Internship Report in Electrical Engineering with emphasis in
Telecommunication Engineering
From
June 21 – August 31, 2021
At
Lonestar Cell MTN Head Office
Network Switching Subsystem (NSS)
Congo Town, Paynesville,
Montserrado County, Liberia
Submitted by
John Pittman Gibson
TU-02708
Senior Student
Department of Electrical Engineering
College of Engineering & Technology
William V.S. Tubman University
November 9, 2021
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TABLE OF CONTENT
Acknowledgement
Executive Summary
Chapter One: Organization Profile
Chapter Two: Internship Placement Review
2.1. Specific Department
2.2.Start and End Date
Chapter Three: .The Training Program
3.2.Departments worked in
3.2.Tasks Assigned
Chapter Four: Daily/Weekly Activities
4.1.Week one
4.2.Week Two
4.3.Week Three
4.4.Week Four and Five
4.5.Week Six and Seven
4.6.Week Eight
4.7.Week Nine
Analysis
Conclusion
Recommendations
References
3
4
5-6
7-8
8
8-10
10-11
12-17
17-18
18-20
20
20-23
23-32
33
34
34
35
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Acknowledgement
A special gratitude goes to my chairman for ensuring that I was fit for internship and
masterminding my internship placement. I want to thank my supervisors and trainers at the
internship site for their knowledge, guidance and supervision while I was going through my
internship. I want to thank everyone who assisted me in any way while I was on my internship.
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Executive Summary
In fulfillment and completion of the course Internship (GENG 310) which is also one of the
requirements for obtaining a Bachelor of Science in Electrical Engineering (BSEE) and in
compliance with my emphasized specific field of study under electrical engineering
(Telecommunications Engineering), I was placed at the Lonestar Cell MTN Head Office in
Congo Town to go through my training.
This report is divided into five chapters. The first chapter gives background of Lonestar Cell
MTN. The second chapter gives an over on where specifically was I place and where I was
placed to where I was placed. The third chapter talks about the departments I work in, their
functionalities and the tasks I was assigned while I was in those departments. The fourth chapter
is called Reflective Journal Entries. It is a reflection of all my activities on a weekly basis
ranging from week one to week nine. The fifth chapter is a combination of conclusion, analyses
and recommendations. The reference is also found after chapter five. There are some extended
documents to this document which including an advanced scripting and the network topology.
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CHAPTER ONE
Organizational Profile of Lonestar Cell MTN
1.1.Introduction to Lonestar Cell MTN
The acronym MTN stands for mobile telephone network. MTN is a worldwide
telecommunication company that specializes in offering mobile communication services over
long distance. MTN Liberia or Lonestar Cell MTN is a national sub-branch of MTN. The
mission of MTN in Liberia is to make customers’ lives brighter. MTN aims to provide affordable
and quality telecom services in Liberia. MTN envisions leading the delivery of a bold, new
digital world to customers. MTN focuses on building a future of the customers by leading the
way through connectivity enablement.
1.2.History of MTN Liberia
Lonestar Cell MTN’s journey in Liberia began in 2001. This journey was begun to heal a nation
devastated by war through connectivity. Between 2002 and 2003 Lonestar Cell MTN opened up
its network to offer free calls for the people of Liberia as civil crisis breaks out in the capital,
Monrovia. Later in 2004, 2005 and 2006, the company became a subsidiary of the MTN Group
after a 60 percent acquisition by South African GSM Company. In 2007, the Lonestar Cell
MTN’s Foundation launched 21 days of Y’ello Care with extensive support to Phebe Hospital in
Bong County. MTN Liberia hit active one million subscribers from 2008 to 2010. From 2015 to
2018, MTN Liberia achieved a trifecta of women empowerment with three women at the helm:
first female Chief Executive Officer, first female Deputy Chief Executive Officer and first
female Board Chair. In 2019, MTN Liberia launched Liberia’s first ever inclusive youth focused
telecommunications product, MTN lug and launched the MTN Prestige.
1.3.Lonestar Cell MTN Policies
According to the MTN policy statement, all SIMs that are activated on the MTN Liberia’s
network will be subjected to deletion and MSISDN recycling once they have gone through an
inactive period of over 270 days. Dormancy or inactivity will be defined as a period within
which a subscriber has not undertaken any Revenue Generating Events.
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Subscribers include Staff, Mobile, Fixed, Pre-paid, Post-paid, Payphones, Mobile Money,
WiMAX and Fixed Mobile numbers. All subscribers in a parent/child account hierarchy will be
considered active as long as the parent/master has Revenue Generating Events.
Revenue Generating events include:

