Alvarion BreezeACCESS EZ AU-EZ, Системное руководство

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Chapter 4 - Operation and Administration Menus and Parameters
BreezeACCESS EZ AU-EZ 71 System Manual
bandwidth. If the Best AU feature is enabled, the SU will scan the defined subset
and the operating frequency/bandwidth will be determined by the Best AU
mechanism (including the optional use of the Preferred AU feature). Otherwise the
SU will try to associate with the first AU it finds. If no AU is found, the SU will
start another scanning cycle.
4.2.6.2.2.2 Avoiding Frequencies with Radar Activity
In some regions, it is important to ensure that wireless access equipment does not
interfere with certain radar systems in the 5 GHz band. If radar is being detected,
the wireless access network should move automatically to a frequency that does
not interfere with the radar system.
The country dependent set of parameters includes also an indication whether DFS
(Dynamic Frequency Selection) should be used. The DFS algorithm is designed to
detect and avoid operation in channels with radar activity. If the current sub-band
does not support DFS, then the DFS parameters configuration submenu is not
available.
When DFS is enabled, the unit monitors the spectrum continuously, searching for
signals with a specific pattern indicating radar activity. Upon detecting radar
activity, the unit immediately stops transmitting on this frequency and starts
looking for another radar-free frequency. The subset of viable frequencies is
configurable.
4.2.6.2.2.2.1 DFS implementation on the AU
The AU maintains a continuously updated database of all applicable frequencies,
where each frequency is marked as Radar Free, Radar Detected or Adjacent to
Radar. The AU attempts to check a new frequency only if it is marked as Radar
Free. If there is no radar activity detected, the units in the sector may use this
frequency to communicate. If a radar activity was detected on a certain frequency,
it will be marked in the database as a Radar Detected frequency. The frequency
will remain tagged as Radar Detected for a predefined period of time called
Channel Avoidance Period. After this period expires, the frequency will be marked
as Radar Free.
If radar activity was detected on a certain frequency, adjacent channels should
not be used as well, according to the bandwidth. For instance, if the bandwidth is
20 MHz, then if radar activity was detected in 5800 MHz, frequencies 5790 MHz
NOTE
Radar detection parameters that are enforced by Country Code specific regulations are editable
only by users with Administrator privileges. When enabling a Country Code that requires particular
DFS settings, the unit automatically applies these settings. Users with Installer privileges will be
able to set a particular Country Code, but they will not be able to change its default DFS settings.