User Manual

Table Of Contents
Chapter 4 - Operation and Administration
BreezeACCESS VL System Manual
180
The link quality can be estimated based on the SNR measurement of the SU at
the AU, which can be viewed in the MAC Address Database option in the Site
Survey menu. If the measured SNR is less than a certain threshold, it is
recommended that the maximum modulation level of the SU be decreased in
accordance with Table 4-11, using the values of typical sensitivity. It is
recommended to add a 2 dB safety margin to compensate for possible
measurement inaccuracy or variance in the link quality.
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.
When the Adaptive Modulation Algorithm is disabled, this parameter will serve to
determine Fixed Modulation Level used for transmissions.
The minimum and maximum values for the Maximum Modulation Level are
defined by the Sub-Band in use. For information on how to view the Sub-Bands
supported by the unit and the supported parameters’ values and options, refer to
section
4.2.2.4
. Currently, all Sub Bands support the entire range of modulation
levels, from 1 to 8. However, the highest modulation level supported by units with
HW revision A is modulation level 7.
The default is the highest supported modulation level (8 for all units with HW
revision B or higher, 7 for units with HW revision A).
Table 4-11: Recommended Maximum Modulation Level*
SNR Maximum Modulation Level
SNR > 23 dB 8
21 dB < SNR < 23 dB 7
16 dB < SNR < 21 dB 6
13 dB < SNR < 16 dB 5
10 dB < SNR < 13 dB 4
8 dB < SNR < 10 dB 3
7 dB < SNR < 8 dB 2
6 dB < SNR < 7 dB 1
* The maximum supported value depends on the unit’s HW revision and on the Max Modulation
Level according to the Sub-Band.