4.Omb421100 Mbts v1r3 Gsm Troubleshooting Issue 1

MBTS Troubleshootingwww.huawei.com

Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

ObjectivesUpon completion of this course you will be able to: course,Know how to find the fault in BTS Know the common fault types Grasp BTS fault disposal method Know how to prevent the fault


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Contents1. 1 BTS3900 Hardware Overview 2.General Procedures of Troubleshooting 3.Procedure of BTS Status Verification 4. 4 Collecting Information for Locating BTS Faults 5. Methods of Fault Judgment and Location 6. Approach to prevent BTS fault


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Structure of the BTS3900 Cabinet

Double radio filter unit

Fan box GSM antenna and TMA control module Baseband unit Direct current distribution unit

-48V CabinetCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page3

Boards and Modules in BBUBSBC: The universal BBU Subrack Backplane type C GTMU: The GSM Transmission, Timing and Management Unit UBFA: The Universal BBU Fan unit type A UPEU: The Universal Power and Environment interface Unit UELP: The Universal E1/T1 Lightning Protection unit UEIU: The Universal Environment Interface Unit


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GTMUThe GSM Transmission, Timing, and Management Unit for BBU (GTMU) controls and manages th entire BTS It provides t l d the ti BTS. id interfaces related to the reference clock, power monitoring, OM, and external alarm collection.Distributes and manages BTS clock signals Provides t e Ethernet po t for te o des the t e et port o terminal maintenance a a te a ce Supports four routes of E1 inputs Provides the CPRI ports for communication with the DRFU p


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GTMU PortsLabel CPRI0CPRI5 ETH FE0 Connector Type T pe SFP RJ45 RJ45 Description p Ports for the communication between the BBU and the RF module; support input and output of the optical and electrical signal . Port f l P t for local maintenance and commissioning l i t d i i i A reserved port that performs the following function: Connects the BBU to a routing device in the equipment room through the Ethernet cable to transmit network information. A reserved port that performs the following function: Connects the BBU to a routing device in the equipment room through the optical cable to transmit network information. A reserved port that performs the following function: Enables the automatic software upgrade from a USB disk. Provids a reference clock for the tester. Provides the input and output of the four E1/T1 signals between the GTMU and the UELP or between the GTMU and the BSC.

FE1

DLC

USB TST E1/T1

USB USB DB26 female


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GTMU IndicatorsLED Color ON OFF RUN Green ON for 1s, OFF for 1s ON for 2s, OFF for 2s , ON for 0.125s OFF for 0.125s ALM Red ON OFF ON OFF ON LIU0-LIU3 Green ON for 0.125s OFF for 0.125s OFF CPRI0CPRI5 Green Red ON ON Status The board is faulty. No power supply is available or the board is faulty. The board is operational. The OML link is abnormal. The board is loading software. A fault occurs in the running board. No alarm is generated. The board is operational. The board is faulty. This link is not used. A remote E1/T1 alarm is generated. This link is operational. The CPRI link is normal. The reception of the optical module is abnormal and an alarm is generated. Description

ACT

Green


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UPEUThe universal power and environment interface unit ( p (UPEU) supports ) pp the -48V /-24V DC power input, supplies power to the boards, modules, and fan in the BBU, and provides access to multiple environment monitoring signalsPort MON 0 MON 1 EXTALM0 EXTALM1 PWR Type RJ45 Description Transmitting two RS485 T itti t environment monitoring signals Transmitting two RS485 environment monitoring signals Transmitting four dry contact alarms Transmitting four dry contact alarms +24 V/-48 V DC power input p p

RJ45 RJ45 RJ45 3V3


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UEIUUEIU is the environment interface board of BBUit can support pp multi-route monitoring signal input UEIU is optional and is only used when more ports are needed

Label MON0 MON1 EXTALM0 EXTALM1

Connector Type RJ45 RJ45 RJ45 RJ45

Description One RS485 signal One RS485 signal Four dry contact signals Four dry contact signals


