Figure 7-1 Crossed Pair Connection - Huawei BTS3900 GSM Commissioning Manual

BTS3900(A) GSM
Commissioning Guide
2.
3.
4.
Example One: Detection of Crossed Pair Connection
The crossed pair connection refers to the incorrect RX and TX connections between two pairs
of E1 cables, as shown in

Figure 7-1 Crossed pair connection

E1 A
E1 B
Perform the loopback method on the BSC side to check for crossed pair connection. Perform
different steps according to different E1 connection modes.
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Issue 02 (2009-04-20)
Check for the crossed pair connection on the LMT.
Perform a physical loopback test to check whether the transmission of the E1 cable is normal
on the BTS side.
Check the transmission channels to ensure that all the transmission channels are available.
NOTE
The detection method in this example is applicable to check for the improper E1 connection between the
BTS and the BSC or the improper E1 connection on the BSC side. This detection method also can be used
to check the improper T1 connection.
Figure
RX
TX
TX
RX
NOTE
Loopback test: Set the port on the BTS side to the directly physical loopback mode. Send the test data,
which carries the E1 port number, to the TX end of the E1 from the BSC side. After the loopback, check
whether the received port information is the same as the transmitted one. If yes, you can infer that the E1
cable is correctly connected. If not, you can infer that the crossed pair connection occurs.
E1 link between the BTS and the BSC (1): BTS→DDF on the BTS side→DDF on the BSC
side→BSC, as shown in
Figure 7-2 E1 link between the BTS and the BSC (1)
E1/T1
E1/T1
BTS
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7-1.
Figure 7-2.
A0 C0
E1/T1
E1/T1
B0 D0
DDF0
7 FAQs for BTS Commissioning
TX
E1 A
RX
RX
E1 B
TX
A1 C1
E1/T1
E1/T1
B1 D1
DDF1 BSC
7-3