THERSON-COFIE THERSON-COFIE REPORT.docx

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KWAME NKRUMAH UNIVERSITY OF SCIENCE AND

TECHNOLOGY

DEPARTMENT OF TELECOMMUNICATIONS ENGINEERING

FIELD TRIP 2011 REPORT

NAME: THERSON-COFIE EMMANUEL LARWEH

INDEX NO: 2659208

DATE: 20TH

MARCH, 2011


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ABSTRACT

This report gives a detailed description of a field trip to some TELECOMMUNICATION companies in Accra

by third year TELECOMMUNICATIONS students from KWAME NKRUMAH UNIVERSITY OF SCIENCE AND

TECHNOLOGY (KNUST). The 2-day trip to MTN and Expresso exposed us to the practical approach based

on the academic work being done in school.


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TABLE OF CONTENT

ABSTRACT.. 2

TABLE OF CONTENT.3

EXPRESSO .............................................................................................................................................................. 4

INTODUCTION ........................................................................................................................................................... 4

SECTIONS/DEPARTMENTS ......................................................................................................................................... 4

POWER DISTRIBUTION SYSTEMS ........................................................................................................................ 4

SWITCHINGROOM .................................................................................................................................................... 7

NETWORKANDOPERATIONCENTRE ........................................................................................................................ 8

MTN. ....................................................................................................................................................................... 9

INTRODUCTION ......................................................................................................................................................... 9

THE GSM NETWORK.......................................................................................................................................... 11

ANTENNADESIGN ................................................................................................................................................... 13

CONCLUSION ............................................................................................................................................................... 14
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EXPRESSO GHANA

INTRODUCTIONWe arrived at Expresso at 11:00 am on the 3

rdof March, 2011.

Accra, Nov. 13, GNA- Expresso Telecom, a mobile telecommunication service provider, formally

launched its services in Ghana after acquiring the assets of Kasapa Network.

The Dubai-based Expresso Telecom focuses on operating CDMA mobile networks across West Africa,

having acquired Intercellular in Nigeria and Kasapa in Ghana, as well as new licenses in Mauritania and

Senegal. Currently, Kasapa serves around 400,000 customers, and is the fourth mobile operator behind

MTN, Tigo and Vodafone.

SECTIONS/DEPARTMENTS

Expresso is distinctively divided into three (3) sections, which are;

Power Distribution System(PDS) Switching and Transmission Room. Network Operation Centre (NOC).

Power Distribution System

Mr. Selorm Temeng took us through the Power Distribution System.


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Power is needed to be maintained at all times 24hr/days. The 240v ac ECG can be interrupted at

all times so it is backed by generators and battery. A battery room is a room in a facility used to house

batteries for large-scale custom-built backup or uninterruptible power systems providing electric power

for telecommunication and computing equipment in datacenters, telephone company central office

facilities, and remote telecommunications stations. The batteries provide direct current (DC) electricity

primarily for uninterruptible power supply (UPS) equipment, which in turn provides continuous,

uninterrupted alternating current (AC) power for the facility. The batteries may provide power for

minutes, hours or days depending on the electrical system design, although most commonly the

batteries power the UPS during brief electric utility outages lasting only seconds

In the application of stationary battery systems for telecommunications equipment, the

equipment is operated on DC power (typically 48 volts in a central office - main telephone switching

center or remote office). During normal operation when utility power is available, the

telecommunications (load) equipment is operated from the DC power supplied from the rectifiers,

which also serve to maintain full charge on the battery systems. In the event of a utility failure, the load

is supported from the battery until an emergency power source can be applied, such as a generator. The

typical design of a battery in the telecommunications application is to provide DC power to the load

equipment for a minimum of four hours if a generator is also installed at the site. If a generator is notinstalled at the site, the typical design of a battery system is to support the load equipment for eight

hours. If a utility outage appears to be for an extended duration (such as during a hurricane or ice storm)

a mobile generator would be mobilized to a site (that does not have a generator installed) to recharge

the battery system and support the site until utility power can be restored.

