GBSS14.0 Troubleshooting Guide(02)(PDF)-En

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GBSS14.0

Troubleshooting Guide

Issue 02

Date 2012-11-07

HUAWEI TECHNOLOGIES CO., LTD.


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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 written

consent 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.

Notice

The purchased products, services and features are stipulated by the contract made between Huawei and the

customer. All or part of the products, services and features described in this document may not be within the

purchase 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 representations

of any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in the

preparation of this document to ensure accuracy of the contents, but all statements, information, and

recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.

Address: Huawei Industrial Base

Bantian, Longgang

Shenzhen 518129

People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

Issue 02 (2012-11-07) Huawei Proprietary and Confidential

Copyright Huawei Technologies Co., Ltd.

i
http://www.huawei.com/


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About This Document

Overview

This 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 Version

The following table lists the product versions related to this document.

Product Name Product Version

BSC6900 V900R014C00

BSC6000 V900R014C00

BTS3900/BTS3900A/BTS3900L/

BTS3900AL/DBS3900

V900R014C00

Intended Audience

This document is intended for:

l Maintenance engineers

l Field engineers

Organization

1 Change in the GBSS Troubleshooting Guide

This chapter describes the changes in the GBSS Troubleshooting Guide.

2 Troubleshooting Procedure

This chapter describes the basic troubleshooting procedure and each step.

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3 Common Maintenance Functions

This chapter describes common maintenance functions used during fault location.

4 Handover Problems

This chapter describes how to locate and troubleshoot handover problems.

5 Call Drops

This chapter describes how to locate and troubleshoot call drops.

6 Access Faults

This chapter describes how to locate and troubleshoot access faults.

7 Voice Problems

This chapter describes how to locate and troubleshoot voice problems.

8 PS Counter Problems

This chapter describes how to locate and troubleshoot PS counter problems.

9 PS Channel Faults

This chapter describes how to locate and troubleshoot PS channel faults.

10 Cell PS Service Faults

This chapter describes how to locate and troubleshoot cell PS service faults.

11 IP Transmission Faults

This chapter describes how to locate and troubleshoot IP transmission faults.

12 Interference Problems

This chapter describes how to locate and troubleshoot interference problems.

13 Faults on Main and Diversity RX Channels

This chapter describes how to locate and troubleshoot faults on main and diversity receive (RX)

channels.

14 No Traffic

This chapter describes how to locate and troubleshoot no traffic on 3900 series base stations.

15 Appendix: How to Collect Fault Information

When faults cannot be rectifiedby referring to this document, collect fault information for

Huawei technical support to quickly troubleshoot the faults. This section describes how to collect

fault information.

Conventions

Symbol Conventions

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

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Symbol Description

Indicates a hazard with a high level of risk, which if not

avoided, will result in death or serious injury.

Indicates a hazard with a medium or low level of risk, which

if not avoided, could result in minor or moderate injury.

Indicates a potentially hazardous situation, which if not

avoided, could result in equipment damage, data loss,

performance degradation, or unexpected results.

Indicates a tip that may help you solve a problem or save

time.

Provides additional information to emphasize or supplement

important points of the main text.

General Conventions

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

Convention Description

Times New Roman Normal paragraphs are in Times New Roman.

Boldface Names of files, directories, folders, and users are inboldface. 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 Conventions

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


Boldface 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.

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

vertical bars. One item is selected or no item is selected.

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{ x | y | ... }* Optional items are grouped in braces and separated by

vertical bars. A minimum of one item or a maximum of all

items can be selected.

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

vertical bars. Several items or no item can be selected.

GUI Conventions

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


Boldface Buttons, menus, parameters, tabs, window, and dialog titles

are in boldface. For example, click OK.

> Multi-level menus are in boldfaceand separated by the ">"

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

Keyboard Operations

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

Format Description

Key Press the key. For example, press Enterand press Tab.

Key 1+Key 2 Press the keys concurrently. For example, pressing Ctrl+Alt

+Ameans the three keys should be pressed concurrently.

Key 1, Key 2 Press the keys in turn. For example, pressing Alt, Ameans

the two keys should be pressed in turn.

Mouse Operations

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

Action Description

Click 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.

Drag Press and hold the primary mouse button and move the

pointer to a certain position.

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Contents

About This Document.....................................................................................................................ii

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

2 Troubleshooting Procedure.........................................................................................................3

2.1 Troubleshooting Flowchart.................................................................................................................................4

2.2 Collecting Fault Information..............................................................................................................................4

2.3 Determining aFault Type...................................................................................................................................7

2.3.1 Fault Types................................................................................................................................ ................7

2.3.2 Methodsfor Determining a Fault Type.....................................................................................................8

2.4 Identifying Fault Causes.....................................................................................................................................9

2.5 Troubleshooting Faults.....................................................................................................................................10

2.5.1 Overview.................................................................................................................................................10

2.5.2 Methodsfor Troubleshooting Faults.......................................................................................................10

2.5.3 Follow-up Procedure...............................................................................................................................11

3 Common Maintenance Functions............................................................................................12

3.1 Maintenance Functions for Identifying Voice Problems..................................................................................13

3.1.1 Querying Call Resource Usage of an MS................................................................................................13

3.1.2 ExternalVoice Loopback........................................................................................................................13

3.1.3 One-Way Audio Detection......................................................................................................................18

3.1.4 Crosstalk Detection..................................................................................................................................20

3.1.5 Optimizing Um Interface Crosstalk.........................................................................................................21

