Alvarion BreezeACCESS II, Системное руководство

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2-2
BreezeACCESS Version 4.5 Commissioning
Manual Revision: 1.0
Configuring the Maximum
Data Rate (Subscriber Units)
The BreezeACCESS units transmit at data rates of 3 Mbps, 2 Mbps and
1Mbps. If the quality of the link is not sufficient, it is recommended to
decrease the value of the Maximum Data Rate. Note that the higher the
data rate, the higher the error rate.
Before reaching a decision on the optimum value for the Maximum Data
rate for a specific SU, it is recommended to acquire the RSSI results
from the AU. These indicate the level at which the AU receives
transmissions from the specific SU (uplink RSSI).
The per SU uplink RSSI can be viewed at the AU as follows:
1.
From the Main Menu , select Site Survey .
2.
In the MAC Address Database submenu, select the Display Association
Info option.
If the installer cannot access the AU (e.g. using Telnet) and cannot
obtain the measurements from the system administrator, the link
quality can be estimated based on the RSSI measurement in the SU as
follows:
1.
From the Main Menu , select Site Survey .
2.
Select the Continuous Link Quality Display option.
Using the assumption that the link is more or less symmetrical,
this value is a good indication to the level at which the SU is
received by the AU.
Once the RSSI results have been obtained, proceed as follows:
1.
If the measured RSSI is less than a certain threshold, it is
recommended to decrease the Maximum Data Rate of the SU in
accordance with the following table (including a 3 dB safety margin
above the applicable sensitivity thrshold).
Table 2-1: Maximum Data Rates and RSSI
2.
Reset the unit for the new configuration to become effective.
Maximum Data
Rate
3 Mbps 2 Mbps 1 Mbps
SU-A/E RSSI>-70dBm -78dBm<RSSI<-70dBm RSSI<-78dBm
SU-I/I-D RSSI>-64dBm -71dBm<RSSI<-64dBm RSSI<-71dBm
SU-R RSSI>-65dBm -74dBm<RSSI<-65dBm RSSI<-74dBm