I am confused when
reading the parameters in 11.13.6 and 11.13.7 (Maximum Sustained Traffic Rate,
Maximum Traffic Burst). These parameters say to describe in the uplink the
policing needing to be done by the SS and in the DL the policing needing done by
the network.
In the UL, is there
a need for the SS to do this policing? The BS scheduler sets the transmission
allowance, so why should a SS police?
I can see a use for
similar parameters as described in these chapters, but then in a system in which
the BS limits the maximum data rate transmission to the SS for the case where
the SS is limited in its output data rate. So: if the SS MAC can only
transmit to the user x bps and has a memory limit y, the BS from this could
shape the traffic to the SS in order to not overflow the SS memory requirements.
This might impose some larger queuing on the BS, but this can be vendor
implemented.
As I see it, the
maximum traffic burst (11.13.7) would only have any use if the egress link speed
on the SS (from the MAC to the end user) is given and lower than the airlink
speed, allowing for a shaping such as described above.
The 11.13.14
(Maximum Latency) parameter seems to be an additional input to a shaped
connection only, so that I can define where I have to be within the min and max
rate to achieve the latency target. On the other hand, this could conflict with
the burst parameter, because we would need to potentially exceed a burst limit
and sustained traffic rate to achieve a given latency. Anybody has any thoughts
on this?
On 11.3.8 (Minimum
reserved traffic rate), is there a mechanism described for the case of
overbooking (all links have traffic to transmit, the aggregate available
traffic is beyond the available BW)? Should all traffic then be derated
proportionally to fit into the available BW? Or is this vendor
defined?
On 11.3.9 (Minimum
tolerable traffic rate), the section as a whole and the definition of T is
confusing. Should T be a vendor defined "fixed" sliding window? If not, how is T
defined? Isn't this parameter really only a watchdog value that is a
different expression for maximum latency? I don't see how this could be
used to realistically define shaping, because you cannot be clairvoyant about
your ingress queue's future to make sure the traffic distribution fulfills
this minimum tolerable requirement? As I said, very confusing
....
Thanks,
Steve