User guide

Understanding Canopy Networks March 2005
Through Software Release 6.1
Issue 1 Page 77 of 425
Canopy System User Guide
Select BHs based on desired data handling capability, desired link range, and whether
the BHs will either operate in a network environment or be collocated with an AP or AP
cluster.
2.4-, 5.4-, and 5.7-GHz BHs can be used with a reflector on either or both ends. In the
U.S.A. and Canada, regular 5.2-GHz backhauls cannot be used with a reflector, due to
regulatory agency restrictions. However, Extended Range (ER) 5.2-GHz BHs use very
low transmit power and are permitted with a reflector in the U.S.A. and Canada, as well
as elsewhere. Where these Extended Range BHs are deployed, reflectors on both ends
are recommended.
On either or both ends of a link, a Canopy Passive Reflector dish extends the
transmission and reception range of the BH.
For a 2.4-GHz BH link, the maximum distance is
◦ 35 mi (56 km) with the dish on both ends.
◦ 15 mi (24 km) with the dish on one end at 10-Mbps modulation.
◦ 5 mi (8 km) with the dish on one end at 20-Mbps modulation.
◦ 5 mi (8 km) with no dish at 10-Mbps modulation.
◦ 3 mi (4.8 km) with no dish at 20-Mbps modulation.
For a 5.2-GHz BH link, the maximum distance is
◦ 10 mi (16 km) with the dish on both ends in 10-Mbps modulation, except that the
dish is not allowed on Model 5200 in the U.S.A. or Canada.
◦ 5 mi (8 km) with the dish on both ends in 20-Mbps modulation.
◦ 2 mi (3.2 km) with the dish on
− one end in 10-Mbps modulation.
− neither end in Model 5200.
◦ 1 mi (1.6 km) with the dish on one end in 20-Mbps modulation.
For a 5.4- or 5.7-GHz BH link, the maximum distance is
◦ 35 mi (56 km) with the dish on both ends.
◦ 10 mi (16 km) with the dish on one end in 10-Mbps modulation.
◦ 5 mi (8 km) with the dish on one end in 20-Mbps modulation.
◦ 2 mi (3.2 km) with no dish at 10-Mbps modulation.
◦ 1 mi (1.6 km) with no dish at 20-Mbps modulation.
8.2.2 BH-BH Data Transfer
Point-to-point Capacity
Canopy BHs communicate with each other using a point-to-point protocol. This point-to-
point protocol uses a 2.5-msec frame. A BH link has higher throughput and lower latency
(typically 5 msec, 2.5 msec in each direction) for two reasons:
◦ Only two endpoints are involved.
◦ No bandwidth request and reservation process is involved.