standard only supports packet switching with its all-IP network. The voice calls in the previous standards, like GSM, UMTS and CDMA2000 are circuit switched, so with the adoption of LTE, carriers will have to re-engineer their voice call network. The devices should be capable of roaming hubbing. In no LTE-coverage areas, the device should fall back to 2G/3G networks..

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