Charged terminated incoming call

All charged outgoing calls

Charged terminated incoming SMS and MMS

All charged mobile oriented outgoing SMS and MMS

Charged sent and received data transactions

Charged Value Added Service transactions

Charged Mobile Money Transactions

Mobile terminated transactions that incur interconnected charges

All roaming events

Subscription fees charged Airtime Recharges
1.4.MTN Liberia Competitor in Liberia
In terms of mobile telecom services, the only competitor MTN Liberia has is Orange Liberia.
Orange Liberia is a French company that replaced MTN Liberia former competitor (Celcom).
Orange Liberia the same services that Lonestar Cell MTN offers ranging from 2G to 4G lite. In
terms of Wi-Fi service, other competitor may be Liberia Telecommunication Cooperation
(LIBTELCO).
1.5.Number of Employees
The number of employees at Lonestar Cell Head office is 273.
1.6.Departments
Some major departments include: Network Department, IT Department, Sales, Marketing,
Human Resource and Board Members.
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CHAPTER TWO
Internship Placement Review
2.1. Introduction to Specific Branch/Department
From the structure of the organization, there are many departments at Lonestar Cell MTN. I was
specifically assigned at Technical/Mobile Networking Department. However, it wasn’t the entire
networking department I was assigned.
The networking department includes all services of mobile network (2G, 3G and 4G) and their
subsystems. Every generation of mobile network has its own subsystems and architecture. In
general, every mobile network generation system is divided into three subsystems (Mobile
station, Radio Access Network and Core Network). The mobile station includes user equipment
like phone, computer, modem etc.
The radio access network is called the base station subsystem (BSS). The BSS consists of cells
which are defined by coverage of towers. In the cells there are BTS (for 2G), node B (for 3G)
and Evolved node B shortly called eNode B. All cells are controlled by one centralized
controllers called Base Station Controller (BSC) for 2G and Radio Network Controller (RNC)
for 3G. For 4G, there is no centralized controller because the eNode B does all the functions of
the node B and the RNC. I was not assigned at the Radio Access Network which means I wasn’t
assigned to any cell to work.
The Core Network is responsible for switching, monitor and control. In 2G, it includes the
Mobile Switching Center (MSC) and other systems connected to the MSC such as the Home
Location Register (HLR), Authentication Center (AuC), Visitor Location Register (VLR) etc. In
3G and 4G, the MSC is known as Packet Core and Evolved Packet Core respectively. The MSC
is a single device but it is not just a device, it is also the center or room where all switching and
control devices are kept. Therefore, I was specifically assigned to work at MSC #03 in terms of
building. MSC #03 is one major switch where majority of the devices and offices for the network
team are found. The other MSCs are used to keep devices.
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2.2. Start-and-end Date of Internship as well as Duration
The internship is required to run for three months. Due to some challenges in placement which
prevented me from starting on the actual date, my internship ran for two months plus one week.
It started on the 21st of June and ended on the 31st of August.
2.3. Departments under networking in which I Got Trained
There are two major departments in which I got trained in. The first department I got trained in
was the Network Operations Center (NOC). The next department was the department that
specializes in BSC and RNC. I got added trainings from other departments such as the Power
Department and transmission department.
CHAPTER THREE
The Training Program Review
3.1. Activities Performed in each Department
3.1.1. Network Operation Center (NOC)
The NOC performs operation; maintenance and control (OMC) function of the network. As the
name suggests, this department controls the network. Control in this context is done four ways:
monitor, troubleshooting, analysis and maintenance. All works of the NOC is done on Operation
Support Subsystem (OSS). There is specific software for each generation that works out of the
OSS but is also connected to the OSS.
Monitor: It is within the NOC the entire network is monitored. Every aspect of the network is
monitored in the NOC. The entire system ranging from the BSS to the NSS is monitored within
the NOC. The first type of monitor that is done within the NOC is to monitor all the cells. The
sole purpose of during this is to know cells that are active and cells that are down. When a cell is
monitored, all services (2G, 3G & 4G) within that cell can be monitored to know whether they
are all active or down. Apart from services, sectors of cells can also be monitored. Whether 2G,
3G, or 4G, many cells are divided into sectors. The sectors can be two, three or six. Sometimes,
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an entire cell cannot be down rather, one or two sectors can be up while the others are down.
Sectorization was implemented at cells to increase capacity of cells and to reduce data and voice
traffic. 2G Cells are monitored from the BSC with the help of WinFiol software. 3G Cells are
monitored from the RNC with the help of putty software. 4G cells do not have centralized
controllers and so they are monitored directly on the Operation Switching Subsystem (OSS). The
OSS can be used to monitor 2G and 3G Cells as well but putty and WinFiol are effective.
Monitor is done through scripting and running of commands. Monitor was not only down to see
sites that were down or active but to also see common and major alarms such as mains failure.
The NOC also does monitoring in the VLR and HLR when issues arise. Monitor is also done in
the MSC so as to monitor the transmission link between the MSC and other MSCs, to monitor all
BSCs, attached networks/systems, other public land mobile network (PLMN) and international
links.
Troubleshooting & Analysis: After monitor is done, if a cell is down, partially down or poorly
operating, troubleshooting can also be done on the OSS to know which aspect of the cell is
affected. Some cells go down due to power lacking while some go down due to transmission
problem. It is also the function of the NOC. After troubleshooting, analysis needs be done before
interpreting the results and updating it for technician to do further troubleshooting at the site
physically.
Maintenance: Once troubleshooting is done, as mobile network engineer, you will have the
expertise to decide whether the problem is software problem, configuration or hardware problem.
If the problem can be solved directly from on the OSS, it will be solved. If it cannot be solved,
then technician or specialist for such problem can be notified. This is an important aspect
because it keeps the network active. The NOC also resolve calls and numbers issues such as
blocking and deblocking numbers and troubleshooting to deduce reasons for which calls are not
going through for certain numbers.
3.1.2. Department Specialized in BSC/RNC Operation
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This department is an advanced department of the NOC. The responsibility of this department is
to do further analysis, advance scripting/configuration and to troubleshoot and repair BSC/RNC
devices if they are faulty.
3.1.3. Transmission
The transmission department is responsible to solve issues on transmission.
3.2. Tasks Assigned as Intern
While serving in the departments enlisted above, I was assigned to the following tasks:
3.2.1. Network Administrator: Here I was charged with all the duties performed by the
engineer that works in the NOC department. All the activities performed in the NOC department
were my responsibility. I worked under supervision for a week and I work as staff without
supervision later.
3.2.2. Making Hourly Report: As network administrator or network operation engineer, I was
assigned with the task of giving update on the status of the network nationwide.
3.2.3. Shift and Daily Reports: This is done at the end of a shift and a day. There are eight
working hours and eight working hour is considered a shift. Three shifts make a day. Before
turning over to another engineer, report is made to the network team and heads. Daily report is
made by the engineer on last shift. I was also assigned these tasks.
3.2.3. Smart Generators Monitor & Control: I was responsible to also monitor smart
generators of certain cells. Smart generators are generators that work and charge batteries,
automatically come on when batteries are low and automatically switch to batteries when
batteries are charged.
Other tasks included:

