communication network linking schools in huye
TRANSCRIPT
PROJECT REPORT
On
COMMUNICATION NETWORK LINKING SCHOOLS IN HUYE DISTRICT.
By
Jean Paul BAMBANZA
Reg.No: UG10102476
Under the guidance of
Dr. Celestin TWIZERE
Submitted to the DEPARTMENT OF ELECTRICAL AND ELECTRONICS
in the FACULTY OF APPLIED SCIENCES
in partial fulfillment of the requirement
for the award of the degree of
BACHELOR OF SCIENCE
in
Electronics and communication Systems Engineering
NATIONAL UNIVERSITY OF RWANDA
FACULTY OF APPLIED SCIENCES
DEPARTMENT OF ELECTRICAL AND ELECTRONICS
October 2011
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Bonafide Certificate
This is to certify that the project report titled “Communication Network Linking Schools in
Huye District” is the bonafide work of Mr. BAMBANZA Jean Paul who carried out research
under my supervision. Certified further, that to the best of my knowledge the work reported
herein does not form part of any other project report or dissertation on the basis of which a
degree or award was conferred on an earlier occasion on this or any other candidate.
Supervisor Head of Department
Dr. Celestin TWIZERE Eng. Ezechiel MANIRAGABA (Msc)
Internal Guide External Guide
Name: Name:
Submitted for University examination held in September 2011 at National University of
Rwanda, University Avenue, Butare, Rwanda.
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Declaration
We declare that, the project entitled, “Communication Network Linking Schools in Huye
District” is original work and has never been submitted to any university or other Institutions of
Higher learning. It is our own research where by other scholar‟s writings were sited and
references provided. We thus declare this is ours and was completed successfully under the
supervisor Dr. TWIZERE Celestin.
BAMBANZA Jean Paul
Signature:
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Abstract
Information and Communication Technologies (ICTs) is one of the very important pillars that
evolve the economy of our country. Provision of telecommunications and Internet access to
people in remote locations can dramatically contribute to changes in the community socio-
economic development.
In other hand, wireless communication technologies are developing faster and are more
popularity due to availability, security and low cost services they provide.
This project concerned of “COMMUNICATION NETWORK LINKING SCHOOLS IN
HUYE USING WIMAX TECHNOLOGY”.
In this project, communication network concepts and applications are described with the various
networking technologies. The WiMAX technology conception and advantages are presented.
Furthermore, a Radio planning study is done through Radio Mobile simulation tool, Calculations
results and a short discussion of the founded result from the deployed network to evaluate the
feasibility of our work. These phases are done with consideration and using the recently WiMAX
network implemented in the Huye district by the National University of Rwanda.
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Dedication
To my late mum
To my father
To my Brothers and Sisters
To my relatives and friends
I dedicate this project.
Jean Paul BAMBANZA
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Acknowledgement
We highly acknowledge our Supervisor Dr. Celestin TWIZERE, for his guidance, inspiration
and constant supervision as well as for providing necessary information regarding the project
through constructive, vibrant and brilliant ideas. Sincere appreciations for his courage,
commitment, competence to assist me fulfill such work. All in all this work couldn‟t be
accomplished without his intervention.
We greatly thank the Government of Rwanda through the Ministry of Education, and the
National University of Rwanda for the successful completion of this dissertation. We owe a deep
sense of gratitude to the staff of the Faculty of Applied Science, especially those of electrical and
electronics engineering department for hectic work of teaching.
Finally and above all, we thank God for his mercy, grace, and goodness to us during all our
studies.
God bless you all.
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Table of Contents
Bonafide Certificate .................................................................................................................... i
Declaration................................................................................................................................. ii
Abstract .................................................................................................................................... iii
Dedication ................................................................................................................................. iv
Acknowledgement ......................................................................................................................v
Table of Contents ...................................................................................................................... vi
List of Tables ............................................................................................................................ xi
List of Figures .......................................................................................................................... xii
List of Abbreviation and Acronyms......................................................................................... xiii
CHAPTER 1: INTRODUCTION ................................................................................................1
1.1.Background of the study ....................................................................................................1
1.2. Statement of the Problem ..................................................................................................1
1.3. The objectives of the study................................................................................................2
1.4. Significance of the study ...................................................................................................2
1.5. Scope of the study .............................................................................................................2
1.6. Organization of the study ..................................................................................................2
CHAPTER 2. COMMUNICATION NETWORK TERMINOLOGIES AND CONCEPTS .........3
2.1. Communication network concepts and fundamentals ........................................................3
2.1.1. Computer Network History ........................................................................................3
2.1.2. Description .................................................................................................................3
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2.1.2.1 Communication.....................................................................................................3
2.1.2.2 A network .............................................................................................................4
2.1.2.3 The Network Architecture .....................................................................................4
2.1.3 Wireless network .........................................................................................................5
2.1.3.1 Wireless LAN .......................................................................................................5
2.1.3.2 Wireless MAN ......................................................................................................5
2.1.3.3 Wireless WAN ......................................................................................................6
2.1.4 Wireless Networks Configuration ................................................................................6
2.1.5 Computer Network ......................................................................................................6
2.1.6. Fixed wireless and Mobile wireless access..................................................................7
2.1.6.1 Fixed Wireless Access ..........................................................................................7
2.1.6.1. Mobile wireless access (MWA)............................................................................8
2.2. WiMAX description .........................................................................................................8
2.2.1. Family of WiMAX standards ......................................................................................8
2.2.2. IEEE 802.16-2004 ......................................................................................................9
2.2.3. Performance characteristics of 802.16-2004 standards ................................................9
2.3. WiMAX network ............................................................................................................ 10
2.3.1. Extending WiMAX Networks .................................................................................. 10
2.3.2. Advantages of WiMAX: ........................................................................................... 11
2.3.3. BreezeMAX system ................................................................................................. 12
2.4. Propagation and path loss models ................................................................................... 13
2.4.1. Free space Propagation model .................................................................................. 13
2.5. Parameters considered when designing a link budget ...................................................... 15
2.5.1. Fresnel Zone ............................................................................................................. 15
2.5.2. Free Space Path Loss ................................................................................................ 15
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2.5.3. Received Signal Level .............................................................................................. 16
2.5.4. Receiver Sensitivity .................................................................................................. 16
2.5.5. Antenna Gain ........................................................................................................... 16
2.5.6. Transmit Power ........................................................................................................ 16
2.5.7. Effective isotropic radiated power ............................................................................ 16
2.6. Link budget calculation ................................................................................................... 17
2.6.1. Receiver sensitivity (Rx) .......................................................................................... 17
2.6.2. Link feasibility formula ............................................................................................ 17
2.6.3. Signal-to-Noise ratio ................................................................................................ 17
CHAPTER 3: NETWORK DESIGN METHODOLOGY .......................................................... 18
3.1. Introduction .................................................................................................................... 18
3.2. Research environment ..................................................................................................... 18
3.2.1. Overview .................................................................................................................. 18
3.2.2. Education ................................................................................................................. 19
3.2.3. Energy ...................................................................................................................... 19