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Ports of the DRFUType Port for transmitting and receiving RF signals Connector N female connector Ports ANT1 ANT2 CPRI0 CPRI1 RX1 in Port for transmitting RF signals between DRFUs QMA female connector RX1 out RX2 in RX2 out Power port 7W2 power connector PWR Used in connection to the antenna subsystem Used in connection to the BBU, or in connection to the upper-level cascaded DRFU Used in connection to the lower-level cascaded DRFU Input port for diversity signals in antenna channel 1 Output port of diversity signals in antenna channel 1 Input port for diversity signals in antenna channel 2 Output port of diversity signals in antenna channel 2 Receives power input Description

CPRI port

SFP female connector


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LEDs of the DRFULED Color On Off RUN Green On for 1s Off for 1s On for 0.125s Off for 0.125s On for 1s Off for 1s AL M Red Off On O On ACT Green Off On for 1s Status Description The Th power input is normal, but th module is i ti l b t the d l i faulty. No power input is available, or the module is faulty. y The module is functional.

The module is loading data.

A fault alarm is generated. No alarm is generated. A fault alarm is generated, need to chang another module. The module is functional and is correctly connected to the BBU. The connection with the BBU is not established. The DRFU is being tested on the SitePage11

Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Off for 1s Maintenance

LEDs of the DRFUOff On for 1s Off for 1s VSWR Red On for 0.125s Off for 0.125s On On (green) CPRI0 Red Green On (red) On for 1s Off for 1s (red) On (green) CPRI1 Red Green On (red) ( ) No VSWR alarm is detected. The VSWR alarm is generated only on the ANT2 port. The VSWR alarms are generated on the ANT1 and ANT2 ports. The VSWR alarm is generated only on the ANT1 port. The CPRI link is functional. The interface module fails to receive signals. The CPRI link has a loss-of-lock error. The CPRI link is functional. The interface module fails to receive signals. g

On for 1s Off for 1s The CPRI rights reserved. error. Copyright 2010 Huawei Technologies Co., Ltd. Alllink has a loss-of-lockPage12 (red)

Ports of MRFUPort Type Label ANT_RX B ANT_TX/ RXA CPRI0 CPRI CPRI1 RX_INB Interconnection port for RF receive signals RX_OUT A PWR MON Connector Type DIN connector DIN connector SFP female connector SFP female connector QMA female f l connector QMA female connector 3V3 power connector RJ45 connector Description

Port for transceiving RF signals

Connecting to the antenna subsystem.

Connecting to the BBU, or the upper-level RFU during the cascading cascading. Connecting to the lower-level RFU during the cascading. Input port of diversity signals in the antenna channel. Output port of diversity signals in the antenna channel. Feeding power. Monitoring port port.

Power supply port Monitoring port


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LEDs of MRFULED Color Status ON OFF RUN Green 1s ON 1s OFF 0.2s ON 0.2s 0 2s OFF ALM Red 1s ON 1s OFF OFF ON OFF VSW R Red OFF ON Description The power input is normal, but the module is faulty. There is no power supply, or the module is faulty. The module is running properly. The software is being loaded to the module module. A fault alarm is generated. No alarm is generated. The module is functional and is correctly connected to the BBU. The connection with the BBU is not set up. No VSWR alarm is generated. The VSWR alarm is generated on the ANT_TX/RX port.Page14

ACT

Green


LEDs of MRFUON (Green) CPRI0 Red Green ON (Red) 1s ON 1s OFF(Red) ON (Green) CPRI1 Red Green ON (Red) 1s ON, 1s OFF (Red) The CPRI link is normal. The interface module fails to receive signals. The CPRI link is out of lock. The CPRI link is normal. The interface module fails to receive signals. The CPRI link is out of lock.


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Appearance of the RRU3908The RRU3908 is an outdoor remote radio unit that processes the baseband signals and the RF signals of the GSM, GSM and processes the RF signals of the UMTS

-48 V DC RRUCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

+220V AC RRUPage16



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General Procedures of TroubleshootingGenerally, Generally the troubleshooting should go through the following four stagesInformation collection Fault judgement Fault location Fault removing


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Locating Fault InformationAlarmAlarm Console Alarm Box M2000

