Atheros wireless card keeps losing signal when signal is too weak

[Paul B. Mahol]

On 3/26/09, Yuri <yuri at rawbw.com> wrote:
> Sam Leffler wrote:
>> Those parameters control the roaming algorithm.  The OP didn't
>> identify their card, freebsd version, or provide any info about their
>> setup or why ifconfig reports "no carrier".  It just sounds like
>> there's a loss in the signal and freebsd gets a beacon miss and tries
>> to reconnect while linux does not.  Once the rssi drops to "10"
>> (presumably 5dBm) minor variations in the environment can become
>> significant (e.g. orientation of a laptop, obstructions, antenna
>> quality) and it's impossible to comment on what's happening w/o
>> detailed information such as provided by athstats.
>>
>> FWIW cardbus cards that follow the reference design closely typically
>> work pretty well and don't benefit from an external antenna.  Vendors
>> of cheap designs often scrimp when it comes to the antenna.  When
>> wireless is inside a case (e.g. a PCI card) then it's worth remoting
>> the antenna but you need to be careful about routing the pigtail(s)
>> and I can't count the number of times I've tracked problems down to
>> faulty cables and/or connections.
>>
>
> I did identify my FreeBSD version and card in my original post, but here
> they are again:
> 7.1-STABLE
> ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
> ath0: <Atheros 5212> mem 0xcffe0000-0xcffeffff irq 16 at device 5.0 on pci0
>
> One way or another little cheap laptop card with ndis driver delivers
> more steady connection then atheros pci card connected to freebsd.
> Maybe like you mentioned Linux has higher tolerance to missing beacons.
> Does it make sense to have a parameter "lost beakon tolerance"?

Perhaps this is what are you looking for:

bmissthreshold count
	     Set the number of consecutive missed beacons at which the station
	     will attempt to roam (i.e., search for a new access point).  The
	     count parameter must be in the range 1 to 255; though the upper
	     bound may be reduced according to device capabilities.  The
	     default threshold is 7 consecutive missed beacons; but this may
	     be overridden by the device driver.  Another name for the
	     bmissthreshold parameter is bmiss.


-- 
Paul