ath(4) and 802.11g speed

JoaoBR joao at
Thu Mar 9 07:46:55 UTC 2006

On Thursday 09 March 2006 01:09, Sam Leffler wrote:
> Daniel O'Connor wrote:
> > In any case I imagine there is no point forcing it to use 54Mbit - it
> > will negotiate the highest speed it can manage based on signal strength
> > and hardware support (for the AP and the card) automatically.
> >
> > I suspect forcing 54Mbit will either not work at all (because the signal
> > isn't strong enough or your hardware doesn't support it), or it will
> > negotiate a speed up to 54Mbit (which would result in no functional
> > change).
> Locking the transmit rate (and that's what setting the media does) can
> be useful but rarely when operating in any configuration but a p2p setup
> where the endpoints are fixed.  The algorithm used to select a transmit
> rate for a frame is very important to getting good performance.  John
> Bickett's sample algorithm, typically used with ath, is pretty good but
> could still be improved.

I am not so sure that the speed is locked when setting to standard speed what 
is 54 for 11a/g and 11Mbps for 11b

the card then chose the the best speed it can negociate with the AP and even 
if connected in 54 or 11Mbps it chose the next lower speed when packages are 
lost but goes up soon the conditions are better again.

but when you set the card to a lower speed as 2 or 5.5 you force it to stay at 
this speed which may be usefull in noisy environments or longer distances 
especially adhoc connections. 


A mensagem foi scaneada pelo sistema de e-mail e pode ser considerada segura.
Service fornecido pelo Datacenter Matik

More information about the freebsd-stable mailing list