915 MHz vs 2.4 GHz Frequency Spectrums
LSI Controls has strong experience in wireless digital
communications. Our original research contributed to our
development of a platform that leveraged the benefits of RF mesh
networking (ZigBee), yet did not compete with existing wireless
protocols, such as Wi-Fi. Wi-Fi and ZigBee mesh protocols are NOT
compatible (can cause conflict). Our research indicates that
transmission in the 915MHz ISM band has the following significant
advantages:
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2.4GHz is the resonant frequency of water (hence microwave ovens operate at this
frequency); communication in this band is hindered in the rain, high hu-midity and
heavy fog, since most of the energy in the transmission is absorbed by the water
molecules in the air
915MHz has 20-30% longer range between nodes (endpoints)
Better Signal-to-Noise ratios
Greater support for range extenders, i.e. support of a need to go up to 40 miles
point to point to bridge two subnets
Our testing and analysis showed 915MHz did not require line of sight be-tween
nodes, but 2.4GHz did require line of sight between nodes
915MHz suffered much less loss going through obstructions including trees,
buildings, metal (poles)
Security cameras, Cell phones & Bluetooth all communicate in the 2.4GHz domain
and interfere with ZigBee mesh protocols
LSI Controls has installations with 915MHz antennas inside metal poles on 80% of
the parking lot with excellent reception and signal integrity
Wi-Fi (e.g. office buildings, residential Wi-Fi gateways, restaurants, cafés, etc.)
broadcast in the 2.4GHz domain; they represent a significant potential inhibitor to
alternate communication protocols in the 2.4GHz band.
“ZigBee,” IEEE802.15.4 and other protocols that use the 2.4GHz radio spec-trum do
NOT speak the same “language” — thus a putting in a new protocol in a crowded
spectrum invites many problems today and more in the future as the prolific
nature of Wi-Fi hotspots expands (e.g. some cell phones can talk in the 2.4GHz
spectrum).
 Please see http://sensys.acm.org/2010/Papers/p309-Liang.pdf
 And Harmful Coexistence Between 802.15.4 (in the 2.4GHz spec-trum) and
802.11: A Measurement-based Study found at http://ieeexplore.ieee.org/xpl/
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www.lsi-industries.com
(844) 444-4476
12/1/15
© 2015
LSI INDUSTRIES INC.
915 MHz vs 2.4 GHz Frequency Spectrums
Real World Experience:
LSI Controls were installed at a facility that heavily uses the 2.4GHz
and 5.8GHz spectrums. They had multiple Wi-Fi networks and
could not support a controls platform in these spectrums. Our
installation with 275 controllers in a 600,000 sq. ft. facility exhibited
flawless communication amongst all the surrounding noise.
Below are pictures of appliances all competing for bandwidth in the
2.4GHz domain. Parking garages, for example, use Wi-Fi security
cameras that will interfere with anything else in the 2.4GHz domain.
Cordless phones communicate in the 2.4GHz domain, also.
www.lsi-industries.com
(844) 444-4476
12/1/15
© 2015
LSI INDUSTRIES INC.