1. Omb411100 Bts＆Dbs3900 Gsm Troubleshooting Issue1.00 (Espa

8/10/2019 1. Omb411100 Bts Dbs3900 Gsm Troubleshooting Issue1.00 (Espa

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GSM BTS Troubleshooting

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During implementation or expansion, we can Interchange BTSs and judge whether thefault is subject to BSC or BTSDuring maintenance, BSC faults do affect some or all of BTS.


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Choose BSC Maintenance > Maintain User Resource > Collect BSC LocalInformation .The LMT integrates the information query with the report generation so that you canobtain the BSC local information quickly and easily.Collecting the local information refers to collecting the local information of the BSC or theBTS on the LMT, including the performance statistics file, log file, and alarm file.By default, the collected information is saved in the following directory: \HWLMT\BSC6000\LMT version number\BscObj\office name\LocaleInfo.Notes

The services are not disrupted during information collection.The local information of up to eight BTSs can be collected simultaneously.

Collect the information about multiple BTSs or file information takes a long time.Therefore, you should accurately select the range of the information collection.The maximum size of the Core Dump file is 1 GB. In normal cases, you are notadvised to collect the information of this file.The network bandwidth should be higher than or equal to 10 Mbit/s.


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Through GUIChoose Configuration > Back Up > Back Up Local Data .Choose Configuration > Back Up > Back Up GOMU Data .

Through MMLRun the ULD CFGFILE command to load the backup files of the configuration data.Run the DLD CFGFILE command to download the backup files of theconfiguration data.Run the BKP CFGFILE command to back up the configuration data.Run the RTR CFGFILE command to restore the configuration data.Run the ULD CFGFILE command to query the backup files of the configurationdata.


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The second method to collect BSC performance measurement information :Start the telnet client, such as PuTTY Software, to login BSC6000Copy all the files under the BSC6000\data\mtndata\pfm directory to the localhard disk.NOTE: If you are prompted to obtain specific rights in coping the files, run thechmod 777 /BSC6000 -R command to change the read-and-write authority.After the files are copied, run the chmod 755 /BSC6000 -R command to recoverthe read-and-write authority.


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Choose Alarm Maintenance > Browse Alarm on the LMTClick Alarm Detail , this alarm will be linked to BSS Alarm Reference for more informationPerform the related operations.

If you choose Save All Alarms from the shortcut menu, all the alarms in this logfile are saved in the local PC as a .txt file.If you choose Save Selected Alarms from the shortcut menu, the selected alarmsare saved in the local PC as a .txt file.If you choose Set Show Columns from the shortcut menu, the alarm informationto be displayed can be set as required.If you choose Alarm Details from the shortcut menu, the detailed informationabout the selected alarms are displayed.

If you choose Filter Alarms from the shortcut menu, the alarm filtering conditionscan be set.


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Log into LMT, click help, open BSS Alarm Reference


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Operation Procedure Choose Alarm Maintenance > Manage Alarm Log File. Click Create . The Create Alarm Log File dialog box is displayedIn the Create Options area, specify Start Time , End Time , File Name, andReturn Count for the file to be created.

The alarm log files will be saved in \\BSC6000 IP address\bsc6000\data\mtndata\alm inGBAM/GOMU


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The default path for loading alarm log files is LMT installation directory\BscObj\officename\Alm.Through MML

Run the LST ALMLOGFILE command to query the alarm log file list.Run the ULD ALMLOG command to load alarm log files.


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Operation Procedure: Choose Alarm Maintenance > Browse Alarm Offline on the LMT.Select an alarm log file and click Open .


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ContextIf the names of alarm log files to be queried are known, you can query the alarmlog files based on the file names. The query results contain only the alarm log filesthat meet the query conditions.The default path for loading alarm log files is LMT installationdirectory\BscObj\office name\Alm .

Through MMLRun the SET ALMLOG command to set the maximum days for the alarm log fileto be saved.Run the LST ALMLOGFILE command to query the alarm log file list.Run the ULD ALMLOG command to load alarm log files.
http://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/set_almlog.htmlhttp://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/lst_almlogfile.htmlhttp://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/uld_almlog.htmlhttp://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/uld_almlog.htmlhttp://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/lst_almlogfile.htmlhttp://localhost/var/www/HED%E5%AE%89%E8%A3%85%E7%A8%8B%E5%BA%8F%E6%96%87%E4%BB%B6/31182949_01.cdp/outfiles/d-huawei-gsm-gbss-documentation.files/bsc/e-bsc-mml/set_almlog.html


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Get BTS Log to GOMU Select this option to extract the BTS log to the GBAM (or GOMU) folder in thefollowing path: \\GBAM (or GOMU) IPaddress\bsc6000\data\mtndata\log\dbg\btslog. After extracted to the GBAM (orGOMU), the log on the BTS is deleted automatically. Select BSC Maintenance ->Maintain Logs -> Upload BSC Log File from the main menu of the LMT toobtain the BTS log file saved on the GBAM (or GOMU).

Get BTS Compressed Log Select this option to compress the BTS log and then extract it to the installationdirectory of the LMT on the local computer. The path is as follows: \HW LMT\LMTversion\BscObj\BSC name\CompressLog. You can view the log by using the logparsing tool.

Browse BTS Log This option allows you to select the BTS name, board type, board number andextraction time, and view the selected BTS log on the LMT.


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RF Subsystem:In BTS3900, DRFU/GRFU is used.In DBS3900, RRU is used.