3.3 Suggestion of choosing WiMAX ..................................................................................... 20
3.3.1. WiMAX Base Station Selection................................................................................ 20
3.3.1.1. Performance ....................................................................................................... 20
3.3.1.2. Innovative Design .............................................................................................. 21
3.3.1.3. Flexible Portfolio ............................................................................................... 21
3.3.2. Antenna selection and positioning ............................................................................ 21
3.3.2.1. Calculating Antenna Coverage ........................................................................... 21
3.3.2.2 Antennae positioning for best results ................................................................... 22
3.4. Research Methodology ................................................................................................... 22
3.4.1. Equipments Required ............................................................................................... 22
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3.4.2. ITS Irregular Terrain model ...................................................................................... 24
3.4.2.1. Area mode ......................................................................................................... 24
3.4.2.2. Point-to-Point (PTP) mode ................................................................................. 24
3.4.3. Site survey................................................................................................................ 24
3.4.4. BS placement ........................................................................................................... 25
3.4.5. Brief description of NUR WiMAX network: ............................................................ 25
3.5. Simulation work ............................................................................................................. 26
3.5.1. Input parameters ....................................................................................................... 26
3.5.1.1. Network parameters ........................................................................................... 26
3.5.1.2. Antenna characteristics ...................................................................................... 27
3.5.1.3. Environmental parameters .................................................................................. 27
3.5.2. Output parameters .................................................................................................... 27
CHAPTER 4. RESULTS ANALYSIS AND INTERPRETATION............................................ 28
4.1. Coverage requirement ..................................................................................................... 28
4.2. Results Presentation ........................................................................................................ 29
4.3. Network path profiles ..................................................................................................... 29
4.3.1. E.A.V Kabutare ........................................................................................................ 30
4.3.2. Ecole Secondaire Kotana .......................................................................................... 30
4.3.3. Ecole Secondaire Nyarunyinya ................................................................................. 31
4.3.4. Groupe Scolaire Gatagara ........................................................................................ 31
4.3.5. Groupe Scolaire Parents de Butare ........................................................................... 32
4.3.6. Petit Seminaire Virgo Fidelis. ................................................................................... 32
4.4. Analysis of the simulation ............................................................................................... 33
4.5. Comparing the simulation and calculation results ............................................................ 35
4.6. Received power in dBm .................................................................................................. 37
x
4.7. Simulation tool limits ...................................................................................................... 37
CHAPTER 5.CONCLUSION AND RECOMMENDATION .................................................... 38
5.1. Conclusion ...................................................................................................................... 38
5.2. Recommendation ............................................................................................................ 38
REFERENCES ......................................................................................................................... 39
APPENDIX .............................................................................................................................. 41
xi
List of Tables
Table 2.1: WiMAX Features [16] .............................................................................................. 12
Table 2.2: GHz Frequency Bands [9]. ....................................................................................... 12
Table 3.1: NUR Base Stations operating Frequencies ................................................................ 25
Table 4.1: Different parameters measured by using Radio Mobile software ............................... 34
Table 4.2: Comparison of calculated and simulation results ....................................................... 36
xii
List of Figures
Figure 2.1: Fresnel Zone to clear obstruction ............................................................................. 15
Figure 3.1: Administrative map of Huye district ........................................................................ 19
Figure 3.2: Radio mobile showing the radio link. ...................................................................... 23
Figure 3.3: NUR WiMAX Network, Cartesian radio coverage .................................................. 26
Figure 4.1: Digital map of Huye mountain BS coverage [radio mobile]. .................................... 28
Figure 4.2: Digital map with sites pointed [radio mobile]. ......................................................... 29
Figure 4.3:WiMAX link from Huye Mountain BS to E.A.V Kabutare ....................................... 30
Figure 4.4:WiMAX link from Huye Mountain BS to E.S Kotana. ............................................. 30
Figure 4.5:WiMAX link from Huye Mountain BS to E.S Nyarunyinya. .................................... 31
Figure 4.6:WiMAX link from Huye Mountain BS to G.S Gatagara ........................................... 31
Figure 4.7: WiMAX link from Huye Mountain BS to G.S parent de Butare............................... 32
Figure 4.8: WiMAX link from Huye Mountain BS to Petit Seminaire Virgo Fidelis .................. 32
Figure 4.9: Received power diagram ......................................................................................... 37
xiii
List of Abbreviation and Acronyms
BPSK: Binary Phase Shift Keying
BS: Base Station
BWA: Broadband Wireless Access
CPE: Costumer Equipment premise
DSL: Digital Subscriber Line
E.S : Ecole Secondaire
EWASA : Energy Water and Sanitation Authority
FWA : Fixed Wireless Access
G.S : Groupe Scolaire
GPS: Global Position Service.
ICT: Information and Communication Technology
IEEE: Institute of Electrical and Electronics Engineers
IP: Internet Protocol
ISP: Internet Service Provider
ITM: Irregular Terrain Model
ITS: Institute of Telecommunication Sciences
LAN: Local area network
LOS: Line of Sight
MAN: Metropolitan Area Network
MHz: Mega Hertz
MINEDUC: Ministry of Education
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MWA: Mobile Wireless Access
NLOS: Non-Line-of-Sight
NUR: National University of Rwanda
OFDM: Orthogonal Frequency Division Multiplexing
PLOS: Partial-Line-of-Sight
PMP: Point to Multipoint
PSTN: Public Switched Telephone Network
PTP: Point-to-Point
QAM: Quadrature Amplitude Modulation
QoS: Quality of Service
QPSK: Quadrature Phase Shift Keying
RF: Radio Frequency
SNR: Signal to Noise Ratio
STRM: Shuttle Radar Topography Mission
SU: Subscriber Unit
UMTS: Universal Mobile Telecommunication System
VoIP: Voice over Internet Protocol
VSWR: Voltage Standing Wave Ratio
Wi-Fi: Wireless Fidelity
WiMAX: Worldwide Interoperability for Microwave Access
SS: Subscriber Station
WAN: Wide Area Network
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CHAPTER 1: INTRODUCTION
1.1.Background of the study
The Rwandan vision 2020 highlights the crucial role that science and technology will play for
Rwandan development. The Rwandan government views Information and Communication
Technology (ICT) as a key tool for transforming the economy, with the education sector playing
an important role in developing the necessary human resources. The Ministry of Education is
active in promoting the shift in practices of teaching and learning, with use of ICT in schools and
is coordinating the One Laptop per Child project in the countrywide; to help people to accelerate
and expand the knowledge of ICT and mainly to help them to get used of how to exploit the
capabilities offered by access to ICT.
Broadband network connectivity is one of the key technologies that enable government to
quickly, efficiently and effectively share resources in government institutions including schools,
to increase network capacity and reliability, support high-quality, high-bandwidth voices, data
and video communication, connect buildings or schools miles apart.
Due to mobility, availability, security and low cost services provided in Wireless Networks,
wireless communications are gaining a great popularity and they are widely deployed and
implemented to support many ICT projects among which education projects and other many e-
learning projects. WiMAX technology is chosen in this work to implement the communication
network linking schools and the case study is Schools in Huye District.
1.2. Statement of the Problem
Schools in Huye district need to be interconnected in order to improve their services such as
sharing educational information in remote areas unreachable by wires; helping young people to
get used of how to exploit the capabilities offered by access to ICT, increasing the capacity of
teachers and students by doing research. Moreover, the National University of Rwanda (NUR)
has implemented a WiMAX network in the Huye district of the Southern province of Rwanda.
This research work aims to study how broadband network technology can be used to provide
connectivity for the schools in Huye District.
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1.3. The objectives of the study
The objective of this study aims the study of the feasibility of the deployment of WiMAX
network in Huye district and to make assessment of how schools can be connected wirelessly so
that they can share data resources in remote areas.
1.4. Significance of the study
1. The study is of a significant use to the designers of ICT development programs especially
MINEDUC, with regard to the development of schools in rural areas.
2. The study is intended to select and identify suitable wireless equipments necessary for the
network linkage of different schools.
3. The study will contribute to schools in rural areas to share data resources in remote areas
unreachable by wires using wireless Broadband technology.
1.5. Scope of the study
The Scope of the study covers both geographical and subjects. Under the geographical scope, the
study is carried out within the geographical limits of Huye district. Under the subject scope the
study covers role that Broadband network connectivity play in the development of education in
Rwanda.