Traffic statistics Drive t t D i test Routine inspection Customer complain


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Judging the Scope of the FaultAfter collecting fault information, you need to analyze information the fault symptom to determine the scope and type of the fault fault. In the BSS, the fault scope refers to the area where the fault happens. It often has something to do with the location of the BSSIf BSC is faulty, usually it affects a part of sites or all of sites If BTS is faulty, usually it only affects itself and the handover faulty success rate of the adjacent cells of the BTS


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Basic Disposal MethodAnalyzing the Alarm InformationAlarm information come from the BSS alarm system, indicated usually through sound, light, LED, and screen output, etc It includes the detailed description of the abnormality, possible causes and restoration suggestions, involves the hardware, link, trunk and CPU loading ratio, etc.. It is a gist for the fault analysis ratio etc and location

Analyzing the Indicator StatusIndicators can indicate the work status of circuit, link, optical path, node and active/standby mode besides that of the corresponding y p g boards, usually used along with the alarm information generally

Analyzing Traffic Statistics Result y gIt is the most useful method for locating RNO fault.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page21

Basic Disposal MethodAnalyzing Apparatus & Meter Test Result It reflects the fault nature with the visual and quantified data Some common Apparatus & Meter Signaling Analyzer, Test phone, Sitemaster, etc. Tracing the Interface It is applied in locating the failure causes of subscriber call connection and inter-office signaling cooperation, etc. The trace result can help to find the cause of call failure directly and locate the problem or to get the index for the subsequent analysis Calling Test It is a simple and quick method to judge whether the call processing function and relative modules of the BSS are normal or not Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page22

Basic Disposal MethodComparison/Interchange Comparison: compare the faulted components or phenomenon with the normal ones, and find the differences so as to find the problem It is usually used in the situation with simple fault range y p g Interchange: if the fault can not be located even after the standby components are replaced, you can interchange the normal components ( (such as board, optical fiber, etc.) with the potential faulted components, , p , ) p p , and to compare the work status so as to specify the fault range or part It is usually used in the situation with complicated fault range Switching/Resetting It can not locate the fault cause accurately, and due to the randomness of software running, the fault may be not able to recur, thus it is difficult to know the real fault and solve the problem This method is just an emergency method, applicable only in the emergent situation


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Check BTS Running Status ProcedureFor one BTS, the following steps can help us verify BTS running status:Browse BTS Device Panel Running Status Overview Check BTS Running Running Status Details Check BTS Initialization Information BTS Setup Details Check BTS Physical Layer- Transmission Status Layer Check BTS Layer2 Message LAPD Status Check BTS Channel Status Monitor Channel Status


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Browse BTS Device PanelBTS Configuration information BTS alarm indicator information BTS boards running information


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Check BTS Running Status


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Check BTS Running Status On the BSC6900 WEB LMT LMT,

choose BTS Maintenance > Query BTS R Q Running St t i Status


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Check BTS Initialization InformationBTS Initialize Progress


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Check BTS Physical Layer

double-click the peripheral of the subrack


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Check BTS Layer2 MessageO the SC6900 On t e BSC6900 WEB LMT, c oose BSC Maintenance , choose SC a te a ce >Maintain Transmission and Signaling > Maintain LAPD Link


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See Remarks


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Check BTS Channel StatusOn the BSC6900 WEBLMT choose BTS Maintenance > WEBLMT, Monitor Channel Status on the menu.


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Collecting Alarm InformationBSC6900 Alarm Interface


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Query Alarm ShieldedIn BSC6900, the command (ADD OBJALMSHLD) is used for adding a shield of alarm Object of BSC, and the command (ADD OBJALMSHLD) is for BTS MML in BSC6900SET ALMSHLD ADD BTSOBJALMSHLD O LST BTSOBJALMSHLD


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Manage Alarm LogBSC6900 Step 1: Query Alarm Log. Step 2: Save the Result

ALMLOG_Result ALMLOG ResultCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page37

Manage Alarm Log

MML i BSC6900 inLST ALMLOG EXP ALMLOG SET ALMCAPACITY


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Manage Alarm LogLST ALMLOG

EXP ALMLOG

SET ALMCAPACITY


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Browsing Configuration Data

Save As

Browse_LAPD_Link _Data DataCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page40

Collecting the Local InformationOn the BSC6900 WEB LMT, choose BSC Maintenance >Collect BSC Local Information The local information is automatically saved to the path: /bam/version_a/ftp/COLLOGINFO.Click the Collect BSC Information tab. On the tab page, select Collect BSC local i f l l information and set th BSC l ti d t the local information. li f ti Click the BTS Fault information tab. On the tab page, select the BTSs of which the information needs to be collected. Click the Collect File tab. On the tab page, select the files of which the information needs to be collected.