For outages longer than a few seconds, the batteries must continue to provide power until an

emergency power source can be started; Facilities that have no emergency power source follow a

written manual protocol that dictates an orderly shutdown of the highest electrical demand equipment

to extend battery life, followed after a specified interval by a complete power-down before the batteries

are exhausted. As mentioned earlier, the batteries most frequently provide power for a UPS during

brief, transient electric utility outages lasting at most, seconds. When electric utility outages last over 15seconds to one minute, the UPS or the Automatic Transfer Switch (ATS) recognizes this as a long

duration power outage and signals an emergency power source to start. After the emergency power

source is started and is allowed to stabilize, an Automatic Transfer Switch disconnects the facility from

the electric utility and connects the emergency power source to provided replacement AC electricity to

the facility, including the UPS. Once the emergency power source, such as a diesel engine-generator

(genset) or gas turbine coupled to a generator, is online, the UPS ceases drawing power from the battery

room, and recharging the batteries begins with DC power supplied by the UPS or a free-standing battery

charger. After electric utility power is restored, the batteries are again called on to supply power during

the very brief period while the Automatic Transfer Switch disconnects the emergency power source and

reconnects the electric utility. Recharging the batteries can add considerable additional load to the

emergency power source, potentially overloading it. To avoid this, most UPS systems large enough to

require a battery room have, as part of their electronic controls, a signal wire from the Automatic

Transfer Switch that the ATS energizes when emergency power is active. When this signal wire is

energized, the UPS recharges the batteries at a preselected reduced rate. When electric utility power is

restored, full rate recharging resumes.

The interval the battery room provides electric power is known as ride-through, and a battery

room is rated by the maximum amount of ride-through time it can provide at maximum rated load. An

approximately reciprocal relationship exists between the ride-through time and the electrical load on


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the batteries. Thus, a battery room rated to provide 15 minutes of ride-through while delivering a

maximum 900 amperes at 48 volts will provide more than 30 minutes of ride-through if the actual

demand is only 450 amperes. The total capacity (product of current and time, or ampere-hours)

increases at lower current discharge rates, an effect called Peukert's law.

The type of battery most commonly employed in battery rooms is the flooded lead-acid battery.

Batteries are installed in groups. Several batteries are wired together in a series circuit forming a group

providing DC electric power at 12, 24, 48 or 60 volts (or higher). Usually there are two or more groups of

series-connected batteries. These groups of batteries are connected in a parallel circuit. This

arrangement allows an individual group of batteries to be taken offline for service or replacement

without compromising the availability of uninterruptible power. Generally, the larger the battery room's

electrical capacity, the larger the size of each individual battery and the higher the room's DC voltage.

UPS-Uninterrupted Power Supply

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup

is an electrical apparatus that provides emergency power to a load when the input power source,

typically the utility mains, fails. A UPS differs from an auxiliary or emergency power system or standby

generator in that it will provide instantaneous or near-instantaneous protection from input power

interruptions by means of one or more attached batteries and associated electronic circuitry for low

power users, and or by means of diesel generators and flywheels for high power users. The on-battery

runtime of most uninterruptible power sources is relatively short515 minutes being typical for

smaller unitsbut sufficient to allow time to bring an auxiliary power source on line, or to properly shut

down the protected equipment.

While not limited to protecting any particular type of equipment, a UPS is typically used to protect

computers, data centers, telecommunication equipment or other electrical equipment where an

unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss.

UPS units range in size from units designed to protect a single computer without a video monitor

(around 200 VA rating) to large units powering entire data centers, buildings, or even cities.


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Switching Room

Mrs. Yvonne Ntiful took as through the switching room.

CDMA is a spread-spectrum technology that allows multiple frequencies to be used simultaneously.

CDMA codes every digital packet it sends with a unique key, and the CDMA receiver responds only to

that key (Walsh codes) and can pick out and demodulate the associated signal. One of the

characteristics

Of CDMA is that it uses multiple levels of diverse reception. Frequency,

Spatial, time, and path diversity. When a signal is received, it is

Received from a number of paths, some directly and others reflected from

Buildings, mountains, or other obstacles. The technology combines all these signals to create a clear and

reliable signal.

For a cell to be routed , certain communications processes has to happen in a split of seconds

which may not be seen or known by the user of a cellular phone.Thus:

Mobile station BTS BSC MSC , then the cycle repeats its self in the reverse direction from

MSC back to the mobile station of the called party.

The Base Station System (BSS)


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All radio-related functions are performed in the BSS, which consists of base station controllers (BSCs)

and the base transceiver stations (BTSs).

BSCThe BSC provides all the control functions and physical links between the MSC and BTS. It is a high-

capacity switch that provides functions such as handover, cell configuration data, and control of

Radio frequency (RF) power levels in base transceiver stations. A number of BSCs are served by an MSC.

