We consider unicast equation based rate control defined as follows. A
source adjusts its rate primarily at loss events to f(p) where p is an
estimator of loss event ratio. Function f is typically the
loss-throughput formula of a TCP source. In absence of loss events,
the send rate can be also increased by an additional mechanism. We
suppose the estimator is unbiased estimator of the loss event interval
(amount of data sent between two consecutive loss events). Indeed, for
the loss event intervals fixed to some value, the throughput x
satisfies x=f(p). However, if loss process is random, it is not clear
how the throughput would relate to f(p). If x<=f(p), we say the
control is conservative. We derive a representation of the throughput,
and obtain that conservativeness is primarily due to various convexity
properties of function f, and variability and correlation structure of
the loss process. In many cases, these factors drive the control to be
conservative, but we also show some reasonable cases of
non-conservative control. However, having observed that our source
should experience larger long-run loss event ratio than TCP would, non
TCP-friendliness becomes less likely. In our study we do not consider
the effects involved due to randomness of the round-trip time.
References:
M. Vojnovic and J.-Y. Le Boudec
the Long-Run Behavior of Equation-Based Rate Control
M. Vojnovic and J.-Y. Le Boudec
Observations on Equation-Based Rate Control
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