1.6. Organization of the study
The study is divided into five chapters. The first chapter is made up of the general introduction
giving the background, the statement of the problem, objectives, significance and the scope of
the study. The second chapter is mainly the review of the related literature with reference to
different sources of data especially from textbooks, annual reports, I-TU Recommendations and
relevant documents without forgetting the primary data. Chapter three describes different
network design methodologies and approaches used to fulfill our goal .The fourth chapter cover
the presentation of the results analysis of research and the fifth one is the conclusion and
recommendation.
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CHAPTER 2. COMMUNICATION NETWORK TERMINOLOGIES AND CONCEPTS
2.1. Communication network concepts and fundamentals
This chapter contains theoretical concepts and fundamentals that support this project. It gives a
brief description about the terms that are used during the development. It also provides
definitions and characteristics; the first part gives a brief communication introduction and
concepts, communication systems and WiMAX description.
2.1.1. Computer Network History
Before the advent of computer networks that were based upon some type of telecommunications
system, communication between calculation machines and early computers was performed by
human users by carrying instructions between them.
Today, computer networks are the core of modern communication. All modern aspects of the
Public Switched Telephone Network (PSTN) are computer-controlled, and telephony
increasingly runs over the Internet Protocol, although not necessarily the public Internet. The
scope of communication has increased significantly in the past decade, and this boom in
communications would not have been possible without the progressively advancing computer
network. Computer networks and the technologies needed to connect and communicate through
and between them, continue to drive computer hardware, software, and peripherals industries.
This expansion is mirrored by growth in the numbers and types of users of networks from the
researcher to the home user [4].
2.1.2. Description
2.1.2.1 Communication
Communication is the activity of conveying meaningful information. Communication requires a
sender, a message, and an intended recipient, although the receiver need not be present or aware
of the sender's intent to communicate at the time of communication; thus communication can
occur across vast distances in time and space.
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2.1.2.2 A network
A network is a collection of computers, printers, routers, switches, and other devices that are able
to communicate with each other over same transmission media. Thus, a network can be anything
from two computers connected by serial cable to thousands of computers connected by high-
speed data communication links dispersed throughout the world. A network provides two
principle benefits:
The ability to communicate;
The ability to share.
2.1.2.3 The Network Architecture
Network architecture is the overall geographical layout of the network and how it connects to
other networks. It determines how data will flow between computers on a network, how the
computer will communicate with one another and how they will share information and resources
as well as the overall geographical layout of the network. In terms of geographical layout, a
network is subdivided as follows:
Local area network (LAN): which is usually a small network constrained to a small
geographic area. With LAN, emphasis is put on fast and powerful data exchange within a
locally restricted area [3].
Metropolitan area networks (MAN): A metropolitan area network (MAN) is a network that
connects two or more local area networks or campus area networks together but does not
extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are
connected to create a metropolitan area network.
Wide area network (WAN): A wide area network (WAN) is a computer network that covers
a large geographic area such as a city, country, or spans even intercontinental distances,
using a communications channel that combines many types of media such as telephone lines,
cables, and air waves. WAN must be able to transmit data on very different data media and
over several thousand kilometers [3].
5
Personal Area Network (PAN): A personal area network (PAN) is a computer network
used for communication among computer and different information technological devices
close to one person. Some examples of devices that are used in a PAN are personal
computers, printers, fax machines, telephones and scanners.
Networks may be classified according to a wide variety of characteristics such as topology,
connection method and scale.
2.1.3 Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any
kind. It is a method by which telecommunications networks and enterprise, installations avoid
the costly process of introducing cables into to a building, or as a connection between various
equipment locations. Wireless telecommunications networks are generally implemented and
administered using a transmission system called radio waves [1], [2]. Wireless network is
subdivided as follows:
2.1.3.1 Wireless LAN
A wireless LAN is a wireless local area network which works to link two or more computers
and/or devices without using wires. This wireless LAN gives users the mobility to move around
within a broad coverage area and still be connected to the network [15].
2.1.3.2 Wireless MAN
Wireless MAN technology brings the network to a building, users inside the building will
connect to it with conventional in-building networks such as, for data, Ethernet (IEEE 802.3) or
wireless local area networks (IEEE 802.11).With appropriate cost reductions, the user‟s
computer could it self use wireless MAN for its access, either with a direct link to a remote BS
or, in typical indoor scenario, with a link to a local indoor BS that receives its access from an
outdoor wireless MAN link or from, for example a cable modem [5].
6
2.1.3.3 Wireless WAN
Wireless wide area networks are wireless networks that typically cover large outdoor areas.
These networks can be used to connect branch offices of business or as a public internet access
system. They are usually deployed on the 2.4 GHz band. A typical system contains base station
gateways, access points and wireless bridging relays [6].
2.1.4 Wireless Networks Configuration
The term wireless networking refers to technology that enables two or more computers to
communicate using standard protocols, but with out network cabling. A wireless network can
also use access point, or Base station. The access point acts like a hub, providing connectivity for
the wireless computers. It can connect the wireless network to a wired network, allowing
wireless computer access to network resources, such as file servers or existing internet
connectivity. There are two types of access points [7]:
Dedicated hardware access point (HAP): Hardware access point offer comprehensive support
of most wireless features.
Software access point which runs on a computer equipped with wireless network interface
card as used as used in an ad-hoc or peer-to-peer wireless network.
A wireless computer can roam from one access point to another, with the software and hardware
maintaining a steady network connection by monitoring the signal strength from in range access
point and locking on the one of the best quality [7].
2.1.5 Computer Network
A computer network, often simply referred to as a network, is a collection of computers and
devices interconnected by communications channels that facilitate communications and allows
sharing of resources and information among interconnected devices. Computer networks can be
used for a variety of purposes [4]:
Facilitating communications. Using a network, people can communicate efficiently and
easily via email, instant messaging, telephone, video telephone calls, and video conferencing.
7
Sharing hardware: In a networked environment, each computer on a network may access
and use hardware resources on the network, such as printing a document on a shared network
printer.
Sharing files, data, and information: In a network environment, authorized user may
access data and information stored on other computers on the network. The capability of
providing access to data and information on shared storage devices is an important feature of
many networks.
Sharing software: Users connected to a network may run application programs on remote
computers.
All networks are interconnected to allow communication with a variety of different kinds of
media, including twisted-pair copper wire cable, coaxial cable, optical fiber, power lines and
various wireless technologies [4].
2.1.6. Fixed wireless and Mobile wireless access
2.1.6.1 Fixed Wireless Access
Fixed wireless Access (FWA) refers to a wireless infrastructure replacing regular cable. It is
known as Radio Fixed Wireless or Local loop, and has the main purpose of replacing the “last
mile “connection between a user and backbone, thus serving as backhaul. There are three
different types of FWA topologies [10]:
Point-to-Point (PTP) systems has two base stations with the communication statistically
configured for a link between these two base stations only .This dedicated link is
characterized by higher bandwidth compared to PMP systems and can utilize directed
antennas.
Point to multipoint (PMP) is an access network with one more powerful base station and
many smaller subscriber stations. Users can get immediate access to the network after
installing only user equipment. Here the subscriber station can deploy directed antennas
towards the base station. Where the base station has Omni-directional or a cluster of directed
antennas.
8
Multipoint to multipoint also called mesh network. This is where there is no centralized
base station. As more user transmitters join the mesh, the covered area is increased. This
architecture adds complexity in routing, QoS and node discovery amongst other things.
2.1.6.1. Mobile wireless access (MWA)
Specifications are provided such that the mobility of SS at 125KMPH is allowed. Put together,
the 802.16.e technology would enable the SS to get the broadband wireless access(BWA) at all
times in all locations, either when the user is stationary, or at pedestrian speed or when travelling
at 125KMPH [14].
