We have had two commercial cotton farms in Mississippi under complete wireless 
local area network coverage for about 3 years in a current demonstration 
project for precision agriculture applications.  The farm in eastern 
Mississippi has about 1600 acres of contiguous farmland with gently rolling 
land.  We used Alvarion BreezeAccess II equipment with an omni antenna at 
thebase station to communicate to three repeater station located at the edges 
of the farm.  Directional panel antennas connected to BreezeAccess II 2.4 GHz 
radios which then went to Breezecomm radios connected to 120 degree sector 
antennas which broadcast into the farm to the equipment in the fields.  THe 
farm equipment was equipped with Breezecom radios attached to omni antennas.  
All of these radios are frequency hopping spread spectrum radios.  These have a 
range of about 2.5 miles talking from sector antennas to omnis.  Wifi will onlu 
have a range of 1500 feet talking to omnis.  An omni antenna is the only cost 
effective practical device to put on a tractor, combine or truck.  The other 
reason we chose Alvarion is that their radios automatically handle mobility.  
That is, they can automatically hand over communcation from sector to sector as 
boudaries are crossed with loosing connection or packets of data.  This system 
has a user data rate of 2 Mbps.  The base station has a Starband satellite link 
to the Internet.  We have also used DirecWay satellite links.

The other farm is located in the Mississippi Dellta and is set up similarly 
with the exception being that the communication from the base station to the 9 
repeater stations is handled using the Waverider 900 MHz radios.  This farm 
consists of over 12000 acrs of cotton farmland separated by various tree lines 
and is roughly oval shaped with the major axis being 12 miles from side to side 
with the farm headquarters situated in the middle.  We needed the 900 MHz 
radios to penetrate the trre lines to reach the Breezecom repeaters with 120 
degree sector antennas to provide field coverage.  THe siganl from the base 
station reaches almost 10 miles so the entire farm is covered by the base 
station.  However, you must use yagi antenna precisely aimed to get reception.  
Thus, the use of the repeater station using Alvarion Breezecom as before.

I can sen you a copy of the research paper we published if this is of further 
interest to you.


Dr. James M. McKinion
Genetics and Precision Agriculture Res. Unit
P. O. Box 5367
Mississippi State, MS  39762
Ph: 662-320-7449
FAX: 662-320-7528

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