GBSS13.0 Troubleshooting Guide(02)(PDF)-En

GBSS13.0

Troubleshooting Guide

Issue 02Date 2012-06-25

HUAWEI TECHNOLOGIES CO., LTD.

Copyright Huawei Technologies Co., Ltd. 2012. All rights reserved.No part of this document may be reproduced or transmitted in any form or by any means without prior writtenconsent of Huawei Technologies Co., Ltd. Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.All other trademarks and trade names mentioned in this document are the property of their respective holders. NoticeThe purchased products, services and features are stipulated by the contract made between Huawei and thecustomer. All or part of the products, services and features described in this document may not be within thepurchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information,and recommendations in this document are provided "AS IS" without warranties, guarantees or representationsof any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in thepreparation of this document to ensure accuracy of the contents, but all statements, information, andrecommendations in this document do not constitute the warranty of any kind, express or implied. Huawei Technologies Co., Ltd.Address: Huawei Industrial Base

Bantian, LonggangShenzhen 518129People's Republic of China

Website: http://www.huawei.comEmail: [email protected]

Issue 02 (2012-06-25) Huawei Proprietary and ConfidentialCopyright Huawei Technologies Co., Ltd.

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About This Document

OverviewThis document provides methods for troubleshooting the GBSS in the following scenarios:l Customers lodge complaints.l Faults are discovered during routine maintenance.l Equipment faults occur abruptly.

Product VersionThe following table lists the product versions related to this document.

Product Name Product VersionBSC6900 V900R013C00BSC6000 V900R013C00BTS3900/BTS3900A/DBS3900 BTS3900V100R013C00 and laterBTS3012/BTS3012AE/BTS3012II/BTS3006C/BTS3002E

BTS3000V200R013C00 and later

BTS3900B/BTS3900E BTS3000V600R013C00 and laterBTS30/BTS312/BTS3012A V302R007 and later

Intended AudienceThis document is intended for:l Maintenance engineersl Field engineers

Organization1 Change in the GBSS Troubleshooting Guide

GBSS13.0Troubleshooting Guide About This Document


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This chapter describes the changes in the GBSS Troubleshooting Guide.2 Troubleshooting ProcedureThis chapter describes the basic troubleshooting procedure and each step.3 Common Maintenance FunctionsThis chapter describes common maintenance functions used during fault location.4 Handover ProblemsThis chapter describes how to locate and troubleshoot handover problems.5 Call DropsThis chapter describes how to locate and troubleshoot call drops.6 Access FaultsThis chapter describes how to locate and troubleshoot access faults.7 Voice ProblemsThis chapter describes how to locate and troubleshoot voice problems.8 PS Counter ProblemsThis chapter describes how to locate and troubleshoot PS counter problems.9 PS Channel FaultsThis chapter describes how to locate and troubleshoot PS channel faults.10 Cell PS Service FaultsThis chapter describes how to locate and troubleshoot cell PS service faults.11 IP Transmission FaultsThis chapter describes how to locate and troubleshoot IP transmission faults.12 Interference ProblemsThis chapter describes how to locate and troubleshoot interference problems.13 Faults on Main and Diversity RX ChannelsThis chapter describes how to locate and troubleshoot faults on main and diversity receive (RX)channels.14 No TrafficThis chapter describes how to locate and troubleshoot no traffic on 3900 series base stations.15 Appendix: How to Collect Fault InformationWhen faults cannot be rectified by referring to this document, collect fault information forHuawei technical support to quickly troubleshoot the faults. This section describes how to collectfault information.

ConventionsSymbol Conventions



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The symbols that may be found in this document are defined as follows.

Symbol DescriptionIndicates a hazard with a high level of risk, which if notavoided, will result in death or serious injury.

Indicates a hazard with a medium or low level of risk, whichif not avoided, could result in minor or moderate injury.

Indicates a potentially hazardous situation, which if notavoided, could result in equipment damage, data loss,performance degradation, or unexpected results.Indicates a tip that may help you solve a problem or savetime.Provides additional information to emphasize or supplementimportant points of the main text.

General ConventionsThe general conventions that may be found in this document are defined as follows.

Convention DescriptionTimes New Roman Normal paragraphs are in Times New Roman.Boldface Names of files, directories, folders, and users are in

boldface. For example, log in as user root.Italic Book titles are in italics.Courier New Examples of information displayed on the screen are in

Courier New.

Command ConventionsThe command conventions that may be found in this document are defined as follows.

Convention DescriptionBoldface The keywords of a command line are in boldface.Italic Command arguments are in italics.[ ] Items (keywords or arguments) in brackets [ ] are optional.{ x | y | ... } Optional items are grouped in braces and separated by

vertical bars. One item is selected.



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Convention Description[ x | y | ... ] Optional items are grouped in brackets and separated by

vertical bars. One item is selected or no item is selected.{ x | y | ... }* Optional items are grouped in braces and separated by

vertical bars. A minimum of one item or a maximum of allitems can be selected.

[ x | y | ... ]* Optional items are grouped in brackets and separated byvertical bars. Several items or no item can be selected.

GUI ConventionsThe GUI conventions that may be found in this document are defined as follows.

Convention DescriptionBoldface Buttons, menus, parameters, tabs, window, and dialog titles

are in boldface. For example, click OK.> Multi-level menus are in boldface and separated by the ">"

signs. For example, choose File > Create > Folder.

Keyboard OperationsThe keyboard operations that may be found in this document are defined as follows.

Format DescriptionKey Press the key. For example, press Enter and press Tab.Key 1+Key 2 Press the keys concurrently. For example, pressing Ctrl+Alt

+A means the three keys should be pressed concurrently.Key 1, Key 2 Press the keys in turn. For example, pressing Alt, A means

the two keys should be pressed in turn.

Mouse OperationsThe mouse operations that may be found in this document are defined as follows.

Action DescriptionClick Select and release the primary mouse button without moving

the pointer.Double-click Press the primary mouse button twice continuously and

quickly without moving the pointer.



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Action DescriptionDrag Press and hold the primary mouse button and move the

pointer to a certain position.



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Contents

About This Document.....................................................................................................................ii1 Change in the GBSS Troubleshooting Guide.........................................................................12 Troubleshooting Procedure.........................................................................................................2

2.1 Troubleshooting Flowchart.................................................................................................................................32.2 Collecting Fault Information..............................................................................................................................32.3 Determining a Fault Type...................................................................................................................................6

2.3.1 Fault Types................................................................................................................................................62.3.2 Methods for Determining a Fault Type.....................................................................................................7

2.4 Identifying Fault Causes.....................................................................................................................................82.5 Troubleshooting Faults.......................................................................................................................................9

2.5.1 Overview...................................................................................................................................................92.5.2 Methods for Troubleshooting Faults.........................................................................................................92.5.3 Follow-up Procedure...............................................................................................................................10

3 Common Maintenance Functions............................................................................................113.1 Maintenance Functions for Identifying Voice Problems..................................................................................12

3.1.1 Querying Call Resource Usage of an MS................................................................................................123.1.2 External Voice Loopback........................................................................................................................123.1.3 One-Way Audio Detection......................................................................................................................173.1.4 Crosstalk Detection..................................................................................................................................193.1.5 Optimizing Um Interface Crosstalk.........................................................................................................203.1.6 Binding MSs to BSC Resources..............................................................................................................203.1.7 Performing Dialing Tests on the Um Interface........................................................................................213.1.8 Performing Dialing Tests on the A Interface...........................................................................................21

3.2 Maintenance Functions for Identifying Transmission Problems......................................................................233.2.1 Crossed Pair Detection............................................................................................................................233.2.2 Monitoring Port BER Seconds................................................................................................................263.2.3 Querying Ethernet Port Attributes...........................................................................................................263.2.4 Performing IP Loopback.........................................................................................................................27

