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[ham-80211] Re: WEP encryption?

David Young dyoung at pobox.com
Sat Jul 31 23:35:34 UTC 2004


On Sat, Jul 31, 2004 at 03:34:33PM -0400, Drew Baxter wrote:
> Supposedly Broadcom has concerns that people will go into military bands if 
> they release the driver.  Really I see this as a situation where people 
> could also buy a Ham radio and irritate public safety by modifying it.

I know that Broadcom has explained its closed wireless sources and closed
documentation along these lines, but I think it is just a smokescreen.
Broadcom has historically been reluctant to provide information for
open-source drivers, even for their ethernet chips, and a little bird
has told me that the wireless product manager at Broadcom is hostile
to open source.  I think the attitude at Broadcom, and at a lot of
semiconductor companies, is that open sources are the sieve through which
their Intellectual Property passes on its way to competitors.  Granted,
a driver exposes a lot of product information, but it's not the kind of
information that gives these semi companies an edge over the competition.
legitimate concern here.  The Atheros radios 

I think it was Atheros who first explained that it could not open-source
the *entire* madwifi (linux)/ath (bsd) driver because *the FCC said
so*.  Well, if you look at the rules that Atheros said applied---the
software-defined radio (SDR) rules---you find that a manufacturer
*elects* to certify under those rules.  I cannot find anywhere in the
FCC ID database that any maker has certified an SDR, let alone Atheros.
There is something else going on here.  Once again, first priority
is that Atheros wants to protect its IP.  My best guess is that it is
regulations in the European Union, not in the U.S., that require for
parts of the Atheros driver sources to be closed.  If somebody can cite
the U.S. rule that requires closed sources, I would sure like to see it!

> People are going to make illegal use of things if they so choose.
> shouldn't ruin moving forward for everyone because of the potential of some 
> bad apples.

I agree.

> I think that the only reason why the SVEASoft firmware allows for up 
> through channel 14 is because the broadcom driver probably lets you set the 
> channels for any country and doesn't have a country lockout in the firmware 
> itself.  But that is an interesting observation and perhaps something to 

I don't know about Broadcom's, but most new wireless cards are
firmware-free.  The host computer sets the channel by programming a
phase-locked loop in a synthesizer IC.  The host sets the transmit power
by writing a register in the baseband processor (basically this is the
RF modem) or in the transceiver.  The host can program other things, like
the carrier-sense threshold.  I think you can set it high enough that it
is effectively "infinity."  This will disable the CSMA/CA access scheme
so that you can try alternatives that are oftentimes more efficient.
The alternatives go by the names TDMA, SEEDEX, etc.

Dave

-- 
David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933




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