Checking Transmission Links

Restarting Sites
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
3G and 4G Cells faults analysis

Testing Radios

Advanced Scripting

Blocking and Deblocking Numbers
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CHAPTER FOUR
Reflective Journal Entries (Daily/Weekly Activities)
In this chapter, I will do a reflection of daily and weekly activities, interpret and evaluate them.
4.1. WEEK ONE (JUNE 21-28) – INTRODUCTORY TRAINING & ASSIGNMENT IN
THE NOC
4.1.1. Introduction and Orientation: On the first day of the training, introduction and
orientation was done. I was introduced to staffs in the MSC #03. I was handed over from the HR
department to the boss and later from the boss of the network team to my trainer/supervisor.
Orientation on mobile network system was done interactively and also on the structure of
Lonestar’s network. The various departments were introduced and their duties were given.
4.1.2. Switch Room: On the following day, I was taken to the Switch room. The devices were
shown and their functions were given. In the switch room, I saw devices for 2G, 3G and 4G. For
2G and 3G, I saw the BSC, RNC, MSC, GMSC, HLR, EIR, VLR, SGSN, and GGSN. For 4G, I
saw the PDN Gateway (P-GW), HSS, S-GW, MME and PCRF. The functions of these devices
are given below:
Mobile switching center (MSC):
This is essentially the same as that within GSM, and it
manages the circuit switched calls under way.
Gateway MSC (GMSC): This is effectively the interface to the external networks.
Packet switched elements
The Serving GPRS Support Node (SGSN): The SGSN was first developed when GPRS was
introduced. Its use has been carried over into the UMTS network architecture. The SGSN
provides a number of functions within the UMTS network architecture.

Mobility management: When a UE attaches to the Packet Switched domain of the
UMTS Core Network, the SGSN generates MM information based on the mobile’s
current location.

Session management: The SGSN manages the data sessions providing the required
quality of service and also managing what are termed the PDP (Packet data Protocol)
contexts, i.e. the pipes over which the data is sent.
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
Interaction with other areas of the network:
The SGSN is able to manage its
elements within the network only by communicating with other areas of the network, e.g.
MSC and other circuit switched areas.

