wi max rru3702 troubleshooting guide v1.0-20100609-a

WiMAX RRU3702 Troubleshooting Guide INTERNAL

Product Name Internal Level

WiMAX DBS3900 Public

Product VersionTotal 34 pages

V300R002

WiMAX RRU3702 Troubleshooting Guide

Prepared by Xu Jianjun, Wang Xiaolun

Date 2010-04-29

Reviewed by

Date

Reviewed by

Date

Approved by

Date

RRU3702 WiMAX Troubleshooting Guide INTERNAL

Huawei Technologies Co., Ltd.

All rights reserved.


Revision History

Date Revision Version

Description Author

2010-05-24 Draft is completedXu Jianjun,

Wang Xiaolun

2023-4-18 Huawei Technologies Proprietary of 34


Acronyms and Abbreviations

Acronym and Abbreviation

Full Spelling

RRU Radio Remote Unit

BBU Base Band Unit

GPS Global Position System

BS Base Station

CPRI Common Public Radio Interface



Contents

1 RRU State Check............................................................................51.1 Basic Check Items of the RRU..........................................................................................................................5

1.2 Query Methods of Check Items.........................................................................................................................6

1.2.1 Checking the Alarms................................................................................................................................6

1.2.2 Checking Whether the RRU Alarms Are Shielded or Manually Deleted.................................................7

1.2.3 Checking Whether the RRU RF Indexes Are Within Normal Range.......................................................8

2 Troubleshooting the Engineering Installation Problems.................102.1 Central Frequency Settings of the Carrier Exceeding the Frequency Range Supported by the RRU.............10

2.2 RRU Activation Failure Due to Incorrect Settings of Carrier Antenna State..................................................11

2.3 Some Carriers Cannot Be Activated Due to Incorrect Multi-Carrier Settings in the Same Sector.................12

2.4 Service VSWR Alarm Reported by the RRU Channel....................................................................................13

2.5 Service VSWR Alarm Reported by the Four RRU Channels..........................................................................18

2.6 Power-on VSWR Alarm Reported by the Four RRU Channels Without Service VSWR Alarm....................19

2.7 Bit Errors Occur on Services Due to Poor Contact of Optical Cable and Optical Module or Damage of Optical Cable.........................................................................................................................................................20

2.8 RRU Resources Unavailable Due to One-Way Audio of the Optical Cable...................................................22

2.9 RRU Resources Unavailable Due to Reverse Connection of the RRU Optical Cable....................................23

2.10 Sector Resources Unavailable Due to Optical Module Fault........................................................................25

2.11 AD9549 Incompatible with V32C02SPC220 and Earlier Versions...............................................................25

2.12 RRU PA Overcurrent Alarm Due to Intermittent Disconnection of the CPRI Link......................................26

3 Troubleshooting the RTWP Interference Problems.........................283.1 Great Differences Between RXRTWP and Single-Carrier RTWP Due to Adjacent Channel Interference.....28

3.2 Difference of RTWP Values Between RRU Channels Exceeding 10 dB........................................................29

4 Knowledge Points........................................................................314.1 VSWR Check...................................................................................................................................................31

4.1.1 VSWR During Power-On.......................................................................................................................31

4.1.2 Service VSWR........................................................................................................................................32



1 RRU State Check

1.1 Basic Check Items of the RRU



Check Item Requirement Query Method

Version Information

The RRU version matches the BBU version.

DSP BRDVER

Basic Configuration

The RRU optical port, carrier, and configuration information are correct.

LST RRU

LST CARRIERBASICINFO

Dynamic Alarm

There is no RRU alarm. See section 1.2.1 "Checking the Alarms."

Alarm Configuration

The RRU alarms are not shielded.

The RRU alarms are not cleared or deleted manually.

See section 1.2.2 "Checking Whether the RRU Alarms Are Shielded or Manually Deleted."

RF Index The RF index is within the normal range.

See section 1.2.3 "Checking Whether the RRU RF Indexes Are Within Normal Range."

Result Symptom Suggestion

Engineering Installation Fault

Incorrect Configuration

The ALM-34026 or ALM-34101 is generated. In this case, check whether the antenna is normal.

See chapter 2 "Troubleshooting the Engineering Installation Problems."

Any of the following alarms occurs: ALM-10077, ALM-34110, ALM-34120, ALM-34122, ALM-34231, ALM-10004, ALM-34011, ALM-34001, ALM-34003, ALM-34005, ALM-34142, ALM-34143, and ALM-34148. In this case, check whether the optical cable and optical module are normal.

