User's Manual

ALFOplus 24GHz (North America) - Release 01.05.0x - MN.00395.E - 004 39
7.1.6 Adaptive code modulation
ACM profiles
In ALFOplus radio family uses Adaptive Code and Modulation (ACM) in order to employ the correct modu-
lation profile depending on the Rx signal quality.
Available ACM profiles are the following:
•4QAM strong
•4QAM
• 16QAM strong
•16QAM
•32QAM
•64QAM
• 128QAM
• 256QAM
• 512QAM
• 1024QAM.
These profiles operate in an RF channel with the following bandwidth:
•7 MHz
•10 MHz
•14 MHz
•20 MHz
•28 MHz
•30 MHz
•40 MHz
•50 MHz
•56 MHz.
ACM switching
The criteria defining the necessity of an ACM switching, upshift or downshift, is the Rx S/N ratio.
• Upshift - When there is an increase of received S/N, the modulation complexity is increased in the
direction from 4QAM strong to 1024QAM increasing the spectral efficiency
• Downshift - When there is a decrease of received S/N, the modulation is reduced in the direction
from 1024QAM to 4QAM strong reducing the spectral efficiency,
In order to configure properly the radio link using ACM facility, an optimization must be found between
max traffic during good propagation conditions and max availability during bad propagation conditions. To
obtain this purpose the ACM in ALFOplus family can be configured via software setting the following pa-
rameters: ACM setting and Tx Power mode.
ACM setting
The ACM can vary modulation profiles between two extremes defined by the operator through software
configuration: Upper Modulation and Lower Modulation.
• Upper modulation - When propagation into the given radio channel is in the better condition (high
Rx S/N), the radio link is working at the maximum throughput defined at Upper Modulation: the
highest modulation profile that ACM can employ