3.1.6 Binding MSs to BSC Resources..............................................................................................................21

3.1.7 Performing Dialing Tests on the Um Interface........................................................................................223.1.8 Performing Dialing Tests on the A Interface...........................................................................................22

3.1.9 Detecting Noise on the A Interface.........................................................................................................24

3.2 Maintenance Functions for Identifying Transmission Problems......................................................................25

3.2.1 Crossed Pair Detection............................................................................................................................25

3.2.2 Monitoring Port BER Seconds................................................................................................................28

3.2.3 Querying Ethernet Port Attributes...........................................................................................................28

3.2.4 Performing IP Loopback.........................................................................................................................29

3.2.5 BTS Tracing............................................................................................................................................30

3.3 Maintenance Functions for Identifying Um and RF Problems.........................................................................31

3.3.1 Monitoring Channel Interference Bands.................................................................................................31

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3.3.2 Testing Passive Intermodulation Interference Online.............................................................................32

3.3.3 Scanning Frequency Spectrum Online....................................................................................................33

3.4 Maintenance Functions Related to Interface Tracing.......................................................................................35

3.4.1 Tracing CS Domain Messages of a Single Subscriber............................................................................35

3.4.2 Tracing PS Domain Messages for a Single Subscriber...........................................................................37

3.5 Maintenance Functions for Identifying PS Problems.......................................................................................39

3.5.1 Monitoring Channel Status......................................................................................................................39

3.5.2 Performing a PDCH Loopback Test........................................................................................................41

3.6 Maintenance Functions for Identifying Clock Problems..................................................................................45

3.6.1 Querying BSC Clock Source Status........................................................................................................45

3.6.2 Querying BSC Board Clock Status.........................................................................................................46

3.6.3 Maintaining BTS Clock...........................................................................................................................47

3.7 Maintenance Functions Related to No Traffic..................................................................................................48

3.7.1 Reporting the No Traffic Alarm Independently......................................................................................483.7.2 No-Traffic Self-Healing..........................................................................................................................49

4 Handover Problems.....................................................................................................................51

4.1 Handover Principles.........................................................................................................................................52

4.1.1 Handover Procedure................................................................................................................................52

4.1.2 Handover Success Rate...........................................................................................................................54

4.2 Locating Handover Problems...........................................................................................................................57

4.2.1 Principles.................................................................................................................................................57

4.2.2 Procedure for Locating Handover Problems...........................................................................................57

4.3 Troubleshooting Handover Problems Due to Hardware Faults........................................................................624.4 Handover Problems Due to Incorrect Data Configurations..............................................................................65

4.5 Troubleshooting Handover Problems Due to Traffic Congestion in the Target Cell.......................................69

4.6 Troubleshooting Handover Problems Due to Poor Um Interface Quality.......................................................71

4.7 Troubleshooting Handover Problems Due to NE Faults..................................................................................75

4.8 Troubleshooting Handover Problems Due to Inappropriate Inter-BSC/Inter-MSC/Inter-RAT Interaction

................................................................................................................................................................................78

5 Call Drops.....................................................................................................................................83

5.1 Call Drop Rate..................................................................................................................................................84

5.2 Locating Call Drops..........................................................................................................................................85

5.2.1 Procedure for Locating Call Drops..........................................................................................................85

5.2.2 Counters Related to Call Drops...............................................................................................................89

5.2.3 Types of Call Drops.................................................................................................................................91

5.3 Troubleshooting Call Drops Due to Poor Um Interface Quality......................................................................94

5.4 Troubleshooting Call Drops Due to Equipment Faults....................................................................................99

5.5 Troubleshooting Call Drops Due to Transmission Faults..............................................................................103

5.6 Troubleshooting Call Drops Due to Incorrect Parameter Settings.................................................................104

6 Access Faults...............................................................................................................................111

6.1 Access Principles............................................................................................................................................113

6.2 Locating Access Faults...................................................................................................................................114

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6.2.1 Procedure for Locating Access Faults...................................................................................................115

6.2.2 Common Causes for Access Faults.......................................................................................................122

6.3 Troubleshooting Access Faults Due to Poor Um Interface Quality...............................................................126

6.4 Troubleshooting Low Immediate Assignment Success Rates Due to SDCCH Congestion..........................132

6.5 Troubleshooting Low Immediate Assignment Success Rates Due to Hardware or Transmission Faults

..............................................................................................................................................................................136

6.6 Troubleshooting Low Immediate Assignment Success Rates Due to Location Updates of Problem MSs

..............................................................................................................................................................................140

6.7 Troubleshooting Low Assignment Success Rates Due to TCH Congestion..................................................143

6.8 Troubleshooting Low Assignment Success Rates Due to Hardware or Transmission Faults........................147

6.9 Troubleshooting Low Assignment Success Rates Due to Inappropriate BSC Configuration.......................151

7 Voice Problems..........................................................................................................................156

7.1 GSM CS Signal Flow.....................................................................................................................................157

7.2 Common Voice Problems and Problem Location Methods...........................................................................162

7.3 Troubleshooting One-Way Audio or No Audio.............................................................................................163

7.4 Troubleshooting Noise...................................................................................................................................169

7.5 Troubleshooting Crosstalk..............................................................................................................................176

7.6 Troubleshooting Echoes.................................................................................................................................182

7.7 Troubleshooting Discontinuous Voice or Low MOS.....................................................................................187

8 PS Counter Problems................................................................................................................193

8.1 PS Counters....................................................................................................................................................194