3.3 Maintenance Functions for Identifying Um and RF Problems.........................................................................283.3.1 Monitoring Channel Interference Bands.................................................................................................283.3.2 Testing Passive Intermodulation Interference Online.............................................................................293.3.3 Scanning Frequency Spectrum Online....................................................................................................30

GBSS13.0Troubleshooting Guide Contents


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3.4 Maintenance Functions Related to Interface Tracing.......................................................................................313.4.1 Tracing CS Domain Messages of a Single Subscriber............................................................................313.4.2 Tracing PS Domain Messages for a Single Subscriber...........................................................................33

3.5 Maintenance Functions for Identifying PS Problems.......................................................................................353.5.1 Monitoring Channel Status......................................................................................................................35

3.6 Maintenance Functions for Identifying Clock Problems..................................................................................373.6.1 Querying BSC Clock Source Status........................................................................................................373.6.2 Querying BSC Board Clock Status.........................................................................................................383.6.3 Maintaining BTS Clock...........................................................................................................................39

4 Handover Problems.....................................................................................................................414.1 Handover Principles.........................................................................................................................................42

4.1.1 Handover Procedure................................................................................................................................424.1.2 Handover Success Rate...........................................................................................................................44

4.2 Locating Handover Problems...........................................................................................................................474.2.1 Principles.................................................................................................................................................474.2.2 Procedure for Locating Handover Problems...........................................................................................47

4.3 Troubleshooting Handover Problems Due to Hardware Faults........................................................................524.4 Handover Problems Due to Incorrect Data Configurations..............................................................................554.5 Troubleshooting Handover Problems Due to Traffic Congestion in the Target Cell.......................................594.6 Troubleshooting Handover Problems Due to Poor Um Interface Quality.......................................................614.7 Troubleshooting Handover Problems Due to NE Faults..................................................................................654.8 Troubleshooting Handover Problems Due to Inappropriate Inter-BSC/Inter-MSC/Inter-RAT Interaction................................................................................................................................................................................68

5 Call Drops.....................................................................................................................................735.1 Call Drop Rate..................................................................................................................................................745.2 Locating Call Drops..........................................................................................................................................75

5.2.1 Procedure for Locating Call Drops..........................................................................................................755.2.2 Counters Related to Call Drops...............................................................................................................795.2.3 Types of Call Drops.................................................................................................................................81

5.3 Troubleshooting Call Drops Due to Poor Um Interface Quality......................................................................845.4 Troubleshooting Call Drops Due to Equipment Faults....................................................................................895.5 Troubleshooting Call Drops Due to Transmission Faults................................................................................935.6 Troubleshooting Call Drops Due to Incorrect Parameter Settings...................................................................94

6 Access Faults...............................................................................................................................1016.1 Access Principles............................................................................................................................................1036.2 Locating Access Faults...................................................................................................................................104

6.2.1 Procedure for Locating Access Faults...................................................................................................1056.2.2 Common Causes for Access Faults.......................................................................................................112

6.3 Troubleshooting Access Faults Due to Poor Um Interface Quality...............................................................1166.4 Troubleshooting Low Immediate Assignment Success Rates Due to SDCCH Congestion..........................1226.5 Troubleshooting Low Immediate Assignment Success Rates Due to Hardware or Transmission Faults..............................................................................................................................................................................126



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6.6 Troubleshooting Low Immediate Assignment Success Rates Due to Location Updates of Problem MSs..............................................................................................................................................................................1306.7 Troubleshooting Low Assignment Success Rates Due to TCH Congestion..................................................1336.8 Troubleshooting Low Assignment Success Rates Due to Hardware or Transmission Faults........................1376.9 Troubleshooting Low Assignment Success Rates Due to Inappropriate BSC Configuration.......................141

7 Voice Problems.......................................................................................................................... 1467.1 GSM CS Signal Flow.....................................................................................................................................1477.2 Common Voice Problems and Problem Location Methods...........................................................................1527.3 Troubleshooting One-Way Audio or No Audio.............................................................................................1537.4 Troubleshooting Noise...................................................................................................................................1597.5 Troubleshooting Crosstalk..............................................................................................................................1657.6 Troubleshooting Echoes.................................................................................................................................1717.7 Troubleshooting Discontinuous Voice or Low MOS.....................................................................................176

8 PS Counter Problems................................................................................................................1838.1 PS Counters....................................................................................................................................................1848.2 Locating PS Counter Problems.......................................................................................................................185

8.2.1 Principles for Locating PS Counter Problems.......................................................................................1858.2.2 Procedure for Locating PS Counter Problems.......................................................................................185

8.3 Troubleshooting Low TBF Establishment Success Rates..............................................................................1868.4 Troubleshooting High TBF Call Drop Rates..................................................................................................1958.5 Troubleshooting Low Average Throughput at the RLC Layer......................................................................2028.6 Troubleshooting Low Percentage of High-Rate Coding Schemes to All Coding Schemes...........................2098.7 Troubleshooting High RLC Data Block Retransmission Rates.....................................................................217

9 PS Channel Faults......................................................................................................................2249.1 Identifying PS Channel Faults........................................................................................................................2259.2 Locating PS Channel Faults...........................................................................................................................2259.3 Troubleshooting PDCH Faults Due to Channel Inactivity.............................................................................2279.4 Troubleshooting PDCH Faults Due to Channel Asynchronization................................................................234

10 Cell PS Service Faults.............................................................................................................24310.1 Remarks on Cell PS Service Faults..............................................................................................................24410.2 Locating Cell PS Service Faults...................................................................................................................24410.3 Troubleshooting Cell PS Service Faults Due to Gb Interface Issues...........................................................25010.4 Troubleshooting Cell PS Service Faults Due to Incorrect Data Configurations..........................................25210.5 Troubleshooting Cell PS Service Faults Due to Hardware Issues................................................................25410.6 Troubleshooting Cell PS Service Faults Due to Incorrect Cable Connections Inside the BSC...................256

11 IP Transmission Faults...........................................................................................................25811.1 Troubleshooting FE/GE Transmission Faults..............................................................................................25911.2 Troubleshooting IP Layer Faults..................................................................................................................26611.3 Troubleshooting PPP or MLPPP Link Faults...............................................................................................27111.4 Troubleshooting LAPD Link Faults.............................................................................................................27611.5 Troubleshooting SCTP Link Faults..............................................................................................................285



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11.6 Troubleshooting IP Path Problems...............................................................................................................29311.7 Troubleshooting DHCP Problems................................................................................................................29811.8 Troubleshooting IP PM Activation Failures.................................................................................................30411.9 Troubleshooting IP Clock Faults..................................................................................................................307

12 Interference Problems.............................................................................................................31612.1 Interference...................................................................................................................................................31712.2 Locating Interference Problems....................................................................................................................31812.3 Troubleshooting Co-channel or Adjacent-Channel Interference..................................................................32112.4 Troubleshooting Intermodulation Interference.............................................................................................32312.5 Troubleshooting Interference from the CDMA Network.............................................................................32812.6 Troubleshooting External Interference.........................................................................................................331

13 Faults on Main and Diversity RX Channels.......................................................................33513.1 Principles of Main and Diversity Reception.................................................................................................33613.2 Locating Faults on Main and Diversity RX Channels..................................................................................33613.3 Troubleshooting Faults on Main and Diversity RX Channels Due to Incorrect Data Configurations.........33813.4 Troubleshooting Faults on Main and Diversity RX Channels Due to Incorrect Antenna Connections.......34113.5 Troubleshooting Faults on Main and Diversity RX Channels Due to Hardware Faults..............................345

14 No Traffic..................................................................................................................................34814.1 Introduction to No Traffic............................................................................................................................34914.2 Locating No Traffic......................................................................................................................................34914.3 Troubleshooting No Traffic Due to No Calls...............................................................................................35414.4 Troubleshooting No Traffic Due to Transmission or Equipment Faults......................................................35514.5 Troubleshooting No Traffic Due to Incorrect Data Configurations.............................................................35714.6 Troubleshooting No Traffic Due to Poor Um Interface Quality..................................................................35914.7 Troubleshooting No Traffic Due to Antenna System Faults........................................................................36114.8 Resetting.......................................................................................................................................................365

15 Appendix: How to Collect Fault Information....................................................................366



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1 Change in the GBSS Troubleshooting GuideThis chapter describes the changes in the GBSS Troubleshooting Guide.