Expresso Ghana owns five base station controllers and they are distributed as follows:

Two BSCs in Accra with one serving greater Accra region and another for Volta and eastern region. One in Kumasi (Bomso) serving Ashanti and Brong -Ahafo region. One in cape coast for central region and western region One in tamale controlling base transceiver stations in northern, upper east and upper west regions.

BTSthe BTS handles the radio interface to the mobile station. The BTS is the radio equipment

(transceivers and antennas) needed to service each cell in the network. A group of BTSs are controlled

by a BSC.

The BTS of Expresso are connected to the BSC by microwave. Expresso owns a number of BSC in Ghana

which are in the following regions; Eastern region, Greater Accra Region, Ashanti region, Central region

and the Northern region.

Within the Switching room is the transmission unit/Division. They use two main antennae; sector

antenna and Microwave antenna. They have the indoor unit and the outdoor unit.

The Indoor Unit (IDU) is the component of the antenna terminal that is located indoors. It is usually the

satellite routers. The IDU is connected to the ODU through RFA.

The Outdoor Unit (ODU) refers to a set of equipment which is placed inside the buildings. It consists of

LNB (Low Noise Block) and block up converter.

Expresso does freely on fibre as a backbone to its technical operations due to its capacity. Fibre has a

capacity of 155Mb which is equivalent to 63E1s. (1) E1 has a capacity of 2Mb. Connection between MUXand the BSC is through fibre. For expression keen element which they deal with is the transmit power.

Hence expresso does transmit with a power of -23dB and expect -30dB.

Network Operations Centre (NOC)

Lye Ayieku took us through the Network Operations Centre.Home locations register (HLR)The HLR is a database used for storage and management of

subscriptions. The HLR is considered the most important database, as it stores permanent data about

Subscribers, including a subscriber's service profile, location information, and activity status. When an

individual buys a subscription from one of the PCS operators, he or she is registered in the HLR of that

operator.

Visitor locations register (VLR)The VLR is a database that contains temporary information about

subscribers that is needed by the MSC in order to service visiting subscribers. The VLR is always


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integrated with the MSC. When a mobile station roams into a new MSC area, the VLR connected to that

MSC will request data about the mobile station from the HLR. Later, if the mobile station makes a call,

the VLR will have the information needed for call setup without having to interrogate the HLR each time.

Short Messaging Service: It allows short messages comprising 160 characters per page to be sent andreceived by Expresso customers.

The Intelligent Network

It enables expresso Ghana to control and manage all services they provide to its customers

The Intelligent Network, typically stated as its acronym IN, is network architecture intended both for

fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing

value-added services in addition to the standard telecom services such as PSTN, ISDN and GSM services

on mobile phones.

The intelligence is provided by network nodes on the service layer, distinct from the switching layer of

the core network, as opposed to solutions based on intelligence in the core switches or telephone

equipments. The IN nodes are typically owned by telecommunications operators (TelecommunicationsService Providers).

IN is based on the Signaling System #7 (SS7) protocol between telephone network switching centers and other

network nodes owned by network operators.Expressos IN helps in call routing, call charging, and it is part ofespressos SS7 network. SS7 is a signalling protocol that is used for signalling over the microwave interface. The IN

is made up of:

Service control point Service management point Service management access point.


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INTRODUCTION

We arrived at MTN at 9:30 am on the 4th March, 2011.

The MTN Group formally took over Ghanas leading mobile telecommunications service

provider, Areeba, a year after it purchased Investcom LLC, Areebas parent company.

MTN acquired Investcom in July 2006. Investcoms takeover added five million more customers to MTN

and has increased the number of countries where the Group operates mobile networks to 21.Announcing the rebranding of Areeba at a media workshop in Accra, the companys corporate service

executive, Mawuena Dumor, said the new name of the company will be reflected in all Areebas

corporate logo in the next few weeks.

Until August 2005 when Investcom bought into Scancom Ghana Limited, the original owners, Areeeba

Ghana was known as Spacefon. After the takeover, it maintained the combined name of Spacefon

Areeba for several months before Spacefon was dropped.

Since its incorporation into the MTN Group, Areeba Ghana has focused on a previous roll out backlog,

commissioning more than 280 base stations during the last three months of 2006, improving service and

call quality and strengthening network infrastructure. The company has launched several innovative

services into the Ghanaian market, a trend the company chief scribe says will continue.Market penetration of mobile telecommunications services in Ghana is growing exponentially. As at

December 2005, Areebas total subscription was 955,000. Today the network commands a clientele well

over two million spread across the 10 regions of the country.