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Collecting the BSS Local InformationBSC6900Step 1: Collect the information to OMU Step 2: Set the upload configuration Step 3: Upload the collected information to LMT


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Collecting BSS Configuration DataIn BSC6900, system support backup the data only in MML interface BSC6900The path of the backup data file in OMU

CFGMML.txt CFGMML txtCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page43

Collecting BSS Configuration DataBKP CFGFILE: Backups the active configuration data into BIN g format EXP CFGMML: Backups the active configuration data into TXT format BKP DB: Back up the configuration data, alarm data, and performance data on the OMU server into BAK format. MML in BSC6900EXP CFGMML BKP DB


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Collecting M2000 Performance Measurement InformationOn the M2000 Client choose Performance > Query Result Client, on the menu.


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Collecting BTS Log FIiesOn the BSC6900 WEB LMTchoose BTS Maintenance > Maintain Site > Browse BTS Log.


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Contents5. 5 Methods of Fault Judgment and Location5.1 Voice Fault 5.2 Antenna & Feeder Fault 5.3 Transmission Fault 5.4 LAPD Link fault 5.5 5 5 Data Configuration fault


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Distinguish Voice Fault from Different SoundsIf there are noise in voice call we can distinguish call, different noise from different interface.A interface noise usually continue and smooth, because A interface bandwidth is 64kbps Abis interface noise usually discontinue and sharp, because Abis interface bandwidth is 16kbps

A interface noise listen

Please double click to

Abis interface noiseCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Please double click toPage49

listen

Basic Operation of Voice LoopbackBSC Maintenance > Query Single-User Resource Single User

When Trace Object is: MSISDN

The input MSISDN number is MTC ( Mobile Terminated Call) number

Query result: see remarks y


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Test TRX Loopback

BIU Loop Test

TRX RF Self L S lf Loop Test


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Test TRX Channel loopback

BTS Voice S o ce Loop Test

TRX Voice Loop Test


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Interface Board Port LoopbackIf the loopback at the port of an interface board fails, you can infer that the transmission from or to the interface board fails. Thus, you can locate the fault on the transmission link


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Interface Board Port Loopback


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Interface Board Port Timeslot Loopbackto perform local or remote loopback for the specified timeslot on the specified interface board. It can be used to locate voice problems by segments. The timeslot loopback on the interface board can be performed on the Abis E1 interface board


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BSS CS Signal FlowBM & TC Separate p

BM& TC CombinedE1 Protec ction DAFU U Unit BTSCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page56

RF Unit

BT Unit

Voice Faults CaseProblem DescriptionCustomers complain that sometimes the silence calls happen. U h Usually, the no-audio problem occurs once or twice ll th di bl t i when about 30 calls are made. This problem happen in only two cells. t ll


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Voice Faults CaseCause analysis yEngineering connection problem

Data configuration problem fi i bl BSC or BTS Hardware fault Radio link interference Clock fault


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Voice Faults CaseHandling ProcessCheck the interconnection data of the BSC and MSC. No error i f is found. d Check the connections and transmission on the A interface and Ater interface. Both are normal. d At i t f B th l The problem occurs on cells distributed in the same BTS. Therefore, maybe the wireless environment interference or that BTS have problem


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Voice Faults CaseHandling Process a d g ocess Use one mobile to call the fixed telephone. Perform massive dialing tests on the BTSs where the fault occurs. After the fault recurs, hold on, and use the single recourse query q y function on the LMT to query timeslot of this call. Timeslot loopback in abis interface, echo is heard through a fixed-line phone. Therefore, it can be determined that the BSC is not faulty. Then, hold on and perform loopback towards the BTS. In this case, no echo is heard through a mobile phone, that means there is fault in BTS.


