User guide

45 Mbps Backhaul User Guide
Issue 3, December 2004 Page 20 of 113
4.2.1 Rules for Collocating
To collocate Canopy 45 Mbps Backhauls and Canopy 5.7 GHz 10 or 20 Mb Backhauls, follow these three rules:
• Use a minimum vertical separation of 6 ft (1.8 m) between the 45 Mbps Backhaul and any other
Canopy module.
• Use 5735, 5755, and 5775 MHz for the 5.7 GHz Access Points or 10 Mb or 20 Mb backhauls.
• Either let the 45 Mbps Backhaul(s) use dynamic frequency selection to select the highest capacity
frequency available, or manually select 5800, 5806, 5812, 5818, 5824, 5830, 5836, or 5842 for the 45
Mbps Backhaul(s).
Note, 100 vertical feet (30 vertical meters) of distance separation is still required between 10 or 20 Mbps
Backhauls and Access Points operating in the same frequency band.
4.2.2 Additional Information for Collocating
The Canopy 45 Mbps Backhaul and other Canopy Backhauls each have their individual frequency constraints.
For example, the 45 Mbps Backhaul employs a sophisticated dynamic frequency selection (DFS) capability.
This allows it to automatically select the highest-capacity frequency currently available for the link. However,
DFS becomes less effective as the spectrum becomes more crowded. In crowded environments, manual
frequency selection may be required to extract the very best performance from the units. DFS measurements are
still very useful, however, because they provide the measurements to confirm that the optimum arrangement has
been achieved.
Access Point clusters typically use three frequencies 20 MHz apart. In a six-sector base station, these
frequencies are typically reused with the same frequency being used in back-to-back sectors. For collocation,
use one end of the band for the Access Point cluster (or 10 Mb or 20 Mb Backhauls), and the other end of the
band for the 45 Mbps Backhaul(s), with at least 25 MHz between the top group of frequencies and the bottom
group of frequencies. The recommended frequencies for the AP cluster are 5735, 5755, and 5775 MHz. Given
these frequencies and a minimum vertical separation of 6ft (1.8m) then the 45 Mbps Backhaul can operate on
5800, 5806, 5812, 5818, 5824, 5830, 5836, or 5842.