The increase in mobile phone use in Ghana is a reflection of the growing trend of the industry in Africa.

A recent survey by the International Telecommunications Union (ITU) found that Africa has become the

worlds fastest mobile phone market.

The report said over the last five years, the continents mobile phone use increased at an annual rate of

65 percent, twice the global average. Africa gained more than 13 million new subscribers in 2003 alone.

Established in Johannesburg, South Africa in 1993 MTN has grown from a local to a global

mobile service company. In 1998 it had 4.1 million subscribers in South Africa but as at last year it had50 million subscribers in 21 countries in Africa and the Middle East.

It has 13 million subscribers in Nigeria, its largest market on the continent: nine million in South Africa

and 2.9 million in Ghana, its third largest market in Africa. Currently as at ending of 2010, MTN has 8.8

million subscribers.


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Operating Regions:

West and central Africa region (WECA) South and east Africa(SEA) Middle east and north Africa (MENA)

Investment of MTN: In 2009 MTN invested about 1 billion in Ghana.

Investment in people: In 2010 MTN spent 2 million Ghana Cedis on staff. They have also providedOnline Academic training for Staff and people.

MTN is built around 5 main core values namely:

Leadership Innovation Relationships Can do spirit Integrity

At the corporate and technology front, MTNs agenda is:

best network plan infrastructural investments and network upgrades continuous localization of senior staff building and sustaining relationships with stakeholders Enriching continuously of lives of staffsOther Achievement:

Re-establishment of 2nd floor maternity block at Korle-Bu. 21 days of Yello


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To effectively roll out very good services in Ghana, MTN follows the following procedure:

THE GSM NETWORK

GSM provides recommendations, not requirements. The GSM specifications Define the functions

and interface requirements in detail but do not address the Hardware. The reason for this is to limit thedesigners as little as possible but still To make it possible for the operators to buy equipment fromdifferent suppliers. The GSM network is divided into three major systems: the switching system (SS),

The base station system (BSS), and the operation and support system (OSS). The Basic GSM networkelements are shown below.

normal cellplanning

survey

systemdesign

implementationand system tuning

traffic andcoverageanalysis


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The Switching System

The switching system (SS) is responsible for performing call processing and subscriber-related functions.The switching system includes the following functional units: Home location registers (HLR)The HLR is a database used for storage and management of

subscriptions. The HLR is considered the most important database, as it stores permanent data aboutsubscribers, including a subscriber's service profile, location information, and activity status. When an

individual buys subscription from one of the PCS operators, he or she is registered in the HLR of thatoperator. Mobile services switching centre (MSC)The MSC performs the telephony switching functions of

the system. It controls calls to and from other telephone and data systems. It also performs such functionsas toll ticketing, network interfacing, common channel signalling, and others.

Visitor location registers (VLR)The VLR is a database that contains temporary information aboutsubscribers that is needed by the MSC in order to service visiting subscribers. The VLR is always

Integrated with the MSC. When a mobile station roams into new Mascara, the VLR connected to thatMSC will request data about the mobile station from the HLR. Later, if the mobile station makes a call,The VLR will have the information needed for call setup without having to interrogate the HLR eachtime. Authentication centre (AUC)A unit called the AUC provides authentication and encryption

parameters that verify the user's identity and ensure the confidentiality of each call. The AUC protects

network operators from different types of fraud found in today's cellular world.


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Equipment identity register (EIR)The EIR is a database that contains information about the identityof mobile equipment that prevents calls from stolen, unauthorized, or defective mobile stations.

The AUC and EIR are implemented as stand-alone nodes or as a combined AUC/EIR node.The Base Station System (BSS) All radio-related functions are performed in the BSS, which consists of

basestation controllers (BSCs) and the base transceiver stations (BTSs). BSCThe BSC provides all the control functions and physical links between the MSC and BTS. It is a

high-capacity switch that provides functions such as handover, cell configuration data, and control ofRadio frequency (RF) power levels in base transceiver stations. A number of BSCs are served by anMSC. BTSthe BTS handles the radio interface to the mobile station. The BTS is the radio equipment(transceivers and antennas) needed to service each cell in the network. A group of BTSs are controlled byaBSC.

