swmike at swm.pp.se
Sun Mar 15 03:23:59 EDT 2015
On Thu, 12 Mar 2015, Narseo Vallina Rodriguez wrote:
> Control-plane latency can affect more than you think and the
> control-plane dynamics can be very complex, including also promotions
> and demotions between UMTS channels to HS(D/U)PA(+) channels which also
> increase user-plane latency. The latter case affects more during long
> flows as a result of fairness policies implemented by the RNC as the
> number of HSPA channels are limited (each HSPA category has a defined
> number of channels using TDM).
Ok, I understand you're trying to get this right, however I don't see this
as the most probable explanation for the use-case described.
Most of the time for this use-case, you'll see the HSPA channels get
properly established after approximately 1 second, and they'll stay up
until the transfer is done.
One RNC vendor I have fairly well knowledge of, would 400 packets of
buffering in the GGSN->RNC->eNodeB->Handset direction. I don't know about
With half a megabit/s of buffer drain, that means max 10 seconds of
buffering if my calculations are correct. There can potentially be
buffering in the GGSN/SGSN as well. This is if everything is working
perfectly. If there are other problems, the drain rate might be slower
than half a megabit/s and this might induce further latency.
Mikael Abrahamsson email: swmike at swm.pp.se
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