02 (2012-06-25)This is the second commercial release of GBSS13.0.Compared with issue 01 (2012-01-05) of GBSS13.0, this issue does not include any new topics.Compared with issue 01 (2012-01-05) of GBSS13.0, this issue incorporates the followingchanges:

content Description7.7 Troubleshooting Discontinuous Voiceor Low MOS

l The typical case is modified.

Compared with issue 01 (2012-01-05) of GBSS13.0, this issue does not excludes any topics.

01 (2012-01-05)This is the first commercial release of GBSS13.0.

GBSS13.0Troubleshooting Guide 1 Change in the GBSS Troubleshooting Guide


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2 Troubleshooting ProcedureAbout This Chapter

This chapter describes the basic troubleshooting procedure and each step.

2.1 Troubleshooting FlowchartThis section shows the troubleshooting flowchart.2.2 Collecting Fault InformationThis section provides methods for collecting information about faults and describes the faultinformation types.2.3 Determining a Fault TypeAfter collecting fault information, analyze the symptoms to determine a fault type.2.4 Identifying Fault CausesTo identify the specific cause of a fault, exclude possible causes by analyzing the symptoms.2.5 Troubleshooting FaultsThis section provides the methods for troubleshooting faults as well as follow-up procedures.

GBSS13.0Troubleshooting Guide 2 Troubleshooting Procedure


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2.1 Troubleshooting FlowchartThis section shows the troubleshooting flowchart.Figure 2-1 shows the troubleshooting flowchart.

Figure 2-1 Troubleshooting flowchart

2.2 Collecting Fault InformationThis section provides methods for collecting information about faults and describes the faultinformation types.

Methods for Collecting Fault InformationBefore troubleshooting a fault, collect the following information:



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l Fault symptomsl Time, place, and frequency of the faultl Fault range and impactl Equipment operating status before the fault occursl Operations performed on the equipment before the fault occurs and the operation resultsl Alarms generated when the fault occurs and the associated alarmsl Board indicator status when the fault occursl Measures taken after the fault occurs and the effects of measuresThe methods for collecting fault information are as follows:l Obtain the symptoms, time, place, and frequency of the fault from the subscribers and

technical support engineers.l Obtain the equipment operating status, symptoms, operations performed before the fault

occurs, as well as measures taken after the fault occurs and the effect of those measuresfrom the equipment operation and maintenance (O&M) engineers.

l Monitor the board indicator status and alarms reported on the LMT to understand thesoftware and hardware operating status.

l Simulate services, measure performance, and trace interface signaling messages tounderstand the fault range and impact.

NOTEIf you encounter severe faults, do not troubleshoot the faults before determining the specific causes. In thiscase, you are advised to collect sufficient information, or contact Huawei for technical support.

Fault Information Typesl Alarm information

Alarm information is exported by the BSS alarm system and reported with any combinationof the following: sounds, lights, indicators, or onscreen indications. Viewing the alarminformation is a common method for analyzing faults.Alarm information includes a description of the fault symptoms and causes, as well as faultrectification suggestions. Alarm information includes detailed information about hardware,links, trunks, and CPU load.In most cases, alarm information is sufficient to locate the specific cause of a fault.Otherwise, you can use the alarm information with other information to locate a fault.

NOTEFor a description of the alarm system, see the BSC6900 GSM LMT User Guide. For details abouthow to handle an alarm, see the BSC6900 GSM Alarm Reference.

l Indicator statusIndicators provide the operating status of boards, circuits, links, optical paths, or nodes.Viewing the indicator status helps quickly locate the general cause of a fault. Becauseindicator status is generally not informative enough to locate a fault, this information isoften used with the alarm information to locate a fault. Table 2-1 uses the SCUa as anexample to describe the board indicators.



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Table 2-1 LEDs on the SCUa boardLED Color Status DescriptionRUN Green ON for 1s and OFF for 1s The board is functional.

ON for 0.125s and OFFfor 0.125s

The board is in loadingstate.

ON There is power supply,but the board is faulty.

OFF There is no powersupply, or the board isfaulty.

ALM Red OFF There is no alarm.ON or blinking There is a fault alarm.

ACT Green ON The board is in activemode.

OFF The board is in standbymode.

LINK (at theEthernet port)

Green ON The link is wellconnected.

OFF The link is disconnected.ACT (at theEthernet port)

Green OFF There is no datatransmission over theEthernet port.

Blinking There is datatransmission over theEthernet port.

NOTEFor a description of indicators on various boards, see the BSC6900 GSM Hardware Description.Operation and maintenance (O&M) engineers should be familiar with indicators to facilitate faultlocation.

l Dialing test resultsDialing tests are performed to determine whether BSS services are normal. In addition,dialing tests are performed to collect information such as MS signaling, network signaling,and detailed fault symptom descriptions.

l Instrument measurement resultsInstrument and meter measurement results are true indication of fault causes. Instrumentmeasurement results are widely used for power supply tests, signaling analysis, waveanalysis, and bit error detection. For example, the procedure for troubleshooting high calldrop rates at a site using a signaling analyzer is as follows: Select some signaling messages related to call drops by using a signaling analyzer.



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Analyze the signaling messages. The timing advance (TA) value approaches 63. Change the data configuration to reduce the cell radius.

NOTEFor details about methods for using an instrument, see the related user guide.

l Traffic statisticsTraffic statistics are generally used to analyze service faults such as call drops and handoverproblems.Traffic statistics can be used with traced signaling messages to troubleshoot high call droprates, low handover success rates, or call exceptions.

NOTEFor details about how to use traffic statistics to analyze problems, see the BSC6900 GSM LMT UserGuide. For counter meanings, see the BSC6900 GSM Performance Counter Reference.

l Signaling messages traced over interfacesSignaling messages are generally used to identify causes of call connection failures or inter-site signaling interaction failures.

NOTEFor details about how to how to trace the signaling messages, see the BSC6900 GSM LMT UserGuide.

2.3 Determining a Fault TypeAfter collecting fault information, analyze the symptoms to determine a fault type.You can also Contact Huawei Customer Service Center to determine a fault type.

NOTEIf a severe fault occurs, Contact Huawei Customer Service Center.

2.3.1 Fault TypesThis section lists the fault types covered in this document.l CS voice problemsl CS service faults

Handover problems Call drops Access problems

l PS service faults PS counter problems PS channel faults No PS service available in a cell

l Equipment faults IP transmission faults Interference Main diversity receive channel faults No traffic



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NOTEDetermine the fault type based on symptoms. Different fault types may have the same symptoms. Forexample, call drops problems may have the same symptoms as handover problems. In this case, methodsfor troubleshooting call drops problems will be linked to the methods for troubleshooting handoverproblems.

2.3.2 Methods for Determining a Fault TypeThis section describes methods for determining a fault type.l Monitoring

Monitoring is a common method for determining fault ranges. You can observe alarms,indicator status, and LMT panel status.

l Analysis of Top N deteriorating performance countersThis method can determine a fault type when performance counters deteriorate. With thismethod, you can sort out the Top N deteriorating performance counters for cells and TRXs.Then, you can determine whether performance counters for certain cells or an entire BSCdeteriorate. For specific cases, see 4 Handover Problems.

l Loopback testsLoopback tests can locate transmission, link, and voice problems. Loopback tests areclassified into hardware loopback tests and software loopback tests. For specific cases, see3.1.2 External Voice Loopback.You can determine whether equipment operates normally and software parameters are setcorrectly by checking the status of the transmission equipment, transmission channels,services, and signaling interaction status after loop back tests are performed. Loopbacktests can also be performed to determine whether transmission faults occur or trunkparameters are set incorrectly. During site deployment or trunk capacity expansion, BSStrunk loopback tests can help determine whether trunk parameters and signaling link dataare configured correctly.