See chapter 2 "Troubleshooting the Engineering Installation Problems."

The BS GPS clock is abnormal. Check the engineering installation of the BS GPS.

Interference

The RTWP or RXRTWP of the RX channel is abnormal.

See chapter 3 "Troubleshooting the RTWP Interference Problems."

1.2 Query Methods of Check Items

1.2.1 Checking the AlarmsLog in to the M2000 client. Check whether the following alarms are generated on the BS:



Alarm ID Alarm Troubleshooting

ALM-34001 RRU Transmitting Channel Gain Exception

See Chapter 2 "Troubleshooting the Engineering Installation Problems." Check whether the alarm is caused by external reasons of the RRU.

ALM-34003 RRU Receiving Channel Exception


ALM-34005 RRU Power Amplifier Overcurrent


ALM-34006 RRU Temperature Exception Contact Huawei TAC for analysis and support.

ALM-34011 RRU Input Power Exception Contact Huawei TAC for analysis and support.

ALM-34015 RRU Output Power Exception Contact Huawei TAC for analysis and support.

ALM-34026 Standing Wave Existence During RRU Power-On

Contact Huawei TAC for analysis and support.

ALM-34101 RRU Standing Wave Existence Contact Huawei TAC for analysis and support.

ALM-34103 RRU ALD Power Supply Exception


ALM-34110 RRU Optical Module Not in Position


ALM-34120 RRU Optical Module Transmitting Performance Deteriorated


ALM-34122 RRU Optical Module Receiving Performance Deteriorated


ALM-34134 RRU Power Supply Exception Contact Huawei TAC for analysis and support..

ALM-34137 RRU Startup Exception Contact Huawei TAC for analysis and support.

ALM-34141 RRU Temperature Sensor Exception




Alarm ID Alarm Troubleshooting

ALM-34142 RRU Self-Test Exception See Chapter 2 "Troubleshooting the Engineering Installation Problems." Check whether the alarm is caused by external reasons of the RRU.

ALM-34143 RRU Running Exception See Chapter 2 "Troubleshooting the Engineering Installation Problems." Check whether the alarm is caused by external reasons of the RRU.

ALM-34148 RRU Clock Exception See Chapter 2 "Troubleshooting the Engineering Installation Problems." Check whether the alarm is caused by external reasons of the RRU.

ALM-34221 RRU Power Surge Protection Exception


ALM-34230 ALD Maintenance Link Exception


ALM-34231 RRU High-Speed Transceiver Receiving Faulty


Method 1: Access the Topology view of the M2000 client. Right-click the BS icon, and choose Query Alarm/Event > Alarm List.

±Method 2: Run the LST ALMAF command to query the alarms.

1.2.2 Checking Whether the RRU Alarms Are Shielded or Manually Deleted

Run the LST ALMCFG command.

1. If you find that any alarm is shielded, run the SET ALMSHLD command to make the alarm unshielded.

2. If you find that any alarm is manually deleted, run the RST BRD command to reset the RRU. Query the BS alarm again to check whether the alarm is reported after the RRU is reset. If the alarm is not reported, go to step 3.



3. Run the RST BRDPWROFF command. Enter the corresponding RRU subrack No. and reset the RRU during power-off. Query the BS alarm again to check whether the alarm is reported.

1.2.3 Checking Whether the RRU RF Indexes Are Within Normal Range

1. Run the DSP RRURADIOPARA and GET RRUVSWR commands to query the RF parameters.

2. The carrier indexes are normal.

HPAPWR (CJ): Output Power of the Cabinet Top After Temperature and Frequency Compensated

RTWP (CN): Strength of the received signal of the carrier

RXRTWP: Strength of the received signal of the channel

VSWR (CL): standing wave ratio

TEMPTRU (CD): Current Working Temperature of the Tru board

PHATEMP (CX): Power Amplifier Temperature

Check Item Normal Range Unit

HPAPWR Single-carrier (EIRP + 3.8) ± 2 dBm

Dual-carrier (EIRP + 3.4) ± 2

RTWP

(no subscriber, no interference)

2.3 GHz

2.5 GHz

5 MHz [-113, -98]

7 MHz [-111.5, -96.5]

10 MHz [-110, -95]

3.5 GHz

5 MHz [-113, -97]

7 MHz [-111.5, -95.5]

10 MHz [-110, -94]

RXRTWP

(no subscriber, no interference)

2.3 GHz

2.5 GHz

[-105, -90]

3.5 [-105, -89]

TEMPTRU < 80 Celsius

PHATEMP < 85 Celsius

VSWR The filter is broadband. < 3.44 -

The filter is broadband. < 4.43 -



When there is any subscriber in the sector, the RTWP and RXRTWP cannot reflect the interference.