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Alarm name: TRX SWR alarm (alarm ID: 4144)Explanation: This alarm is reported when the reverse power of the power outputports of a TRX is overhigh or cables are not connected properly to the poweroutput ports (TX1, TX2, and TCOM) of the TRX. For a DRRU, this alarm is reportedwhen the SWR of the antenna feeder system exceeds the critical alarm threshold ofthe DRRU. This alarm is also reported when no antenna feeder is connected to theantenna port of the DRRU.

Alarm name: DRRU SWR alarm (alarm ID: 4222)Explanation: This alarm is reported when the SWR of the antenna feeder systemexceeds the warning alarm threshold.


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Check the forward power and reverse power on the LMT of the BSC, calculate the VSWRby using the following formula, and check whether the calculation result is greater thanthe threshold for reporting a VSWR alarm to determine the generation of thecorresponding alarm.

Formula: X (dB) = Reverse power (dBm) Forward power (dBm)Reflection factor Y= 10exp (X/20)VSWR = (Y + 1)/(Y - 1)Assume that the forward power is 44.4 dBm and the reverse power is 36.5 dBm.The VSWR is 2.35 and is greater than the threshold (2.0) for generating a promptVSWR alarm. You can infer that a prompt VSWR alarm can be generated.

Check the VSWR of boards. Compare the VSWR of boards with the preceding calculation

results to determine that a VSWR alarm can be generated.


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Workaround Solutions:Change the threshold for reporting a VSWR alarm on the LMT of the BSC toprevent the BTS from reporting a VSWR alarm. A major VSWR alarm can becleared only after the TRX is reset. You are advised not to reset the TRX because ifyou do not handle the problem in time, the boards may go faulty.


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Note:Mechanism for reporting SWR alarms of the RRU: The RRU software performs adetection every two minutes, and an SWR alarm is report only when the SWRexceeds the alarm threshold continuously for three cycles, that is, an SWR alarmmay be reported only when the power is transmitted for six minutes.


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Balanced circuitThe balanced circuit is also called the differential circuit, which uses two lines totransmit identical signals in reverse directions. The E1 cable of 120 ohm is thetypical balanced circuit. Balanced cables are required for balanced circuits. That is,the twisted pair cables which form a signal loop.

Non-balanced circuitThe non-balanced circuit uses one transmission signal cable and one public groundcircuit. The E1 cable of 75 ohm is the typical non-balanced circuit. Non-balancedcables are required for non-balanced circuits. That is, the coaxial cables.

The products of Huawei which adopt E1 interfaces support the two working modes.Usually, the 75-ohm working mode is used in China and the 120-ohm working mode isused in overseas markets, depending on the specific customer requirements.


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E1 Local AlarmThis alarm is reported when the E1 chip of the BTS main control module does notreceive correct signals and causes the interruption of the BTS transmission.

E1 Remote AlarmThe alarm is reported when the BTS transmission is interrupted because the upperlevel BTS has not received correct E1 signals.

LAPD AlarmThe DTRU reports this alarm upon detecting that an LAPD link is not available.


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NoteCross connection check disrupts the services on the port. Huawei recommends thatthis check is performed only during the deployment or the upgrade.There are different types of cable connection errors, such as transmit and receiveconnection error. No cross connection does not mean that there are no other typesof cable connection errors.Cross connection check is available for only active boards or independent boards.To check for cross connections of standby boards, set them to active boards first.The port to be checked does not generate alarms.If the alarm method is used, ensure that the connection to the peer port is normaland that no loopback occurs.

If the loopback mode is used, perform remote loopback through remote short-circuiting or through a command on the remote port. The port for the Ater OMLsupports only remote short-circuiting.


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Working Principle of LOOP_METHOD:In loopback test mode, set the port on the remote equipment to the remoteloopback mode or directly physical loopback mode. At the local E1 port, insert thetest data (containing the port number information) into the TX signals. After theloopback, check whether the received port information is the same as thetransmitted one. If the same, it indicates that the E1 cables are correctly connected.If not, it indicates that that the fault in cross connections occurs.The advantage of loopback detection is that ports can be detected in batches andfaults in cross connections can be located effectively. The disadvantage ofloopback detection is that the loopback must be performed on the DDF or remoteE1 port.

Working Principle of ALM_METHOD:In alarm test mode, disable the TX function of the local E1 port, thus enabling theremote port to generate the LOS alarm. As a result, the remote alarm indication(RAI) is inserted to the TX signal of the remote port. If the E1 cables are connectedcorrectly, the local port receives the RAI. If the E1 cables are incorrectly connected,no alarm is generated at the local port.The alarm test is used to locate the faults related to the one-way audio duringnetwork maintenance or used in the case of loopback failure in the deployment.The advantage of alarm-based detection is that loopback is not performed on theremote E1/T1 ports. The disadvantage of alarm-based detection is that you canonly check whether the E1 cables are connected correctly but cannot acquire portinformation or detect the ports in batches.


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Details of the DIP Switch S1

Details of the DIP Switch S2


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When loopback to BSC side, the Abis port state is not normal, check the Abis E1connection to BSC is correct or not, and GEIUB is work normally or not.


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When loopback to BTS side, check the LIU indicator in GTMU board is not off, that is tosay the transmission between DDF to BTS is not ok.If BSC and BTS problem have been eliminated, we can infer the fault is caused by thegrounding problem or transmission device problem.


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E1 Local Alarm (alarm ID: 4714)E1 Remote Alarm (alarm ID: 4716)SFP Port Local Alarm (alarm ID: 4210)SFP Port Remote Alarm (alarm ID: 4212)


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In cross connection, the E1/T1 port can receive signals from the physical layer and noalarm is generated, but the signals are sent by a wrong E1/T1 port at the peer end.


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GSM BTS Troubleshooting P-60

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1. Omb411100 Bts＆Dbs3900 Gsm Troubleshooting Issue1.00 (Espa