NOTELoopback tests are also performed to locate transmission faults.

l Process of eliminationThis method can exclude both software problems and hardware problems. To excludesoftware problems, disable a certain function or feature to check whether a fault can berectified. If the fault is rectified, the function or feature is abnormal. Otherwise, the functionor feature is normal.To exclude hardware problems, replace faulty boards.For example, when troubleshooting co-channel or adjacent-channel interference, replacethe cell ARFCN with an ARFCN without interference (such as an E-GSM900 ARFCN).Then, check whether the interference problem is resolved.

l Regularity identificationIdentifying problem regularity helps to narrow the fault range. When narrowing the faultrange, consider the following factors:1. Whether a certain board is faulty2. Whether a certain DSP is faulty3. Whether a certain transmission path is faulty4. Whether a certain TRX is faulty5. Whether a certain type of MS is faulty



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6. Whether a certain type of channel is faulty7. Whether an enabled feature is abnormal, such as Flex TSC, downlink power control,

or BCCH power consumption reduction8. Whether an alarm is reported multiple timesFor example, if a Cell Out of Service alarm is reported, check whether one or multiple cellsare out of service. If only one cell is out of service, the TRX serving this cell may be faulty, or the cell

data configurations may be incorrect. If multiple cells are out of service, determine whether these cells are served by one or

multiple BTSs. If these cells are served by one BTS, check whether any transmission alarms (such

as LAPD or E1 alarms) are reported. If any transmission alarms are reported, a powerfailure or transmission faults may have occurred at the BTS. If these cells are served by multiple BTSs, check whether these BTSs are located in

the same area. If these BTSs are located in the same area, the power may have failedor the optical fibers in the area may be damaged.

l Comparison/InterchangeProblems can be identified by comparing faulty components with normal components orby interchanging the possibly faulty components with normal components. Use the comparison method when there is only a single fault type. Use the interchange method when there are multiple fault types. Interchange can be

used for the following items:1. TRXs and boards2. Transmission cables3. Antennas4. ARFCNs

For example, when severe interference in a certain cell cannot be eliminated aftertroubleshooting cable connection faults, interchange the antenna system for the abnormalcell with that for a normal cell. If the interference is eliminated, the original antenna systemis faulty. For details, see the typical case in 12.4 Troubleshooting IntermodulationInterference.

2.4 Identifying Fault CausesTo identify the specific cause of a fault, exclude possible causes by analyzing the symptoms.Generally, you need to analyze the causes of the following faults:l Service faults

When a CS or PS service fault occurs, check the interfaces within the BSS to determinewhether it is faulty. If the BSS is faulty, continue identifying the fault cause. When a handover or access problem occurs, start measuring traffic statistics and tracing

signaling messages. Then, determine the fault location according to protocols.l Subsystem faults

Subsystem faults include clock, interface link, and equipment faults. These faults havenarrow ranges and are generally associated with alarms. In addition, information including



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board indicators and error messages is available. Therefore, it is easy to identify the causesof subsystem faults.

2.5 Troubleshooting FaultsThis section provides the methods for troubleshooting faults as well as follow-up procedures.

2.5.1 OverviewTroubleshooting faults is a process of taking proper measures to rectify faults and restore asystem to good working order. Methods for troubleshooting faults include cable connectioncheck, board replacement, data configuration modification, board switchover, and boardresetting.Consider the following items when troubleshooting a fault:l Use different troubleshooting procedures according to fault types.l Verify that the fault is rectified after the troubleshooting procedure.l After a fault is rectified, review the troubleshooting process, record the key points, and

provide preventive and improvement measures.NOTEWhen severe faults occur, Contact Huawei Customer Service Center.

2.5.2 Methods for Troubleshooting FaultsThis section provides methods for troubleshooting faults.l Fault isolation

Isolation is the act of isolating the fault location from the surrounding service unit to preventthe fault from adversely impacting ongoing services.For example, when a DSP on a DPU is faulty and the DPU cannot be replaced immediately,run the MML command INH DSP to isolate the DSP. For details, see the typical case in7.4 Troubleshooting Noise.

l Switchover/resettingDuring a switchover, services are switched from an active device to a standby device. Youcan compare the system operating status before and after the switchover. By resetting partof a device or the whole device, you can determine the software operating status.Exercise caution when using switchover/resetting methods for the following reasons: Both methods are auxiliary methods used only in an emergency. Both methods can prevent a fault from recurring in a short time due to software bugs.

However, they cannot identify the root cause of a problem. This may lead to equipmentfaults or operation instability.

Resetting may lead to service interruptions or even system crash, affecting normal BSSoperations. For example, some or all services over the A interface are interrupted. In thiscase, perform the following operations:1. Check whether any A interface transmission alarms have been reported on the BSC.2. Reset the MSC interface board communicating with the A interface board.3. Switch over the active and standby A interface boards.



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4. When the BSC works in BM/TC separated mode, switch over the active and standbyAter interface boards in the BM subrack.

5. Switch over the XPU boards where SS7 signaling links are configured.6. Perform local loopback tests on the port of the Ater interface board in the BM subrack.

Then, check whether the Ater interface board can receive messages it has sent.l Replacement

If other methods are ineffective, replace faulty equipment such as boards, cables, orantennas.

NOTE

1. If a fault persists after a board is replaced, reinsert the board instead of shipping the board backto Huawei headquarters.

2. If no equipment is available for replacing the faulty equipment, remove and then reinstall theequipment.

2.5.3 Follow-up ProcedureThis section describes the handling operations performed after a fault is rectified.l After a fault is rectified, query the equipment status, board indicators, and alarms to verify

that the faulty NE is operating normally. In addition, perform dialing tests and check trafficstatistics to verify that services are operating properly.

l If the fault persists, collect fault location information and Contact Huawei Customer ServiceCenter.



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3 Common Maintenance FunctionsAbout This Chapter

This chapter describes common maintenance functions used during fault location.

3.1 Maintenance Functions for Identifying Voice ProblemsThis section describes maintenance functions for identifying voice problems.3.2 Maintenance Functions for Identifying Transmission ProblemsThis section describes maintenance functions for identifying transmission problems.3.3 Maintenance Functions for Identifying Um and RF ProblemsThis section describes maintenance functions for identifying Um and RF problems.3.4 Maintenance Functions Related to Interface TracingThis section describes maintenance functions related to interface tracing.3.5 Maintenance Functions for Identifying PS ProblemsThis section describes maintenance functions for identifying PS problems.3.6 Maintenance Functions for Identifying Clock ProblemsThis section describes maintenance functions for identifying clock problems.

GBSS13.0Troubleshooting Guide 3 Common Maintenance Functions


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3.1 Maintenance Functions for Identifying Voice ProblemsThis section describes maintenance functions for identifying voice problems.

3.1.1 Querying Call Resource Usage of an MSThis section describes how to query the call resource usage of an MS.

Function DescriptionThis function queries the call resource usage of an MS that has set up a call and is used to identifyBSS voice problems. The query can be performed by entering the MS's Mobile StationInternational ISDN Number (MSISDN), International Mobile Subscriber Identity (IMSI),Temporary Mobile Subscriber Identity (TMSI), or International Mobile Equipment Identity(IMEI).