8.2 Locating PS Counter Problems.......................................................................................................................195

8.2.1 Principles for Locating PS Counter Problems.......................................................................................195

8.2.2 Procedure for Locating PS Counter Problems.......................................................................................195

8.3 Troubleshooting Low TBF Establishment Success Rates..............................................................................196

8.4 Troubleshooting High TBF Call Drop Rates..................................................................................................205

8.5 Troubleshooting Low Average Throughput at the RLC Layer......................................................................212

8.6 Troubleshooting Low Percentage of High-Rate Coding Schemes to All Coding Schemes...........................219

8.7 Troubleshooting High RLC Data Block Retransmission Rates.....................................................................227

9 PS Channel Faults......................................................................................................................234

9.1 Identifying PS Channel Faults........................................................................................................................235

9.2 Locating PS Channel Faults...........................................................................................................................235

9.3 Troubleshooting PDCH Faults Due to Channel Inactivity.............................................................................237

9.4 Troubleshooting PDCH Faults Due to Channel Asynchronization................................................................245

10 Cell PSService Faults.............................................................................................................253

10.1 Remarks on Cell PS Service Faults..............................................................................................................254

10.2 LocatingCell PS Service Faults...................................................................................................................254

10.3 Troubleshooting Cell PS Service Faults Due to Gb Interface Issues...........................................................260

10.4 Troubleshooting Cell PS Service Faults Due to Incorrect Data Configurations..........................................262

10.5 Troubleshooting Cell PS Service Faults Due to Hardware Issues................................................................264

10.6 Troubleshooting Cell PS Service Faults Due to Incorrect Cable Connections Inside the BSC...................266

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11 IP Transmission Faults...........................................................................................................268

11.1 Troubleshooting FE/GE Transmission Faults..............................................................................................269

11.2 Troubleshooting IP Layer Faults..................................................................................................................276

11.3 Troubleshooting PPP or MLPPP Link Faults...............................................................................................281

11.4 Troubleshooting LAPD Link Faults.............................................................................................................287

11.5 Troubleshooting SCTP Link Faults..............................................................................................................296

11.6 Troubleshooting IP Path Problems...............................................................................................................304

11.7 Troubleshooting DHCP Problems................................................................................................................310

11.8 Troubleshooting IP PM Activation Failures.................................................................................................316

11.9 Troubleshooting IP Clock Faults..................................................................................................................319

12 Interference Problems.............................................................................................................329

12.1 Interference...................................................................................................................................................330

12.2 Locating Interference Problems....................................................................................................................331

12.3 Troubleshooting Co-channel or Adjacent-Channel Interference..................................................................334

12.4 Troubleshooting Intermodulation Interference.............................................................................................336

12.5 Troubleshooting Interference from the CDMA Network.............................................................................341

12.6 Troubleshooting External Interference.........................................................................................................344

13 Faults on Main and Diversity RX Channels.......................................................................348

13.1 Principles of Main and Diversity Reception.................................................................................................349

13.2 LocatingFaults on Main and Diversity RX Channels..................................................................................349

13.3 Troubleshooting Faults on Main and Diversity RX Channels Due to Incorrect Data Configurations.........351

13.4 Troubleshooting Faults on Main and Diversity RX Channels Due to Incorrect Antenna Connections.......35413.5 Troubleshooting Faults on Main and Diversity RX Channels Due to Hardware Faults..............................358

14 No Traffic..................................................................................................................................361

14.1 Introduction to No Traffic............................................................................................................................362

14.2 LocatingNo Traffic......................................................................................................................................362

14.3 Troubleshooting No Traffic Due to No Calls...............................................................................................367

14.4 Troubleshooting No Traffic Due to Transmission or Equipment Faults......................................................368

14.5 Troubleshooting No Traffic Due to Incorrect Data Configurations.............................................................370

14.6 Troubleshooting No Traffic Due to Poor Um Interface Quality..................................................................372

14.7 Troubleshooting No Traffic Due to Antenna System Faults........................................................................37414.8 Resetting.......................................................................................................................................................378

15 Appendix: How to Collect Fault Information....................................................................379

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

02 (2012-11-07)

This is the second commercial release of GBSS14.0.

Compared with issue 01 (2012-06-30) of GBSS14.0, this issue does not include any new topics.

Compared with issue 01 (2012-06-30) of GBSS14.0, this issue incorporates the following

changes:

content Description

11.2 Troubleshooting IP Layer Faults The troubleshooting procedure is optimized.

11.4 Troubleshooting LAPD Link Faults The troubleshooting procedure is optimized.

11.5 Troubleshooting SCTP Link Faults The troubleshooting procedure is optimized.

11.6 Troubleshooting IP Path Problems The troubleshooting procedure is optimized.

Compared with issue 01 (2012-06-30) of GBSS14.0, this issue does not excludes any topics.

01 (2012-06-30)

This is the first commercial release of GBSS14.0.

Compared with issue Draft A (2012-04-26) of GBSS14.0, this issue does not include any new

topics.

Compared with issue Draft A (2012-04-26) of GBSS14.0, this issue incorporates the following

changes:

content Description

7.7 Troubleshooting Discontinuous Voice

or Low MOS

l The typical case is modified.

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Compared with issue Draft A (2012-04-26) of GBSS14.0, this issue does not excludes any topics.

Draft A (2012-04-26)

This is the Draft A release of GBSS14.0.

