User's Manual Part 1

System Overview of Subscriber Module MeshMAX 5054 Series User Guide
Changing Basic Configuration Information
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During boot-up, the unit scans the available frequency and selects the best channel. If the unit subsequently detects
interference on its channel, it rescans to find a better channel. Upon finding a new channel, the unit is required to wait 60
seconds to ensure that the channel is not busy or occupied by radar, and then commences normal operation. (In Canada,
if the channel was previously blacklisted, the unit scans for 600 seconds before commencing normal operation if the
selected channel frequency is in the 5600 - 5650 MHz range).
If you are using the unit in a country and band that require DFS, keep in mind the following:
• DFS is not a configurable parameter; it is always enabled and cannot be disabled.
• You cannot manually select the device’s operating channel; you must let the unit select the channel. You may make
channels unavailable by manually “blacklisting” them and preventing those channels being selected, in accordance
with local regulations or interference. You can also display the Channel Blacklist Table to view the channels that have
been blacklisted.
• In compliance with FCC regulations, the unit uses ATPC (Automatic Transmit Power Control) to automatically adapt
transmit power when the quality of the link is more than sufficient to maintain a good communication with reduced
transmit power. See Transmit Power Control for more information.
Dynamic Frequency Selection (DFS) is enabled automatically based upon the country and band you select. You can tell
DFS is in use because the Frequency Channel field on the Interfaces page displays only the DFS-selected frequency.
DFS scans all available frequencies, starting with the DFS preferred channel (when configured) and skipping blacklisted
channels, to select the operating frequency automatically.
A country/band selection with DFS enabled causes the Base Station to come up in scan mode. It scans the available
frequencies and channels to avoid radar and selects a channel with the least interference.
NOTE: Scanning is performed only on the frequencies allowed in the regulatory domain of the country/band selected
when it is required for radar detection and avoidance.
The SU also comes up in scan mode to scan all available frequencies to find a BSU with which it can register. Scanning
may take several minutes. After establishing a wireless link, the wireless LED stops flashing and continues to shine
green.
NOTE: Because DFS may need to scan for radar on multiple channels, you must allow a sufficient amount of time for the
units to start up. This is considerably longer than when the unit is not using DFS. This is expected behavior.
Startup time is within four minutes if no radar is detected, but up to one minute is added for every selected
channel that results in radar detection.
DFS is required for three purposes:
1. Radar avoidance both at startup and while operational. To meet these requirements, the BSU scans available
frequencies at startup. If a DFS-enabled channel is busy or occupied with radar, the system will blacklist the channel
for a period of 30 minutes in accordance with FCC, IC, and ETSI regulations. Once fully operational on a frequency,
the BSU actively monitors the occupied frequency. If interference is detected, the BSU blacklists the channel, logs a
message and rescans to find a new frequency that is not busy and is free of radar interference.
Radar detection is performed only by the BSU and not by the SU. When an SU is set to a country/band in which DFS
is used, it scans all available channels upon startup looking for a BSU that best matches its connection criteria (such
as Base Station System Name, Network Name, and Shared Secret). The SU connects to the BSU automatically on
whatever frequency the BSU has selected. Because of this procedure, it is best to set up the BSU and have it fully
operational before installing the SU, although this is not required. If a BSU rescans because of radar interference, the
SU loses its wireless link. The SU waits 30 seconds (when the Mobility feature is enabled, the SU starts scanning for
a BSU instantly rather than waiting 30 seconds); if it finds that it could not receive the BSU in this amount of time, it
rescans the available frequencies for an available BSU.
2. Guarantee the efficient use of available frequencies by all devices in a certain area. To meet this requirement, the
BSU scans each available frequency upon startup and selects a frequency based upon the least amount of noise and
interference detected. This lets multiple devices operate in the same area with limited interference. This procedure is