Huawei MA5600 Manual page 85

NGN Cases
Handling Proces
we display the working mode of the PVM eth interface: 100M half duplex.
s:
we display the working mode of the IPMB eth interface 6 , : 100M full duplex.
After changing the working mode of the PVMB eth interface to 100M full duplex, the packet loss rate is 0%.
Suggestions and
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Summary:
5.9 Household Alarm Working Abnormally Due to the Large Packet Disassembly Duration
Title:
Household Alarm Working Abnormally Due to the Large Packet Disassembly Duration
ID: SE0000394396
Update Time: 2009-06-26 10:08:00
Views: 1
Author: z58814
Product Family: Integrated Access
Fault Type: Narrow-band Voice Service
Keywords: Packet disassembly duration, voice channel delay, alarm, DTMF
Permission 04Common Users Permission
Level:
Phenomenon De
BSIA of country Y turns to carrier C through OFCOM. The report says that after the services of
scription:
carrier B are transferred to the lines of carrier C, the household alarm system cannot work in the
normal state. The MSAN is suspected to be abnormal.
Alarm Informati
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on:
Cause Analysi
The household alarm system automatically dials the alarm center through the household
s:
telephone line, and transmits related instructions to the alarm center through the DTMF signals.
In this manner, the automatic alarm function is implemented.
After the phone carrier is replaced, the household alarm cannot work in the normal state. First,
we should confirm in which phase the problem occurs: dialing phase, connection phase, or
conversation phase. Then, we can determine which phase is abnormal.
According to the standard document NICC1704 of country Y, the household alarm adopts the
Fast Format Protocol and DTMF signals to transmit messages, which lays a high requirement on
call channel delay. Carrier C, however, is a new carrier that provides the VoIP-based voice
service. The call channel delay from the terminal user to the server on the PSTN network may
be large. The call channel delay is suspected to some extent.
Handling Proce
After the problem recurs on site, use a recording pen to record the voice on the line. After
ss:
analyzing the recorded voice, do as follows:
1) According to the recorded voice, the problem occurs in the conversation phase.
2) Use the Cooledit to view the waveform of the recorded voice, and compare it with the
corresponding standard (see the attachment). It is found that when the problem occurs, the ACK
message (1.4 kHz single audio) sent from the alarm has a large delay. As a result, the server
considers that the ACK message is not received in time and considers the alarm failure.
3) In the MSAN, the adjustable parameters that affect the delay are jitter buffer and packet
disassembly duration. In the current version, jitter buffer is dynamically adjusted according to
the network quality. Changing jitter buffer may not make a difference. The packet assembly
duration, however, is set by the softswitch. Currently, the packet assembly duration is set to 20
ms instead of 10 ms recommended by NICC.
4) Change jitter buffer to 20 ms. It is found that the problem persists. Restore jitter buffer to its
default value and change the packet assembly duration from 20 ms to 10 ms. Then the alarm
works in the normal state. According to the waveform, the protocol is complied with.
5) After tests for several times, it is confirmed that the packet assembly duration is the key factor
that affects the alarm. After the packet assembly duration is changed from 20 ms to 10 ms, the
problem is completely solved.
For the related documents and record materials, see the attachment.
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Chapter 5 UA5000 Narrow-band Service
Product: UA5000