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HUAWEI 3G (Node B) SITE MAINTANANCE

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ACKNOWLEDGEMENT

I would like to thank the Almighty God for enabling me finishing my training period safely.

I would like to send my appreciation to the TECH-MASTERS Telecom and Electrical

Engineering Company for accepting me to be one of their trainees.

A text such as this would not be possible without the help and support from workers at the

company for their generous help. I would like to thank Mr. Ambrose Raymond, Mgena Mhina,

Mr. Abdallah from Huawei TZ, all Airtel Engineers who came across my way, and all other TM

workers for their help and assistance to me whenever I encountered a problem during my PT.

I want to thank my mother Ms. Editha Kikoba, my father Mr. Ramadhan Kikoba, and all my

family members who supported me from the beginning of my studies financially and morally

until now. Also I would like to thank my fiance Madam Annastazia Angello for her

encouragement to me during my hard difficult work.

Thank you all.

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1 INTRODUCTION 3G is the short term which represents the word “Third Generation”. It’s aGSM

technology which was designed purposely to beat the CDMA (anti-GSM) technology which was

found to work accurately with a very minimal cost as compared to GSM technology. In contrast

to normal GSM technology (2G), 3G sites works mainly on 1800MHz frequency directional

Antenna where in 2G both 900MHz and 1800MHz directional Antenna can be used. To make

sure that GSM technology can’t be beaten by CDMA in the market, then WCDMA technology

were designed which is the one we call 3G technology of which Huawei call it Node B site.

Figure 1: Block diagram of a node B site

In this report we are going to cover a little on safety precautions,3G site installations, and

site maintenance which will be divided in two categories i.e sensitive areas in 3Gsite and

troubleshooting and clearing any possible 3G site fault. To start with let’s look on safety

precautions.

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2 SAFETY PRECAUTIONS TO BE OBSERVED IN THE Node B SITE

To make sure that you are safe in the node B site you should have the

following things:

I. Don’t climb up the tower without a safety belt

II. Don’t stay inside the site compound without a safety cap

III. Don’t do any node B work without wearing safety boots

IV. Don’t touch any node B radio without wearing the ESD wrist strap

V. If possible wear gloves to protect your hands

VI. You should believe in yourself in order to do 3G installation better

3 3G SITE INSTALLATION In this part we are going to cover a little on 3G site installation so as to make a reader

understand how to maintain the site with reference to how it was done.

3.1 Antenna and RRU assembling This is the first step to be done during 3G site installation. Procedures on how to

assemble the antenna are as follows:

I. Open the Antenna box carefully and take out the small box in it which contains antenna

Brackets

II. Open that small box and take out the brackets, attach those brackets to the antenna at

their respective points (up or bottom)

III. Connect RF jumpers at the bottom part of the Antenna and cover the connection point by

water proof tape

IV. Attach it to its pole ready for RRU connection

V. Attach the RRU bracket to the antenna pole and tight them

VI. Insert the RRU into its brackets and tight its top screw.

VII. The antenna and RRU are now ready to be lifted to the tower

VIII. Tie the assembled antenna and RRU above using strong rope passing through the pulley

IX. Lift the system above carefully and install the pole brackets to the leg of the tower

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3.2 Installing the APM30 BTS To install the APM30 BTS you must observe the following:

i. Read the design document and observe the suggested position if can handle the BTS

ii. Lay on the base and get mark of each bolt hole onto the slab

iii. Drill the holes as marked above

iv. Install the BTS base and tight it properly as shown in figure below

Fig. the BTS base

v. Install the battery cabinet onto the base and tight it

Fig. Battery cabinet installed on the base

vi. Open the screw holes and cable holes on top of the battery cabinet

vii. Install the radio cabinet on top of the battery cabinet and tight it properly

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Fig. Radio cabinet installed on top of battery cabinet

viii. Ground both battery and radio cabinets.

ix. Connect the three phase AC power cable from the circuit breaker to the radio cabinet

3.3 Installing BBU, SLPU and Rectifier After installation of APM30 BTS the BBU, SLPU and Rectifier should be also installed

into the radio cabinet. They must in there because:

BBU is the brain of node b site. It is the one which performs all telecom activities such as

Add/Drop Multiplexing, data encryption, conversion of light to electrical signal etc.

