ZXG10 BS21 (V2.2) Compact Outdoor BTS for GSM Maintenance Manual
144
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¾
If yes, check whether alarms occur at the TIC board, LAPD board
and BOSN board. If yes, eliminate the corresponding faults.
¾
Implement transmission self-loop at the BSC side. If the alarm of
the LAPD broken-link disappears, the BSC-side equipment is normal.
¾
Check whether faults occur during transmission. Use a BER tester
to measure the bit error ratio of the transmission. If abnormal,
eliminate the transmission fault including transmission equipment
and grounding faults.
iii.
If LAPD broken-links only occur at one ETRM layer, check whether
the backplane cable is correctly connected.
iv.
If LAPD broken-links only occur at a ETRM, reset the ETRM. If the
fault still stays there, replace the ETRM module.
7.
Precautions
No transmission alarms occurring at the BSC side does not mean the
transmission is normal, since the transmission alarm of BSC only
appears in the case of broken physical connection, while the
transmission bit error or poor grounding does not result in alarms.
W i d e - s p r e a d T r a n s i e n t I n t e r r u p t i o n o f B S
C a r r i e r L A P D
1.
Symptom
LAPD broken-link occurs in some base stations at nearly the same time
and automatically gets normal in 10 ~ 20 seconds without any
handling.
2.
Source
The background O&M system reports related alarms.
3.
Related parts
Faults between MP and the LAPD board, transmission equipment.
4.
Fault analyzing and locating
The fault is caused by:
i.
Interrupted or unstable transmission (intermittent) interrupts the
BS LAPD, which features transmission alarms or alarm records.
ii.
The faults between the internal MP of BSC and the LAPD board
result in the transiently interrupted LAPD link, which features the
strict consistency of the LAPD interruption time with its recovery
time (accurate to the second level) on the carrier of the same LAPD
board, while different LAPD boards have a little difference in
interruption time and recovery time.
iii.
The BS-side CMM reset causes the LAPD to be transitorily
interrupted, which features the little difference between the carrier
LAPD interruption time and its recovery time of the BS (about
several seconds).
Содержание ZXG10 BS21
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