Billing: The SGSN is also responsible billing. It achieves this by monitoring the flow of
user data across the GPRS network. CDRs (Call Detail Records) are generated by the
SGSN before being transferred to the charging entities (Charging Gateway Function,
CGF).
Gateway GPRS Support Node (GGSN): Like the SGSN, this entity was also first introduced
into the GPRS network. The Gateway GPRS Support Node (GGSN) is the central element within
the UMTS packet switched network. It handles inter-working between the UMTS packet
switched network and external packet switched networks, and can be considered as a very
sophisticated router. In operation, when the GGSN receives data addressed to a specific user, it
checks if the user is active and then forwards the data to the SGSN serving the particular UE.
Home location register (HLR):
This database contains all the administrative information
about each subscriber along with their last known location. In this way, the UMTS network is
able to route calls to the relevant RNC / Node B. When a user switches on their UE, it registers
with the network and from this it is possible to determine which Node B it communicates with so
that incoming calls can be routed appropriately. Even when the UE is not active (but switched
on) it re-registers periodically to ensure that the network (HLR) is aware of its latest position
with their current or last known location on the network.
Equipment identity register (EIR):
The EIR is the entity that decides whether a given UE
equipment may be allowed onto the network. Each UE equipment has a number known as the
International Mobile Equipment Identity. This number, as mentioned above, is installed in the
equipment and is checked by the network during registration.
Authentication centre (AuC):
The AuC is a protected database that contains the secret key
also contained in the user’s USIM card.
The Home Subscriber Server (HSS) component has been carried forward from UMTS and
GSM and is a central database that contains information about all the network operator’s
subscribers.
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The Packet Data Network (PDN) Gateway (P-GW) communicates with the outside world ie.
Packet data networks PDN, using SGi interface. Each packet data network is identified by an
access point name (APN). The PDN gateway has the same role as the GPRS support node
(GGSN) and the serving GPRS support node (SGSN) with UMTS and GSM.
The serving gateway (S-GW) acts as a router, and forwards data between the base station and
the PDN gateway.
The mobility management entity (MME) controls the high-level operation of the mobile by
means of signalling messages and Home Subscriber Server (HSS).
The Policy Control and Charging Rules Function (PCRF) is a component which is not shown
in the above diagram but it is responsible for policy control decision-making, as well as for
controlling the flow-based charging functionalities in the Policy Control Enforcement Function
(PCEF), which resides in the P-GW.
On the remaining days of this week, I was assigned to the NOC and was taught the following:
4.1.1.Logging into the Putty, winfiol and the OSSThese three software can be logged into by
typing in the staff username and password.
4.1.2.Logging into the BSC and RNC: The first step in monitoring the network is being able to
log onto the network. There are three BSCs in the entire network for lonestar (EVOBSC02,
EVOBSC03 and EVOBSC4). The acronym EVOBSC stands for evolved BSC which means the
EVOBSC is the new and evolved version of BSC due to its upgrade in functions and
intelligence. To log on an EVOBSC, the username has to be scripted followed by the password,
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followed by the commands (vt100 & mml -a) and the BSC will open. For 3G UMTS, there are
two RNCs (EVORNC02 and EVORNC03). To log on an RNC, the putty software is logged on
first. If the staff wants to log on the EVORNC02, the command amos evornc02 will be type and
access will be given.
4.1.3.Checking for 2G, 3G & 4G sites that are down: After the putty winfiol and the specific
BSC is logged on, to see the list of all cells in a BSC, the command “rlcrp:cell=all;” is run. For
3G Sites, the command strt is run after logging in the RNC. Sectors with zeros on their entire
row are down and sites whose sectors are all down are considered down completely. 4G cells
that are down can be checked directly from the OSS.
Sometimes, a cell cannot be down entirely rather a particular sector. Sometimes, an entire sector
cannot be down rather a particular cabinet. So sometimes in a cell, only a particular cabinet can
be down. A cabinet is a small housing that contain components of the Base Transceiver
Substation (BTS) or Radio Base Station (RBS). The components of the BTS or RBS include
radios, transceivers, duplexing units etc. There are two types of cabinets. They are 900 cabinet
and 1800 cabinet. The 900 cabinet is the cabinet that transmitting and receiving frequency bands
are 935-960MHz and 890-915MHz respectively while the 1800 cabinet is the cabinet whose
transmitting and receiving frequency bands are 1805-1880MHz and 1710-1785MHz. Some cells
have only 1800 or 900 cabinet. Additionally, sometimes some cells or sectors can be restarting or
might have just been restored but the zeros can still be indicated which suggests that they are
down. Because of these, whenever the command is run and certain sites appears to be down,
further check can be done. This step is called, checking cell’s managed objects (MO). When the
MOs of a cabinet is checked and all the managed objects (radios, transceiver, duplexing unit,
multiplexers etc.) are not blocked, then that particalur cabinet is not down. When all the cabinets
or sectors are down, then the cell is completely down.
4.1.4.Checking the Cabinets in the sectors of a Cell: Some sectors have a single cabinet. In
some cells, one of the sectors can contain the 900 cabinet while the other(s) can have the 1800
cabinet. In some cells, every sector have both 900 and 1800 cabinets. The first step in checking
the cabinet is to determine the transmission group (TG) number by running the command
“rxtcp:moty=rxotg,cell=cell ID;”. The TG number (s) will display. Next, the command
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“rxmsp:moty=rxotg-TG#” to know the site name and the cabinet assigned to that TG number. To check
whether the cabinet or sector is down or active now, the command “rxmsp:mo=rxotg-TG#,subord;”. All
the managed objects will display. If BLO appears infront of some, then the cabinet might be down due to
faulty spare and if BLO appears infront of all, then the entire cabinet is down and is most likely due to
power issue. BLO infront of any MO indicates that the MO is blocked.
4.1.5.Checking for alarms in BSC: Alarms display automatically immediately there is a fault.
However, it is important to manually check for alarms because only recent alarms can be seen.
However, every minute or few minutes, it is required for the engineer to check for alarms by
using the command “allip:acl=a2;”
4.1.6.Making Hourly Report: Hourly report is an update that can be given every hour. This
update covers information on the following:
i)
Outages: Outage refer to sites that are down either due to power, transmission,
faulty spare or software issue like configuration or license. Cells or sectors of
cells with outages can be updated every hour.
ii)
Availability: Availability can be given in two forms. The first is the average
availability for 2G, 3G, & 4G both nationwide and in montserrado. The
availability tells whether a service is having good performance or poor