When there is no subscriber on the BS and the RTWP and RXRTWP are abnormal, see the troubleshooting method is chapter 3 "Troubleshooting the RTWP Interference Problems."



2 Troubleshooting the Engineering

Installation Problems

2.1 Central Frequency Settings of the Carrier Exceeding the Frequency Range Supported by the RRU

[Fault Phenomenon]

The sector resources are not available. The fault phenomenon is as follows:

1. Run the DSP CARRIERSTATUS command. The result shows that the operation status is unavailable.

2. Run the MOD CARRIERBLOCKFLAG command. The RRU cannot be activated.

[Related Alarm]

ALARM 10001-Unavailable Carrier Resource



Specific Problem=The configured carrier parameter (Effective Isotropic Radiated Power or ARFCN) is invalid.

[Troubleshooting Method]1. Run the GET TRAFFICCAPABILITY (for V3R2) or DSP TRAFFICCAPABILITY

(for V3R3) command to check the central frequency range that can be configured on the RRU.

Bandwidth Central Frequency

5M MINFREQ+2.5 MHz MAXFREQ-2.5 MHz

7M MINFREQ+3.5 MHz MAXFREQ-3.5 MHz

10M MINFREQ+5 MHz MAXFREQ-5 MHz

2. Run the LST CARRIERBASICINFO command to query the central frequency and bandwidth actually configured. Check whether the central frequency is correct.

− If the configured central frequency and bandwidth are the same as those planned, you can infer that the configuration is correct. The frequency band of the actually installed RRU is incorrect, and you need to use the RRU with correct frequency band.

− If the configured central frequency and bandwidth are different from those planned, you can infer that the configured central frequency is incorrect and exceeds the range supported by the RRU.

[Suggestion]

Run the MOD CARRIERBASICINFO command to set the central frequency correctly.

2.2 RRU Activation Failure Due to Incorrect Settings of Carrier Antenna State

[Fault Phenomenon]

The RRU cannot be activated, and the VSWR alarm is reported.

[Related Alarm]


ALM-34101 RRU Standing Wave Existence (reported during the activation)

[Troubleshooting Method]1. Run the LST SECTOR command to check whether the sector antenna is set to 4T4R or

2T2R.

2. Run the LST CARRIERBASICINFO command to check whether the carrier ANTBITMAP is set to 4T4R, 2T2R_LEFT, or 2T2R_RIGHT.

3. On the local side, check whether the RRU antenna port and antenna connection are consistent with the configuration information.



− The antennas are connected to channels A and B, but the configured value is 2T2R_RIGHT. The correct value is 2T2R_LEFT.

− The antennas are connected to channels C and D, but the configured value is 2T2R_LEFT. The correct value is 2T2R_RIGHT.

− The configured value is 4T4R, but channels AB or CD are not connected to antennas. You must modify the channels that are not installed with antennas.

Figure 2-1 Mapping between RRU channels and antennas

[Cause Analysis]

The configured channels are not connected to antennas. The VSWR alarm is detected during the RRU power-on. When the RRU is being activated, the service VSWR alarm is reported, and the sector resources are not available.

[Suggestion]1. Run the MOD CARRIERBASICINFO command to modify the antenna state.

2. After the RRU is powered off and then powered on, check whether the alarm is reported again.

2.3 Some Carriers Cannot Be Activated Due to Incorrect Multi-Carrier Settings in the Same Sector

[Fault Phenomenon]

After the BS is configured with multiple carriers, the carriers on the same RRU cannot be activated at the same time. After a carrier is activated, if you activate the other carriers, the system prompts activation failure. Query the state of the carriers. The resource state is available, but the operation state is unavailable.

[Related Alarm]

None.



[Cause Analysis]

When multiple carriers are configured, the following requirements must be met:

The bandwidths of the carriers must be the same.

The frequency difference supported by each carrier cannot exceed 30 MHz.

The actual connection of the optical cable must be consistent with the carrier settings.

[Troubleshooting Method]1. Run the LST RRU command to query the optical port settings.

2. Check the optical cable connection of the RRU. Check whether the BS settings are consistent with the actual connection of the optical cable.

3. Run the LST CARRIERBASICINFO command to query all carriers in the same sector.

4. Make sure that the bandwidths of the carriers are the same, and the central frequency difference between the carriers is within the normal range.

