therson-cofie therson-cofie report.docx
TRANSCRIPT
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
1/16
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
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
2/16
2 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
3/16
3 | P a g e
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
http://localhost/var/www/apps/conversion/tmp/scratch_14/Copy%20of%20trial%20report.docxhttp://localhost/var/www/apps/conversion/tmp/scratch_14/Copy%20of%20trial%20report.docxhttp://localhost/var/www/apps/conversion/tmp/scratch_14/Copy%20of%20trial%20report.docx -
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
4/16
4 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
5/16
5 | P a g e
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
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
6/16
6 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
7/16
7 | P a g e
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)
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
8/16
8 | P a g e
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
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
9/16
9 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
10/16
10 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
11/16
11 | P a g e
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
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
12/16
12 | P a g e
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
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
13/16
13 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
14/16
14 | P a g e
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:
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
15/16
15 | P a g e
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.
-
7/28/2019 THERSON-COFIE THERSON-COFIE REPORT.docx
16/16
16 | P a g e
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.