RRU3702 WiMAX Troubleshooting Guide

WiMAX RRU3702 Troubleshooting Guide INTERNAL
Product Name Internal Level
WiMAX DBS3900 Public
Product Version Total 34 pages
V300R002
WiMAX RRU3702 Troubleshooting Guide
Prepared by Xu Jianjun, Wang Xiaolun Da
te
2010-04-29
Reviewed by Da
te
Reviewed by Da
te
Approved by Da
te

RRU3702 WiMAX Troubleshooting Guide INTERNAL
Huawei Technologies Co., Ltd.
All rights reserved.

Revision History
Date Revision Version Description Author
2010-05-24 Draft is completed Xu Jianjun,
Wang Xiaolun
2015-6-25 Huawei Technologies Proprietary Page 3 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...........................................................................................................................6
1.1 Basic Check Items of the RRU................................................................................................................................6
1.2 Query Methods of Check Items...............................................................................................................................7
1.2.1 Checking the Alarms.........................................................................................................................................7
1.2.2 Checking Whether the RRU Alarms Are Shielded or Manually Deleted..........................................................9
1.2.3 Checking Whether the RRU RF Indexes Are Within Normal Range..............................................................10
2 Troubleshooting the Engineering Installation Problems...................................................12
2.1 Central Frequency Settings of the Carrier Exceeding the Frequency Range Supported by the RRU...................12
2.2 RRU Activation Failure Due to Incorrect Settings of Carrier Antenna State........................................................13
2.3 Some Carriers Cannot Be Activated Due to Incorrect Multi-Carrier Settings in the Same Sector.......................14
2.4 Service VSWR Alarm Reported by the RRU Channel..........................................................................................15
2.5 Service VSWR Alarm Reported by the Four RRU Channels................................................................................20
2.6 Power-on VSWR Alarm Reported by the Four RRU Channels Without Service VSWR Alarm..........................21
2.7 Bit Errors Occur on Services Due to Poor Contact of Optical Cable and Optical Module or Damage of Optical
Cable.............................................................................................................................................................................22
2.8 RRU Resources Unavailable Due to One-Way Audio of the Optical Cable.........................................................24
2.9 RRU Resources Unavailable Due to Reverse Connection of the RRU Optical Cable..........................................25
2.10 Sector Resources Unavailable Due to Optical Module Fault..............................................................................27
2.11 AD9549 Incompatible with V32C02SPC220 and Earlier Versions.....................................................................27
2.12 RRU PA Overcurrent Alarm Due to Intermittent Disconnection of the CPRI Link............................................28
3 Troubleshooting the RTWP Interference Problems............................................................30
3.1 Great Differences Between RXRTWP and Single-Carrier RTWP Due to Adjacent Channel Interference..........30
3.2 Difference of RTWP Values Between RRU Channels Exceeding 10 dB..............................................................31
4 Knowledge Points......................................................................................................................33
4.1 VSWR Check.........................................................................................................................................................33
4.1.1 VSWR During Power-On................................................................................................................................33
4.1.2 Service VSWR.................................................................................................................................................34

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
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
RTWP Interference Problems.
"
1.2 Query Methods of Check Items
1.2.1 Checking the Alarms
Log 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
and support.
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
and support.

Alarm ID Alarm Troubleshooting
ALM-34142 RRU Self-Test Exception See Chapter 2"Troubleshooting the
ALM-34143 RRU Running Exception See Chapter 2"Troubleshooting the
ALM-34148 RRU Clock Exception See Chapter 2"Troubleshooting the
ALM-34221 RRU Power Surge Protection
Exception
and support.
ALM-34230 ALD Maintenance Link
Exception
and support.
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]
3. 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
4. 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-34026 Standing Wave Existence During RRU Power-On
ALM-34101 RRU Standing Wave Existence (reported during the activation)
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 3.1 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]
4. Run the MOD CARRIERBASICINFO command to modify the antenna state.
5. 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.
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.
The troubleshooting is as follows:
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, 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.
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.
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-
The inner core is
twisted.
Correct the inner core and perform the power-
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.

≥ 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.
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.
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]
ALM-34026 Standing Wave Existence During RRU Power-On
[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.
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.
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]
4. Reinsert the optical modules on the BBI and RRU tightly. If the alarm is not cleared, go
to the next step.
5. 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.
6. Replace the optical modules on the BBI and RRU. If the alarm is not cleared, go to the
next step.
7. 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.
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 RXPOWE
R
OUTPUTPOWER INPUTPOWE
R
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.
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.
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.

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.

RRU3702 WiMAX Troubleshooting Guide

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