User guide

Understanding Canopy Networks March 2005
Through Software Release 6.1
Issue 1 Page 73 of 425
Canopy System User Guide
8 MEETING LINK REQUIREMENTS
8.1 AP-SM LINKS
8.1.1 AP-SM Link Distances
APs and Subscriber Modules are available in 900-MHz, 2.4-GHz, 5.2-GHz, 5.4-GHz, and
5.7-GHz frequency bands. Due to regulatory agency restrictions, a 5.2-GHz SM cannot
be used with a reflector in the U.S.A. or Canada. A 2.4-GHz or 5.7-GHz SM can be used
with a Canopy Passive Reflector dish. This reflector extends the maximum span of a link.
For a 900-MHz AP-SM link, the range in typical conditions is 40 miles (64 km). However,
you can set the 900-MHz AP to a range as great as 120 miles (more than 190 km) to
establish links across longer distances where the Fresnel zone is clear and the RF
environment is uncontested.
For a 2.4-GHz AP-SM link, the maximum distance is
◦ 15 mi (24 km) with the reflector on the SM.
◦ 5 mi (8 km) with no reflector.
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NOTE:
Greater distances with the reflector may be attempted for 2.4-GHz
links. See Max Range on Page 195.
For a 5.2-GHz AP-SM link, the maximum distance is 2 mi (3.2 km) with no dish.
For a 5.4-GHz AP-SM link, the maximum distance is 2 mi (3.2 km) with or without a
reflector.
For a 5.7-GHz AP-SM link, the maximum distance is
◦ 10 mi (16 km) with the reflector on the SM.
◦ 2 mi (3.2 km) with no reflector.
8.1.2 AP-SM Data Transfer
Point-to-multipoint Capacity
Canopy APs communicate with SMs using a point-to-multipoint protocol. An AP-SM link
has lower throughput and higher latency than a backhaul link for two reasons:
◦ Many endpoints are involved.
◦ The bandwidth request and reservation process consumes bandwidth.
In the 900-MHz frequency band range, round-trip latency is typically
◦ 40 msec with software scheduling.
◦ 15 msec with hardware scheduling.