Distance Problems

John Breeden jbreeden at plumhall.com
Thu Aug 14 13:40:46 EDT 2003

It's not the Prism chipset, it's the 802.11b protocol itself. Transmissions
are ACK'd by the receiver. ROUND TRIP distances greater than 20-30 miles
will exceed the transmitter's timer.

The usual symtom is really low throughput due to retransmissions, though I
wouldn't rule out NO throughput given the distance :-)

The timer is locked in the Prism's firmware and as far as I know Jouni has
never adressesed this "feature" :-)

An interim "solution" is StarOs http://www.star-os.com/. It'll let you set
the timer's timeout - what StarOs calls "long distance links". I am not
associated with StarOs in any way, other than needing to "cure" the same

StarOs IS NOT open source, though it's based on BSD, and BSD's license. It's
cheep - $30 and runs on Intel and Sokeris.

John Breeden
Kamuela, Hawaii

> -----Original Message-----
> From: hostap-bounces at shmoo.com [mailto:hostap-bounces at shmoo.com]On
> Behalf Of Joe Parks
> Sent: Thursday, August 14, 2003 6:04 AM
> To: Michael Shuler
> Cc: hostap at shmoo.com
> Subject: Re: Distance Problems
> On Thu, 2003-08-14 at 01:00, Michael Shuler wrote:
> > We are having a problem with ~20 mile PTP link using hostap as in AP
> > "master" mode on one side and Client "managed" mode on the
> other.  The AP
> > will show the association with good signal and noise levels but
> the client
> > will not associate.  We also tried using a WinXP laptop hooked up to the
> > same PCMCIA card (Zcomax/SMC) and antenna combination with no
> luck...we are
> > however able to associate to an Orinoco AP that is 10 ft. away from the
> > hostap AP system (on a different frequency of course) so we
> know the link is
> > physically possible.  We drove 10 miles close and tried the same config
> > standing on the ground instead of on the grain elevators (150'
> each) and it
> > worked great.  This would lead me to believe that there is some sort of
> > timing issue in the hostap driver that needs to be increased to
> support long
> > distance links.  I noticed that the AP appears to be receiving
> packets but
> > not transmitting any.  Any help would be appreciated.
> I seem to recall someone mentioning a while back (check the archives)
> that the Prism chipset has a very tight timing that prevents links over
> 15 miles.   If there is a way to override this I haven't heard about it.
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