SLPU acts as the link between the RF side and MW side hence it accepts the E1 cable

from transmission DDF and exchange information with the BBU via UFLP cable.

The BTS accepts three phase AC voltage but only -48V DC is needed to power on RRU

and BBU. For that reason the rectifier is needed to convert AC power into DC power.

Procedures for those device installations are as follows:

Open the BBU box carefully and take it out

Adjust its screw to fit into cabinet and tight those screws

Open the SLPU box carefully and install it in the empty space inside the cabinet

Cut the ground cables attached inside the cabinet and ground the SLPU and BBU

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Fig. SLPU and BBU grounding point

Open the Rectifier dummy and insert in the rectifier module. Tight it properly

That is all about BBU, SLPU and Rectifier installation

3.4 OPTIC FIBER AND DC POWER CABLE INSTALLATIOS

After installation of above components the last thing is installation of fiber and dc power

cable. This is done in the following steps:

Get the actual antenna height and estimate the dc power cable length to fit the whole line

from the BTS

Cut three pieces and label them at the beginning and end points

Lift them up the tower with their top ends being clipped with lags

Align them nicely at the end and connect them to their respective sector

Lift up three fiber cables slowly and carefully

Dress them well at the top and leave a reasonable loop before connection, then terminate

it at their desired sectors

Clamp the optic fiber and RRU dc power cable nice from up the tower to downward

Dress them well inside the shelter/BTS and terminate them inside the APM30 BTS CPRI

(Optic fiber ) cable can be terminated as follows

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Turn the puller on the optical module outwards

Fig. Optical module

Insert the optical module into the CPRI port on the GTMU, WBBPb, WBBPd or

LBBP and then insert the optical module of the same type into the CPRI_W or

CPRI_E into the RRU

Fig. inserting CPRI terminals into the Optical module

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Fig. Installed CPRI’s

Label both RRU DC Power cable and CPRI cable

Fig. Labeled CPRI and Power cable

3.5 E1 testing and connection

The Airtel 3G (Huawei equipment) project was based on only RF side equipment.

Transmission side was left in hands of the existing vendors such as Motorola, Erickson and

Nokia Siemens who are the most GSM equipment provider for Airtel Tanzania. So as to ensure

proper connection between those two different equipment the E1 cable were provided. Before

installation you must do the following:

Contact the site engineer responsible for that site to drop (enable) the E1 at a

specified port

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Make a loop to those given ports so that Huawei switching room can observe the

given port as being active

If the port loop is well seen into the Huawei switching room then you can

confidently punch (clone) the E1 cable at that port using a clone tool.

Run that cable from Transmission DDF/OVP to the SLPU and terminate it

properly

Run the cable from SLPU to WMPT board onto the BBU

Connect the Fast Ethernet cable from SLPU to WMPT

Turn on the site and call the Huawei switching room engineer to confirm the site

availability

If the site is available send the WMPT code to that Huawei switching room

Engineer so that he/she can load the BBU configurations. Note: you can also load

configuration directly at the site by using LMT software

Power on the site

3.6 Installing Battery and FAN power cable

In the node B site there must be an alternative when AC power goes off.

To ensure that the site is all the time up, batteries were being provided

Their installations are done depending on the capacity of single battery.

