Transmission Interface Handling G.703 2048 kbit/s
32.3.4
Supervision of Transmission Faults
The function is initiated during restart of DXU.
The configuration of fault supervision can only be performed when the
AO DP (Digital Path) is in state "Disable". The reporting to the BSC is
performed when the AO DP is in state "Enable". When the AO DP is
enabled, all fault supervision states are set to zero.
Reports are sent to the BSC is sent to the BSC when the alarm status is
changed or when the BSC requires it.
Fault supervision of the PCM line is performed according to /ITU-T
rec. G.732 section 4/ and /GSM:08.54:4.0.0/.
This includes detection of the following fault conditions:
•
LOF (Loss of Frame Alignment)
•
CSES (Consecutive Severely Errored Seconds) or excessive bit
ERATE (Error RATE)
•
LOS (Loss Of incoming Signal)
•
AIS (Alarm Indication Signal)
•
RAI (Remote Alarm Indication)
•
UAST (UnAvailable STate supervision)
Fault handling is according to Diagnostic and Fault Handling
functionality.
LOF commences
CRC-4 is OFF: Three consecutive frame alignment signals in TS0
received with an error.
CRC-4 is ON: CRC multiframe alignment has not been achieved within
a search time of 500 ms or three consecutive frame alignment signals in
TS0 received with an error or CRC multiframe alignment is lost during
monitoring for incorrect frame alignment (
≥
915 errored CRC blocks out
of 1000).
LOF ceases
CRC-4 is OFF: Recovery of frame alignment signal.
CRC-4 is ON: Recovery of CRC multiframe alignment signal.
CSES commences
More than N SES (Severely Errored Seconds) detected consecutively.
The criteria for SES are described in Section Severely Errored Seconds
supervision on page 195.
This condition is set instead of ERATE when quality supervision
including CRC-4 is used.
CSES ceases
More than N non-SES detected consecutively.
EN/LZT 123 2697
R5A
1998-08-13
191 (306)
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