Procedure1. On the LMT, run the MML command DSP CALLRES, then press Enter or click Assist.2. Set User Query Type to BYTMSI(By TMSI), BYIMSI(By IMSI), BYMSISDN(By

MSISDN), or BYIMEI(By IMEI). The corresponding MS identifier (ID) is displayed.NOTEl If you set User Identity Type to BYMSISDN(By MSISDN), set the MSISDN to the number of

the peer end. When querying the call resource usage of the calling MS, set the MSISDN to thecalled number. When querying the call resource usage of the called MS, set the MSISDN to thecalling number (the Calling Line Identification Presentation function must be enabled).

l If you set User Identity Type to BYTMSI(By TMSI) or BYIMSI(By IMSI), confirm thereallocation policy configured on the MSC side. If the MS's TMSI is used to set up a call, setUser Query Type to BYTMSI(By TMSI) to query the call resource usage. If the MS's IMSI isused to set up a call, set User Query Type to BYIMSI(By IMSI) to query the call resourceusage.

l If you set User Identity Type to BYIMEI(By IMEI), determine whether the MSC can obtainthe IMEI.

3. Set the ID based on the specified User Query Type. Then, click Exec.

Operation ResultsThe query result shows the call resource usage of the MS, including information about the BMsubrack, TC link, A interface, and Ater interface. The query result also includes informationsuch as digital signal processor (DSP) number, channel number, service type, circuitidentification codes (CICs) on the A interface, as well as timeslots occupied by the GEIUA,GEIUB, and GEIUT.

3.1.2 External Voice LoopbackThis section describes how to start or stop external voice loopback and query the status of thecurrent voice loopback.

Function DescriptionVoice loopback refers to routing voice data back to its source over the same path it was sent on.By comparing the sent voice with the looped-back voice, voice problems can be identified



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segment by segment. This function is used to identify voice problems such as one-way audio,no audio, crosstalk, or noise on a BSC or BTS.Currently, voice loopback can be performed in all 14 positions of the BSC and BTS. Figure3-1, Figure 3-2, and Figure 3-3 show 12 loopback positions in a BSC in three networking modes.The loopback positions are the same for multi-core boards.

Figure 3-1 Abis over TDM + A over TDM

Figure 3-2 Abis over IP + A over TDM

Figure 3-3 Abis over TDM + A over IP



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NOTE

1. TDM BTSs support only MSC-oriented loopback testing on the TMU. BTSs do not support loopbacktesting on the TRU. Only IP BTSs and high-speed data link control (HDLC) BTSs support both MSC-oriented and MS-oriented loopback testing on the DPTU.

2. In TDM networks, the loopback testing is performed over the Ater and Abis interfaces at 64 Kbit/swhereas services are processed over the two interfaces at 16 Kbit/s or 8 Kbit/s. As a result, a loopbacktest of the channel used by one subscriber may lead to loopback tests of the channels used by othersubscribers on the same 64 Kbit/s timeslot.

Procedurel Choosing menu items

1. Click Device Maintenance on the LMT main page. The Device Maintenance tabpage is displayed.

2. On the BSC Maintenance tab page, choose BSC Maintenance > Maintain UserResources > Remote Speech Channel Loopback. The Remote Speech ChannelLoopback dialog box is displayed.

3. In the Remote Speech Channel Loopback dialog box, set the parameters as required,and click Start. A message is displayed, informing you that the loopback issuccessfully started.

NOTE

l If you select MSISDN in the Trace Object Symbol Type area, set the MSISDN to thenumber of the peer end.l (Recommended) If the calling party is traced, set the MSISDN to the called number.l If the called party is traced, set the MSISDN to the calling number (the Calling Line

Identification Presentation function must be enabled).l If you select TMSI or IMSI in the Trace Object Symbol Type area, confirm the

reallocation policy configured on the MSC side.l If the MS's TMSI is used to set up a call, you can select TMSI in the Trace Object

Symbol Type area to query the call resource usage.l If the MS's IMSI is used to set up a call, set Trace Object Symbol Type to IMSI to

query the call resource usage.l If you select IMEI in the Trace Object Symbol Type area, determine whether the MSC

can obtain the IMEI.4. After the loopback is started, click Query to query the remote speech channel

loopback.5. Click Cancel stop the remote speech loopback.

NOTE

To end a remote speech loopback, select IMSI, IMEI, TMSI, or MSIDSN in the Trace ObjectSymbol Type area to ensure that the parameter setting in the Trace Object Symbol Type areais the same as that is previously set for the loopback.

l Running MML commands1. After a call is set up successfully, run the MML command STR CALLRESLOP on

the LMT, and press Enter or click Assist.2. Set the relevant parameters, and click Exec to start the loopback3. After the loopback is complete, run the MML command STP CALLRESLOP to stop

the loopback.



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Operation Results1. The expected loopback effect is TDM three-way audio. That is, subscriber A can

communicate with subscriber B. In addition, during an MS-oriented loopback test of thechannel used by subscriber A, subscriber A can hear his or her own voice and subscriberB can hear subscriber A's voice. Three-way audio is not implemented in IP mode. Therefore,in IP mode, subscriber B cannot hear subscriber A's voice during an MS-oriented loopbackon subscriber A.

2. Three-way audio is implemented for loopback testing in the BSC TC subrack in either TDMor IP mode.

3. When FG2a is configured over the A, Abis, or Ater interface, a subscriber can hear his orher own voice and the peer end's voice during a loopback over these interfaces, but the peerend cannot hear any voice regardless of whether the loopback is MSC- or MS-oriented.

4. During a loopback on an IP BTS, a subscriber can hear his or her own voice and the peerend's voice, but the peer end cannot hear any voice regardless of whether the loopback isMSC-oriented or MS-oriented.

5. Table 3-1 lists the loopback results for various positions when the ID of subscriber A isused to perform loopback. The results are similar if the ID of subscriber B is used.

Table 3-1 Loopback resultsLoopback Position andDirection

InterfaceBoard Type

Subscriber A Subscriber B

NSS Interface Unit (MSCDirection)

TDMinterfaceboard

Can hear B but notself

Can hear self butnot A

IP/HDLCinterfaceboard

Cannot hear self orB


NSS Interface Unit (MSDirection)

TDMinterfaceboard

Can hear self butnot B

Can hear A butnot self



Cannot hear A orself

NSS TC (Near AbisInterface) (MSC Direction)



NSS TC (Near AbisInterface) (MS Direction)



NSS TC (Near A Interface)(MSC Direction)



NSS TC (Near A Interface)(MS Direction)



NSS TNU (Near AbisInterface) (MSC Direction)





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Loopback Position andDirection

InterfaceBoard Type


NSS TNU (Near AbisInterface) (MS Direction)



NSS TNU (Near AInterface) (MSC Direction)



NSS TNU (Near AInterface) (MS Direction)



NSS Ater Interface Unit(MSC Direction)

TDMinterfaceboard






NSS Ater Interface Unit(MS Direction)

TDMinterfaceboard






BSS Ater Interface Unit(MSC Direction)

TDMinterfaceboard






BSS Ater Interface Unit(MS Direction)

TDMinterfaceboard






BSS TC (Near AbisInterface) (MSC Direction)



BSS TC (Near AbisInterface) (MS Direction)



BSS TC (Near A Interface)(MSC Direction)



BSS TC (Near A Interface)(MS Direction)





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Loopback Position andDirection

InterfaceBoard Type


BSS TNU (Near AbisInterface) (MSC Direction)



BSS TNU(Near AbisInterface) (MS Direction)



BSS TNU (Near AInterface) (MSC Direction)



BSS TNU (Near AInterface) (MS Direction)



BSS Interface Unit (MSCDirection)

TDMinterfaceboard






BSS Interface Unit (MSDirection)

TDMinterfaceboard






TMU/PTU (MSCDirection)

Non-IP BTS Can hear B but notself


IP BTS Cannot hear self orB


TMU/PTU (MS Direction) Non-IP BTS Can hear self butnot B


IP BTS Can hear self butnot B


3.1.3 One-Way Audio DetectionThis section describes how to detect one-way audio or no audio on the BSS.

Function DescriptionThis function is used to detect one-way audio or no audio by checking uplink and downlinkvoice and data transmission of a BSC or BTS. When one-way audio or no audio is detected,record the call resource information and determine the faulty device to efficiently identify theproblems.