Compared with issue 01 (2012-01-05) of GBSS13.0, this issue includes the following new topics:

l 3.1.9 Detecting Noise on the A Interface

l 3.2.5 BTS Tracing

l 3.5.2 Performing a PDCH Loopback Test

l 3.7 Maintenance Functions Related to No Traffic

l 3.7.1 Reporting the No Traffic Alarm Independently

l 3.7.2 No-Traffic Self-Healing

Compared with issue 01 (2012-01-05) of GBSS13.0, this issue incorporates the following

changes:

content Description

7.4 Troubleshooting Noise l The operations related to noise detection

are added to the troubleshooting

description.

l Voice log collection is added to the

problem location information table.

9.3 Troubleshooting PDCH Faults Due to

Channel Inactivity

The operations related to PDCH loopback

tests are added to the troubleshooting

description.

9.4 Troubleshooting PDCH Faults Due to

Channel Asynchronization

The operations related to PDCH loopback

tests are added to the troubleshooting

description.

11.4 Troubleshooting LAPD Link Faults The BTS tracing result is added to the


11.6 Troubleshooting IP Path Problems The BTS tracing result is added to the


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

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2Troubleshooting ProcedureAbout This Chapter

This chapter describes the basic troubleshooting procedure and each step.

2.1 Troubleshooting Flowchart

This section shows the troubleshooting flowchart.

2.2 Collecting Fault Information

This sectionprovides methods for collecting information about faults and describes the fault

information types.

2.3 Determining a Fault TypeAfter collecting fault information, analyze the symptoms to determine a fault type.

2.4 Identifying Fault Causes

To identify the specific cause of a fault, exclude possible causes by analyzing the symptoms.

2.5 Troubleshooting Faults

This sectionprovides the methods for troubleshooting faults as well as follow-up procedures.

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2.1 Troubleshooting FlowchartThis section shows the troubleshooting flowchart.

Figure 2-1shows the troubleshooting flowchart.

Figure 2-1Troubleshooting flowchart

2.2 Collecting Fault InformationThis section provides methods for collecting information about faults and describes the fault

information types.

Methods for Collecting Fault Information

Before troubleshooting a fault, collect the following information:

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l Fault symptoms

l Time, place, and frequency of the fault

l Fault range and impact

l Equipment operating status before the fault occurs

l Operations performed on the equipment before the fault occurs and the operation results

l Alarms generated when the fault occurs and the associated alarms

l Board indicator status when the fault occurs

l Measures taken after the fault occurs and the effects of measures

The 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 measures

from the equipment operation and maintenance (O&M) engineers.

l Monitor the board indicator status and alarms reported on the LMT to understand the

software and hardware operating status.

l Simulate services, measure performance, and trace interface signaling messages to

understand the fault range and impact.

NOTE

If you encounter severe faults, do not troubleshoot the faults before determining the specific causes. In this

case, you are advised to collect sufficient information, or contact Huawei for technical support.

Fault Information Types

l Alarm information

Alarm information is exported by the BSS alarm system and reported with any combination

of the following: sounds, lights, indicators, or onscreen indications. Viewing the alarm

information is a common method for analyzing faults.

Alarm information includes a description of the fault symptoms and causes, as well as fault

rectification 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.

NOTE

For a description of the alarm system, see theBSC6900 GSM LMT User Guide. For details abouthow to handle an alarm, see theBSC6900 GSM Alarm Reference.

l Indicator status

Indicators 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. Because

indicator status is generally not informative enough to locate a fault, this information is

often used with the alarm information to locate a fault. Table 2-1uses the SCUa as an

example to describe the board indicators.

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Table 2-1LEDs on the SCUa board

LED Color Status Description

RUN Green ON for 1s and OFF for 1s The board is functional.

ON for 0.125s and OFF

for 0.125s

The board is in loading

state.

ON There is power supply,

but the board is faulty.

OFF There is no power

supply, or the board is

faulty.

ALM Red OFF There is no alarm.

ON or blinking There is a fault alarm.

ACT Green ON The board is in active

mode.

OFF The board is in standby

mode.

LINK (at the

Ethernet port)

Green ON The link is well

connected.

OFF The link is disconnected.

ACT (at the

Ethernet port)

Green OFF There is no data

transmission over theEthernet port.

Blinking There is data

transmission over the

Ethernet port.

NOTE

For a description of indicators on various boards, see theBSC6900 GSM Hardware Description.

Operation and maintenance (O&M) engineers should be familiar with indicators to facilitate fault

location.

l Dialing test results

Dialing 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 results

Instrument and meter measurement results are true indication of fault causes. Instrument

measurement results are widely used for power supply tests, signaling analysis, wave

analysis, and bit error detection. For example, the procedure for troubleshooting high call

drop 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.

NOTE

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

l Traffic statistics

Traffic statistics are generally used to analyze service faults such as call drops and handover

problems.

Traffic statistics can be used with traced signaling messages to troubleshoot high call drop

rates, low handover success rates, or call exceptions.

NOTE

For details about how to use traffic statistics to analyze problems, see theBSC6900 GSM LMT User

Guide. For counter meanings, see theBSC6900 GSM Performance Counter Reference.

l Signaling messages traced over interfaces

Signaling messages are generally used to identify causes of call connection failures or inter-

site signaling interaction failures.

NOTE

For details about how to how to trace the signaling messages, see theBSC6900 GSM LMT User

Guide.

2.3 Determining a Fault Type

After collecting fault information, analyze the symptoms to determine a fault type.

You can also Contact Huawei Customer Service Center to determine a fault type.

