Chapter 21: Integrated Upstream Agility
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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system operator desires to only specify an SNR threshold, then Threshold2 and Threshold1 can be set to zero. If the system
operator desires to specify only error thresholds, then Threshold3 can be set to be a very large value.
From the triggers listed in the table above, it can also be seen that Integrated Upstream Agility will define all of the
improvement triggers to be Boolean expressions that have the particular form given by:
Improvement Trigger = {SNR> Threshold3} AND { %unc. fec errors < Threshold2 AND %(unc + cor) fec
errors < Threshold1 }
Where: Threshold3 is the maximum acceptable signal to noise ratio (measured in tenths of a dB) for the current state
before attempting a transition to the next state
Threshold2 is the minimum acceptable percentage (measured in thousandths of a percent) of uncorrectable FEC
errors for the current state
Threshold1 is the minimum acceptable percentage of FEC errors (uncorrectable plus correctable) for the current
state
The system operator can specify the unique values of thresholds 1, 2, and 3 for each trigger within the state machine. All
three of the conditions must be met before an improvement trigger is triggered. If the system operator desires to only
specify an SNR threshold, then Threshold2 and Threshold1 can be set to be very large values. If the system operator
desires to only specify error thresholds, then Threshold3 can be set to zero.
Trigger Precedence
For all of the trigger entries associated with a particular current state of the state machine, the trigger with the lowest
trigger_ID takes precedence over other triggers. For example, consider a state machine with the following three triggers:
Trigger 10 — a degradation trigger at 18 dB configured to change to state 2
Trigger 15 — a degradation trigger at 22 dB configured to change to state 4
Trigger 20 — a degradation trigger at 26 dB configured to change to state 6
If the SNR drops from 30dB to 15dB in one sample period, then all three triggers would be activated. Because trigger 10
has precedence, triggers 15 and 20 are ignored and the state machine goes directly from its current state to state 2. Thus,
trigger precedence can be used to skip intermediate states when conditions deteriorate rapidly.