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NOTE

l One-way audio logs are saved in \bam\common\fam\famlogfmt\.l BSC6900 V900R013 supports one-way audio detection in IP and TDM transmission modes.l The BTS TRXs must support one-way audio detection. In addition, BTSs of GBSS 13.0 support one-

way audio detection in IP transmission mode.l One-way audio detection cannot be used with the local switching function. Therefore, before enabling

one-way audio detection, ensure that the local switching function is disabled.

ProcedureBefore one-way audio detection is enabled, check the transmission mode of the Abis interfaceand run the MML commands SET BSCBASIC and SET GCELLSOFT. The specificoperations in different scenarios are described as follows:l Scenario 1: TDM transmission is used for the A, Ater, and Abis interfaces.

1. SET BSCBASIC: SpeechAlmPeriod=12, SPEECHCHANALARMTHRES=10,SPEECHCHANRESUMEALARMTHRES=6,MuteTestLogStyle=LEV1_MUTETEST_LOG_REC-0&LEV2_MUTETEST_LOG_REC-1&IP_MUTETEST_LOG_REC-0&CIC_MUTETEST_LOG_REC-0, SpeechErrorForceHOSwitch=OFF;

2. SET GCELLSOFT: IDTYPE=BYID, CELLID=0,TCMUTEDETECTFLAG=ENABLE, MUTECHECKCLASS1PERIOD=5,EXCEPFRAMETHRES=25, MUTECHECKCLASS2SWITCH=ENABLE,DETECTFRAMEPERIOD=2, MUTECHECKPEIROD=4;

l Scenario 2: IP transmission is used for the A, Ater, and Abis interfaces.1. SET BSCBASIC: SpeechAlmPeriod=12, SPEECHCHANALARMTHRES=10,

SPEECHCHANRESUMEALARMTHRES=6,MuteTestLogStyle=LEV1_MUTETEST_LOG_REC-0&LEV2_MUTETEST_LOG_REC-0&IP_MUTETEST_LOG_REC-1&CIC_MUTETEST_LOG_REC-0, SpeechErrorForceHOSwitch=OFF;

2. SET GCELLSOFT: IDTYPE=BYID, CELLID=0,TCMUTEDETECTFLAG=ENABLE, MUTECHECKCLASS1PERIOD=5,EXCEPFRAMETHRES=25;

l Scenario 3: The transmission modes of the A, Ater, and Abis interfaces are different, andIP transmission is used for the A, Ater, or Abis interface.1. SET BSCBASIC: SpeechAlmPeriod=12, SPEECHCHANALARMTHRES=10,

SPEECHCHANRESUMEALARMTHRES=6,MuteTestLogStyle=LEV1_MUTETEST_LOG_REC-0&LEV2_MUTETEST_LOG_REC-1&IP_MUTETEST_LOG_REC-1&CIC_MUTETEST_LOG_REC-0,SpeechErrorForceHOSwitch=OFF;

2. SET GCELLSOFT: IDTYPE=BYID, CELLID=0,TCMUTEDETECTFLAG=ENABLE, MUTECHECKCLASS1PERIOD=5,EXCEPFRAMETHRES=25, MUTECHECKCLASS2SWITCH=ENABLE,DETECTFRAMEPERIOD=2, MUTECHECKPEIROD=4;

Operation Resultsl Each time the BSC detects one-way audio, a log prefixed by [CDIG] is recorded. To obtain

the log, run the MML command COL LOG.



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l No tool is required to open the log. You can use EXCEL to open the log file. SubType inthe logs can be used to select the appropriate transmission mode used by the BSC. If theBSC uses TDM transmission mode, select SubType:TDM_L2. If the BSC uses IPtransmission mode, select SubType:IP_MUTE.

l All resource information related to a call is recorded after one-way audio occurs during thecall. Therefore, when any node is faulty, the faulty node information is recorded in all logs.Table 3-2 shows the mapping between the faulty nodes and the fields in the logs.

Table 3-2 Mapping between the faulty nodes and the fields in the logsAnalysis Item Field Field DescriptionBTS TrxId TRX IDAbis interface AbisSubrackNo Subrack number of the Abis

interface boardAbisSlotNo Slot number of the Abis

interface boardAbisPort Port number of the Abis

interface boardTNU TNURack Subrack number of TNU

TNUSlot TNU slot numberTNUPort TNU port number

TC resources TcSubRackNo TC subrack numberTcSlotNo TC slot numberTcDspNo TC DSP number

A interface Acic CIC numberAter interface AterLinkNo Ater link number

3.1.4 Crosstalk DetectionThis section describes how to detect crosstalk on the BSS.

Function DescriptionThis function detects crosstalk due to abnormal data exchange between a BTS and the BSC.Crosstalk on the Um and A interfaces cannot be detected.

Procedure

CAUTIONThis function must be configured on both the BSC and the BTS.



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1. To enable this function on the BSC, run the MML command SET BSCBASIC with CrossCall Detect Time Threshold set to the recommended value 10.

Operation ResultEach time the BSC detects crosstalk, a crosstalk log is recorded. The crosstalk logs are recordedtogether with one-way audio logs. You can run the MML command COL LOG to obtain one-way audio log files prefixed by [CDIG].No tool is required to open the log files. You can open the log file in .xls format.When the number of crosstalks on the BSC exceeds Speech Channel Alarm Threshold,ALM-21814 BSS Internal Voice Channel Abnormal is reported.

3.1.5 Optimizing Um Interface CrosstalkThis section describes how to enable crosstalk optimization for the Um interface.

Function DescriptionThis function is used when severe crosstalk occurs over the Um interface in a cell. The symptomsof crosstalk over the Um interface are as follows: 1. The crosstalk occurs during a call ratherthan at the beginning of a call. 2. The Um interface quality for a party in the call is poor. 3. Thevoices of two parties at the peer end can be heard.

NOTEWhen this function is enabled, the BSC sends a Channel Rel message to the MS after a call is dropped. Inaddition, the BSC delays the value of the timer T3109 to enable the MS to release Um interface resources.However, traffic may be congested in the cell because channel reassignment is delayed. Therefore,determine whether to enable this function according to site requirements. This function is disabled bydefault.

ProcedureRun the MML command SET GCELLSOFT with Um Interface Crosstalk OptimizationAllowed set to YES(Allowed).

3.1.6 Binding MSs to BSC ResourcesThis section describes how to bind MSs to BSC resources.

Function DescriptionThis function applies only to the binding of the specified Ater or digital signal processor (DSP)resources during site deployment, swapping, fault location, or maintenance.

Procedure1. Run the MML command SET RSVRES to reserve TC and BM resources of a BSC.2. Run the MML command SET USRRESBIND to set the parameters to bind MSs to the

reserved resources.



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NOTEl A maximum of two MSs can be bound to the reserved resources.l In downlink setup messages, a country code prefix may be added to the calling number. Therefore, if

First User Type or Second User Type is set to MSISND, First User Identity or Second UserIdentity must be set to a value prefixed with the country code to ensure data consistency.

Operation ResultsPerform a dialing test using the specified Ater or DSP resources to check whether voice problemsare caused by faults in the DSP or Ater interface. If so, troubleshoot the voice problems. Then,run the MML command SET USRRESBIND to release the bound resources.

3.1.7 Performing Dialing Tests on the Um InterfaceThis section describes how to perform dialing tests on the Um interface.

Function DescriptionThis function locates problems on the Um interface by specifying TRXs or channels in the testcell for the test MS.

Procedure

CAUTIONThe channels on which the timeslots are specified must be traffic channels (TCHs). If thechannels are not TCHs, the timeslots on these channels are automatically filtered out. Therefore,dialing tests cannot be performed on these timeslots.