performance. It ranges from zero to 100. The second way was learned in the
following week.
iii)
Smart Generators: Smart Generators are special generators with intelligence that
can be manually or automatically turned on and off. Smart generators are used
with batteries at some cells in the remote areas. They run for eight hours while the
batteries run for five hours. When the smart generators are running, the batteries
can be charging. When the generator reaches certain fuel and voltage levels, the
batteries are expected to be charged and automatic switch from generator to
battery is expected else, there is a problem or the generator might be on manual
mode. When the battery reaches certain hybrid levels after being on for about five
hours, it is expected for the generator to switch on automatically else, there might
be problem. The generators and batteries are configured on a centralized
computed controlled system such that their performance can be monitored
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remotely. In the smart generators update, information on whether the site is on
hybrid (battery) or generator, fuel level, voltage level and performance of the
devices (faulty or not) can be given.
a)List of 3G Sites that are down
b)Checking for 2G Outages
c)Alarms
in
BSC
d) Checking the 1800 Cabinet of SOS Cell (Sector C)
e)Checking Cell’s Managed Resources
Smart Generators
4.2. Week Two (June 28-July 2)
In week two, I started to work under monitor and supervision. As intern I did work that I was
taught in week one. Each day I go to work, I log on the entire system, log on the OSS, log on the
BSC and RNC and I start to monitor and make update. However, I did not only work under
supervision with week one activities, I was also taught to do the following:
4.2.1. Troubleshooting a 3G & 4G cell
Troubleshooting is done using putty software. The software can first be logged on. Next, the, the
site can be logged on. For 3G, the command amos plus the cell ID can be input. For 4G, the
command amos plus L_cell ID can be input. For instance, to log on Harper 1 site whose cell id is
HA222, the command amos HA222 (for 3G) or amos L_HA222 can be input. Another way is by
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clicking on the site directly from on the OSS. After, the user name and password will be
required. The next thing to do is to input the command lt all which request site’s data. The user
name for all 3G and 4G sites is rbs because it is particularly the rbs of the site that you are
logging on. Some require password, if they do, the password is also rbs. Once this step is done,
access can be given to the site. To see all the site’s resources and their performances, the
command invx or invrx can be input. Information on everything about the cell will display
(radios, antennas, basebands, fans, temperature, power, traffic, license, transceivers etc.). If I
want to check for information on specific portions of the cell, specific commands can be input as
exemplified below:
i.
Checking whether cell is active: st cell
ii.
Checking sectors: st sectors
iii.
Checking for 3G traffic: get.noofra
iv.
Checking for 4G traffic: ue –admitted print
v.
Checking radios: st rru or st plaugin
vi.
Show number of carrier: lsr sccp
vii.
Check License: get license
viii.
Check for alarms: alt
ix.
Checking for detailed alarm info: ala
4.2.2. Making Shift Report
At the end of every shift, an individual is required to make report on the outages experienced
while on shift, whether a cell is still down or restored, when did the site go down, when was it
restored, how many services went down and it root cause.
4.3. WEEK THREE (JULY 5 – JULY 9)
Week two training became added responsibility in this week. I did not only do the jobs of week
one but also all that I was taught. In addition to my jobs, the following were taught while I was
working:
4.3.1.Resetting a Cabinet or Sector: Sometimes a cabinet or sector can go down and restore
automatically due to fading. Fading refers to the attenuation of signals by interference. When the
18
sector or cabinet is behaving like this, a quick restart can be done. To carry on this process, TG
number can be determined first. Once it is determined, the following commands are executed:
rxbli:mo=rxotg-72,subord,force;
rxese:mo=rxotg-72,subord;
rxesi:mo=rxotg-72,subord;
rxble:mo=rxotg-72,subord;
4.3.2.Transceiver Blocking/Unblocking
When the alarm “BTS INTERNAL” displays, there is a problem within the BTS. This ramifies
when a transceiver (TRx), receiving antenna (Rx), transmitting antenna (Tx) or any other
managed object is blocked automatically. When this happens, the following commands can be
executed:
rxbli:mo=RXOTRX-36-10,subord,force;
rxese:mo=RXOTRX-36-10,subord;
rxesi:mo=RXOTRX-36-10,subord;
rxble:mo=RXOTRX-36-10,subord;
4.3.3. Antenna Blocking/Unblocking
rxbli:mo=RXORX-72-7,force;
rxese:mo=RXORX-72-7;
rxesi:mo=RXORX-72-7;
rxble:mo=RXORX-72-7;
4.3.4.Restarting Node B: Sometimes the data and voice traffic gets high on the node B of a cell.
This causes degrade fading in the cell’s performance and causes the cell not to take traffic.
Traffic here refers to calls and data usage. To resolve this issue, I was taught how to restart a
node B. A node B is an equivalent of 2G GSM BTS in 3G UMTS. The function of the node B is
to modulate/demodulate, spread/despread, encrypt/decrypt, perform handover, frequency hoping,
produce carriers etc. To restart the node B, the following commands are executed:
cvls
cvset restart
cvms restart startable
cvls
acc 0 manualrestar ---> to restrt 3G cabinet
3
0
0
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4.3.4.Working in the HLR: I was also taught few things about the HLR. The HLR is logged on
the same way the BSC can be logged on. I learned how to check a subscriber data whether it is
active or not. I learned how to block and unblock number. I also learned the follow:
To define LAI
mglcp:lai=all;
mglci:lai=618-01-13;
MGLCI:CELL=SAN21A,LOCNO=4-231886011591;
How to define APN on number
hgapp:apnid=all; to see all APN
hgsnc:msisdn=231886501364,nam=0,keep;
hgpdi:msisdn=231886501364,apnid=8,eqosid to drfine
To put 3G setting
hgsdc:msisdn=231880294837,sud=bs3g-1;
4.3.5.Working in the MSC: I also learned how to logged on with username and password. I
learned how to do the following: international and inter-MSCs routing, Device State Survey and
checking for alarms.
4.4.WEEK FOUR & FIVE (JULY 19-30)
For these two weeks, I was placed on schedule to work on shift independently. I worked and
executed all that I learned since I started my internship. I worked on day shift (8AM – 5PM),
second shift (6PM – 11AM) and on last shift (12AM – 7AM).
6.1.WEEK SIX (AUGUST 2-6) – BSC/RNC OPERATION
In this week, I was transferred to the BSC/RNC Operation Department. This department does
advanced scripting than the NOC. In the first week of this department, I was taught the
following:
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6.1.Functions of BSC/RNC and Identifying Them
6.1.1.BSC: The BSC manages the radio resources for one or more BTSs. It handles radio
channel setup, frequency hopping, and handovers. The BSC is the connection between the
mobile and the MSC. The BSC also translates the 13 Kbps voice channel used over the radio link
to the standard 64 Kbps channel used by the Public Switched Telephone Network (PSDN) or
ISDN.
It assigns and releases frequencies and time slots for the MS. The BSC also handles intercell
handover. It controls the power transmission of the BSS and MS in its area. The function of the
BSC is to allocate the necessary time slots between the BTS and the MSC. It is a switching
device that handles the radio resources. Additional functions include:

Control of frequency hopping

Performing traffic concentration to reduce the number of lines from the MSC

Providing an interface to the Operations and Maintenance Center for the BSS

Reallocation of frequencies among BTSs

Time and frequency synchronization

Power management

Time-delay measurements of received signals from the MS
6.1.2.RNC: Like the BSC in GSM, RNC is the governing element in UMTS UTRAN that
controls all node Bs. The RNC does radio resource management, modulation/demodulation,
encryption/decryption, DAC, ADC, spreading/dispreading, power management and mobility
functions.
6.2.Health Check: Health check is the act of checking certain aspects of a cell to determine the
cell’s performance. The following can be done under health check:
get.maxtotal
st sctp
st ip
deb rru
bl rru
license iu status
uer -c sin31
:
:
:
:
:
:
:
max power
sctp status
to check ip status
to deblock rru
To block rru
check status of license
to see user on internet
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6.3.Activating OL and UL
rlsli:cell=brw21a,sctype=ol;
rlsli:cell=brw21b,sctype=ol;
rlsli:cell=brw21c,sctype=ol;
6.4.BSC & RNC Backup from Computer Local System to OSS using WS-FTP
Backup is done to reserve BSC and RNC information on the computer local system in order to
prevent losing of information. The following steps are employed for BSC backup:

Open the WS-FTP

Open the backup folder on the local system

Open the BSC files within the backup folder

Open the specific BSC within the BSC folder

Connect to the same BSC on the OSS, select the file with the latest date and click on the
backup button.
The following steps are followed to backup RNC:

Open the RNC folder

Create new folder

Connect to the RNC (2 or )
Fixing

Copy the Node folder and
Redundancy

Open the created folder

Push the nodes in the created folder
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4.7.WEEK SEVEN (AUGUST 9-13) – LTE CELLS SITES ANALYSIS
In this exercise, we did troubleshooting for one week on all the LTE sites. As we troubleshoot,
we did fault analysis and recorded 4G sites with faults so as to solve the problems and put in for
spare. Below is the fault analysis table:
4.8.WEEK EIGHT (AUGUST 13 – 20) – TRANSMISSION DEPARTMENT
4.8.1.Separation of directions and duplex transmission
4.8.1.1.Duplex Transmission
The most frequent form of communication is the bidirectional communication which allows
simultaneous transmitting and receiving. A system capable of doing this is called fullduplex.
Modern digital mobile radio systems are always full-duplex capable. Essentially, two basic
duplex procedures are employed: Frequency Division Duplex (FDD) using different frequency
bands in each direction, and Time Division Duplex (TDD) which periodically switches the
direction of transmission.
Frequency Division Duplex: The frequency duplex procedure has been used already in analog
mobile radio systems and is also used in digital systems. For communication between a mobile
23
and a base station, the available frequency band is split into two partial bands, to enable
simultaneous sending and receiving. One partial band is assigned for uplink (from mobile to base
station) transmissions and the other partial band is assigned for downlink (from base station to
mobile) transmissions. • Uplink band: transmission band of the mobile and receiving band of the
base station. • Downlink band: receiving band of the mobile and transmission band of the base
station. To achieve good separation of both directions, the partial bands must be a sufficient
frequency distance apart, i.e. the frequency pairs of a connection assigned to uplink and
downlink must have this distance band between them.
Time Division Duplex: Time duplexing is therefore a good alternative, especially in digital
systems with time division multiple access. In this case, the transmitter and receiver operate only
quasisimultaneously at different points in time, i.e. the directional separation is achieved by
switching in time between transmission and reception, and thus no duplexing unit is required.
Switching occurs frequently enough that the communication appears to be over a
quasisimultaneous full-duplex connection. However, out of the periodic interval T available for
the transmission of a time slot only a small part can be used, so that a time duplex system
requires more than twice the bit rate of a frequency duplex system.
4.8.1.2.Multiple Access
The radio channel is a communication medium shared by many subscribers in one cell. Mobile
stations compete with one another for the frequency resource to transmit their information
streams. Without any other measures to control simultaneous access of several users, collisions
can occur (multiple access problem). Since collisions are very undesirable for a connectionoriented communication like mobile telephony, the individual subscribers/mobile stations must
be assigned dedicated channels on demand.
Frequency Division Multiple Access: Frequency Division Multiple Access (FDMA) is one of
the most common multiple access procedures. The frequency band is divided into channels of
certain bandwidth such that each conversation is carried on a different frequency (Figure 2.5).
The effort in the base station to realize an FDMA system is very high.
24
Time Division Multiple Access: Time Division Multiple Access (TDMA) is used in digital
mobile radio systems. The individual mobile stations are cyclically assigned a frequency for
exclusive use only for the duration of a time slot, which obviously requires frame
synchronization between transmitter and receiver. Furthermore, in most cases the whole system
bandwidth for a time slot is not assigned to one station, but the system frequency range is
subdivided into sub-bands, and TDMA is used for multiple access to each sub-band. The subbands are known as carrier frequencies, and the mobile systems using this technique are
designated as multicarrier systems (not to be confused with multicarrier modulation). GSM
employs such a combination of FDMA and TDMA; it is a multicarrier TDMA system. The
available frequency range is divided into frequency channels of 200 kHz bandwidth each (with
guard bands between to ease filtering), with each of these frequency channels containing eight
TDMA conversation channels. Thus, the sequence of time slots assigned to a mobile station
represents the physical channels of a TDMA system. In each time slot, the mobile station
transmits a data burst. The period assigned to a time slot for a mobile station thus also determines
the number of TDMA channels on a carrier frequency. The time slots of one period are
combined into a so-called TDMA frame.
Code Division Multiple Access: Systems with Code Division Multiple Access (CDMA) are
broadband systems, in which each subscriber uses the whole system bandwidth (similar to
TDMA) for the complete duration of the connection (similar to FDMA). However, usage is not
exclusive, i.e. all of the subscribers in a cell use the same frequency band simultaneously. To
separate the signals, the subscribers are assigned orthogonal codes. The basis of CDMA is a
band-spreading or spread spectrum technique. The signal of one subscriber is spread spectrally
over a multiple of its original bandwidth. Typically, spreading factors are between 10 and 1000;
they generate a broadband signal for transmission from the narrowband signal, and this is less
sensitive to frequencyselective interference and disturbances. Furthermore, the spectral power
density is decreased by band spreading, and communication is even possible below the noise
threshold (David and Benkner, 1996).
25
4.8.2.Transmission Devices (Function and Identification)
4.8.2.1.RBS
An RBS includes all radio and transmission interface equipment needed on site to provide radio
transmission for one or several cells. The RBS 2000 family is Ericsson’s second generation of
RBS offering products with a low total lifetime cost1. This is achieved by functions including
long Mean Time Between Failure (MTBF) performance and short Mean Time To Repair
(MTTR). In addition, this product line is quick and easy to install thus giving the possibility to
achieve a rapid network roll out. RBS 2000 provides products for both indoor and outdoor
installations and is available for GSM 900, GSM 1800 and GSM 1900.
RBS Functions
RBS functionality can be divided into the following areas:
• Radio resources
• Signal processing
• Signaling link management
• Synchronization
• Local maintenance handling
• Functional supervision and testing
All types of RBS within the RBS 2000 series have the following characteristics:

Support for user flexibility by providing modular hardware and software designs.

Transceiver oriented design, which stresses using as little common equipment as possible
ensuring dependable performance.