NOTE

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

2.3.1 Fault Types

This section lists the fault types covered in this document.

l CS voice problems

l 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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NOTE

Determine the fault type based on symptoms. Different fault types may have the same symptoms. For

example, call drops problems may have the same symptoms as handover problems. In this case, methods

for troubleshooting call drops problems will be linked to the methods for troubleshooting handover

problems.

2.3.2 Methods for Determining a Fault Type

This 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 counters

This method can determine a fault type when performance counters deteriorate. With this

method, 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 tests

Loopback tests can locate transmission, link, and voice problems. Loopback tests are

classified into hardware loopback tests and software loopback tests. For specific cases, see

3.1.2 External Voice Loopback.

You can determine whether equipment operates normally and software parameters are set

correctly by checking the status of the transmission equipment, transmission channels,

services, and signaling interaction status after loop back tests are performed. Loopback

tests can also be performed to determine whether transmission faults occur or trunk

parameters are set incorrectly. During site deployment or trunk capacity expansion, BSS

trunk loopback tests can help determine whether trunk parameters and signaling link dataare configured correctly.

NOTE

Loopback tests are also performed to locate transmission faults.

l Process of elimination

This method can exclude both software problems and hardware problems. To exclude

software problems, disable a certain function or feature to check whether a fault can be

rectified. If the fault is rectified, the function or feature is abnormal. Otherwise, the function

or 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 isresolved.

l Regularity identification

Identifying problem regularity helps to narrow the fault range. When narrowing the fault

range, consider the following factors:

1. Whether a certain board is faulty

2. Whether a certain DSP is faulty

3. Whether a certain transmission path is faulty

4. Whether a certain TRX is faulty

5. Whether a certain type of MS is faulty

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6. Whether a certain type of channel is faulty

7. Whether an enabled feature is abnormal, such as Flex TSC, downlink power control,

or BCCH power consumption reduction

8. Whether an alarm is reported multiple times

For example, if a Cell Out of Service alarm is reported, check whether one or multiple cells

are 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 power

failure 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/Interchange

Problems can be identified by comparing faulty components with normal components or

by 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 boards

2. Transmission cables3. Antennas

4. ARFCNs

For example, when severe interference in a certain cell cannot be eliminated after

troubleshooting cable connection faults, interchange the antenna system for the abnormal

cell with that for a normal cell. If the interference is eliminated, the original antenna system

is faulty. For details, see the typical case in 12.4 Troubleshooting Intermodulation

Interference.

2.4 Identifying Fault Causes

To 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 determine

whether 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 causes

of subsystem faults.

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

2.5.1 Overview

Troubleshooting faults is a process of taking proper measures to rectify faults and restore a

system to good working order. Methods for troubleshooting faults include cable connection

check, board replacement, data configuration modification, board switchover, and board

resetting.

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.

NOTE

When severe faults occur, Contact Huawei Customer Service Center.

2.5.2 Methods for Troubleshooting Faults

This section provides methods for troubleshooting faults.

l Fault isolation

Isolation is the act of isolating the fault location from the surrounding service unit to prevent

the 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 DSPto isolate the DSP. For details, see the typical case in

7.4 Troubleshooting Noise.

l Switchover/resetting

During a switchover, services are switched from an active device to a standby device. You

can compare the system operating status before and after the switchover. By resetting part

of 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 equipment

faults or operation instability.

Resetting may lead to service interruptions or even system crash, affecting normal BSS

operations. For example, some or all services over the A interface are interrupted. In this

case, 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 standby

Ater 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, or

antennas.

NOTE

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

to Huawei headquarters.

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

equipment.

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 traffic

statistics to verify that services are operating properly.

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

Center.

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3Common Maintenance FunctionsAbout This Chapter

This chapter describes common maintenance functions used during fault location.

3.1 Maintenance Functions for Identifying Voice Problems

This section describes maintenance functions for identifying voice problems.

3.2 Maintenance Functions for Identifying Transmission Problems

This section describes maintenance functions for identifying transmission problems.

3.3 Maintenance Functions for Identifying Um and RF Problems

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

3.4 Maintenance Functions Related to Interface Tracing

This section describes maintenance functions related to interface tracing.

3.5 Maintenance Functions for Identifying PS Problems

This section describes maintenance functions for identifying PS problems.

3.6 Maintenance Functions for Identifying Clock Problems

This section describes maintenance functions for identifying clock problems.

3.7 Maintenance Functions Related to No Traffic

This section describes the maintenance functions related to no traffic.

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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 MS

This section describes how to query the call resource usage of an MS.

Function Description

This function queries the call resource usage of an MS that has set up a call and is used to identify

BSS voice problems. The query can be performed by entering the MS's Mobile Station

International ISDN Number (MSISDN), International Mobile Subscriber Identity (IMSI),

Temporary Mobile Subscriber Identity (TMSI), or International Mobile Equipment Identity

(IMEI).

Procedure

1. On the LMT, run the MML command DSP CALLRES, then press Enteror click Assist.

2. Set User Query Typeto BYTMSI(By TMSI), BYIMSI(By IMSI), BYMSISDN(By

MSISDN), or BYIMEI(By IMEI). The corresponding MS identifier (ID) is displayed.

NOTE

l If you set User Identity Typeto 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 the

called number. When querying the call resource usage of the called MS, set the MSISDN to the

calling number (the Calling Line Identification Presentation function must be enabled).

l If you set User Identity Typeto 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, set

User Query Typeto BYTMSI(By TMSI)to query the call resource usage. If the MS's IMSI is

used to set up a call, set User Query Typeto BYIMSI(By IMSI)to query the call resource

usage.

l If you set User Identity Typeto BYIMEI(By IMEI), determine whether the MSC can obtain

the IMEI.