2.2. WiMAX description
WiMAX (Worldwide Interoperability for Microwave Access) is the trade name for a group of
wireless technologies that emerged from the IEEE 802.16 Wireless MAN (Wireless Metropolitan
Area Network) family of standards. It uses an air interface based on orthogonal frequency
division multiplexing (OFDM), very robust against multi-path propagation and frequency
selective fading [17].
WiMAX uses a technique of adaptively modulating the signal to adapt to changing channel
conditions. This technique alternates these four specified types of digital modulation depending
on the robustness of the connection: Binary Phase shift keying (BPSK), Quadrature Phase Shift
Keying (QPSK), 16 Quadrature Amplitude Modulation (16-QAM), and 64 Quadrature
Amplitude Modulation (64-QAM), to modulate bits to the complex constellation points. The aim
of adaptive modulation usage in WiMAX OFDM PHY based system, is to combat the temporal
variation in quality on multipath fading channel [8].
2.2.1. Family of WiMAX standards
In 2001, the WiMAX Forum was created in order to promote the standard and to help ensure
compatibility and interoperability across multiple vendors, much like the Wi-Fi Alliance does for
the IEEE 802.11x family of standards.
9
First, the WiMAX adopted, in January 2003, of 802.16a standard (2-11 GHz) which has all but
been forgotten as the focus recently has been on IEEE 802.16-2004, which is also known as
802.16REVd or .16-2004. 802.16-2004 is an improvement to the .16a standard that was certified
in October 2004. Separately, there is also IEEE 802.16e, another variation of WiMAX that
follows the 802.16-2004 standards, but is incompatible with it.
The one thing that both of these proposed standards have in common is that they address the
same frequency range (sub 11GHz). For our case study, where we want to provide network for
schools in the same network communication services, we are more concerned with the IEEE
802.16-2004, a fixed wireless access technology.
2.2.2. IEEE 802.16-2004
As we said, this WiMAX standard is a fixed wireless access technology, meaning that it is
designed to serve as a wireless DSL replacement technology, to compete with the incumbent
DSL or broadband cable providers or to provide basic voice and broadband access in
underserved areas where no other access technology exists; examples include developing
countries and rural areas in developed countries where running copper wire or cable does not
make economic sense. 802.16-2004 is also a viable solution for wireless backhaul for Wi-Fi
access points or potentially for cellular networks, in particular if licensed spectrum is used.
Finally, in certain configurations, WiMAX Fixed can be used to provide much higher data rates
and therefore be used as a T-1 replacement option for high-value corporate subscribers [8].
2.2.3. Performance characteristics of 802.16-2004 standards
Based upon modeling done by one of the technology's proponents, 802.16-2004, the fixed
version of the WiMAX standard, should be able to achieve throughput of 11Mbps, assuming the
use of an outdoor antenna and a 3.5MHz paired channel allocation1 in the 3.5GHz spectrum
band. With NLOS (non-LOS), the claimed average throughput decreases to 8Mbps with a cell
radius of 100meters in a dense urban area and reaching a few kilometers in a rural deployment.
802.16-2004 can also support VoIP (Voice over Internet Protocol), and assuming that the G.729
(8kbps) codec is used, it reportedly supports up to 96 simultaneous voice calls in a 3.5MHz radio
channel [8].
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2.3. WiMAX network
In its simplest form, a WiMAX network consists of a WiMAX base station and multiple
WiMAX subscriber stations (fixed or mobile). WiMAX base station is mounted on a tower.
WiMAX subscriber station is WiMAX customer premise equipment (CPE) that is located inside
the house. WiMAX base station on the tower communicates wirelessly with the WiMAX
subscriber station located inside the house. WiMAX base station on the tower is physically wired
to the Internet service provider's (ISP) network through fiber optic cables. At the ISP network
terminus, data aggregated from all base stations are sent to the Internet backbone through high-
speed high-capacity “thick" fiber-optic cables. A subscriber is associated with a particular base
station for each Internet access session, but each Internet access session could be from a different
location.
The point-to-multipoint (PMP) operation mode is used for communication between a base station
and multiple subscriber stations; point-to-point (PTP) operation mode is used for communication
between two base stations (for backhaul purposes). In the mesh mode of operation, subscriber
stations connect to each other to form a mesh topology. This is useful when a particular
subscriber station is not in the vicinity of a base station (or a relay station) but can reach a base
station through another subscriber station. In multihop mode, as against the mesh mode, a
subscriber station can reach a base station through multiple hops consisting of only relay stations
and base station. Relay stations are used to extend network coverage and improve system
throughput [19].
2.3.1. Extending WiMAX Networks
In cities with very large number of high-rise buildings, WiMAX signals from a fixed subscriber
or a mobile subscriber may not reach the base station due to obstructions caused by these
buildings. One naive solution to this problem is to increase the number of base stations so that
the probability of a subscriber being obstructed by buildings is very less. However, due to the
cost of WiMAX base stations, this could be prohibitively costly. An alternate solution is to use
WiMAX relay stations. WiMAX relay stations are low-cost counterparts of WiMAX base
stations.
11
With relay stations, in a situation where signals from a subscriber cannot reach the base station,
the fixed subscriber station or the mobile subscriber station can connect to a relay station if one
is available. Signals from the subscriber station could then take multiple hops to the base station
through one are more relay stations thereby improving the range of network coverage [19].
2.3.2. Advantages of WiMAX:
The advantages of using IEEE 802.16/WiMAX technology for wireless communication services
can be summarized as follows:
High bandwidth: Due to the large transmission bandwidth, transmission delay for high
quality images such as ultrasound and images can be reduced considerably.
Quality of Service support: With the predefined QoS framework, transmission of data can
be performed efficiently.
WiMAX infrastructure is very easy and flexible therefore it provides maximum reliability
of network and consent to actual access to end users.
WiMAX coverage: The single station of Wimax can operate and provide coverage for
hundred of users at a time and manage sending and receiving of data at very high speed with
full of network security. It also has high speed of connectivity over long distance and high
speed voice and is needed for a kind of network.
Adaptive modulation and coding: Adaptive modulation and coding scheme can connect
more users. It is a technique to maximize throughput and able to setup connection in a low
signal strength and noisy environment.
Mobility support: WiMAX offer optimized handover which support fully mobility
application such as voice over internet protocol (VoIP). It has also the power saving
mechanism which increases the battery life of handheld devices.
Strong security: WiMAX supports extensible security feature for reliable data exchange. It
uses Advanced Encryption Standard (AES) encryption for secure transmission and for data
integrity; it uses data authentication mechanism [18].
12
Property Value
Range 50 km (LOS), 6-8 km (NLOS)
Data Rate 70 Mbps (shared)
Spectrum 2.3 - 2.7 GHz, 3.4 - 3.6 GHz, 5.8 GHz (unlicensed)
Access Types Fixed, nomadic/portable, mobile
Modes of operation Point-to-point, point-to-multipoint, mesh mode, multihop mode
Channel Size 1.5 MHz to 20 MHz (exible)
Spectral Efficiency 3.7 (bit/s)/Hz (for 802.16-2004)
Table 2.1: WiMAX Features [16]
2.3.3. BreezeMAX system
The BreezeMAX system is the one chosen by the National University of Rwanda WiMAX
project to provide the Southern Province of Rwanda, and especially the University, with this
modern communication system. BreezeMAX 3000 is Alvarion's WiMAX platform for the 3 - 4
GHz licensed frequency bands. It is designed specifically to meet the unique requirements of the
wireless Metropolitan Area Network (MAN) environment and to deliver broadband access
services to a wide range of customers. BreezeMAX supports a wide range of network services,
including Internet access, VPNs and Voice over IP [9].
