User manual

Chapter 2 - Managing a Single Device/Cell Air Interface Frequency Page
AlvariCRAFT Device Manager 46 User Manual
2.4 Air Interface Frequency Page
To simplify installation and changes, most of the parameters that determine the
frequency to be used are set in the AU/BU. The SU/RB should be configured with
a minimal set of parameters to ensure that it will be able to automatically detect
and use the frequency/bandwidth used by the AU/BU, including possible
changes in this frequency (Automatic Sub Band Select feature).
To simplify the installation process the SU/RB scans a definable frequencies
subset after power-up. The defined frequencies subsets may include frequencies
from more than one Sub-Band, enabling automatic detection of both frequency
and bandwidth. If the Best AU/BU feature is enabled, the SU/RB will scan the
defined subset and the operating frequency/bandwidth will be determined by the
Best AU/BU mechanism (including the optional use of the Preferred AU/BU
feature). Otherwise the SU/RB will try to associate with the first AU/BU it finds. If
no AU/BU is found, the SU/RB will start another scanning cycle.
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 indication 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.
The unit maintains a continuously updated database of all applicable frequencies,
where each frequency is marked as Radar Free, Radar Detected or Adjacent to
Radar. The unit attempts to check a new frequency only if it is marked as Radar
Free. If a radar activity was detected on a certain frequency, it will be marked in
the database as a Radar Detected frequency. The unit will not attempt to check for
radar activity in frequencies marked as Radar Detected. A certain time after
detecting radar activity on a frequency, it will be removed from the list of Radar
Detected frequencies and will be marked as Radar Free. If radar activity was
detected on a certain frequency, adjacent channels should not be used as well,