1. Run the MML command SET UMTESTPARA to configure the mobile stationinternational ISDN number (MSISDN), site, cell, TRX, and timeslot for the test MS. If noTRX or timeslot is configured, dialing tests are performed in the specified cell by default.

Operation Resultsl If only one timeslot is specified for dialing tests and calls are connected, the test MS makes

calls on the specified timeslot.l If only one timeslot is specified for dialing tests and calls are not connected, the timeslot

may be specified on a non-TCH channel or faulty TCH.l If two or more timeslots are specified for dialing tests, one call can occupy only one timeslot.

Therefore, calls must be initiated in succession to perform dialing tests on all specifiedtimeslots. The timeslots on two half-rate channels can be occupied twice.

3.1.8 Performing Dialing Tests on the A InterfaceThis section describes how to perform dialing tests on the A interface.

Function DescriptionPerform a dialing test on the A interface to troubleshoot voice problems caused by poortransmission quality on the A interface. During the dialing test, the BSC identifies the test MS,



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receives the DTMF message from the MS, and records the dialing test result according to thereceived DTMF message. If A Interface Block CIC is set to YES(Yes), the BSC blocks thecircuit occupied by a call when the call is released. Therefore, the circuit for the dialing testcannot be occupied by other calls. If A Interface Block CIC is set to NO(No), a large numberof dialing tests are performed on the A interface circuits that the MSC allocates to the BSC.

Procedure

CAUTIONl Do not set A Interface Block CIC to YES(Yes) when services are in progress. If A Interface

Block CIC is set to YES(Yes), circuits on the A interface are blocked automatically. In thissituation, resources on the A interface may be insufficient.

l This function does not apply to the A over IP mode.

l To enable automatic dialing tests on the A interface, perform the following operations:1. Run the MML command SET ATESTPARA to enable automatic dialing tests on the

A interface. Set Automatic Dialing Test on A Interface to YES(Yes). Set MSISDN in A Interface Test to the called number. Specify A Interface Uplink One-Way DTMF Message, A Interface Downlink

One-Way DTMF Message, A Interface No Audio DTMF Message, A InterfaceNoise DTMF Message, or A Interface Normal DTMF Message as the DTMFmessages that the test MS sends during dialing tests. Set A Interface Block CIC to YES(Yes). This indicates that the circuit used by

the call during a dialing test is automatically blocked when the call is released. Inthis situation, resources on the A interface may be insufficient. Therefore, do notset A Interface Block CIC to YES(Yes) when services are in progress. Set A Interface Sampling Test to YES(Yes) and set A Interface E1/T1 Sampling

Number to the number of timeslots to be tested.l To disable automatic dialing tests on the A interface, perform the following operations:1. Run the MML command SET ATESTPARA with Automatic Dialing Test on A

Interface set to NO(No) to disable automatic dialing tests on the A interface.

Operation Results1. If you enter the DTMF message that is specified by running the MML command SET

ATESTPARA on the calling MS, the call duration, circuit identification code (CIC),channel information, and Abis interface information are recorded in the dialing test log file.The recorded information can be used to locate the following voice problems: uplink ordownlink one-way audio, no audio, and noise.

2. During a dialing test on the A interface, one dialing test log is recorded when a DTMFmessage is received. The path to save the dialing test log file is \mbsc\bam\common\fam\famlogfmt. The prefix of the dialing test log file name is [AIDG]. You can use EXCELto open log files.

3. You can obtain the information about CICs, DPC, and Ater interface based on the DTMFmessages corresponding to voice problems, and comprehensively analyze whether voice



22

problems are caused by faults in the A interface. Table 3-3 lists the format of log files thatrecord the information about dialing tests on the A interface.

Table 3-3 Format of log files that record the information about dialing tests on the Ainterface

No. Information1 Call start time (in format of YYYY.MM.DD

HH:MM:SS)2 DTMF message type3 DPC4 CIC5 Mobile phone number6 Carrier number and channel number7 Information about the Abis interface:

l If the TDM transmission is used on the Abisinterface, the following information is logged:subrack number, slot number, port number,timeslot number, and sub-timeslot number for aninterface board.

l If the Abis interface over IP is used, IP addressand ports used on the Abis interface board islogged.

l If the HDLC transmission is used on the Abisinterface, the HDLC port and sub-port numbersare logged.

8 Ater interface data such as Asub interface link No.,Asub timeslot number in the link, and Asub interfacedata rate.NOTE

The information is unavailable in TC/BM combined mode.

3.2 Maintenance Functions for Identifying TransmissionProblems

This section describes maintenance functions for identifying transmission problems.

3.2.1 Crossed Pair DetectionThis section describes how to enable crossed pair detection.



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Function DescriptionA crossed pair is classified into big crossed pair and small crossed pair. A big crossed pair refersto crossed TX/RX between two pairs of E1 cables, as shown in Figure 3-4. A small crossed pairrefers to crossed TX/RX between an E1 cable in a pair and an E1 cable in another pair, as shownin Figure 3-5. When a crossed pair occurs on an E1 port of a device, the physical layer signalsare available and no alarm is triggered. However, upper-layer links are disconnected and servicesare interrupted because data from other ports is received.

Figure 3-4 Big crossed pair

Figure 3-5 Small crossed pair

There are a large number of E1 cables at a site and checking E1 connections is time-consuming.BSC6900V900R011 supports crossed pair detection, which helps determine whether a crossedpair is occurring on E1 ports and provides the relevant problem location information. Crossedpair detection applies only to small E1 crossed pairs over the A, Abis, and Ater interfaces.There are two methods to detect small crossed pairs: loopback detection and alarm-baseddetection. If alarm-based detection is used, ensure that the connection to the peer port is normaland that no loopback occurs. If loopback detection is used, perform remote loopback byconnecting TX and RX ports (physical loopback) or by sending commands. Only physicalloopback can be performed on the ports of Ater operation and maintenance links (OMLs).



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NOTE1. To perform loopback detection, do as follows: Set the port on the remote device to remote loopback

or physical loopback without modifying configuration data. Import the test data (containing the portnumber) into the local E1 port. After performing the loopback, check whether the received portinformation is the same as the imported data. If the received port information is the same as the importeddata, the E1 cables are connected correctly. If the received port information is not the same as theimported data, the cables are crossed.

2. To perform alarm-based detection, do as follows: Disable the TX function of the local E1 port, whichcauses the remote E1 port to generate a loss of signal (LOS) alarm. The remote alarm indication (RAI)is inserted into the TX signals of the remote port. If the E1 cables are connected correctly, the localport receives the RAI. If the E1 cables are crossed, no alarm is generated on the local port.

3. The restrictions of the crossed pair function are as follows:l Crossed pair detection can be performed only on the E1 electrical interfaces of the EIUa or PEUa

boards.l If the RX and TX connectors of the E1 cable for one port are incorrectly connected as a self-

loopback on the DDF, this fault cannot be detected using loopback detection.l When the E1 interface boards work in active/standby mode, this function can be performed only

on the active board.l When the E1 interface boards work in active/standby mode, alarm-based detection can be

performed only when the Y-shaped cable networking mode is used.l Before performing alarm-based detection, there must be no loopback on the remote port.l Do not perform crossed pair detection unless necessary because doing so may interrupt services.

Notify telecom operators of possible impacts on a live network before performing alarm-baseddetection for online maintenance.

l Crossed pair detection commands must be executed in sequence. The next command for crossedpair detection cannot be executed until after the current detection command is executed completely.

l No alarm is reported on the E1 port on which crossed pair detection is to be performed.l Although loopback detection can be performed on a single port or a whole board, alarm-based

detection can be performed only on a single port.

ProcedureRun the MML command CHK E1T1CRS to enable crossed pair detection.