BreezeMAX products are currently available in the 3.3 GHz, 3.5 GHz and 3.6 GHz frequency
bands and the actual NUR BreezeMAX uses the 3.3 GHz band. Here is a table for the 3.3 GHz
frequency band.
Series (band) Duplex Separation Uplink Frequency Downlink Frequency
3.3e 50 MHz 3366-3385 MHz 3316-3335 MHz
3.3f 50 MHz 3381-3400 MHz 3331-3350 MHz
3.3g -76 MHz 3300-3324 MHz 3376-3400 MHz
Table 2.2: GHz Frequency Bands [9].
13
A BreezeMAX system comprises the following:
Customer Premise Equipment (CPE): BreezeMAX Subscriber Units and Alvarion's Voice/
Networking Gateways.
Base Station (BS) Equipment: BreezeMAX Base Station equipment, including the modular
Base Station and its components and the stand-alone Micro Base Station.
Networking Equipment: Standard switches/routers and other networking equipment,
supporting connections to the backbone and/or Internet.
Management Systems: SNMP-based Management, Billing and Customer Care, and other
Operation Support Systems.
2.4. Propagation and path loss models
Path loss (or path attenuation) is the reduction in power density (attenuation) of
an electromagnetic wave as it propagates through space. Path loss normally includes propagation
losses caused by the natural expansion of the radio wave front in free space, when the signal
passes through media not transparent to electromagnetic waves, diffraction losses when part of
the radio wave front is obstructed by an opaque obstacle, and losses caused by other phenomena.
And in our case we are dealing with Line of Sight in which there are no obstacles due to the
earth‟s surface or other obstacles. Path loss is expressed in dB and depends on [26]:
The distance between transmitting and receiving antennas.
Line of sight clearance between the receiving and transmitting antennas.
Antenna height.
2.4.1. Free space Propagation model
The free space propagation model is used to predict the received signal strength when the
transmitter and receiver have a clear, unobstructed line-of-sight path between them. The free
space power received by a receiving which is separated from a radiating transmitter antenna by a
distance d, is given by the free space equation.
rttr GGd
PP
2
4
(2.1)
14
If the losses are also present, we can rewrite the above equation as:
(2.2)
Where
24
dFSPLLp
22
24
fdc
FSPL
(2.3)
In dB, the equation (2.3) becomes
22
2
log10log104
log10 fdc
FSPL
fdc
FSPL log20log204
log20
dfFSPL log20log204.32 (f in MHz, d in Km)
If d is given in miles the equation becomes:
dfFSPL log20log206.36 (f in MHz, d in miles)
And in dB, the equation (2.2) becomes.
FSPLGGPP trtr
Where Pt is the transmitted power in dBm, Pr is the received power in dBm, Gt is the transmitter
antenna gain (base station) in dB, Gr is the receiver antenna gain (subscriber station) in dB, d is
p
rtt
rttr
LL
GGP
L
GG
dPP
00
2
4
15
the separation distance between transmitter and receiver in meters, L is the system loss factor not
related to propagation (L≥1), and λ is the wave length in meters.
2.5. Parameters considered when designing a link budget
2.5.1. Fresnel Zone
Radio waves travel in a straight line, unless something refracts or reflects them. The energy of
spread out the farther they get from the radiating source like ripples from a rock thrown into a
pond. The area that the signal spreads out into is called the Fresnel zone. If there is an obstacle in
the Fresnel zone, part of the radio signal will be diffracted or bent away from the straight-line
path. The practical effect is that on a point-to-point radio link, this refraction will reduce the
amount of RF energy reaching the receive antenna. The thickness or radius of the Fresnel zone
depends on the frequency of the signal; the higher the frequency, the smaller the Fresnel zone.
Figure2.1 shows how the Fresnel zone is fattest in the middle. As distance increase, the Fresnel
Zone gets father. For long ranges, higher antennas are required for the Fresnel Zone to clear
obstacles [28].
Figure 2.1: Fresnel Zone to clear obstruction
2.5.2. Free Space Path Loss
As signals spread out from a radiating source, the energy is spread out over a larger surface area.
As this occurs, the strength of that signal gets weaker. Free space path loss (FSPL), measured in
dB, and specifies how much the signal has weakened over a given distance.
dfFSPL log20log204.32 (f in MHz, d in Km) (2.4)
16
Converting distance in miles
dfFSPL log20log206.36 (f in MHz, d in miles) (2.5)
2.5.3. Received Signal Level
Received signal level is the actual received signal level (usually measured in negative dBm)
presented to the antenna port of a radio receiver from a remote transmitter.
2.5.4. Receiver Sensitivity
Receiver sensitivity is the weakest RF signal level (usually measured in negative dBm) that a
radio needs to correct here your format receive in order to demodulate and decode a packet of
data without errors.
2.5.5. Antenna Gain
Antenna gain is the ratio of how much an antenna boosts the RF signal over a specified low-gain
radiator. Antennas achieve gain simply by focusing RF energy. If this gain is compared with an
isotropic radiator, it is measured in dBi. If the gain is measured against a standard dipole
antenna, it is measured in dBd. Note that gain applies to both transmit and receive signals.
2.5.6. Transmit Power
The transmit power is the RF power coming out of the antenna port of a transmitter. It is
measured in dBm and does not include the signal loss of the coax cable or the gain of the
antenna.
2.5.7. Effective isotropic radiated power
Effective isotropic radiated power (EIRP) is the actual RF power as measured in the main lobe
(or focal point) of an antenna measured in (dBm). It is equal to the sum of the transmit power
into the antenna (in dBm) added to the dBi gain of the antenna minus cable losses (Ct).
ttt CGPEIRP (2.6)
17
2.6. Link budget calculation
2.6.1. Receiver sensitivity (Rx)
The minimum RF signal power level required at the input of a receiver for certain performance.
The antenna transmitted power equal to the transmitted output power minus cable loss plus the
transmitting antenna gain. In the case of a real system, we must consider the actual antenna gains
and cable losses in calculating the received signal power Pr:
FSPLGGPP trtr (2.7)
2.6.2. Link feasibility formula
To determine if a link is feasible, compare the calculated received power level with the receiver
sensitivity threshold. The link is theoretical feasible if Received signal power level >= RX
If the receive power level is greater than or equal to the receiver sensitivity threshold then the
link may be feasible since the signal should be strong enough to be successfully interpreted by
the receiver [28].
2.6.3. Signal-to-Noise ratio
SNR (Signal- to –Noise ratio) measurements provide information on the actual operating
condition of the receiver, including interference, noise levels, and signal strength. Those
measurements are also done by the BS. It is the SNR level, which determines the type of
modulation to be used. This is an important parameter in digital data transmission because it
indicates how the network is powerful against the noise. It is a measure of system error
performance. The higher the SNR is, the higher is the quality of the received signal. This is
determined in the formula below:
Noisepower
rSignalpoweSNR 10log10
Where SNR is the signal-to-noise ratio in decibels (dB).
18
CHAPTER 3: NETWORK DESIGN METHODOLOGY
3.1. Introduction
Research methodology is a system of collecting data for research project, and methodology
refers to a set of methods and principles that are used when studying a particular kind of work.
Having presented the background information, different technologies that can help to connect
schools in the district and the advantages of WiMAX to be deployed for such network, the
research design of this work is now explained.
This chapter begins by a general description of the area and the environment of interest (Huye
district and its schools). Then, as Wireless network design is a process to determine the number
of BSs and their placement to provide sufficient signal coverage and capacity to the designated
area, BS placement within our area of interest is discussed. From there, a detail on Site survey
and Simulation study are explained.
