The addition of directional antennas and diversity can really help. The
direction antennas can be placed high up in the cat walks facing down
and using antenna diversity helps mitigate multipath signals. (Of course
with 802.11n both client and AP have multiple receivers and transmitters
for multipath can be used to advantage)
Placing radios under the chairs and tables can attenuate the signal but
will also increase in multipath which will probably negate any gains
with the attenuation. Using the GHz channels is also key as you have so
many more no interfering channels to load balance across.
Earlier this year the University of Maine at Orono hosted 800 middle
school kids in one auditorium using only 802.11b enabled Macbooks which
the students acquired from the Maine Laptop Initiative.
(http://www.maine.gov/mlti/index.shtml) Using reduced power and Yaggi
antennas up in the cat walks we were able to support 650 concurrent
users before things went south. Interestingly we have almost perfect
symmetrical load balancing across the AP's connected to a Cisco4404 with
Aggressive Load Balancing turned on. We only used 1 6 and 11 over a
total of 17 AP's in a 5000 square foot auditorium.
From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of Schwartz, Roger
J
Sent: Tuesday, August 18, 2009 12:16 PM
To: [email protected]
Subject: [WIRELESS-LAN] Large numbers of clients in one room
We used directional panels and four channels 1, 4, 7 & 11 in our
auditoriums, with no complaints. Our Cisco controls handles the load
balancing.
Roger Schwartz
University of Tennessee Health Science Center
Memphis, Tn
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