Alvarion BREEZEACCESS SW VERSION 5.1 - Manual (Page 110)

Chapter 3 - Commissioning
BreezeACCESS VL System Manual
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3.4 Configuring the Subscriber Unit’s
Maximum Modulation Level
This section describes how to configure the maximum modulation level for
Subscriber Units.
NOTE
If the unit is associated with the AU, then the final configuration of the Maximum Modulation Level
parameter may be performed remotely, for example, from the site of the AU or from another site.
To configure the Maximum Modulation Level:
1
If the SNR of the SU at the AU is too low, it is recommended that you
configure the Maximum Modulation Level parameter to a value that is lower
than the maximum supported by the unit. This can decrease the number of
retransmissions due to attempts to transmit at modulation levels that are too
high for the actual quality of the link.
2
Check the SNR of the SU at the AU. You can use Telnet to view the SNR
values in the MAC Address Database, which can be accessed from the Site
Survey menu. If the ATPC algorithm is not enabled in both AU and SU, the
test should be done with the Initial Power Level at the SU configured to its
maximum value. If the SNR is lower than the values required for the
maximum modulation level according to Table 3-3, it is recommended that
you decrease the value of the Maximum Modulation Level.
NOTE
The SNR measurement at the AU is accurate only when receiving transmissions from the
applicable SU. If necessary, use the Ping Test utility in the Site Survey menu to verify data
transmission.
3
Configure the Maximum Modulation Level according to Table 3-3, using the
typical SNR values. It is recommended that a 2 dB margin be added to
compensate for possible measurement inaccuracy or variance in the quality of
the link.