3.2. Research environment
3.2.1. Overview
The Huye district is among the eight numbered districts of the Southern province of Rwanda. It
has fourteen sectors with a population of appreciatively 290 677 people and a surface of 528.5
km2. Huye district boarders with Nyanza district in the North, Gisagara in the East, Nyaruguru in
the South West and Nyamagabe in the North West.
The greater part of the district, most urban, is in a plain with some urban architecture like the
Campus buildings, some administration and business offices while the other part, more rural, is
over hills. Figure 3.1 represents an administrative map [20].
19
Figure 3.1: Administrative map of Huye district
3.2.2. Education
The department of education includes education services of literacy, nursery education, primary
education, professional training, secondary education (General and optional) and higher learning
institutions such as National University of Rwanda, Nyakibanda Senior Seminary, the Faculty of
Theology and a branch of catholic university of Rwanda at TABA.
3.2.3. Energy
The district is characterized by a remarkable electricity power shortage. 27 primary schools, 23
secondary schools, and 3 higher institutions have electricity power from EWASA. Only 8
primary schools, 2 secondary schools, use solar energy. 2 primary schools and 7 secondary
schools have internet access with either wired or wireless connectivity. Lack of infrastructure in
remote areas hinders use of ICT facilities. An unreliable supply of electrical power is a challenge
in the provision of ICT based services in rural. In order to enable schools in rural areas to
participate in knowledge based economy, ways must be found to improve ICT access for
schools. There are need to expand both network coverage as well as increase the infrastructure.
20
3.3 Suggestion of choosing WiMAX
Regard of rural area of Huye district, according to geographic situation of that area, WiMAX has
been chosen as a wireless technology that fit to distribute the star topology for the connection to
the base station with WiMAX.
WiMAX variants operate both on licensed frequencies and on unlicensed frequencies. Licensed
WiMAX operates in the 10 to 66GHz range; unlicensed WiMAX operates in the 2.4 to 11 GHz
range. In addition, some of the frequencies utilized by WiMAX are subject to interference from
rain fade. The unlicensed WiMAX frequencies are subject to RF interference from competing
technologies and competing WiMAX networks.
WiMAX has theoretical maximum bandwidth of 75Mbps. This bandwidth can be achieved by
using 64QAM 3/4modulation. 64QAM can only be utilized under optimal transmission
conditions. WiMAX supports wide range of modulation algorithms to enable the most bandwidth
to be realized under all conditions, LOS and NLOS conditions and its communication range can
be 50km. However, according to advantages and disadvantages of WiMAX, we can conclude
that WiMAX is the best solution of wireless technology which can support education network
according to the services offered and geographical area [21].
3.3.1. WiMAX Base Station Selection
The WiMAX base station is one of the most critical elements in the infrastructure solution set.
Choosing a base station on cost alone can negatively impact coverage, total cost of ownership,
and most importantly, the customer experience. The critical selection factors of WiMAX base
station selection are considered in three categories:
3.3.1.1. Performance
The high performance base station with fixed mobility continuously communicates with nearby
base stations and transfers weak device connections to the base station with the best connection,
with no disruption to the user. To ensure true high performance, the base station and devices
must: Extend connectivity range, improve mobile performance, ensure strong connection and
Prioritize subscriber base station.
21
3.3.1.2. Innovative Design
WiMAX operators need an innovative base station design that will meet their environmental
requirements, including offering all outdoor base stations without air conditioning, base stations
that can be mounted on building walls, and base stations with high capacity. Innovative base
station design incorporates light weight infrastructure, ease of deployment, and lower cost.
3.3.1.3. Flexible Portfolio
A flexible portfolio of WiMAX base stations is critical to surviving, and even thriving on,
market or competitive changes. A truly flexible base station must have efficient spectrum usage,
support multiple configurations; deliver coverage versus capacity and smooth fixed to mobile
migration.
Choosing the right base station for your WiMAX deployment is one of the most critical elements
of an end-to-end WiMAX solution. A true high performance base station with innovative design
and a flexible portfolio will enable operators to customize their business models, increase
capacity, reduce costs, and speed time to revenue through a differentiated customer experience
[22].
3.3.2. Antenna selection and positioning
The role of the antenna in wireless communication system is paramount. The choice of antennae
is crucial for the optimum wireless coverage, signal quality, signal strength, availability and
scalability. Fundamental antenna properties include the impedance and VSWR (Voltage
Standing Wave Ration), amplitude radiation patterns, 3 dB beam width, directivity, gain,
polarization and, bandwidth [23].
3.3.2.1. Calculating Antenna Coverage
The antenna coverage determines the achievable distance of an RF wireless link. In particular
case both signal strength and the achievable distance of an RF wireless system depend on the
antenna gain and are improved by reducing both the vertical and horizontal direction that the
antenna is able to transmit to and receive signals from. Considering the achievable distance and
to the needed signal strength the forward gain should be at least 16 dBi for BS in our system.
22
3.3.2.2 Antennae positioning for best results
Positioning, orientation and the power output of the antennae ultimately determine the
performance of any wireless access point. Factors such as line of sight, obstacles and other issues
(as discussed above) are directly related to the performance of the link. To specify the
emplacement access point (Customer promise equipment) we made inspection of different sites
to identify the most relevant point to assure the best coverage and clearance.
3.4. Research Methodology
When one dealing with wireless network design, there are steps to be fulfilled when you are
focusing the radio planning. The network design problem may be classified into different
categories according to the problem objective: Coverage, Interference, Cost and Capacity. Each
of these approaches has advantages and inconvenient and the choice of one of them is done
according to which result you are expecting to get [24].
In this work, the following steps have been pursued for the radio planning of our network: BS
placement, to seek best site for good coverage of schools in the district, to analyze radio link
performance at different subscriber sites; and a simulation work is also done for comparison with
the calculated results. Different materials have been required for the fulfillment of our goal.
3.4.1. Equipments Required
In order to fulfill our objectives, we needed some equipment and software tools. The equipments
needed are the following ones:
A GPS (Global Positioning System) to get geographic coordinates of different schools
locations which are our demand nodes to be covered by the network.
An Alvarion WiMAX CPE (Customer Point Equipment) antenna with some accessories to
execute field measurement on sites.
A portable computer machine.
BreezeLITE software: Alvarion's BreezeLITE is an SNMP (Simple Network Management
Protocol) application designed for on-line management of BreezeMAX system components.
23
BreezeLITE allows accessing a wide array of monitoring and configuration options,
including:
Device Manager for Base Station and Micro Base Station, including SUs (Subscriber
Units).
Unit status and current configuration verification
Selected unit configuration modification
Service Profiles verification and modification
Service Provisioning
On-line performance data monitoring and statistics collection
A special MS Office Excel Add-In for effective tabular and graphical display of collected
data.
Radio Mobile software: It is a simulation tool, used to predict the performance of a radio
system. It allows calculations of link budgets in a wide frequency range.
Figure 3.2: Radio mobile showing the radio link.
Radio mobile uses digital terrain elevation data for automatic extraction of path profile between
an emitter and a receiver. Here, Radio mobile will determine the visibility case of each radio
link.
In case of line of sight (LOS) a 2-ray calculation and the clearance of the Fresnel zone will be
used. Most models have in common this method for the LOS cases. In case of an obstructed path
(PLOS or NLOS) the Irregular Terrain Model (ITM) is applied.
24
3.4.2. ITS Irregular Terrain model
The Institute for Telecommunication Sciences (ITS), USA/Colorado model of radio propagation
is a general purpose model that can be applied to a large variety of engineering problems. The
model, which is based on the electromagnetic theory and on statistical analyses of both terrain
features and radio measurements, predicts the median ability of the signal in time and in space.