The provided batteries were 12V each. This feature forces the installer to connect the

batteries in series so as to get the required voltage (-48V) so us to make all radios up

Procedures on how to install them are as follows:

i. Insert each battery on its given space in the battery cabinet

ii. Open their caps marked + and –

iii. Unscrew the seen screws and join the + terminal to the – terminal using the

provided bar

iv. Do the same till all batteries are well joined and cover up the terminals with the

opened cap

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Fig. series connection Battery backup

v. You can now turn on the battery switch of the APM30 BTS

That’s all about batteries, but their fan is not working

To make the battery Fan work do the following

i. Measure the length from DCDB to the Fan terminal point

ii. Cut the two cables to fit the measured length

iii. Clip the lags to one end of those cable and insert and tight them according to

polarity

iv. Run them to the DCDB and terminate them

v. Turn on the FAN using its switch. Note: the Fan should start up.

4 3G SITE MAINTANCE

4.1 SENSITIVE AREAS

From part 3.0 to 3.6 we have seen the general site installation which covered almost all

physical parts. Other parts were not discussed because either uses existing equipment or have

already being installed directly from factory. In this section we have to navigate through each

part and see how potential and delegate it is. To begin we will start from up the tower to down

inside APM30 BTS.

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4.1.1 Antenna and RF jumpers

Antennas used in node B site are directional 1800MHz antenna. Its main objective is to

link the BTS and MS at its sector (pointing direction). It receives and transmit RF signals within

1800MHz bandwidth.

These are 2.5m length coaxial cable used to join the 1800MHz antenna to RRU. They are

very potential as they are the one which first receives RF signal from the Antenna and transmit

them to the RRU for more actions. It also receive RF signal from the RRU to the directional

Antenna.

In order to ensure proper communication between the MS and BTS then the Antenna

should be okay and RF jumpers should be routed properly (polarity) and being tightened

properly otherwise there will be a lot of call drops and no network coverage will be sensed in

that sector.

Fig. Antenna and it RF jumpers being terminate to the RRU

4.1.2 RRU and its connected cables

RRU is simply the Radio Remote Unit. It is there for many purposes but mainly is for

conversion of RF signal to Light wave signal and vice versa. It receives RF signal from

the antenna through RF jumpers and convert them to Light waves so that can be

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transmitted through the optic fiber cable. It also receives Light waves from the BBU

through Optic fiber and convert it to RF and send it to the antenna transmit for MS

communication.

As seen above, the RRU accepts three types of cables, one optic fiber, one DC

Power cable (-48V) and two RF jumpers from the Antenna.

RF jumpers makes sure that the connectivity of RRU to the Antenna is there

always for MS communications.

The power cable carries -48V from the DCDB inside the APM30 BTS to make

sure that the radio (RRU) is on throughout its operation otherwise no communications

between RRU and antenna or BBU.

Optic fiber cable (CPRI) is optic cable which carries signal from/to the BBU. It

interconnects the RRU and BBU. For data exchange to be performed properly the

following conditions should be fulfilled:

The RRU and BBU should have the average power of -48V DC so as to make them run

properly therefore their power switches inside APM30 BTS should be ON otherwise fiber

alarm will be observed. To be sure of this see the LED’s onto the RRU should be lighting

The fiber should be terminated properly to their required ports. Note: The optic

module should be inserted inside its slot properly before terminating the CPRI

otherwise there will be a fiber alarm

RF jumpers should be connected properly from antenna to RRU

The fiber cable should have no short circuit i. e not damaged/broken

4.1.3 BBU

This is also the radio known as Base Band Unit which performs a lot of jobs in a node B

site. It is the central brain of the node B site as being explained in part 3.3. If this is

damaged then no communication for the whole site. To ensure network availability this

part should be on all the time

4.1.4 SLPU

As being explained in part 3.3 this is also a very important part for transmission purposes

therefore it is recommended to make it exist into the site, although its less important

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4.1.5 Rectifier

This is the converter of AC to DC. It is the very important part as most electronic devices

uses DC power other than AC. In node B site also all radios uses DC power, basically -

48V

4.1.6 Transmission DDF/OVP

This is the only transmission part in node B site. It can be newly installed (Huawei

product) or existing one (Erickson, Nokia Siemens or Motorola). If this side is not ok

then no transmission will be done at that site hence the site will be down. Make sure that

all E1 cables used in the node B site are well cloned into the DDF/OVP to make the site

up always.

