Power levels / HostAP documentation

[Jean Tourrilhes]

On Fri, Oct 31, 2003 at 10:04:08AM -0500, Henry Qian wrote:
> 
> 
> > -----Original Message-----
> > From: Jean Tourrilhes [mailto:jt at bougret.hpl.hp.com] 
> > Sent: Thursday, October 30, 2003 2:12 PM
> > To: Henry Qian
> > Cc: hostap at shmoo.com
> > Subject: Re: Power levels / HostAP documentation
> > 
> > 
> > On Thu, Oct 30, 2003 at 01:47:11PM -0500, Henry Qian wrote:
> > > Jean,
> > > 
> > > What is the definition of Link Quality?  I have read Link 
> > Quality in 
> > > man page of iwconfig, still don't get its exactly meaning.  If I am 
> > > implementing a driver, how do I present this number?  Since 
> > it usually 
> > > takes the form of x/y, does -y represent a noise floor?  Or it's a 
> > > free expression for wifi driver to decide whatever number 
> > it likes to 
> > > use, so different cards might have different meaning?
> > 
> > 	Yes, it's a totally fuzzy number, and that's the beauty of it.
> > 	If you talk about weather, you can usually say :
> > 		Weather : good - fair - average - crap
> > 		Temperature : 25C - 10C - 0C
> > 	Signal strenght is like temperature, it has a precise 
> > physical definition agreed on by everybody. Link Quality is 
> > like weather quality, everyone has it's own scale.
> > 	So, just decide what you think is most useful, and 
> > stick it in there.
> > 
> > > Thanks,
> > > 
> > > Henry
> > 
> > 	Jean
> > 
> 
> It still would be nice to have a definitive formula for Link Quality.  To wifi driver it's a snapshot or near past average, not a forecast and it has a very limited number of link quality indicator inputs, like rssi, current transmit rate, retry counter, error counter, etc.
> 
> Henry

	If you want something with a well defined formula, just use
signal strength. dBm have a very precise definition and are used by
all the pro.
	For link quality, I prefer to leave space for creativity.

	Jean