Actually,
Not true, you mention 802.11, not 802.11b. I have been in a vehicle (3 years
ago) crossing cells driving down I95 near Melbourne, FL doing 80Mph without
dropping a packet. We were doing this with 802.11 while downloading mail
with lots of attachments and surfing the web without a burp and not always
with LOS. To be fair, our 802.11 has a patented seamless high-speed roaming
that does 20ns switching. They use true time/space antenna diversity (native
in the equipment) to assist with the NLOS ability and multipath mitigation.
The company was (is) Airwire.net. Now that same vehicle is fitted with a
camera that can be panned and zoomed from an Internet connection while
mobile at high speed. it is a somewhat famous "rolling billboard" since it
is a white Hummer with Airwire.net airbrushed along the side and a
plexiglass dome-covered high res camera on the roof and several antennas.

These type networks, by the way have been implemented fairly large scale. We
routinely implement these type networks for police and fire departments.
This all just part of the great big unlicensed world that that most are not
even aware exist...and they do...and they have for several years.

Patrick J. Leary
Chief Evangelist, Alvarion, Inc.
Executive Committee Member, WCA/LEA
[EMAIL PROTECTED]
Ph: 760.494.4717
Cell: 770.331.5849
Fax: 509.479.2374


-----Original Message-----
From: Kevin Lahey [mailto:[EMAIL PROTECTED]]
Sent: Friday, December 06, 2002 6:07 PM
To: [EMAIL PROTECTED]
Subject: [BAWUG] 802.11 at speed?


I'm curious about using 802.11 from my car.

No less an authority than Jim Thompson explained to me at BAWUG
last night that 802.11 was useless when the two communicating 
systems had a greater than 40-mph speed differential.  This is
apparently due to the doppler shift.

As he pointed out, this wouldn't be a big problem with cars driving
past access points, but would make it tough to put a directed
antenna pointing down the road, since the cars would close in
on it at fairly high speeds.  I guess an omni way off the side of
the road could provide service for a reasonable distance.

Could anybody expand on this for me?  I have to admit that I've
had visions dancing in my head of in-car access for quite awhile,
and I'd hate to think that it was unlikely to work...

Thanks,

Kevin
[EMAIL PROTECTED]
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