User's Manual Part 1

Configuration MeshMAX 5054 Series User Guide
Configuring the Subscriber Module
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The DDRS algorithm requires data traffic (a minimum of 128 frames) to raise the rate to a higher value. Although roaming
occurs successfully, the previous scenario causes applications to drop their sessions; hence session persistence is not
maintained.
NOTE: You must know the data rate required for the applications running and you must ensure (during network
deployment) that the ranges and RF links can support the necessary data rate. You also must set the default
DDRS data rate at the capacity necessary for the application so that it connects to the next Base Station at the
required capacity if roaming occurs. Set the “Default DDRS Data Rate” (ddrsdefdatarate) to a greater value (24,
36, 48 or 54 Mbps, for example) for applications requiring session persistence when roaming occurs.
Roaming Configuration
Click Configure > Network > Roaming to configure Roaming.
Enable or disable the Roaming feature in the Roaming Status drop-down box. The default value is disabled.
NOTE: To enable roaming, you must enable Roaming Status on both the BSU and the SU.
An SU scans all available channels for a given bandwidth during roaming. In order to reduce the number of channels an
SU has to scan and thus decrease the roaming time, a channel priority list that tells the SU what channels to scan is
implemented. Each channel in the channel priority list is specified with its corresponding bandwidth and the priority with
which it should be scanned, either “Active” (standard priority), “Active High” (high priority), or “Inactive”.
An SU will scan all channels indicated as “Active” during roaming. However, it will scan active channels indicated as
“High Priority” before scanning active channels indicated as standard priority. Channels that are not going to be used in
the wireless network should be configured as “Inactive” so that the SU can skip over those channels during scanning
saving this way time.
A BSU broadcasts the channel priority list to all valid authenticated SUs in its sector. It re-broadcasts the channel priority
list to all SUs every time the list is updated on the BSU. For information for configuring the channel priority list on the BSU
see the Tsunami MP.11-R Installation and Management Guide.
Note that an SU may roam from one BSU with a bandwidth setting to another BSU with a different bandwidth setting.
Since in this case more channels need to be scanned than with only one channel bandwidth setting, it is important that
the channel priority list mentioned above is properly used to limit scanning time.
When Scanning Across Bandwidth on the SU is enabled, the SU supports bandwidth selection of the communications
channel of either 20 MHz, 10 MHz, or 5 MHz, as available. This allows the BSUs in the network to be set to different
bandwidths while an SU can still roam from one BSU to the next, because it will not only scan other frequencies (when
the signal level or quality are lower than the threshold) but it will also switch to other bandwidths to find a BSU that may
be on another bandwidth than its current one.
During roaming, the SU will start scanning first the channels on its current
bandwidth from the “Active” channel list
provided by the BSU in order to find a BSU to register, since that is the most likely setting for other BSUs in the network.
If the SU cannot find an acceptable roaming candidate, it will switch bandwidth and start scanning channels on that