It is designed for the use at frequencies between 20 MHz and 20 GHz, for a wide variety of
distances and antenna heights, and for those problems where terrain plays an important role. The
ITS model has 2 modes of operation [25]:
3.4.2.1. Area mode
This mode is used in cases where the exact terrain is not known. So, it has some limits and the
terrain roughness is approximated from a user-entered value of change in terrain height.
3.4.2.2. Point-to-Point (PTP) mode
Using PTP mode, part of the input consists of certain “path parameters” i.e. the model retrieves a
terrain profile based on the user entered latitude and longitude values for the transmitter and
receiver. Statistical and environmental parameters are used with terrain profile in calculating
path loss. Radio mobile software is using the ITM model in PTP-mode because of the easy to
access SRTM (Shuttle Radar Topography Mission) data on the internet.
3.4.3. Site survey
A wireless site survey, sometimes called an RF site survey, is the process of planning and
designing a wireless network. The site survey is done for the BS placement selection. For the BS
placement, the survey is a computer-based one. Through a simulation tool, Network Simulator
software (Radio mobile software), best sites locations for our network are simulated. Choice
between those points is made considering other parameters such as infrastructure facilities.
25
3.4.4. BS placement
For a given communication network technology we want to implement, the design is important
to evaluate the feasibility and the parameters to take into account such as configurations,
equipments location before implementation. For the BS(s) location, the position for our case can
be found by variety of different design approaches have been proposed within this objective [26].
However, radio mobile tool provide with the function “find best position”, the best position to
place the BS, and for a good coverage for all subscribers. And for the best BS placement there
other parameters to take into consideration to facilitate like the road accessibility, existing power
supply installation, a Tower support for BS antenna and so on. Moreover, we know that the
National University of Rwanda has implemented recently a WiMAX network in Huye district.
NUR WiMAX BS has therefore been chosen to provide the network as a facility for our project.
3.4.5. Brief description of NUR WiMAX network:
The University introduced a WiMAX network in addition to the Wireless Local Area Network to
provide connections to the remote area. It contains two base stations, one at Huye Mountain
station (Huye BS), and the other one on the top of a water Tank (Itanki BS), in the campus place.
The two BSs have sectorial antennas looking one another, a Micro Base station Architecture and
the following operating frequencies:
BS Name Duplex separation Uplink Frequency Downlink Frequency
HUYE 50 MHz 3379 MHz 3329 MHz
ITANKI 50 MHZ 3373 MHz 3323 MHz
Table 3.1: NUR Base Stations operating Frequencies
26
Figure 3.3: NUR WiMAX Network, Cartesian radio coverage
This Cartesian radio coverage obtained using radio mobile and as we see the two antennas are
Huye BS located at Huye Mountain and Itanki BS located in NUR. Red color describes the
coverage of those BSs where the signal is strength and yellow colored area is where the signal is
becoming low when we move away from the source of the signal.
3.5. Simulation work
Simulation work have been done using a radio mobile tool, and basically consists of LOS(Line
of sight) and is principally based on ITS model which is the ITS Longley-Rice Radio
Frequency propagation model. When doing simulation work there is Input parameters and result
found after simulation which is Output:
3.5.1. Input parameters
Before any plot can be produced, 3 main radio input parameters must be defined for the Radio
Mobile program:
3.5.1.1. Network parameters
It contains parameters of all main elements in the network such as digital cartography, technical
parameters of the equipment(s) you want to simulate. Apart the digital cartography of Africa
which can be found in the Radio mobile STRM files and by the Google earth software, among
the technical parameters to find.
27
3.5.1.2. Antenna characteristics
These characteristics include:
Polarization: in accordance to the usage in the network the polarization has to be set
'horizontal' or „vertical‟ and the polarization of the NUR WiMAX antennas is vertical.
Height of antennas: The Huye and Itanki Base Stations are installed upon towers with height
of 40 and 20meters respectively. The Subscribers antenna height is estimated at 10 meters.
Geographical coordinates depending on chosen sites.
Transmitted Power = 28 dBm, Sensitivity threshold= -85.7dBm for the best modulation type
(QAM 16 3/4
), Gain=16dBi for both transmission and reception.
3.5.1.3. Environmental parameters
These options set some of the calculation parameters in the ITS algorithm used in the program.
The atmospheric conditions like climate and weather vary in the different areas of the world, and
affect both the refractive index of free air and play an important role in determining the strength
and fading properties of radio signals.
3.5.2. Output parameters
These are the results found after simulation such as the radio link performance. The radio link
performance as described by Roger for Radio Mobile is part of the link budget and describes the
performance of the Up- or Downlink [25].
After doing different steps like site survey, describing criteria for WiMAX base station
placement and identifying equipments needed, simulation work was performed. The results
analysis and interpretation are in the following part.
28
CHAPTER 4. RESULTS ANALYSIS AND INTERPRETATION
In this chapter, the simulation output results (path profiles) and calculations are presented. Radio
Mobile is a software network planning and modeling tool. It provides for the regulation,
modeling, planning and measurement of all network types that use the radio spectrum. We use
Radio Mobile software to calculate the coverage of WiMAX base station using site specification
information gathered Huye district.
4.1. Coverage requirement
The coverage analysis calculates the total propagation losses experienced by the network and
displays the resulting receiver sensitivity and field strength experienced at each in the area. In
this project, 22 schools have been chosen randomly as a sample schools in the district. The
chosen schools are Centre Scolaire Elena Guerra, Ecole Secondaire Kotana, Ecole secondaire
Butare, College Imena, E.A.V kabutare, E.N.D.P Karubanda, Ecole Secondaire Mbogo, Ecole
Secondaire Kamwami, Ecole Secondaire Mutunda, Ecole Secondaire Mwurire, E.S
Nyarunyinya, Ecole Secondaiare Sovu , Ecole Secondaiare St Jean de Bosco de Butare, Ecole
Autonome de butare, G.S Gamysheer, G.S Gatagara, G.S Officiel de Butare, G.S des Parents de
Butare, Petit Seminaire Virgo fideris , Ecole Secondaire Maza and Ecole Regina Pacis de Butare.
Figure 4.1: Digital map of Huye mountain BS coverage [radio mobile].
29
According to the topography of Huye, we found that it is possible to have large signal coverage
from the BS placed at Huye Mountain.
4.2. Results Presentation
The presentation of results is done through path profiles for the simulation work and the
calculations of minimum signal received level at each school sites. The digital map of our sample
network points is first shown below.
Figure 4.2: Digital map with sites pointed [radio mobile].
4.3. Network path profiles
The path profiles are drawn using Radio Mobile which is a radio propagation and virtual
mapping software. To evaluate the reliability of each RF link, a RF path analysis and minimum
received signal power calculations were performed. And in the following we shall make sure that
we have a line of sight with at least 60% of the first Fresnel zone clear of obstructions as well.
The 6 path profiles shown bellow are the worst case of the 22 schools chosen randomly. These
path loss models are shown in Figure 4.3 to Figure 4.8. The analysis and explanations of results
are considered in the following section.
30
4.3.1. E.A.V Kabutare
Figure 4.3:WiMAX link from Huye Mountain BS to E.A.V Kabutare
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to E.A.V Kabutare. The signal arrives at the destination without any obstacle.
4.3.2. Ecole Secondaire Kotana
Figure 4.4:WiMAX link from Huye Mountain BS to E.S Kotana.
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to E.S Kotana. The destination receives signal of the best quality.
31
4.3.3. Ecole Secondaire Nyarunyinya
Figure 4.5:WiMAX link from Huye Mountain BS to E.S Nyarunyinya.
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to E.S Nyarunyinya. Height of the receiving antenna needs to be increased so as to
receive the best quality signal.
