Proxim 5012-SUI, Руководство по установке и управлению

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Configuration Tsunami MP.11 5012/5054-SUI Installation and Management
Network Parameters
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• Fast scanning is the scanning procedure performed when the average local SNR for the current BSU is very low
(below the fast scanning threshold) and the number of retransmitted frames is greater than the fast scanning
retransmission threshold given in%, so that the current session should terminate as soon as possible. During this
procedure, the SU scans other active channels as fast as possible.
Roaming can only occur if the normal scanning or fast scanning procedure is started under the following conditions:
1. If the roaming is started from the normal scanning procedure (after the SU scans all the active channels), the SU
selects the BSU with the best SNR value on all available channels. The SU roams to the best BSU only if the SNR
value for the current BSU is still below the slow scanning SNR threshold, and best BSU offers a better SNR value for
at least roaming threshold than the current BSU. The SU starts a new registration procedure with the best BSU
without ending the current session.
2. If the roaming is started from the fast scanning procedure, the SU selects the first BSU that offers better SNR than the
current BSU, and starts a new registration procedure with the better BSU without ending the current session.
Roaming with Dynamic Data Rate Selection (DDRS) Enabled
When an SU roams from BSU-1 to BSU-2 and DDRS is enabled, the data rate at which the SU connects to BSU-2 is the
default DDRS data rate. If this remains at the factory default of 6 Mbps, there can be issues with the application if it
requires more then 6 Mbps (for example multiple video streams).
Applications requiring a higher data rate could experience a slight data loss during the roaming process while DDRS
selects a higher rate (based upon link conditions).
When the applications re-transmit at a possibly slower rate, the WORP protocol initially services the data at 6 Mbps and
increases the data rate up to the "Maximum DDRS Data Rate" (
ddrsmaxdatarate ) one step at a time. Because the
applications are not being serviced at the best possible rate, they further slow down the rate of data send.
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.
For a discussion on how to configure DDRS, see Dynamic Data Rate Selection (DDRS) .
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.