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

Operation Results

The query result shows the call resource usage of the MS, including information about the BM

subrack, TC link, A interface, and Ater interface. The query result also includes informationsuch as digital signal processor (DSP) number, channel number, service type, circuit

identification codes (CICs) on the A interface, as well as timeslots occupied by the GEIUA,

GEIUB, and GEIUT.

3.1.2 External Voice Loopback

This section describes how to start or stop external voice loopback and query the status of the

current voice loopback.


Voice 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. Figure

3-1, Figure 3-2, and Figure 3-3show 12 loopback positions in a BSC in three networking modes.

The loopback positions are the same for multi-core boards.

Figure 3-1Abis over TDM + A over TDM

Figure 3-2Abis over IP + A over TDM

Figure 3-3Abis 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 loopback

testing 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/s

whereas services are processed over the two interfaces at 16 Kbit/s or 8 Kbit/s. As a result, a loopback

test of the channel used by one subscriber will lead to loopback tests of the channels used by other

subscribers on the same 64 Kbit/s timeslot.

Procedure

l Choosing menu items

1. Click Device Maintenanceon the LMT main page. The Device Maintenancetab

page is displayed.

2. On the BSC Maintenancetab page, choose BSC Maintenance> Maintain UserResources> Remote Speech Channel Loopback. The Remote Speech Channel

Loopbackdialog box is displayed.

3. In the Remote Speech Channel Loopbackdialog box, set the parameters as required,

and click Start. A message is displayed, informing you that the loopback is

successfully started.

NOTE

l If you select MSISDNin the Trace Object Symbol Typearea, set the MSISDNto the

number of the peer end.

l (Recommended) If the calling party is traced, set the MSISDNto the called number.

l If the called party is traced, set the MSISDNto the calling number (the Calling Line

Identification Presentation function must be enabled).

l If you select TMSIor IMSIin the Trace Object Symbol Typearea, 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 TMSIin the Trace Object

Symbol Typearea to query the call resource usage.

l If the MS's IMSI is used to set up a call, set Trace Object Symbol Typeto IMSIto

query the call resource usage.

l If you select IMEIin the Trace Object Symbol Typearea, determine whether the MSC

can obtain the IMEI.

4. After the loopback is started, click Queryto query the remote speech channel

loopback.

5. Click Cancelstop the remote speech loopback.

NOTE

To end a remote speech loopback, select IMSI, IMEI, TMSI, or MSIDSNin the Trace Object

Symbol Typearea to ensure that the parameter setting in the Trace Object Symbol Typearea

is the same as that is previously set for the loopback.

l Running MML commands

1. After a call is set up successfully, run the MML command STR CALLRESLOPon

the LMT, and press Enteror click Assist.

2. Set the relevant parameters, and click Execto start the loopback

3. After the loopback is complete, run the MML command STP CALLRESLOPto stopthe loopback.

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Operation Results

1. 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 the

channel used by subscriber A, subscriber A can hear his or her own voice and subscriber

B 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 loopback

on subscriber A.

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

or IP mode.

3. When FG2a is configured over the A, Abis, or Ater interface, a subscriber can hear his or

her own voice and the peer end's voice during a loopback over these interfaces, but the peer

end 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 peer

end's voice, but the peer end cannot hear any voice regardless of whether the loopback is

MSC-oriented or MS-oriented.5. Table 3-1lists the loopback results for various positions when the ID of subscriber A is

used to perform loopback. The results are similar if the ID of subscriber B is used.

Table 3-1Loopback results

Loopback Position andDirection

InterfaceBoard Type

Subscriber A Subscriber B

NSS Interface Unit (MSC

Direction)

TDM

interface

board

Can hear B but not

self

Can hear self but

not A

IP/HDLC

interface

board

Cannot hear self or

B

Can hear self but

not A

NSS Interface Unit (MS

Direction)

TDM

interface

board

Can hear self but

not B

Can hear A but

not self

IP/HDLC

interface

board

Can hear self but

not B

Cannot hear A or

self

NSS TC (Near AbisInterface) (MSC Direction)

Can hear B but notself

Can hear self butnot A

NSS TC (Near Abis

Interface) (MS Direction)

Can hear self but

not B

Can hear A but

not self

NSS TC (Near A Interface)

(MSC Direction)

Can hear B but not

self

Can hear self but

not A

NSS TC (Near A Interface)

(MS Direction)

Can hear self but

not B

Can hear A but

not self

NSS TNU (Near Abis

Interface) (MSC Direction)

Can hear B but not

self

Can hear self but

not A

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InterfaceBoard Type


NSS TNU (Near Abis


Can hear self but

not B

Can hear A but

not self

NSS TNU (Near A


Can hear B but not

self

Can hear self but

not A

NSS TNU (Near A


Can hear self but

not B

Can hear A but

not self

NSS Ater Interface Unit

(MSC Direction)

TDM

interface

board

Can hear B but not

self

Can hear self but

not A

IP/HDLC

interface

board

Cannot hear self or

B

Can hear self but

not A

NSS Ater Interface Unit

(MS Direction)

TDM

interface

board

Can hear self but

not B

Can hear A but

not self

IP/HDLC

interface

board

Can hear self but

not B

Cannot hear A or

self

BSS Ater Interface Unit

(MSC Direction)

