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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State 5 has a lower theoretical throughput than States 3 and 4, because its lower modulation order and increased FEC
strength both tend to lower the overall theoretical throughput of the resulting upstream channel. However, it is more
tolerant of upstream noise, so it may be able to provide adequate PER performance. If not, a degradation trigger will force
the Upstream Agility state machine to transition from State 5 to State 6.
State 6 has a theoretical throughput identical to that of State 5, but it is positioned in a different portion of the upstream
spectrum in the hope that no noise will be encountered in that part of the spectrum. If State 6 does not produce an
acceptable PER performance, then the MSO in this example has decided not to attempt any other channel configurations.
The users on that channel must content themselves with the performance defined by State 6. If the Upstream Agility state
machine is operating in States 2-6, then any improvements in the channel conditions could cause an improvement trigger
to push the state machine back one state toward the default state (State 1). Improvement triggers cause a hop to the next
lower state, that is, towards State 1; degradation triggers cause a hop to the next higher state.
Using Tables Instead of Diagrams
Many other types of state machines can be created with the general definitions given above. It is important to note that
state diagrams are only one way to represent state machines. Another way is to use state tables. For example, the state
diagram above can also be represented by the table below. For completeness, we have added more detail around the
definition of the degradation triggers and the improvement triggers. As shown in the table below, each state has a unique
set of degradation triggers and improvement triggers.
Use the following commands to create the triggers shown in the table below:
configure cable spectrum-group trigger 10 degradation fec_err 4000 ufec_err 3000 SNR 220
configure cable spectrum-group trigger 20 improvement fec_err 2000 ufec_err 1000 SNR 250
Table 86.
State Table That Matches the State Diagram
States
Triggers
Current
Next
Num.
Definition
1
2
10
{SNR<22 dB} AND {%unc. fec errors>3% OR %(unc + cor) fec errors> 4% }
2
3
10
{SNR<22 dB} AND {%unc. fec errors>3% OR %(unc + cor) fec errors> 4% }