4.1.7 FAN

There are two types of fan being used in node B site, one is at the top above rectifiers for

radio cooling and the other is at the battery cabinet to cool up batteries. All these fan are

very important hence they should be on always so as to ensure allowable temperature

inside the BTS.

4.1.8 Batteries

This part also should be there so as to ensure no shortage of power. They are just standby waiting

for AC main power failure so that they can take up the action.

4.2 TROUBLESHOOTINT AND CLEARING 3G FAULTS/ALARMS There is no site which can stay for eternal life without some problems. It can be seen very

early after installation due to poor installation or sometime after installation due to external

factors such as wind, people and any non/living thing passing across the equipment and disturb

it. As an engineer or a technician in charge you should be able to translate alarm into physical

action/thing. There many alarms which can be seen in the node B site but common alarms are:

Fiber alarm/Sector is down alarm. As explained in part 4.1.2 the possible reasons for this

alarm is:

i. Power failure at the RRU. This is the common reason as it happens when either

the RRU switched was accidently turned off, the open/short circuit at the RRU

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terminal or open circuit at the DCDB terminal where due to poor installation

someone accidently pulled off the cable from its connector. How do you know

about this problem? You can know it by :

o Swap the power terminal at the DCDB and check status of the CPRI with

alarm if it exist

o Swap the CPRI themselves, if the alarm exist

o Check the power connector of that sector and try to pull out the cables if

one of the cable comes out then that is where the problem is, insert it

properly and connect the power. The alarm should clear, if not

o Climb up the tower with a meter and check the status of RRU LED’s, if

they UP then the problem is not power, if they are not up then test

continuity of the circuit using the multi-meter. If you get continuity then

connect the cables properly. Alarm should clear. If the LED’s comes up

but still alarm is on then see procedure below.

ii. Fiber cable (CPRI) not well terminated especial the optic module not well

inserted into its slot. Disconnect the CPRI cable at the BBU/RRU and reconnect

it. The alarm should clear

Temperature and Humidity Alarm. This fault can be caused due to fan failure or over

temperature due to Air condition failure. To solve this make sure all your fan are on and

well operating

Site is down alarm. This situation occurs due to:

a) BBU is OFF, check the status of the BBU before doing anything

b) No power supply to the BBU, check the if AC power and Battery DC power is there c) E1 cable is loose/disconnected, if the above reasons doesn’t apply try to check E1 cable at both

ends (SLPU and DDF/OVP)

5 RECOMMENDATIONS

I would like to recommend that if you are a site Engineer you should update yourself with a new

technologies emerging every day. Telecom companies should also train their engineer about their

expected technology to be used by such company so as to ensure good supervision and

acceptance to be of high quality as currently other engineer accepts sites which they even

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understand. Subcontractors company have to be systematic in their plans otherwise they will

never grow due to poor money management. Also I would like to recommend that, our university

should value the potential found in students so as to use them to save the country.

6 CONCLUSION 3G network is very portable and easy to be instaled, it ensures data reliability and speed.

It is better in data communications other than voice communications although it fe=its

also well in voice communication.

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7 REFERENCES 1. DBS3900 Installation Guide (03) by Huawei Technologies Co. LTD 10/06/2011

2. Training by Huawei Engineer Mr. Abdallah about 3G networks

3. 3G installation training by Mhina a TM Director.

8 ABREVIATIONS

3G: means Third Generation

DCDB: Direct Current Distribution Board

BTS: Base Tranceiver station

GSM: Global Systems for Mobile Communications

CDMA: Code Division Multiple Access

WCDM: Wide CDMA

DDF: Data Distribution Frame

BBU: Base Band Unit

RRU: Radio Remote Unit