Specifications

Chapter 4 - Operation and Administration Menus and Parameters
BreezeACCESS 4900 167 System Manual
* The maximum supported value depends on the unit's HW revision and on the Max Modulation Level
according to the Sub-Band.
4.2.6.5.6 Control Modulation Level
This feature controls the modulation for ACK frames sent by the unit. The ACK
modulation can either be set dynamically based on the modulation of the frame it
acknowledges or it can be enforced to modulation level 1. The latter is particularly
useful for asymmetric links.
For instance, if one unit in the link is capable of receiving frames in modulation 8,
while the other can only receive in modulation 2, in theory one of the units should
send its data traffic using modulation 8. However, unless it receives the
corresponding ACK feedback in modulation 2 or 1, it will not be able to
synchronize and will bring its own Tx modulation down as a result. Setting the
ACK modulation to level 1 at the other side of the link will fix this, allowing the
unit to acknowledge that frames sent in modulation 8 are successfully received.
The available options are:
 Basic Rate - Sets 3 modulation thresholds for the sent ACK frames depending
on the modulation of the received frame:
Table 4-16: 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
Table 4-17: Basic Rate Mechanism
Received Frame Modulation Sent ACK Frame Modulation
1,2 1
3,4 3
5,6,7,8 5