Hughes HX System System Overview page 56

Chapter 5 • Bandwidth management
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data session. This minimum CBR is low jitter, as the
bandwidth is assigned to the satellite router until the CBR
session terminates. Termination of the CBR session is based
on idle period. Figure 7 illustrates the CBR feature of the HX
System.
• Maximum rate – The maximum amount of bandwidth that
the modem will be allocated.
• Threshold level – The level of usage at which the satellite
router will be allocated an additional fixed amount of
bandwidth (described in the Step increment bullet item).
The step-up threshold is a percentage of the currently
assigned bandwidth that, once reached, creates an increase
in the allocated bandwidth. The increase amount is
dictated by step-size.
The step-down threshold is a percentage of the currently
assigned bandwidth that, once reached, creates a decrease
in the allocated bandwidth. The decrease amount is
dictated by step-size.
The threshold level is defined as the following ratio:
Bandwidth Used by the Satellite Router
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Bandwidth Assigned or Allocated
For example, if the threshold level is 80%, when the
utilization level exceeds 80%, an additional step increment of
bandwidth is allocated to the satellite router. The utilization
or load of the channel is evaluated every 500 ms.
• Step increment – The fixed amount of bandwidth, in kbps,
that will be allocated to a satellite router as it requires more
than the minimum CBR amount. The HX System uses the
threshold level (defined above) to determine when to allocate
additional step increments. The HX System continues to
allocate step increments up to the maximum rate of the
modem or until the bandwidth of the inroute is exhausted.
The step-up threshold is a percentage of the currently
assigned bandwidth that, once reached, creates an increase
in the allocated bandwidth. The increase amount is
dictated by step-size.
The step-down threshold is a percentage of the currently
assigned bandwidth that, once reached, creates a decrease