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Issue Draft A (2012-11-30)Huawei Proprietary and Confidential
DBS3900
RRU3252/RRU3256 Hardware Maintenance GuideAbout This Document
About This Document
Purpose
This document describes routine maintenance procedures for an RRU3252/RRU3256 (referred
to as RRU in this document), such as equipment preventive maintenance and power-on and
power-off operations. It also describes how to replace the RRU and optical modules.
Product Version
The following table lists the product version related to this document.
Product Name
DBS3900 LTE TDDV100R005C00 and later versions
Intended Audience
This document is intended for:
lSystem engineers
lSite maintenance engineers
Organization
1 Change History
Product Version
This chapter describes changes in the RRU3252/RRU3256 Hardware Maintenance Guide.
2 Preventive Maintenance Items for an RRU
Preventive maintenance for an RRU improves RRU reliability. You are advised to perform
scheduled maintenance yearly.
3 Powering On and Powering Off an RRU
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RRU3252/RRU3256 Hardware Maintenance GuideAbout This Document
After an RRU is powered on, the RRU indicator status and voltage must be checked. Before an
RRU is powered off, you must decide whether to power off the RRU in a normal situation or an
emergency based on onsite requirements.
4 Replacing an RRU
A distributed base station consists of RRUs and a BBU. Replacing an RRU interrupts all the
services carried by the RRU, and alarms are generated.
5 Replacing an Optical Module
An optical module provides optical-electrical conversion ports, enabling optical transmission
between an RRU and other devices. Optical cables inserted into an optical module must be
removed before the optical module is replaced. Replacing an optical module interrupts CPRI
signal transmission.
Conventions
Symbol Conventions
The symbols that may be found in this document are defined as follows.
SymbolDescription
Indicates a hazard with a high level of risk, which if not
avoided, will result in death or serious injury.
Indicates a hazard with a medium or low level of risk, which
if not avoided, could result in minor or moderate injury.
Indicates a potentially hazardous situation, which if not
avoided, could result in equipment damage, data loss,
performance degradation, or unexpected results.
Indicates a tip that may help you solve a problem or save
time.
Provides additional information to emphasize or supplement
important points of the main text.
General Conventions
The general conventions that may be found in this document are defined as follows.
Convention
Times New RomanNormal paragraphs are in Times New Roman.
BoldfaceNames of files, directories, folders, and users are in
ItalicBook titles are in italics.
Issue Draft A (2012-11-30)Huawei Proprietary and Confidential
2 Preventive Maintenance Items for an RRU..............................................................................2
3 Powering On and Powering Off an RRU..................................................................................4
3.1 Powering On an RRU.........................................................................................................................................5
3.2 Powering Off an RRU........................................................................................................................................6
4 Replacing an RRU.........................................................................................................................7
5 Replacing an Optical Module...................................................................................................10
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RRU3252/RRU3256 Hardware Maintenance Guide2 Preventive Maintenance Items for an RRU
2 Preventive Maintenance Items for an RRU
Preventive maintenance for an RRU improves RRU reliability. You are advised to perform
scheduled maintenance yearly.
DANGER
While working at a high place, be careful not to drop any objects. Falling objects may cause
serious injury or death. All maintenance personnel must wear a helmet and avoid standing in
areas with a danger.
The items listed in the following table are not mandatory but strongly recommended. Table
2-1 lists the preventive maintenance items for an RRU.
Table 2-1 Preventive maintenance items for an RRU
SN
Checklist
1All RRUs are properly installed and in good conditions.
2Cables at the cable inlet of a cabinet are sealed properly.
3All RF cables are intact and free from any cracks, cuts, or other damage.
4All RF cable connectors are sealed properly.
5All RF cable conduits are in good conditions.
6All power cables are intact and free from any cracks, cuts, or other damage.
7All power cable connectors are in good conditions.
8All power cable conduits are in good conditions.
9All shield layers of power cables are in good conditions.
10All power cables are sealed properly.
11All CPRI fiber optic cables are intact and free from any cracks, cuts, or other damage.
12All screws are tightened on the cover plate of the maintenance cavity.
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RRU3252/RRU3256 Hardware Maintenance Guide2 Preventive Maintenance Items for an RRU
SNChecklist
13All optional RET cables are intact and free from any cracks, cuts, or other damage.
14Connectors of all optional RET cables are sealed properly.
15All optional alarm cables are securely installed and free from any damage.
If any of the statements in the checklist cannot be complied with, perform the following
corrective actions:
1.Tighten all connections.
2.Report any other faults found when filling in the checklist to the supervisor, because only
qualified or trained field engineers are permitted to climb towers for further repairs.