TDM

interface

board

Can hear B but not

self

Can hear self but

not A

IP/HDLC

interface

board

Cannot hear self or

B

Can hear self but

not A

BSS Ater Interface Unit

(MS Direction)

TDM

interface

board

Can hear self but

not B

Can hear A but

not self

IP/HDLC

interface

board

Can hear self but

not B

Cannot hear A or

self

BSS TC (Near Abis


Can hear B but not

self

Can hear self but

not A

BSS TC (Near Abis


Can hear self but

not B

Can hear A but

not self

BSS TC (Near A Interface)

(MSC Direction)

Can hear B but not

self

Can hear self but

not A

BSS TC (Near A Interface)

(MS Direction)

Can hear self but

not B

Can hear A but

not self

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InterfaceBoard Type


BSS TNU (Near Abis


Can hear B but not

self

Can hear self but

not A

BSS TNU(Near Abis


Can hear self but

not B

Can hear A but

not self

BSS TNU (Near A


Can hear B but not

self

Can hear self but

not A

BSS TNU (Near A


Can hear self but

not B

Can hear A but

not self

BSS Interface Unit (MSC

Direction)

TDM

interface

board

Can hear B but not

self

Can hear self but

not A

IP/HDLC

interface

board

Cannot hear self or

B

Can hear self but

not A

BSS Interface Unit (MS

Direction)

TDM

interface

board

Can hear self but

not B

Can hear A but

not self

IP/HDLC

interface

board

Can hear self but

not B

Cannot hear A or

self

TMU/PTU (MSC

Direction)

Non-IP BTS Can hear B but not

self

Can hear self but

not A

IP BTS Cannot hear self or

B

Can hear self but

not A

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

not B

Can hear A but

not self

IP BTS Can hear self but

not B

Cannot hear A or

self

3.1.3 One-Way Audio Detection

This section describes how to detect one-way audio or no audio on the BSS.


This function is used to detect one-way audio or no audio by checking uplink and downlink

voice 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 the

problems.

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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.

Procedure

Before one-way audio detection is enabled, check the transmission mode of the Abis interface

and run the MML commands SET BSCBASICand SET GCELLSOFT. The specific

operations 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_RE

C-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_RE

C-0, SpeechErrorForceHOSwitch=OFF;



EXCEPFRAMETHRES=25;

l Scenario 3: The transmission modes of the A, Ater, and Abis interfaces are different, and

IP 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;



EXCEPFRAMETHRES=25, MUTECHECKCLASS2SWITCH=ENABLE,

DETECTFRAMEPERIOD=2, MUTECHECKPEIROD=4;

Operation Results

l

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

the logs can be used to select the appropriate transmission mode used by the BSC. If the

BSC uses TDM transmission mode, select SubType:TDM_L2. If the BSC uses IP

transmission mode, select SubType:IP_MUTE.

lAll 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 3-2shows the mapping between the faulty nodes and the fields in the logs.

Table 3-2Mapping between the faulty nodes and the fields in the logs

Analysis Item Field Field Description

BTS TrxId TRX ID

Abis interface AbisSubrackNo Subrack number of the Abis

interface board

AbisSlotNo Slot number of the Abisinterface board

AbisPort Port number of the Abis

interface board

TNU TNURack Subrack number of TNU

TNUSlot TNU slot number

TNUPort TNU port number

TC resources TcSubRackNo TC subrack number

TcSlotNo TC slot number

TcDspNo TC DSP number

A interface Acic CIC number

Ater interface AterLinkNo Ater link number

3.1.4 Crosstalk Detection

This section describes how to detect crosstalk on the BSS.


This 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

CAUTION

This 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 BSCBASICwith Cross

Call Detect Time Thresholdset to the recommended value 10.

Operation Result

Each time the BSC detects crosstalk, a crosstalk log is recorded. The crosstalk logs are recorded

together with one-way audio logs. You can run the MML command COL LOGto 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 Crosstalk

This section describes how to enable crosstalk optimization for the Um interface.


This function is used when severe crosstalk occurs over the Um interface in a cell. The symptoms

of crosstalk over the Um interface are as follows: 1. The crosstalk occurs during a call rather

than at the beginning of a call. 2. The Um interface quality for a party in the call is poor. 3. The

voices of two parties at the peer end can be heard.

NOTE

When this function is enabled, the BSC sends a Channel Rel message to the MS after a call is dropped. In

addition, 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 by

default.

Procedure

Run the MML command SET GCELLSOFTwith Um Interface Crosstalk Optimization

Allowedset to YES(Allowed).

3.1.6 Binding MSs to BSC Resources

This section describes how to bind MSs to BSC resources.


This function applies only to the binding of the specified Ater or digital signal processor (DSP)

resources during site deployment, swapping, fault location, or maintenance.

Procedure

1. Run the MML command SET RSVRESto reserve TC and BM resources of a BSC.

2. Run the MML command SET USRRESBINDto set the parameters to bind MSs to the

reserved resources.

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NOTE

l 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 Typeor Second User Typeis set to MSISND, First User Identityor Second User

Identitymust be set to a value prefixed with the country code to ensure data consistency.

Operation Results

Perform a dialing test using the specified Ater or DSP resources to check whether voice problems

are caused by faults in the DSP or Ater interface. If so, troubleshoot the voice problems. Then,

run the MML command SET USRRESBINDto release the bound resources.

3.1.7 Performing Dialing Tests on the Um Interface

This section describes how to perform dialing tests on the Um interface.