Design and use are aimed at keeping system life cycle costs low.
The RBS 2000 series is based on standardized hardware units called Replaceable Units (RU).
The major RU’s are:

Distribution switch Unit (DXU)

Transceiver Unit (TRU)
26

Combining and Distribution Unit (CDU)

Power Supply Unit (PSU)

Energy Control Unit (ECU)
a) Distribution switch Unit (DXU): The DXU performs the following tasks:
•
Provides an interface to the BSC
•
Manages the link resources and connects the traffic time slots from the BSC link
to the TRU’s
•
Controls signaling to the BSC and performs concentration
•
Extracts synchronization information from the link and generates a timing
reference for the RBS In addition, the DXU has a database which stores
information about installed hardware.
b) Transceiver Unit (TRU): One TRU includes all functionality needed for handling one
radio carrier (i.e. the 8 time slots in one TDMA frame). It is responsible for radio
transmitting, radio receiving, power amplification and signal processing. The TRU
contains a radio frequency test loop between the transmitter and the receiver. This
facilitates TRU testing by generating signals and looping them back. TRU’s are
connected by a bus to enable frequency hopping. Some RBS products can contain up to 6
TRUs.
c) Combining and Distribution Unit (CDU): The CDU is the interface between the TRUs
and the 2-way antenna system. The task of the CDU is to combine signals to be
transmitted from various transceivers and to distribute received signals to the receivers.
All signals are filtered before transmission and after reception using bandpass filters. A
range of CDU types have been developed to support different configurations within the
RBS 2000 family. They consist of different types of CDUs, including:
•
Without combiners
•
With hybrid combiners
•
With filter combiners to support large configuration.
d) Power Supply Unit (PSU): The PSU rectifies the power supply voltage to the +24 VDC
necessary for RBS operation.
27
e) Energy Control Unit (ECU): The ECU controls and supervises the power equipment
and regulates the environmental conditions inside the cabinet. The RBS 2000 is preassembled at the factory including program load and parameter settings making a quick
startup possible. Assembly can also be carried out on site. The RBS software
isdownloaded from the BSC and stored in a non-volatile (flash memory) program store.
In a working RBS, this flash memory keeps cell down time low because traffic does not
need to be interrupted. Power failure recovery can also be done quickly.
4.8.2.2.Baseband Unit
Baseband refers to the original frequency range of a transmission signal before it is modulated.
Baseband can also refer to a type of data transmission in which digital or analog data is sent over
a single non-multiplexed channel.
A baseband unit (BBU) is a unit that processes baseband in telecomm systems. A typical
wireless telecom station consists of the baseband processing unit and the RF processing unit
(remote radio unit – RRU). The baseband unit is placed in the equipment room and connected
with RRU via optical fiber. The BBU is responsible for communication through the physical
interface. A BBU has the following characteristics: modular design, small size, low power
consumption and can be easily deployed.
A BBU in a cellular telephone cell site is comprised of a digital signal processor to process
forward voice signals for transmission to a mobile unit and to process reverse voice signals
received from the mobile unit. The digital signal processor also serves to produce a first
supervisory audio tone (SAT) for transmission to the mobile unit by generating successive digital
SAT samples which are decoded into a continuous tone. Finally, the digital signal processor
detects the presence of a second SAT generated by the mobile unit by sampling and processing
successive samples of the second SAT and measuring the power.
4.8.2.3.Remote Radio Unit (RRU)
Radio Remote Unit(RRU) is the distributed and integrated frequency unit that connects to an
operators network with the User Equipment’s (UE’s) like Cell Phone and mobile devices.
28
The logical term “distributed and integrated” is because traditionally the radio architecture for
cellular system is based on a single-standalone system (Base Stations) usually installed indoor
but now, the cellular architecture is divided.
So now the BTS (Base Transceiver Station) is the integration of various radio unit like BBU and
RRU. Despite installing only in indoor, radio units are now install in the tower below the
Antenna.
The RRU is connected to the base station via the fiber optic link which is bi-directional link. The
optical interface link is also known as CPRI (Common Public Radio Interface). CPRI is a
interface protocol developed by combination of major telecom equipment’s manufacturing
company like Nokia, Alcatel, Cisco and many more.
The RRU helps to reduce the coaxial feed line losses, increase system efficiency and provide
high level of flexibility in cellular site construction. Undoubtedly, this helps in upgrading to new
equipment’s and devices more easily.
RRU Functions:
1) Acts as a Transceiver: transmit and receive the user signals to the base station and vice-versa.
2) Provides back to back support and connectivity between user equipment’s like power,
delay,etc.
3) Control and process the EM signals received from the Antenna via Jumper(Hollow Guide).
4) Provide interface between two physical link: Optical and EM (Electromagnetics).
5) Provide Controlling support of the Auxiliary equipment’s like RCU (Remote Control Unit)
for electrical tilt adjustment generally known as RET(Remote Electrical Tilt).
6) Generate and sends the different signals like VSWR, RET, ACT,etc.
RRU Hardware Description:
1) CPRI Port: There is 2 port generally name as CPRI0 and CPRI1. However there may be 1’s
in some model. The name at suffix may vary. Its function is to connect to BBU.
29
2) RF Port: We say it as a Jumper port. Generally, the number of jumper port may vary with
model and company’s architecture. At least there is 2 jumper port, one of which is for
Tx(Transmission) and another for Tx/Rx(Transmission/Receiver also known as Transceiver).
The RF port is conneted to the Antenna via Jumper Cable.
3) RET Port: There is at least one RET port for connection to RCU. Mostly, the connector is
DB9 in Huawei but may vary with other company’s. RCU is connected to the Antenna. RET
cable connects the RCU and RRU.
4) Power Supply Port: There is one port for powering the RRU. Mostly blue and black. Blue is
for negative (-) and black is for zero(0). Generally all RRU operates in -48V.
5) Ground Port: There is two OT port for the grounding. The ground cable: mostly copper
wire, one end is connected to RRU and another end into Bus Bar nearby RRU. Thus it
provides the surge and high voltage protection of RRU and thus keeping safe from natural
weather and climates.
I was also taught how to connect and test RRU.
4.8.2.4.RUS
The RUS is a multi-standard Radio Unit in the RBS6xxx family. Depending on the associated
Digital Unit (baseband), it can provide GSM, WCDMA or LTE carriers. It offers 20 MHz of RF
bandwidth and has a wideband multi-channel power amplifier (MCPA). If used for GSM (such
as driven by a DUG 20), it can operate 4 soft-TRX inside one RUS.
RF Side: The RUS has a band-width of 20MHz, and there can be multiple “sofware defined” RF
carriers within that band-width. In case of GSM, it can have four TRX/carriers in that band.
The standard RUS unit permits a TX power of 20W. However, using software licenses, the
power can be increased to 40W or even 60W.
Front-haul: The RUS has two CPRI links, each with their own proprietary connector. They
don’t have a SFP slot, as interconnection with the DUL/DUW/DUG20 is happening over short
(less than 0.5m) copper patch cables. However, as the DU side is a SFP form-factor, the signals
are assumed to be identical, just on a different mechanical connector.
30
The cable between standard SFP (DU side) and RUS proprietary connector is called “RPM 777
211/00900”.
4.8.2.5.Digital Unit for GSM (DUG 20): This is the 2G Digital unit for RBS 6xxx. It combines
the baseband processing and back haul interface of up to 12 TRx in 1..6 logical BTS. The DC
power supply of DUG is -48V and 70W maximum power consumption. I learned how to connect
the DUG.
4.8.2.7.PDU: A PDU is used to distribute power, typically to networking and computer hardware
housed in a rack in a data center. A basic PDU has one input and multiple outputs, each designed
to supply power to one piece of equipment. A stable power supply is critical in data centers.
Higher-spec PDUs can be monitored to check their efficiency. Here we breakdown the types of
PDU typically used, together with their key features.
4.8.2.8.Microwave link antenna & BTS Antenna: The microwave link antenna establishes the
communication between two towers. They transmit or receive signals between two towers in a
line of site communication.
The BTS antennas are the antennas that communicate with the UEs. The transmit and receive
signals between the UEs and the BTS.
Baseband Unit
RRU
Testing RRU
NPU
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4.8.3.Lonestar’s Network Topology
I was taught the Network Topology. The network
topology shows sites that link with one another. Some
links have one major site and many linked sites. If one
site goes down, all other sites after that site in the link
will go down. In this case, a huge outage can be
experienced.
4.8.4.Troubleshooting OML FAULT ALARM
A fault exists in the communications link between the BSC and the BTS. Alarm can come in as
either Major or Critical. It can come in on the CF, TRX, or both. 90% of the time is due to a
down or faulty E. IT Can also result from a faulty TRX or loss of communication from the BSC
to the TRX.
4.9.WEEK NINE (AUGUST 23-28)
In this week, I was evaluated. After I passed the evaluation, I was interviewed by the HR’s
office. After, I received letter signifying the completion of my program.
32
CHAPTER 5
Analysis, Conclusion and Recommendation
5.1.Crital Analysis: In the class room, I learned about some communication theory, modulation
techniques, modes of transmission, GSM structure, and satellite communication. At internship
site, some theoretical learning also continued. These theories were transformed into practical
experience while on internship. For instance, the functions of the BSC was learned and it was
demonstrated on how the BSC does huge control.
5.2.SWOT Analysis
5.2.1. Strengths of Lonestar’s Cell MTN: The company is able to offer services on three
generations (2G, 3G, and 4G). The company has the highest number of promotions and services.
The company has the highest amount of coverage and customers.
5.2.2. Weakness: One of the company’s major problem is capacity. As it is the oldest,
the company faces issues with places with huge population which leads to network traffic
and problems in making calls by customers. The company is yet to have a complete 4G
service. The company still have some network devices in some old subsystems that need
upgrade. Another weakness is there are some major places where the company’s
coverage has not reached. Another major weakness is the company don’t have her own
technicians to manage towers. A seperate group of individuals called I-Engineers cut
contract with the company to solve issues at towers. This limited my opportunity to work
at some towers.
5.2.3.Opportunities: The company has the huge amount of customers. This gives the
company the opportunity to generate huge revenue that can enable her to solve major
challenges.
5.2.4.Threats: One major threat to the company is the complaints of customers on
challenges faced by the company. Due to some of the old devices found in the system and
the capacity issue, there is a likely hood that customers move to another company if poor
quality is experienced. When many customers are lost, there will be a decrease in revenue
which might affect the company’s ability to compete with opponent.
33
5.3.Conclusion
During my internship, I worked in three major departments. In the first five weeks, I worked in
the NOC. In the next two weeks, I worked in the BSC/RNC operations department. In the next
one week, I worked in the transmission department where I learned the basis. In the last week, I
was evaluated. After working as intern, I am able to operate, monitor and troubleshoot network,
solve some major network problems, do advancing scripting to solve some problems, work in the
entire OSS (BSC, RNC, MSC, HLR), understand transmission and see some transmission
devices. I was able to see and identify many mobile network devices. I was able to understand
the evolution of mobile network generation and how they worked together. I also got general
working experiences. I was able to relate my theoretical knowledge to a practical experience.
5.4.Recommendations
To help solve some of the challenges, I recommend the following:
1. The company should upgrade old devices in the network.
2. The company should increase the coverage of some cells where there is a huge network
traffic.
3. The company should train their own technicians to take care of towers.
4. The company should do a study on the entire network and rebrand it for effectiveness and
reliability.
5. The company should upgrade to full 4G service and prepare for competition on the most
trending service (5G).
34
References
The following persons agreed for their names to be used as references:
1. Madame Johnett Horace: Human Resource Manager, Lonestar’s Head Office.
Contact: +231886567857
2. Mr. Nathaniel Sekou: NOC’s Manager. Contact: +231886501585
3. Mr. Siaka Kpaka: NOC’s Supervisor, Contact: +231886501596
4. Anthony Barshea: BSC/RNC Specialist
5. Dovert Andrews: Transmission Department
35