Bandwidth Central Frequency

10 M ≤20 MHz

7 M ≤23 MHz

5 M ≤25 MHz

[Suggestion]

Modify the related carrier parameters to meet the requirements of multi-carrier settings.

2.4 Service VSWR Alarm Reported by the RRU Channel

[Fault Phenomenon]

The RRU TX channel is closed. Some of the RRU channels report the VSWR alarm. After the RRU is reset and powered off, the VSWR alarm persists.



For example, the following figure shows that channel A has a high-precision VSWR alarm, and channels B, C, and D are normal. In the following figure, the red line means that the alarm exists, and the green line means that no alarm exists.

[Related Alarm]

ALM-34026 Standing Wave Existence During RRU Power-On (maybe not exist)

ALM-34101 RRU Standing Wave Existence (reported during the activation)

[Cause Analysis] The engineering installation quality of the antenna system is poor. The antenna VSWR is

high.

The antenna is not properly connected to the RRU. The connector is loose.

The connectors of the RRU and antenna are damaged, for example, metal filings are created due to internal scrapping.

The antenna system is broken, damaged, or wet.

The RRU is bumped by external force during the transportation or installation. Therefore, the antenna port or filter is damaged or deformed.

[Troubleshooting Method]

The troubleshooting is as follows:

1. Check the configuration. For more information, see section 2.2 "RRU Activation FailureDue to Incorrect Settings of Carrier Antenna State." If the configuration is correct, the problem is related to the engineering installation or the RRU itself. Go to step 2.

2. Locate the problem according to the following procedure:



Step 1 Query the power-on VSWR on the M2000 or local Web LMT.

Test Result Cause Analysis

Suggestion

< 2.5 Error alarm Collect the RRULog. Contact Huawei TAC for analysis and support.

≥ 2.5 To be confirmed Go to Step 2.

Test Requirement

Save the test results.

Step 2 Power off the RRU and check the RRU antenna connector.


Suggestion

The connector is loose.

The connector is improperly connected.

Fasten the connector and perform the power-on test. If the fault persists, go to Step 3.

The connector is not loose.

To be confirmed Go to Step 3.

Step 3 Power off the RRU and check whether the RRU antenna port and the antenna connector are abnormal.




Suggestion

There are metal filings.

The engineering installation is not standardized or the problem is caused by external force.

Clear the metal filings and perform the power-on test. If the fault persists, go to Step 4.

The inner core is twisted.

Correct the inner core and perform the power-on test. If the fault persists, go to Step 4.

The antenna port is generally deformed.

The problem is not solved after the power-on test.

Collect the RRULog. Contact Huawei TAC for support.

There is no exception.

To be confirmed Go to Step 4.

Step 4 Power off the RRU and use the Site Master to test the antenna VSWR. If the test instrument is not available, go to Step 5.


Suggestion

≥ 1.5 The antenna VSWR is high.

Collect the RRULog. Contact Huawei TAC for analysis and support.

< 1.5 To be confirmed Go to Step 5.

Test Requirement

Save the VSWR values and screen snapshots of the Site Master.

Step 5 Reconnect the RRU antenna port and the antenna, power on the RRU, and then check whether the alarm is cleared.


Suggestion

The alarm is cleared. The antenna or connection is abnormal.

The operation is completed.

The alarm is not cleared.

The RRU may be faulty.

Go to Step 6.



Step 6 Perform the comparison test.

Swap the antennas on channels A and B.

Power on the RRU again. Check the test result after swapping the antennas. There are four scenarios as follows:

In the following figure, the red line means that the alarm exists, and the green line means that no alarm exists.

(a) (b)

(c) (d)



Test Result

Channel A

Channel B

Cause Analysis Suggestion

a The alarm is cleared.

No alarm is generated.

The connection between channel A and antenna a is abnormal.

Reconnect the cables carefully.

b The alarm is cleared.

The alarm is generated.

Antenna a is abnormal. Check antenna

c The alarm is generated.

No alarm is generated.

Channel A of the RRU is abnormal.

Contact Huawei TAC for support.d The alarm is

generated.The alarm is generated.

Channel A and antenna a of the RRU are abnormal.

2.5 Service VSWR Alarm Reported by the Four RRU Channels

[Fault Phenomenon]

The carrier resources and RF resources are unavailable. The four RRU channels report the VSWR alarm. The RRU TX channel is closed. After the RRU is reset and powered off, the VSWR alarm persists.

As shown in the following figure, channels A, B, C, and D report the VSWR alarm. The red line means that the alarm exists.

