Re: [RFC/T][PATCH][V3] mac80211: Exponential moving average estimate for rc80211_simple

[Stefano Brivio <stefano.brivio@polimi.it>]

On Mon, 26 Nov 2007 22:30:05 +0100
Mattias Nissler <mattias.nissler@gmx.de> wrote:

> This changes rc80211_simple failed frame percentage estimation to use an
> exponential moving average method. Failed frames percentage is sampled
> over time and a smoothed average is computed. This average is examined
> periodically and the rate adjusted eventually.

This can be seen as a particular example of a PID controller [1]. It's
actually a PI controller, with no derivative terms in it. It could be
interesting to implement a regular PID controller.

This is clearly a MIMO model, with the setpoints being a reasonable value
of TX failures and the highest achievable rate, the process input being the
bitrate and the process output being TX failures and successes; and
obviously, the big issue being the implementation without floating-point.
Thus, with some tuning, you could probably get a very good rate control
algorithm.

I just wanted to share this thought ATM, but I'll try to elaborate more if I
happen to have some spare time.

[1] http://en.wikipedia.org/wiki/PID_controller


-- 
Ciao
Stefano