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Voice Faults CaseStart BTS Voice channel loopback MS still without any loopback, echo. And continue starting TRX Voice channel loopback, MS can hear echo That mean voice fault happen in DBUS echo. of GTMU board . Replace GTMU with normal one, and the fault disappear. Finally we find out the problem is DBUS.


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BTS/DBS3900 System Structure

RXU

RXU


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Introduction of VSWR AlarmVoltage Standing Wave RatioThe ratio of the maximum/minimum values of standing wave pattern along a t tt l transmission line to which a load is i i li t hi h l d i connected. VSWR value ranges from 1 (matched load) to infinity for i fi it f a short or an open l d F most b h t load. For t base station t ti antennas the maximum acceptable VSWR =PF^0.5+PR^0.5/(PF^0.5-PR^0.5)


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Fault SymptomAfter a major VSWR alarm is generated the TRX generated, automatically disables the power amplifier, and thus the services of the TRX are interrupted interrupted. After a prompt VSWR alarm is generated, the coverage range of the TRX decreases. The TRX can clear prompt VSWR alarms but cannot clear major VSWR alarms. Major VSWR alarms cannot be cleared after they are generated unless the TRX board is reset.


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Possible Causes of VSWR AlarmConnections at the power output port of the RF unit and feeder are not secure Faulty RF unit Antenna system problem Data configuration error


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Preliminary Cause IdentificationC ec the ogs and alarms. Check t e logs a d a a s Check whether alarms are generated. Determine the types and severities of the alarms. Check the data configuration. Check h th the t Ch k whether th antenna mode configured i consistent d fi d is i t t with the physical connections of the antenna. If the data configured is inconsistent with the physical connections of the antenna, the BTS generates a VSWR alarm. Check the forward power, reverse power and the VSWR of the power power, boards.


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Suggestions on On-site TroubleshootingUse SiteMaster to check the VSWR of the antenna port. If the VSWR of the p antenna port is greater than 2.5, the possible cause of the problem is incorrect cable connections of the antenna system. Ask the construction team to check the cable connections. If the VSWR of the antenna port is greater than 2 but smaller than 2.5, perform the f ll i operations: f h following iInterchange the two TRXs of the cell but do not change the antenna of the cell. cell Observe for about 10 minutes to check whether the alarms can be cleared and determine whether the TRX module or the antenna is faulty. On the BSC side, check whether the alarms are generated or cleared after the boards are interchanged. If you do not handle the problem in time, the boards may go faulty. Monitor the th quality of th project t ensure th t th b lit f the j t to that the boards d not go f lt d do t faulty.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page68

Case: Antenna System FaultsProblem DescriptionA newly deployed GSM BTS3900 uses the S3/2/2 configuration. After new sites configuration are added, the second TRX on the first DRFU in cell 1 of the BTS3900 reports an SWR alarm. After the TRX SWR alarm is reported, the services of the TRX are completely interrupted, which seriously impacts network services. On-site connections in cell 1:ANT

Alarm InformationTRX SWR alarm (alarm ID: 4144)Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page69

Case: Antenna System FaultsCause AnalysisImproper connection between the TRX and the antenna system t Higher SWR of the antenna system TRX faults ANT port of the TRX not connected to the antenna system p y BSC data configuration error


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Case: Antenna System FaultsHandling ProcessCheck the connections between the TRX and the antenna system. No connection error or poor contact is found. All t N ti t ti f d parts of the antenna system are connected properly. Replace the TRX board. The alarm persists. Use a tool (SiteMaster) to measure the SWRs of the antenna port jumper, lightning arrester, TMA, and antenna of the duplexer unit. The SWRs are normal.


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Case: Antenna System FaultsHandling ProcessCheck the data configuration of the BSC. The Tx/Rx modes of two DRFUs in cell 1 are Double Antenna that is, two antennas Antenna, is transmit signals and the main diversity receives signals. Seen from the DRFU hardware connection diagram of the cell, the signals of the second TRX of the first DRFU are transmitted from ANT2, but the TRX is not connected to the antenna system. As a result, the TRX reports the SWR alarm. Change the Tx/Rx mode of the two DRFUs in cell 1 to Single g g Antenna Double Receiver. The alarm disappears and the TRX runs properly.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page72

