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by changing the absolute receive power level above which the channel is normally considered busy.
The threshold is set to -62 dBm by default however; it may be necessary to increase the CCA
threshold in order to allow the transmission to not appear in contention when used in a noisy
environment. CCA values can be set independently for Root and Non Root Bridge. One can also
perform a clear channel assessment by sweeping the UNII-3 band using a spectrum analyzer at the
deployment site. Always, attempt to choose the channel with the least interference for the bridge
link.
One can also adjust the Fragmentation Threshold value in the bridge, which determines the size at
which packets are fragmented (sent as several pieces instead of as one block). Use a lower setting
in areas where communication is poor or where there is a great deal of radio interference. Also one
can run the link test at every frequency and watch for signal quality, signal level and the number of
retries. Choose the best channel with good signal quality and minimum number of retries. One
should clearly understand the relationship between signal level and quality for example; a high signal
level might have poor signal quality indicating a potential interference issue. In this scenario, one
might wish to try another channel.
6 Installation Guide
The Cisco Systems 1400 Series Wireless Bridge is designed to be installed in an outdoor
environment, typically, on a tower or a tall building. Typical types of bridge installations are shown
below.
Figure 29.
Typical 1400 Wireless Bridge Installations
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Dual RG6
Grounding
Lightening arrestor
LMR
Dual RG6
