User guide

Release9.5ReleaseNotes



Issue2,October2009  Page53
8.2 COLLOCATING5.4‐GHzAND5.7‐GHzMODULES
For collocation design, the 5.4-GHz and 5.7-GHz frequency bands are essentially one continuous
band. When collocating 5.4-GHz and 5.7-GHz modules, use the guidelines for collocating
modules within a band listed under Collocating Same-Frequency Band Modules on Page 53.
Alternatively, either
 provide 100 ft (30 m) of vertical separation between the 5.4-GHz and 5.7-
GHz radios.
 if 100 ft (30 m) of vertical separation is not possible, provide as much vertical
separation as possible, and choose frequencies far apart within the
combined
5.4-GHz and 5.7-GHz bands. The physical and spectral separation and local
RF conditions, influenced by tower geometries, layout and position of
modules, and use of reflectors on BHs, among other variables, may support
good performance, but testing and monitoring will be required to confirm that
they do.
For example, when collocating a cluster of six 5.4-GHz APs with a cluster of six 5.7-GHz APs, all
hardware scheduled, set them all to the same range, downlink data %, and control slots, and use
standard frequency re-use around each cluster (ABCABC).
For another example, when collocating a cluster of six 5.4-GHz APs with a 5.7-GHz BH that is
retrofitted with a reflector, provide 100 vertical feet of separation. If this is not possible
1. choose channels for the AP that are at the bottom of the 5.4-GHz band.
2. choose a channel for the BH that is at the top of the 5.7-GHz band.
3. locate the modules so the reflector on the BH shields the APs from the BH
module.
4. ensure the over-illumination around the edges of the reflector is not directed at
the APs.
5. confirm with simultaneous link tests.
Background
Why are 5.4-GHz and 5.7-GHz bands considered one band for Canopy collocation, whereas
other bands (say 5.2-GHz and 5.7-GHz) are considered separate? 5.4-GHz and 5.7-GHz radios
use the same radio front end, whereas 5.2-GHz and 5.7-GHz Canopy modules have different
radio front ends. For collocation design, the 5.4-GHz and 5.7-GHz bands are essentially one
continuous band, albeit one with possibilities for large spectral separation of channels.
8.3 COLLOCATINGSAME‐FREQUENCYBANDMODULES
Canopy can avoid self-interference if collocated modules in the same frequency band are of the
same type, start each frame transmission at the same time, and start each frame reception at the
same time. If you collocate radios of the same frequency band, do the following also:
 Within the same band, collocate only one type of module (only APs, only
BHMs, or only BHSs).
 Use a CMM, so that transmit start times are in sync.
 Use identical scheduler type (hardware or software)
 Either