Voice channels (FTTH, DOCSIS, VoLTE)

Jean-Francois Mezei jfmezei_nanog at vaxination.ca
Mon Nov 21 19:13:13 UTC 2016

On 2016-11-21 02:53, Mikael Abrahamsson wrote:

> Typically it travels on another "bearer" compared to Internet traffic.
> http://blog.3g4g.co.uk/2013/08/volte-bearers.html
> Think of bearers as "tunnels" between the mobile core network and the 
> device. 

Many thanks for the pointer. The fact that VoLTE has its own dedicated
APN explains things.

I am however a bit confused on the "bearer" term.

Say a carrier has spectrum in 700Mhz  bands A and B  each 5mhz in each
direction, bonded together as a single 10mhz (each way) channel.

The docunment states:
"R.92 requires the use of a particular set of radio bearers"

Does this mean that a bearer is given specific spectrum within a block
(such as a dedicated colour on a fibre) or that it is just given
dedicated capacity on the single data channel formed by LTE compressing
all of the spectrum into one big channel ?

I though I understood the concept when the name "tunnel" had been
mentioned because I understand that a handset estabishes a "hopping"
tunnel with local IP which changes as you move from tower to tower, but
the tunnel itself maintains a permanent IP connection that remains
unchanged as you move from tower to tower. In such a concept, I could
understand each tunnel (one to the data APN, one to the IMS/VoLTE APN)
having bandwidth allocations.

But when the text brought up "radio bearer", I got confused again sicne
radio implies breaking the spectrum apart, which would reduce LTE
compression efficiency.

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