Case: Antenna System FaultsSuggestions and Summary:For the BTS3900, the Tx mode and Rx mode of most TRXs are Diversity Independency or Combining and Receive Diversity Diversity, and the default Tx/Rx mode of the antenna system is Double Antenna. In this case, if only one dual-polarized antenna is used, a cell supports two TRXs at most. When only one dual-polarized dual polarized antenna is used, if a single cell supports three or four TRXs, y you need to change the Tx/Rx mode of the antenna system to g y Single Antenna Double Receiver. Otherwise, the TRX will report SWR alarms and fail to run properly.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page73



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Principles of E1 TransmissionThe physical connection of the E1 system consists of one pair of RX cables and one pair of TX cables. The code word on the E1 cable contains clock information; therefore, no additional clock signals are required. In practice, the working mode of the E1 system is classified into two types:Balanced circuit Non balanced Non-balanced circuit


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Locate Transmission faultBSC6900 EIUa UELP BBU

GTMU


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Related AlarmAlarm ID:4714, E1 Local Alarm ID:4714 Alarm ID:4716, E1 Remote Alarm Alarm ID:4102, LAPD Alarm


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Possible Causes of Transmission FaultE1 Local/Remote FaultThe transmission link is not available. Cross Connection The hardware is faulty faulty. The settings for the DIP switches of the BTS are not correct. Grounding problem problem.


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Checking for the E1/T1 Cross ConnectionCHK E1T1CRS :< SRN >< SN >< MTHD>< PN > Test MethodALM_METHOD LOOP_METHOD


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Checking for the E1/T1 Cross ConnectionLOOP_METHOD LOOP METHODPort 1 Port 2 Port A1 Port A2 Port A3

ALM_METHOD ALM METHODDisable TX Receive RAI Alarm Disable TX Port B1 Port B2 Port B3

Port 3


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Dip switches in GTMUOn the GTMU, there are five DIP switches (S1-S5), each of (S1 S5), which has four bits. DIP switches S1 and S2 must be set together. togetherS1 is used to select the E1 resistance. S2 is used to select the grounding mode of E1/T1 cables.In 75-ohm E1 transmission mode, the GTMU is grounded by default (with S2 set to OFF).


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Test BER of the BTS TransmissionMicrowave or Optical Fib O ti l Fiber

E1 Cable DDF

E1 Cable BTS

BSC

Transmission Equipment

BER Tester


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Handling Procedure Eliminate BSC ProblemE1 alarm appear Y Loopback to BSC side, check port state in BSC side is normal? N BSC Abis port is faulty? N BSC Abis transmission board is faulty? N Abis transmission is faulty? y Eliminate the problem is caused by BSCCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Y

Move BTS to another BSC Abis port p Change another board Change transmission cable i BSC side bl in id Alarm Recover ?Page83

Y

Y

Handling Procedure Eliminate BTS g ProblemE1 alarm appear Y Loopback to BTS side, check port state in BTS side is normal? N Check the GTMU is faulty ? N Abis transmission is normal? Eliminate the problem is caused by BTS yCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Y Change another board Y Change transmission cable in BTS side Alarm Recover ?

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Case : Transmission FaultDescriptionAlarm consoleLoss of E1/T1 Signals (LOS), LAPD OML Fault

AnalysesTransmission device, board or E1 cables is faulty


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Case : Transmission FaultHandling procedureStep1: analyze the information from alarm console ,and judge h th there i something wrong with BSC or BTS j d whether th is thi ith Step2: perform self-loop test over BSC and check BSC Maintenance->Maintain Transmission and Signaling->Query Interface Board Port State, the state is normal. Step3: perform self-loop test over BTS and check the LIU indicator of GTMU board is ON. Step4:Change UELP board and fault disappear


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Possible Causes of LAPD Link FaultLAPD link FaultE1 fault. Transmission error. BSC Data configuration error. Faulty hardware of RF unit.


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Handing Procedure of Locating the LAPD Link FaultStep 1: Ch k h th th St 1 Check whether the LAPD alarms are generated l t d with some other alarmsIf an SFP alarm is reported, the SFP port may be faulty. Check whether the link generating an LAPD alarm is configured on the SFP port and clear the SFP alarm. If an E1 alarm is reported, the E1 p p , port may be faulty, or y y, transmission is abnormal. Check whether the link g generating an LAPD alarm is configured on the E1 port and g g p clear the E1 port alarm.