[Related Alarm]

ALM-34026 Standing Wave Existence During RRU Power-On (maybe not exist)

ALM-34101 RRU Standing Wave Existence

[Cause Analysis] The installation quality of the four antenna systems is poor.

The RRU is bumped by external force during the transportation or installation. Therefore, the two filters are damaged.



The RRU is faulty.

[Troubleshooting Method]1. Check the configuration. For more information, see section 2.2 "RRU Activation Failure

Due to Incorrect Settings of Carrier Antenna State." If the configuration is correct, go to the next step.

2. Comparison test: Swap the antennas of RRU1 (on which the four channels are all normal) and RRU0 (which is faulty), as shown in the following figure.

3. Power on RRU0 and RRU1, and observe the test result.

Test Result

RRU0 RRU1 Suggestion

a The alarms on the four channels are cleared.

The alarm is not generated on the four channels.

Reconnect the cables carefully.

b The alarm is generated on the four channels.

The alarm is not generated on the four channels.

Contact Huawei TAC for support.

c Other cases. For more information about the troubleshooting, see section 2.4 "Service VSWR Alarm Reported by the RRU Channel."

2.6 Power-on VSWR Alarm Reported by the Four RRU Channels Without Service VSWR Alarm

[Fault Phenomenon]

The four RRU channels report the power-on VSWR alarm. The service VSWR alarm, however, is not reported. The RRU is working normally.



[Related Alarm]


[Cause Analysis] If the RRU is connected with an external narrowband filter, the fault is caused by the

restriction of the RRU3702 specifications. When the entire frequency band of the RRU filter is being scanned (at least 80 MHz frequency band is scanned), the connected external filter causes high VSWR values of the filtered frequency band. Therefore, the VSWR alarm is reported during the power-on. For the service VSWR, however, only the configured frequency band of the carrier is checked. Therefore, no service VSWR alarm is reported. The restriction of the RRU specifications is removed in the V3R2C03 and V3R3.

The RRU production or delivery problems exist.

[Troubleshooting Method]1. Check whether an external narrowband filter (Duplexer) is installed between the RRU

and the antenna. If no external duplexer is installed, go to the next step.

2. Run the DSP ELABLE (for V3R2 version) or DSP BRDMFRINFO (for V3R3 version) command. Enter the correct subrack number. Send the RRU electronic label to the R&D engineers for checking whether the RRU production or delivery problems exist.

2.7 Bit Errors Occur on Services Due to Poor Contact of Optical Cable and Optical Module or Damage of Optical Cable

[Fault Phenomenon]

The uplink and downlink services have bit errors, and the service provision is fluctuating. If the problem becomes worse, the RRU resources are unavailable.



[Related Alarm]

ALM-10077 CPRI Link Disconnection

One of the following three alarms may occur:

ALM-34143 RRU Running Exception (Specific Problem=RRU optical port Serdes abnormal)

ALM-34148 RRU Clock Exception

ALM-34231 RRU High-Speed Transceiver Receiving Faulty

[Cause Analysis]

The optical cable is not properly connected to the optical module, or the optical cable interface is polluted externally, or the optical cable is damaged. Therefore, the attenuation of the optical cable is great, and the optical strength reaching the RX optical module is weak. Because the optical strength decreases, the bit errors may occur when the optical module performs decoding. The BS clock signal extracted from the optical channel may be unstable. Therefore, the RRU reports the alarm.

[Troubleshooting Method]1. Check whether the ALM-34143, ALM-34148, and ALM-34231 alarms are reported.

2. Run the DSP OPTIINFO command to query the BBI optical port information.

Query result:

Optical Port

Power AlmThreshold

TX RX TxHigh TxLow RxHigh RxLow

0, 1, 2 Variable value

Variable value

Fixed value

Fixed value

Fixed value

Fixed value

For different models of optical modules, the alarm thresholds of the four indexes (TxHigh, TxLow, RxHigh, and RxLow) are different. Compare the TX power, RX power, and alarm threshold, and check whether the values are reaching the thresholds.

3. Run the GET OPTICALPORTINFO command to query the RRU optical port information, and then observe the value of INPUTPOWER.

The following table lists the RX alarm thresholds of the optical module.

Alarm INPUTPOWER AlmThreshold (μW)

Finisar

FTLF8524P2BNL

AVAGO AFBR-57R5APZ



RX optical power serious insufficiency alarm

10 1

RX optical power insufficiency alarm 16 49

For the Finisar FTLF8524P2BNL model, when the RX power is lower than 30 μW, the uplink bit error probability increases.

For the AVAGO AFBR-57R5APZ model, when the RX power is lower than 80 μW, the uplink bit error probability increases.

