Voice – Bearer Aware, Bearer Adaptive or Bearer Agnostic?

It seems I am not the only one thinking quite positivity about Voice over LTE via Generic Access Network (VOLGA). Recently, Ajit Jaokar posted an interesting article in which he mentions that with VOLGA, the traditional circuit switched voice service becomes a bearer aware application, as it can choose between a 2G circuit bearer, a 3G circuit bearer and an IP based bearer over LTE. All seamlessly with handovers during the call with all bells and whistles attached!

An interesting way to look at it even more so as the bearer awareness does not come into play on the mobile device but actually in the network. This is because the controlling entity for the voice call, the mobile switching center (MSC), sits in the network and is informed by the network that a different bearer should be selected. It can then decide to go along, arrange for the network to prepare the handover and then instructs the device to make the jump.

So maybe VOLGA makes voice even more than bearer aware!? So far the term 'bearer aware' has mostly been used for applications being aware what kind of networks are available at a time and then make a choice as to which IP network to use or to stay put in case a network is available but the cost attached to it is too high to make the application feasible.

In the case of voice, however, the service can ensure continuity by jumping from one bearer to another. So terms like 'bearer adaptive' or maybe even 'bearer agnostic'  come to my mind, because that voice call will just work over any kind of network the device supports.

It could even work over the Wi-Fi you have at home if you extend the idea of VOLGA. Not for the moment, as the standard currently focuses on LTE, but in the future, who knows?

5 thoughts on “Voice – Bearer Aware, Bearer Adaptive or Bearer Agnostic?”

  1. I am reading about VoLGA lately, and found that is interesting.

    Operators seem adopting different attitude and action on how to bring voice service into LTE.

    My consideration is, does an UE need to support all of them including this VoLGA and CSFB etc, for roaming (especially in another country)?

  2. I also have been reading about VoLGA. I have couple of questions. First how will operator migrating from CDMA to LTE implement this. Second recently i was reading about CS over HSPA, in that basically you would use HSPA radio bearers but core would be legacy CS. Can such a thing be used in LTE ?

  3. Hi Rohit,

    Good questions, thanks!

    CDMA migration: Not sure, so far I’ve only seen the specifications for a GSM/UMTS MSC. I don’t know if that can be applied to a CDMA mobile switching center as well. I guess Verizon would have to join the VOLGA club to make that work.

    CS over HSPA: It would be transparent for VOLGA as the MSC is not really involved in the decision of whether the call goes over a dedicated air interface bearer or over the shared channel.

    Kind regards,

  4. Hi Xiaowei,

    I think that since there is no consensus in the industry, mobiles are likely to support more than one method. Not ideal…


  5. Martin

    Thank you for your reply. I wonder how easy or difficult will be for carriers such as Verizon to route voice calls through 1xRTT core similar to VoLGA approach.

    As as you said MSC/RNC’s would not be aware, i think this can be done by software upgrade at nodeB’s/RN’s to map the voice traffic to shared channel and the schedular shall take of the rest.


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