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Handing Procedure of Locating the LAPD Link FaultStep 2 Ch k h th th St 2: Check whether the current BTS version i an officially released t i is ffi i ll l d version. If yes, proceed with the next step. es ith ne t step If no, load the formal BTS version. Step 3: Check whether the LAPD alarms are cleared automatically and are reported repetitively in the case of no operation. If the alarms are cleared automatically and are reported repetitively, the possibility of configuration problem can be eliminated. Therefore eliminated Therefore, check the E1 cables or the CPRI cables connecting to the TRXs. If the alarms are not cleared automatically, proceed with the next automaticallyCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

step.

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Handing Procedure of Locating the LAPD Link FaultStep 4: Check the scope of the LAPD alarms. You can narrow the scope of problem location based on the common features of the problems problems. The alarms may be reported by all the LAPD links on a DBUS, on an E1 cable, on a board, at a site, or at most of the sites controlled by the same BSC. Step 5: Check whether cross connections exist. Run the CHK E1T1CRS MML command on the Local Maintenance Terminal (LMT) to check whether cross connections exist on the Abis port.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page91



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Typical Faults of Incorrect BTS Data ConfigurationAntenna mode and TX/RX mode incorrect Alarm system configuration fault TRX slot mismatch with physical configuration RNP&RNO parameters fault


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Antenna mode and TX/RX mode incorrectWhen configuring Transmit Mode , Transmit Transmit Mode, Transmit Independency or Combining can be chosen. How can we know whether Transmit Independency or Transmit Transmit Independency Transmit Combining is used? It will b d id d b antenna mode. Wh 2 TRXs are ill be decided by t d When TRX used in one DRFU,If the antenna mode is Single antenna or Double antenna(1TX), the transmit mode must be Transmit Independency I d d If the antenna mode is Double antenna(2TX), the transmit mode must be Transmit CombiningCopyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page94

DRFU Antenna ModeSingle Feeder Single Feeder (1TX + 1RX), for one DRFU configuration Single Feeder (1TX + 2RX), for two DRFUs configuration Double Feeder Double Feeder (1TX + 1RX), for one DRFU configuration Double Feeder (1TX + 2RX) for one DRFU configuration 2RX), Double Feeder (2TX + 2RX), for one DRFU configuration Double Feeder (2TX + 4RX), for two DRFUs configuration


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Transmit Mode and Receive ModeDRFU transmit modeTransmit independency or combining PBT Dynamic PBT Diversity transmitter

DRFU receive modeMain diversity receiver Four diversity receiver


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Alarm system Configuration PrinciplePhysical alarm interface Boards of BTS3900

Logical l L i l alarm configuration of BTS3900


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Alarm system Configuration PrincipleLogical slot number 0 1 2 3 6 7 8 9 10 11 16 17 Board type DEMU DEMU APMU/DPMU APMU/DPMU DTCU DTCU FMU/FMUA FMU/FMUA FMU/FMUA FMU/FMUA GATM GATMPage98

Bus number 0 1 0 1 0 1 0 0 1 1 0 1




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BTS fault preventionHardware: installation specifications is most important!give more attention to E1 connector give more attention to feeder connector give more attention to waterproofer of antenna and feeder system Confirming the grounding and lightning protection g g g g gp


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BTS fault preventionChecking Running statusRun the DSP BTSSTAT command to query the operating status of the BTS. Run the DSP GCELLSTAT command to query the operating status of the cell.

Checking the software versionRun the R th DSP BTSVER command t query th running software d to the i ft version of the BTS board.

Do calling test for every timeslot lli f i l


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SummaryBTS related knowledge is helpful for troubleshooting Follow the troubleshooting process The method of collecting fault information and p procedure of eliminating the faults g The processing of the typical faults


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4.Omb421100 Mbts v1r3 Gsm Troubleshooting Issue 1

Documents

1tx 2rx

1tx 1rx

dry contact signals

bsc6900 web lmt

cross connections exist

active configuration data

transmit network information

interface board fails