[Suggestion]1. Reinsert the optical modules on the BBI and RRU tightly. If the alarm is not cleared, go

to the next step.

2. Use alcohol to clean the optical cable connectors on the BBI and RRU. Reconnect the optical cable and optical module. If the alarm is not cleared, go to the next step.

3. Replace the optical modules on the BBI and RRU. If the alarm is not cleared, go to the next step.

4. Contact Huawei TAC for support. After Huawei engineers analyze the problem, decide whether to replace the optical cable.

2.8 RRU Resources Unavailable Due to One-Way Audio of the Optical Cable

[Fault Phenomenon]

The CPRI link is interrupted, and the RRU resources are unavailable.

[Related Alarm]


ALM-10081 BBU CPRI Optical Port Performance Degraded

or


ALM-34122 RRU Optical Module Receiving Performance Deteriorated

[Cause Analysis]

The optical cable between the BBI and RRU has the problem of one-way audio. Therefore, the CPRI link cannot perform the link negotiation. The BBU reports the CPRI link interruption alarm.



[Troubleshooting Method]1. Run the DSP OPTIINFO command (for C03 version) to query the BBI optical port

information. Check whether the optical module has RX power and TX power.

2. Run the GET OPTICALPORTINFO command to query the RRU optical port information. Check whether the optical module has RX power and TX power.

3. If the query results of the preceding two steps comply with the following table, you can infer that the optical cable has one-way audio.

BBI RRU Cause Analysis

TXPOWER

RXPOWER

OUTPUTPOWER

INPUTPOWER

Available Unavailable Available Available The RRU TX optical cable and the BBI RX optical cable have one-way audio.

Available Available Available Unavailable The RRU RX optical cable and the BBI TX optical cable have one-way audio.

[Suggestion]

Replace the optical cables.

2.9 RRU Resources Unavailable Due to Reverse Connection of the RRU Optical Cable

[Fault Phenomenon] Before C03 version: The sector resources are unavailable. The BS reports the RRU input

power abnormal alarm.

In C03 version: The BBU CPRI Optical Interface Fault alarm is reported. The system automatically deactivates the sector.

[Related Alarm] Before C03 version

ALM-10001 Unavailable Carrier Resource

ALM-34011 RRU Input Power Exception

ALM-34110 RRU Optical Module Not in Position (may be reported)

ALM-10080 BBU CPRI Optical Module Not in Position (may be reported)

In C03 version

ALM-10004 BBU CPRI Optical Interface Fault



Specific Problem=Improper CPRI Port Connection

[Cause Analysis] Before C03 version: The optical cable is connected to the CPRI1 optical port of the

RRU. During the activation, there is no data transmission over the configured optical cable, and the input digit domain power is low. Therefore, the carrier is deactivated, and the carrier resources are unavailable.

In C03 version: The BS automatically checks whether the positions of the optical cable and optical port are consistent with the configuration. If the optical cable is reversely connected, the preceding alarms are reported, and the sector is automatically deactivated.


Before C03 version:

Run the LST RRU command, and check the RRU optical port settings. If one optical port is configured, go to step 2. If two optical ports are configured, go to step 3.

If the RRU is connected with one optical cable, run the GET OPTICALPORTINFO command to query the RRU optical port information. Check INPOSITIONSTATUS and IPUTPOWER.

CPRI0 CPRI1 Cause Analysis

INPOSITION NOT INPOSITION Normal

NOT INPOSITION INPOSITION The optical cable is reversely connected.

When the optical cable is reversely connected, the CPRI0 has no RX power, but the CPRI1 has RX power.

If the RRU is connected with two optical cables, the fault cannot be located by checking whether the optical module is in position. You need to deactivate the carriers one by one until only one carrier remains. Check whether the RRU repeatedly deactivates the carrier. If no alarm is generated, you can infer that the optical cable is connected correctly.

[Suggestion] If the RRU is configured with one optical port, correct the optical port on the local side.

The following figure shows the correct position of the CPRI0.



If the RRU is configured with two optical ports, you can correct the optical ports on the local side or modify the BS settings (to back up the settings, modify the backup settings, and upload the new settings). The solution is determined based on the actual on-site conditions.

2.10 Sector Resources Unavailable Due to Optical Module Fault

[Fault Phenomenon]

The sector resources are unavailable.

[Related Alarm]


ALM-34110 RRU Optical Module Not in Position

or


ALM-10080 BBU CPRI Optical Module Not in Position (may occur)

ALM-10081 BBU CPRI Optical Port Performance Degraded (may occur)

ALM-10082 BBU CPRI Optical Module Fault (may occur)

[Cause Analysis] The RRU optical module is damaged or not in position.