This function locates problems on the Um interface by specifying TRXs or channels in the test

cell for the test MS.

Procedure

CAUTION

The channels on which the timeslots are specified must be traffic channels (TCHs). If the

channels 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 UMTESTPARAto configure the mobile station

international ISDN number (MSISDN), site, cell, TRX, and timeslot for the test MS. If no

TRX or timeslot is configured, dialing tests are performed in the specified cell by default.

Operation Results

l 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 specified

timeslots. The timeslots on two half-rate channels can be occupied twice.

3.1.8 Performing Dialing Tests on the A Interface

This section describes how to perform dialing tests on the A interface.


Perform 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 the

received DTMF message. If A Interface Block CICis set to YES(Yes), the BSC blocks the

circuit occupied by a call when the call is released. Therefore, the circuit for the dialing test

cannot be occupied by other calls. If A Interface Block CICis set to NO(No), a large number

of dialing tests are performed on the A interface circuits that the MSC allocates to the BSC.

Procedure

CAUTION

l Do not set A Interface Block CICto YES(Yes)when services are in progress. If A Interface

Block CICis set to YES(Yes), circuits on the A interface are blocked automatically. In this

situation, 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 ATESTPARAto enable automatic dialing tests on the

A interface.

Set Automatic Dialing Test on A Interfaceto YES(Yes).

Set MSISDN in A Interface Testto 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 Interface

Noise DTMF Message, or A Interface Normal DTMF Messageas the DTMF

messages that the test MS sends during dialing tests.

Set A Interface Block CICto YES(Yes). This indicates that the circuit used by

the call during a dialing test is automatically blocked when the call is released. In

this situation, resources on the A interface may be insufficient. Therefore, do not

set A Interface Block CICto YES(Yes)when services are in progress.

Set A Interface Sampling Testto YES(Yes)and set A Interface E1/T1 Sampling

Numberto 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 ATESTPARAwith Automatic Dialing Test on A

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

Operation Results

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

ATESTPARAon 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 or

downlink one-way audio, no audio, and noise.

2. During a dialing test on the A interface, one dialing test log is recorded when a DTMF

message 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 EXCEL

to 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

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problems are caused by faults in the A interface. Table 3-3lists the format of log files that

record the information about dialing tests on the A interface.

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

interface

No. Information

1 Call start time (in format of YYYY.MM.DD

HH:MM:SS)

2 DTMF message type

3 DPC

4 CIC

5 Mobile phone number

6 Carrier number and channel number

7 Information about the Abis interface:

l If the TDM transmission is used on the Abis

interface, the following information is logged:

subrack number, slot number, port number,

timeslot number, and sub-timeslot number for an

interface board.

l If the Abis interface over IP is used, IP address

and ports used on the Abis interface board is

logged.

l If the HDLC transmission is used on the Abis

interface, the HDLC port and sub-port numbers

are logged.

8 Ater interface data such as Asub interface link No.,

Asub timeslot number in the link, and Asub interface

data rate.

NOTEThe information is unavailable in TC/BM combined mode.

3.1.9 Detecting Noise on the A InterfaceThis section describes how to detect noise on the A interface.


The noise detection function provides an important method for the BSS to locate noise problems.

In A over TDM mode, the TC module of the BSC performs noise detection on the PCM code

streams over the A interface, records the calls experiencing the noise problem, and generates

logs.

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NOTE

l This function is used only in A over TDM mode and does not take into account the transmission mode

on the Abis interface.

l This function is mutually exclusive with the following features: GBFD-117701 BSC Local Switch,

GBFD-117702 BTS Local Switch, and GBFD-115701 TFO(Tandem Free Operation).

l The CPU usage of the digital signal processor (DSP) enabled with this function increases by up to 3%.

Procedure

l Enabling the noise detection function

1. Run the MML command SET GCELLSOFTto enable the noise detection function.

In this step, set the following parameters as follows:

Set Noise Detect Switchto ON(On).

Set Noise Detect Periodto 5.

Set Noise Detect Thresholdto 15.

Set Noise Detect Levelto HIGH(High).

Set Fuzzy Noise Switchto OFF(Off).

l Disabling the noise detection function

1. Run the MML command SET GCELLSOFTto disable the noise detection function. In

this step, set Noise Detect Switchto OFF(Off).

Operation Results

l You are advised to analyze voice logs after this function is enabled for at least one hour

during peak hours.

l The BSC automatically saves voice logs in the following directory: \bam\common\fam

\famlogfmt\.

l The procedure for analyzing voice logs is as follows:

1. On the BSC LMT, click Device Maintenance. The Device Maintenancetab page is

displayed.

2. Choose BSC Maintenance> Maintain User Resources> Voice Log Analysisfrom

the BSC Maintenancetab page. The Voice Log Analysisdialog box is displayed.

3. In the Voice Log Analysisdialog box, set Log Typeto A interface noise, and set

other parameters to appropriate values. Then, click Analyze. The analysis result isdisplayed in a table, showing the information about possible fault points.

3.2 Maintenance Functions for Identifying TransmissionProblems

This section describes maintenance functions for identifying transmission problems.

3.2.1 Crossed Pair Detection

This section describes how to enable crossed pair detection.

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A crossed pair is classified into big crossed pair and small crossed pair. A big crossed pair refers

to crossed TX/RX between two pairs of E1 cables, as shown in Figure 3-4. A small crossed pair

Documents

GBSS14.0 Troubleshooting Guide(02)(PDF)-En