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A31003-H3150-S104-2-7620, 03/2009
HiPath 4000 V5, IP Solutions - HG 3500 & HG 3575, Service Documentation
Maximum delay (configurable)
Key:
Average delay (adaptive)
Minimum delay (configurable)
Packets
Adaptive jitter buffer: The average delay ranges
between the minimum and maximum delay and tends to
be as low as possible.
Del
ay
Measured time
Figure 10
Minimum delay for adaptive jitter buffer
Minimum and maximum delay values are still adhered to if packets are lost.
2.5.6 Packet Loss Control in Adaptive Jitter Buffer
In the case of the adaptive jitter buffer, the average delay is automatically
readjusted. The aim of this is to achieve a good balance between having the
shortest possible average delay on the one hand and the lowest possible packet
loss on the other.
You can set which of these factors is attributed more importance using the
"Preference Parameter". Using values from 0 to 8, you can specify whether
decreasing the delay or avoiding packet loss should be prioritized when
calculating the average delay. In this case, 0 denotes "Avoid packet loss as far as
possible" and 8 denotes "Maintain shortest possible average delay". An average
value (4) is predefined.
Rule of thumb: setting the value to 0 results in approx. 10 ms longer average
delay and setting it to 8 results in approx. 10 ms shorter average delay than that
applicable when the average value is set to 4.
2.5.7 Parameters for Jitter Buffer Configuration
To understand the delay parameters, it is important that the values are aligned
with the compensable network jitter. As is the case for all IP gateways or
terminals, the actual transmission times for voice packets in HG 3500 and HG
3575 also fluctuate around a constant ideal value. This deviation (jitter at
transmitting end) is already taken into account during implementation.
These parameters can be set via the AMO STMIB (for HG3575) or the AMO
CGWB (for HG 3500).
gateways_02_terms.fm
Terms
Jitter Buffer
21
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