The BBU optical module is damaged or not in position.

[Troubleshooting Method]1. Check whether the RRU optical module is in position. If the optical module is not in

position, connect the optical module properly. If the alarm is not cleared, go to step 2.



2. If the RRU optical module is in position, reinsert the RRU optical module. If the alarm is not cleared, replace the RRU optical module.

3. If the RRU optical port and optical module are normal, check the BBI optical port and optical module.

[Suggestion]

If the optical module is damaged, replace it.

2.11 AD9549 Incompatible with V32C02SPC220 and Earlier Versions

[Fault Phenomenon]

The sector resources are unavailable. The CPRI link interruption alarm is periodically reported. The RRU self-test is abnormal, the RRU operation is abnormal, and the RRU clock abnormal alarm persists.

[Related Alarm]

ALM-10077 CPRI Link Disconnection (periodicity reports)

ALM-34142 RRU Self-Test Exception

ALM-34143 RRU Running Exception

ALM-34148 RRU Clock Exception

[Cause Analysis]

The new AD9549s are incompatible with V300R002C02SPC220 and earlier versions.

[Troubleshooting Method]1. Run the DSP ELABLE command to query the RRU information. Run the DSP

BRDVER command to query the BS version. Pre-warning must be given if the following conditions are met:

Manufactured Date of RRU Current Software Version of BS

After 2010-02 V300R002C02SPC220 and earlier versions

2. Query the BS alarms. Make sure that the following alarms exist: ALM-10077, ALM-34142, ALM-34143, and ALM-34148.

[Suggestion]

Perform troubleshooting according to the pre-warning notice Warning [2010 001] on CPRI Link Faults Due to the Changing of Chips Used by Some RRUs of the DBS3900 WiMAX (which can be obtained from http://support.huawei.com).



2.12 RRU PA Overcurrent Alarm Due to Intermittent Disconnection of the CPRI Link

[Fault Phenomenon]

The BS reports the RRU overcurrent alarm. The RRU resources are unavailable. Before the overcurrent alarm is reported, the CPRI link disconnection occurs.

[Related Alarm]

ALM-34005 RRU Power Amplifier Overcurrent


[Cause Analysis]

The CPRI link is intermittently disconnected, which causes incorrect measurement of digit domain power on the RRU. Therefore, the TX power is too high, and the PA has transient overcurrent.

[Troubleshooting Method]1. Run the LST ALMLOG command to query the BS alarm. Observe whether the ALM-

10077 is reported before the overcurrent alarm ALM-34005 is generated, and whether the ALM-10077 is quickly cleared.

If yes, you can infer that CPRI intermittent disconnection causes the overcurrent. You need to check whether the optical cable and optical module are normal.

If the CPRI alarm is not reported, got to step 2.

2. Run the DSP ELABLE command to query the RRU ESN. Collect the RRULOG and contact the GTAC personnel to analyze the log.

3. Reset the RRU. If the alarm is not cleared, go to step 4.

4. Run the RST BRDPWROFF command to power off the RRU. If the alarm is not cleared, replace the RRU.

[Suggestion]

Check the optical cable and optical module.



3 Troubleshooting the RTWP

Interference Problems

3.1 Great Differences Between RXRTWP and Single-Carrier RTWP Due to Adjacent Channel Interference

[Fault Phenomenon]

When there is no subscriber in the sector, the execution result of the DSP RRURADIOPARA command shows that the difference between the RXRTWP and RTWP of a channel is too great.

Carrier Bandwidth RXRTWP-RTWP

10 MHz > 5dB

7 MHz > 6.5dB

5 MHz > 8dB

Check whether the other RF indexes of the RRU are within the normal range. The display positions of the RXRTWP and RTWP are shown in the following figure.

Impact: The uplink service may have bit errors. If the problem becomes worse, the terminals cannot access the network.



[Related Alarm]

None.

[Cause Analysis]

The RXRTWP is the RX signal strength measured in the entire 30 MHz frequency band of the RRU channel. The RTWP is the RX signal strength measured in the carrier (10 MHz, 7 MHz, and 5 MHz) bandwidth.

When the antenna receives the interference signal of the adjacent channel, the TX signal strength measured in the entire 30 MHz bandwidth increases. Therefore, the difference between the RXRTWP and the RTWP is too great.


Run the DSP RRURADIOPARA command to calculate the difference between the RXRTWP and the RTWP.