Operation ResultsAfter the MML command is executed successfully, a window is displayed, indicating whethercable connections are faulty, as shown in the following figure.+++ HUAWEI 2009-06-15 16:43:29O&M #27137%%CHK E1T1CRS: SRN=0, SN=15, BT=EIUa, MTHD=ALARM_METHOD, PN=0;%%RETCODE = 0 Execution succeeded.

Check E1/T1 Cross Connection---------------------------- Subrack No. Slot No. Link No. Check Result Cross Link No.

0 15 0 Not Cross (Number of results = 1)

--- END



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3.2.2 Monitoring Port BER SecondsThis section describes how to detect the bit error rate (BER) seconds on an E1/T1 port. Thisfunction helps you learn about the transmission quality of the link corresponding to the port inreal time.

Function DescriptionIf any bit error occurs on the E1/T1 port, you can start this task to obtain data such as BERS,critical BERS, unavailable seconds, frame errors, CRC errors. Based on the data, you canevaluate the operating status of the transmission network and identify the causes for the bit errorsin combination with the performance of the peer end. The AEUa/PEUa/EIUa/OIUa/POUc boardsupports this function.

Procedure1. On the LMT, click Monitor. The Monitor tab page is displayed.2. In the Monitor Navigation Tree, choose Monitor > Common Monitoring. Then, double-

click BERS Monitoring.3. In the BERS Monitoring dialog box that is displayed, set the relevant parameters. Then,

click Submit.

Operation ResultsAfter the monitoring task is started, a monitoring window is displayed, showing the real-timemonitoring result by list and chart. The task name and related parameters are displayed in thetitle bar of the window, as shown in Figure 3-6.

Figure 3-6 Monitoring results

3.2.3 Querying Ethernet Port AttributesThis section describes how to query the attribute of Ethernet ports on the local maintenanceterminal (LMT) when the BTS discards a large number of packets.



26

Function DescriptionThis function applies to poor voice quality on the BTS side in the following scenarios:l The alarms ALM-25881 MAC Excessive Frame Error Rate and ALM-25897 IP Excessive

Frame Error Rate are generated.l The network quality is poor.

Procedure1. Run the MML command DSP BTSETHPORT to query the status of an Ethernet port.

l Set Cabinet No., Subrack No., Slot No. according to the location of the GTMU.l Set Port No. based on the requirements of the live network. This parameter is optional.

If this parameter is empty, the status of the two types of Ethernet ports will be queried.If this parameter is set to 0, the status of the electrical ports will be queried. If thisparameter is set to 1, the status of the optical ports will be queried.

Operation Resultsl The BTS works in full-duplex mode, and the transmission rate of the BTS is consistent

with that of the peer device.l If multiple query results show that the Receive CRC Error Packages is large and increases

significantly, the BTS has discarded a large number of packets.

3.2.4 Performing IP LoopbackThis section describes how to perform an IP loopback test. IP loopback is used to locatetransmission faults and to check whether the settings of any trunk parameters are correctly inAbis over IP mode. For example, loop back voice signals on an IP channel section by section tolocate voice problems.

Function DescriptionThis function applies only to the Abis over IP mode. To check whether an exception occurs onthe BSC side, perform an IP loopback test on the BSC side. To check whether an exceptionoccurs on the Abis or Um interface, perform an IP loopback test between the BSC and the BTS.If the test result shows that no exception occurs on the Abis interface and the transmission delayis shorter than 15 ms, exceptions may occur on the transmission link between the Abis interfaceand the BSC or on the Um interface.

ProcedureNOTE

l Only one IP loopback test can be started for one digital signal processor (DSP).l A maximum of two IP loopback tests can be started for one board.l A maximum of two IP loopback tests can be started for one BTS.l A maximum of four IP loopback tests can be started for one BSC.l IP loopback tests are incompatible with ping tests.l IP loopback tests can be started only when a GBSS13.0 BTS is used.

1. Run the MML command SET BTSIPLOPTST to set IP loopback parameters for the BTSto be tested.



27

2. Run the MML command STR IPLOPTST to start an IP loopback test. If Loop type is setto LOCAL_LOOP(LOCAL_LOOP), the test will be performed on the BSC side. If Looptype is set to REMOTE_LOOP(REMOTE_LOOP), the test will be performed betweenthe BSC and the BTS.

3. Run the MML command DSP IPLOPTST to query the test result. Compare the value ofNumber of sent packets with that of Number of received packets shown in the test result.If the two values are the same, no packet is discarded during this loopback. If the two valuesare different, packets are discarded during this loopback.

4. Run the MML command STP IPLOPTST to stop the IP loopback test.

Operation ResultsIf the output of the MML command DSP IPLOPTST shows that the value of Number of sentpackets is the same as that of Number of received packets, no packet is discarded during thisloopback. If the two values are different, packets are discarded during this loopback.

3.3 Maintenance Functions for Identifying Um and RFProblems

This section describes maintenance functions for identifying Um and RF problems.

3.3.1 Monitoring Channel Interference BandsThis section describes how to view the interference band of idle channels to monitor interferenceon these channels.

Function DescriptionThis section describes how to detect the interference band of an idle channel to monitor theinterference conditions on the channel.

Procedurel Choosing menu items

1. On the LMT, click Device Maintenance. The Device Maintenance tab page isdisplayed.

2. On the BTS Maintenance tab page, choose BTS Maintenance > Monitor ChannelInterference Band. The Monitor Channel Interference Band tab page is displayed.

3. On the displayed Monitor Channel Interference Band tab page, set the relevantparameters. Then, click Start.

NOTE

In the Device Navigation Tree, right-click the target BTS, and choose Monitor ChannelInterference Band from the shortcut menu.

l Running MML commandsRun the MML command DSP CHNJAM to monitor the interference band on a channel.



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Operation ResultsFigure 3-7 is an example of the menu operation results. The interference bands on all thechannels are displayed and refreshed every 10s.

Figure 3-7 Monitor Channel Interference Band dialog box

3.3.2 Testing Passive Intermodulation Interference OnlineThis section describes how to test passive intermodulation interference in online mode.

Function DescriptionThis function is used to check whether the live network is experiencing passive intermodulationinterference. Online passive intermodulation interference tests have no impact on ongoingservices. To check whether the live network is experiencing passive intermodulationinterference, calculate the difference between the uplink receive level measured when the celltransmits power with services performed and that measured when the transmit power of allcarriers and channels in the cell reaches the maximum values. Then, compare this level differencewith the level difference decision threshold. Downlink power is available for all normal services,and therefore the accuracy of the level difference decision result is associated with the proportionof the duration when services are performed to the entire test duration. This proportion can beused as the level difference decision threshold. Run the MML command STR BTSRFTST toset the level difference decision threshold.

ProcedureNOTE

l Only one of common passive intermodulation interference tests, online passive intermodulationinterference tests, offline passive intermodulation interference tests, CDMA network interference tests,online frequency spectrum scanning, and offline frequency spectrum scanning can be performed in acell once.

l Only one online passive intermodulation interference test can be performed in a BSC.1. Run the MML command STR BTSRFTST to start an online passive intermodulation

interference test. You are advised to set parameters as follows:l Set Test Type to PIMONLINE(Online Antenna Passive Intermodulation Test).l Set Difference Threshold to 10.l Set Service Rate Threshold to 20.



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2. Run the MML command STP BTSRFTST to stop the online passive intermodulationinterference test.

NOTE

Operation ResultsEach carrier in the cell reports a result of the online passive intermodulation interference test,but the power transmitted by other carriers affects this result. Therefore, if all carriers in the cellreport valid test results, the test is valid. If one or multiple carriers in the cell report invalid testresults, the test is invalid. To obtain valid test results, perform this test again during off-peakhours, or change the proportion of ongoing services to all normal services to 40% and performthis test again.After the test is stopped, the test results are displayed by running the MML command S

GBSS13.0 Troubleshooting Guide(02)(PDF)-En

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