On 11/21/16 11:13 AM, Jean-Francois Mezei wrote: > 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"
the radio bearers described are are the signaling radio bearers. their existence is independent of of the link/mac layer configuration. The mac layer layer (e-utra) exists below the l2 bearers. https://en.wikipedia.org/wiki/E-UTRA > 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. these are URBs they are terminated between the UE and the P-GW > 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. SRB and URB are the l2 presentation of the tunnels established for user and signaling traffic. > > >
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