ATH rate and rssi considerations

Sam Leffler sam at
Sun Feb 3 05:27:24 UTC 2008

JoaoBR wrote:
> I understand the difference between FBSD v.6 and v.7 regarding the RSSI value 
> displayed by `ifconfig ath list stat` on a machine running ath as hostap and 
> the reasons for this change but I think it is not so a very good idea at the 
> end, I explain why.

I am unaware of any change; perhaps you can explain what you see has 

> BTW `ifconfig ath0 list ap` on the client station does it well, showing the 
> signal strength and the noise level.
> By only showing the RSSI value I have no chance to guess what is wrong with a 
> station with a low rssi. Perhaps the client antenna is bad aligned or if 
> interference or something else is drawing the rssi down. If I had the signal 
> strength and it is good I could say it is not antenna alignment but something 
> else by looking at the noise level. So now the sys-adm has a hard time 
> figuring out what is going on.
> At the end it is not only the cosmetic issue, in fact the signal strength of 
> the ATH cards felt down, by 5-10 points or when looking at percentage, by 
> almost 50%. This is measured on the client with any 11abg card and as well on 
> freeBSD with the same ath card as on the AP.

I'm guessing you're asking to have noise floor data available when you 
view the station table but only see it when you list the scan cache 
contents?  If so then it's possible I didn't rev the api's on 6.x as 
they were done on 7.x.  In general I am not backporting many wireless 
changes because the architecture has changed massively between 6.x and 
7.0.  I expect people that want the new functionality will migrate.  If 
that's not possible and someone wants to do the work to backport code 
they are free too--I have far more useful ways to spend the limited time 
I have to work on freebsd.

> *** I like to suggest that this is reconsidered and displayed as in FBSD v.6x 
> or displaying S:N which than would be much more useful on an AP and making 
> sense ***
> At the same time the rssi change came up the RATE displayed when running OFDM 
> as 11g or 11a went amok, any station which had before a at least 12,24 or 
> higher RSSI felt down to 5.5 or often lower, most of them to 1 or 2M. Can you 
> tell why ? In order to answer possible daughts, I change the AP which runs 
> 7-STABLE, lets say a 6.3 or a early 7-Stable (~07/2007) with same configs and 
> wthout touching the antenas the RSSI comes back to normal and the noise leevl 
> is less and at the end the signal strength measured on the client station 
> (whatever 11a/b/g gear) almost doubles.

Sorry, I didn't follow the above.  If there's a bug please file a PR and 
provide the details necessary to followup.  In particular show the 
command lines and displays you have issues with.


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