Figure 11-2 Physical Loopback Of The E1/T1 Cable On The Bts Side; Table 11-2 Meaning Of The States Of The Liu Led (Uelp Used) - Huawei BTS3900 GSM Commissioning Manual

11 FAQs for BTS Commissioning
2.
3.
For example, the physical loopback test is performed to troubleshoot the UELP failure, which
is one of the physical link faults.
1.
2.
3.
11-4
Check whether the E1 link on the BTS side is normal through the physical loopback test.
Check the transmission channels. Ensure that all transmission channels are available.
Check the connection between the E1/T1 cable and the OUTSIDE port on the UELP and
check the connector at the end of the E1/T1 cable. If any connector is damaged or does not
work properly, replace it with a new connector.
Check the connection between the E1 transfer cable and the INSIDE port on the UELP and
the connection between the E1 transfer cable and the E1/T1 port on the GTMU. Check the
connectors at both ends of the cable. If any connector is damaged or does not work properly,
replace it with a new connector.
Perform the physical loopback test and troubleshoot the fault in the UELP.
(1) On the BTS side, disconnect A from C, disconnect B from D, and then connect A to
B on the DDF, as shown in
is formed. The normal E1/T1 connection between the BTS and the BSC consists of
the connection between A and C and connection between B and D.

Figure 11-2 Physical loopback of the E1/T1 cable on the BTS side

E1/T1
E1/T1
BTS
(2) Check the status of the LIU LED corresponding to the E1/T1 cable in loopback mode.
Table 11-2 describes the meaning of the states of the LED.

Table 11-2 Meaning of the states of the LIU LED (UELP used)

If...
The LED is OFF,
The LED is ON or blinks at 4 Hz,
(3) Disconnect the E1 transfer cable and the E1/T1 cable. Then, directly connect the E1/
T1 cable to the E1/T1 port on the GTMU.
(4) When the UELP is not used, determine whether the E1/T1 link is normal based on the
status of the LIU LED on the GTMU panel, as listed in
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Copyright © Huawei Technologies Co., Ltd
Figure 11-2. Thus, a physical loopback on the BTS side
A C
E1/T1
E1/T1
B D
DDF
Then...
The E1/T1 link on the BTS side is
normal. Troubleshooting the UELP
failure is successful. The testing task on
the BTS side is complete.
The E1/T1 link on the BTS side is not
normal. Continue to troubleshoot the
fault in the UELP.
BTS3900 GSM
Commissioning Guide
BSC
Table 11-3.
Issue 03 (2008-07-15)