The Operation and Support System

The operations and maintenance centre (OMC) is connected to all equipment inthe switching system and

to the BSC. The implementation of OMC is called the operation and support system (OSS). The OSS isthe functional entity from whichthe network operator monitors and controls the system. The purpose ofOSS is tooffer the customer cost-effective support for centralized, regional and local operational and

maintenance activities that are required for a GSM network. Animportant function of OSS is to provide anetwork overview and support themaintenance activities of different operation and maintenance

organizations.

Additional Functional ElementsOther functional elements are as follows: Message centre (MXE)The MXE is a node that provides integrated voice, fax, and data messaging.Specifically, the MXE handles short message service, cell broadcast, voice mail, fax mail, email,

And notification. Mobile service node (MSN)The MSN is the node that handles the mobile intelligent network (IN)services. Gateway mobile services switching centre (GMSC)a gateway is a node used to interconnect twonetworks. The gateway is often implemented in an MSC. The MSC is then referred to as the GMSC.

GSM interworking unit (GIWU)The GIWU consists of both hardware and software that providesan interface to various networks for data communications. Through the GIWU, users can alternate

between speech and data during the same call. The GIWU hardware equipment is physically located at

the MSC/VLR.

ANTENNA DESIGN

MTN GH considers the following architecture for antenna design:


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Vertical beam width Gain Horizontal Beam width Weight Frequency

THE MULTI MILLION ULTRA MODERN SWITCHING CENTRE-SAKAMAN

This multi-dollar switching is one of its kinds. They are only three in Africa; One in Cameroon, the other in South

Africa and the last one in Ghana. It consists of all the MSC, BSC and the others as described above. MTN acquired

this to cater for the majority of customers they have. This is to provide good Grade of Service as required by N.C.A

(National Communications Authority).There are four main containers holding telecom equipment and airconditioning systems. This can be classified basically under the following headings:

Base station subsystem(BSS) Network switching subsystem(NSS) Generators and Batteries Core data network(CDN)

BASE STATION SUBSYSTEM

The main part of the Base Station Subsystem is the Base station controller (BSC). The Base Station Controller

manages the radio resources for one or more BTSs. It is responsible for:

Management of mobility on MTN It collects data from base transceiver stations and the mobile devices.

MTN uses two major brands of BSCs namely Ericsson and Huawei. They are all connected with single mode fibre

cables. The BSCs uses SS7 signaling on the air interface.

NETWORK SWITCHING SUBSYSTEM

The network switching subsystem comprises of the Mobile Switching system (MSC) for intra network calls and the

Gateway Mobile switching centre (GMSC) for handling internetwork calls and international calls. The main functions

of the parts of the network are discussed below:

Mobile switching centre (MSC): it is responsible for call control, call charging (in conjunction with HLR), italso manages the mobility of MTN subscribers. It has the Home Location Register (HLR) built-in in most

cases. The home location register has a database of the subscribers on MTN network that stores permanently

subscriber information. The msc also has the visitor location register built in. The VLRis responsible for

storing temporary information of MTN subscribers who are on roaming.

Authentication centre (AUC): It is responsible for providing security information to the network. It does thisby authenticating users with the help of the Home location register.


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Equipment Identity Register: it checks the International mobile equipment identity numbers. It makes sureno stolen mobile devices are used on the MTN network.

Short Messaging Service (SMS) and Value Added services (VAS): A convenient facility of theGSM network is the short message service. A message consisting of a maximum of 160 alphanumericcharacters can be sent to or from a mobile station. This service can be viewed as an advanced form of

alphanumeric paging with a number of advantages. If the subscriber's mobile unit is powered off or hasleft the coverage area, the message is stored and offered back to the subscriber when the mobile is

powered on or has re-entered the coverage area of the network. This function ensures that the message

will be received. One of the valued Added Service MTN provides is call waiting. This service enablesthe mobile subscriber to be notified of an incoming call during a conversation. The subscriber can answer,

reject, or ignore the incoming call. Call waiting is applicable to all GSM telecommunications servicesusing a circuit-switched connection.

CONCLUSION

The trip exposed the students on the demands and requirements of every company. Also, the students

were made aware of the various job opportunities TELECOMMUNICATION engineers can do in the

Telecom industry. We also had a chance to see the ultra modern equipments the various companies

have. Furthermore we saw the difference between MTN and Expresso as to do with CDMA against GSM.

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