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RRU3252/RRU3256 Hardware Maintenance Guide3 Powering On and Powering Off an RRU
3 Powering On and Powering Off an RRU
About This Chapter
After an RRU is powered on, the RRU indicator status and voltage must be checked. Before an
RRU is powered off, you must decide whether to power off the RRU in a normal situation or an
emergency based on onsite requirements.
3.1 Powering On an RRU
Set the corresponding circuit breaker on the auxiliary power device for the RRU to ON, and
check the operating status of the RRU by observing the status of RRU indicators.
3.2 Powering Off an RRU
You can power off an RRU either in a normal situation or an emergency. A normal situation
refers to the cases such as equipment reparenting or anticipated interruption of regional mains
supply. An emergency refers to the cases such as a fire, smoke, and water damage at the site.
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RRU3252/RRU3256 Hardware Maintenance Guide3 Powering On and Powering Off an RRU
3.1 Powering On an RRU
Set the corresponding circuit breaker on the auxiliary power device for the RRU to ON, and
check the operating status of the RRU by observing the status of RRU indicators.
Prerequisites
lThe RRU hardware is installed and RRU cable connections are secure.
lThe input voltage of the RRU ranges from -32 V DC to -60 V DC.
Context
CAUTION
After you unpack an RRU, you must power on it within 24 hours. If you power off the RRU for
maintenance, you must restore power to the RRU within 24 hours.
Procedure
Step 1 Set the corresponding circuit breaker on the auxiliary power device for the RRU to ON to power
Step 2 Keep the RRU running for three to five minutes to check the status of RRU indicators. For
Step 3 Take corresponding actions based on the status of the indicators.
on the RRU.
DANGER
Do not look into the optical module without eye protection after the RRU is powered on.
details, see RRU Indicators.
NOTE
If RRUs are cascaded, check the status of all RRU indicators.
If...
The RRU is working properlyEnd the power-on check task.
The RRU is faultySet the circuit breaker to OFF. Rectify the
Then...
fault, and then go to Step 1.
----End
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RRU3252/RRU3256 Hardware Maintenance Guide3 Powering On and Powering Off an RRU
3.2 Powering Off an RRU
You can power off an RRU either in a normal situation or an emergency. A normal situation
refers to the cases such as equipment reparenting or anticipated interruption of regional mains
supply. An emergency refers to the cases such as a fire, smoke, and water damage at the site.
Procedure
lPower-off in a normal situation
Set the corresponding circuit breaker on the auxiliary power device for the RRU to OFF.
lPower-off in an emergency
CAUTION
Power-off in an emergency may damage the RRU, and do not use it in normal situations.
1.Power off the auxiliary power device for the RRU.
2.If time permits, set the corresponding circuit breaker on the auxiliary power device
for the RRU to OFF.
----End
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RRU3252/RRU3256 Hardware Maintenance Guide4 Replacing an RRU
Step 6 Disconnect cables from the cabling cavity and the bottom of the RRU.
Step 7 Use an M4 Phillips screwdriver to loosen the captive screws on the two hoist clamps on the main
mounting bracket, as shown in Figure 4-1.
NOTE
In scenarios where RRUs are installed in centralized mode, the RRU in the middle can be removed without
removing the two RRUs on its right and left sides, in the same procedure as that for removing a single RRU.
Figure 4-1 Loosening the screws on the main mounting bracket
Step 8 Hold the RRU and move it upwards to remove it, as shown in Figure 4-2.
Figure 4-2 Removing an RRU
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RRU3252/RRU3256 Hardware Maintenance Guide5 Replacing an Optical Module
5 Replacing an Optical Module
An optical module provides optical-electrical conversion ports, enabling optical transmission
between an RRU and other devices. Optical cables inserted into an optical module must be
removed before the optical module is replaced. Replacing an optical module interrupts CPRI
signal transmission.
Prerequisites
Context
Procedure
Step 1 Wear ESD gloves.
lNew optical modules are sufficient and the type of them is the same as that of the faulty
ones based on the labels on optical modules.
lThe following tools and materials are available: M4 Phillips screwdriver, ESD gloves, and
ESD box or bag.
lOptical modules are hot-swappable when the same CPRI port is used.
lIt takes about 5 minutes to replace an optical module on the RRU, which involves removing
fiber optic cables and a faulty optical module, installing a new optical module and the fiber
optic cable, and waiting for CPRI links to recover.
CAUTION
Take proper ESD protection measures, for example, wear ESD gloves, to prevent electrostatic
damage to the boards, modules, or electronic components.
Step 2 Use an M4 Phillips screwdriver to loosen the protection screw on the cover plate of the RRU
cabling cavity and then pull the handle outwards to open the cover plate.
Step 3 Record the connections of the optical module and fiber optic cables.
Step 4 Press the latch on the connector of the fiber optic cable, and then remove the connector from the
faulty optical module.
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