[Suggestion]

For the signal carrier, the adjacent channel interference is out-band interference. When the interference signal is weak, the service is not affected. When the interference signal is strong, however, the uplink service is affected and bit error occurs. Therefore, the interference source must be removed.

3.2 Difference of RTWP Values Between RRU Channels Exceeding 10 dB

[Fault Phenomenon]

Run the GET RRURTWP, DSP RRURADIOPARA, or carrier tracing command to query the RTWP value of the carrier. The result shows that the difference between the RTWP values of different channels exceeds 10 dB. The terminal may fail to access the network, or the uplink service may have a large amount of bit errors.

RRU RTWP

--------

RXIDDEX SECTORID CARRIERID RTWP(0.1dBm)

0 0 0 -905

1 0 0 -1004

2 0 0 -1008

3 0 0 -1005

(Number of results = 4)

[Related Alarm]

None.

[Cause Analysis] The channel VSWR is high.



The RRU RX channel is abnormal.

The RRU TX channel signal leaks to the RX channel.


When there is no subscriber, you can perform the following operations:

1. Check whether the VSWR of the channel is higher than that of other channels, and whether the VSWR alarm is reported. If the VSWR alarm is reported, see section 2.4 "Service VSWR Alarm Reported by the RRU Channel" and check the antenna installation quality to clear the VSWR alarm. If the VSWR is normal, go to the next step.

2. Close the TX channel of channel 0. Observe whether the RTWP of channel 0 is recovered.

SET TXLOGICSWITCH: RACKNO=0, SUBRACKNO=23, BOARDNO=0, TXNO=0, SWITCH=OFF;

If the RTWP of channel 0 is recovered, you can infer that the TX channel signal of channel 0 leaks to the RX channel. If the RTWP of channel 0 is not recovered, go to the next step.

3. Close the TX channels of other channels one by one. Observe whether the RTWP of channel 0 is recovered. If the RTWP of channel 0 is recovered, you can infer that the signal of a certain TX channel leaks to the RX channel of channel 0. If the RTWP of channel 0 is not recovered, you can infer that the problem is not related to the TX channel, and channel 0 is faulty.

4. Deactivate and activate the RRU. Check whether the RTWP is recovered. If the RTWP is not recovered, record the RRU ESN.

[Suggestion]

Collect the RRULOG and contact Huawei GTAC personnel to handle the problem.



4 Knowledge Points

4.1 VSWR Check

4.1.1 VSWR During Power-On Alarm mechanism: Scan the entire frequency band of the RRU filter. During the RRU

power-on or when the main control board runs a command to detect the VSWR, if the detected VSWR value exceeds the configured threshold 2.5, the alarm is reported, but the RRU channel state is not changed. The RRU reports the alarm when the VSWR exceeds 2.5 no matter the antenna port is connected to the load or antenna.

Prerequisite: The RRU is functional. The RRU model supports the detection function. The OM transmission link of the BS is normal. The RRU3701 does not support the VSWR detection function during power-on.

Test method:

1. Run the STR VSWRTEST command on the Web LMT to perform the test. The command is a hidden command supported by C03 and later versions.

2. Perform the query on the M2000. This operation automatically deactivates the RRU. When the test is completed, the RRU is automatically activated. Therefore, the service is interrupted for three to five minutes in normal cases.



Detection precision: 1.4 ± 0.2. It can replace the Site Manager to determine the actual VSWR of the antenna.

4.1.2 Service VSWR Alarm mechanism: Scan the frequency band (5 MHz, 7 MHz, and 10 MHz) actually

configured on the RRU. The detection period is 0.5s.

The alarm is reported if the VSWR value is greater than or equal to 3.44 (for broadband filter)/4.43 (for narrowband filter) consecutively for 10 times. The system closes the TX channel and deactivates the RRU alarm.

Prerequisite: The RRU is activated, the TX channel is available, and the set-top port has TX power. For the RRU3701, the modules with some frequency bands cannot check the service VSWR.

Query method: Run the GET RRUVSWR command or use the dynamic carrier tracing.

Detection precision: The lower threshold of the alarm is set to 1.4, that is, the alarm is not reported when the antenna system VSWR is less than 1.4. The upper threshold of the alarm is not less than 1.8. You can determine whether the antenna is normal based on the service VSWR alarm. The service VSWR test result cannot be regarded as the actual VSWR value of the antenna.


wi max rru3702 troubleshooting guide v1.0-20100609-a

Documents

rru channels

rru alarms

rru state check

rru resources unavailable

rru rf indexes

rru activation failure

service vswr alarm

carrier settings