4.3.4. Groupe Scolaire Gatagara
Figure 4.6:WiMAX link from Huye Mountain BS to G.S Gatagara
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to G.S Gatagara. The signal received is of good quality but can be increased by increasing
height antenna of subscriber station.
32
4.3.5. Groupe Scolaire Parents de Butare
Figure 4.7: WiMAX link from Huye Mountain BS to G.S parent de Butare
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to G.S Parent de Butare. The destination receives signal of the best quality.
4.3.6. Petit Seminaire Virgo Fidelis.
Figure 4.8: WiMAX link from Huye Mountain BS to Petit Seminaire Virgo Fidelis
The figure above shows the profile of transmitted WiMAX signal from mountain Huye base
station to Petit Seminaire Virgo Fidelis. The signal is good at the destination.
33
4.4. Analysis of the simulation
The analysis and explanation of these figures are based on the data given in the simulation.
These data are used as parameters for simulation using Radio Mobile software. The digital maps
are used to determine the altitudes of 22 sites considered in our case study and also to get the
distance between them. From there, it was easy to draw profile from Huye mountain base station
to different subscriber station (Schools). The table 4.1 shows different parameters measured by
using Radio Mobile software. These parameters include: The distance between Huye mountain
Base station and different sites (Schools), The True North Azimuth, Magnetic North Azimuth,
Elevation angle, the propagation mode is line-of-sight, obstruction, and the terrain elevation
variation.
34
Links Distance
(Km)
True North
Azimuth
( 0)
Magnetic
North
Azimuth
( 0)
Elevation
Angle
( 0)
LOS with
Minimum
clearance
(F1 at Km)
Obstruction
(dB)
Terrain
elevation
(m)
BS-Centre Scolaire
Elena Guerra
7.7
118.13
117.87
-3.947
0.6 at 7.4
0.6
532.9
BS-College Imena 6.61 223.62 222.62 4.072 7.3at 5.71
1.5 486.1
BS-E.A.V Kabutare
8.67
120.63
120.38
-3.534
5 .3at 8.01
8.01
524
BS- E.N.D.P Karubanda
6.74
115.75
115.49
4.315
4.9at 6.74
-0.6
540.1
NUR BS – E.S Butare
0.90
331.85
331.60
-0.0075
15.3at0.25
3.2
55.1
BS- E.S Kamwami
8.37
56.33
56.08
-3.6152
1.3at 8.27
-3.427
578.7
BS- E.S Kotana
13.34
43.59
43.33
- 2.489
2.5at11.38
3.0
548.5
BS-E.S Mbogo
8.67
120.63
120.38
-3.554
4.9at 8.5
1.4
524.8
BS- E.S Mutunda
6.21
79.48
79.20
-4.796
6 .8 at 5.0
1.4
534.0
BS- E.S Mwurire
8.1
73.80
73.55
-2.9098
6.4at 8.0
-1.1
536.1
BS- E.S Nyarunyinya
10.21
308.29
308.04
-3.2814
2.1at1 0.3
0.7
607.0
BS-Ecole Secondaire
Sovu
2.5
59.88
59.62
-11.134
3.4 at 0.3
-1.7
467.9
BS-E.S St Jean Bosco de
Butare
6.2
341.78
341.52
-4.5597
1.4 at 0.2
2.6
560.9
BS-Ecole Autonome de
Butare
7.8
116.30
116.04
-3.865
3.4 at 7.4
0.8
538.7
BS-Ecole Regina Pacis de Butare
9.5
140.16
139.90
-2.950
2.6 at 9.4
2.5
569.9
BS-Groupe Scolaire
Gatagara
8.1
123.21
123.95
-3.5464
6.7 at 8.0
3.2
524.0
BS-G.S Officiel de
Butare
8.0
125.29
125.04
-3.6152
3.6 at 7.9
-2.7
537.0
BS-G.S Parents de
Butare
7.9
111.02
110.76
-4.0220
1.2 at 7.7
-0.9
548.5
BS-Petit Seminaire
Baptiste
7.8
108.79
108.53
-4.0963
4.6 at 7.7
1.4
557.9
BS-G.Scolaire
Gamysheer
6.2
118.10
117.85
-4.4957
4.9 at 6.1
-3.0
532.6
BS-E.Secondaire Maza
6.6
223.6
223.36
4.1155
6.7 at 5.7
-1.7
486.1
Table 4.1: Different parameters measured by using Radio Mobile software
35
4.5. Comparing the simulation and calculation results
Let us calculate the free space path loss and the minimum signal power requirements at each site
(School) that can keep school connected to the base station and receive a good signal. Let‟s take
an example of one site which is Centre Scolaire Elena Guerra.
Using equation 2.4, fdFSPL log20log2045.32
3200log20790.7log4520.32
dBm38.120
Using equation 2.7, FSPLGGPP trtr
dBmdBidBidBm 38.120161628
dBm38.60
The calculated results are the free space path loss and the minimum signal power received at
Centre Scolaire Elena Guerra respectively. The received signal by subscriber station depends on:
The transmitted power of antenna, the antenna gain, the sensitivity of the receiving antenna and
the antenna height.
Specifications of used antenna are: The antenna gain =16dBi in both transmission and reception,
the transmitted power is 28dBm and the receiver sensitivity is -85.7dBm using QAM 64 ¾
modulations. All calculated signal power at each subscriber station is shown in the table 4.2 in
which we can find the results of simulation. We recall that the objective is to make comparison
of these two results (calculated result and receiver sensitivity threshold) and this comparison will
lead us to the conclusion to know if the signal in the reception will be bad or good.
By comparing the last two columns of table 4.2, we can draw a conclusion that all subscriber
stations (schools) will receive a good signal, this is because the power of reception required at
the reception is higher to the sensitivity obtained through simulation and the assumptions we
used in the simulation is suitable and result in signal powers at all schools are higher than the
required signal to keep the schools connected to the base station.
36
Links Distance
(Km)
Free space
loss (dBm)
Minimum
Signal Power
(dBm)
Calculated
received power
(dBm)
Receiver
sensitivity
threshold
(dBm)
Huye_BS-Elena Guerra 7.79 180.38 -61.9 -60.38 -82.7
Huye_BS-college Imena 6.61 178.95 -56.8 -58.95 -82.7
Huye-BS-E.A.V kabutare 8.67 180.31 -61.3 -63.31 -82.7
Huye_BS-E.N.D.P
Karubanda
6.74 180.31 -61.8 -59.11 -82.7
NUR Itanki BS- E.S Butare 0.90 161.63 -39.8 -41.58 -82.7
Huye_BS-E.S kamwami 8.37 181.0002 -59.8 -61.004 -82.7
Huye_BS-E.S kotana 13.34 180.9.55
-68.1 -65.053 -82.7
Huye_BS-E.S Mbogo 8.67 181.31 -65.1 -60.31 -82.7
Huye_BS-E.S Mutunda 6.21 178.51 -61.7 -58.41 -82.7
Huye_BS- E.S mwurire 8.1 180.83 -63.1 -60.71 -82.7
Huye_BS-E.S
Nyarunyinya
10.21 180.83 -60.4 -62.73 -82.7
Huye_BS-Ecole
Secondaire Sovu
2.53 110.61 -61.3 -50.61 -82.7
Huye_BS-E.S St Jean
Bosco de Butare
6.2 119.128 -60.2 -51.342 -82.7
Huye_BS-Ecole Autonome
de Butare
7.8 121.117 -69.5 -61.112 -82.7
Huye_BS-Ecole Regina
Pacis de Butare
9.5 122.865 -70.5 -62.865 -82.7
Huye_BS-G.Scholaire
Gatagara
8.1 121.384 -68.8 -61.384 -82.7
Huye_ BS-G.S.Officiel de
Butare
8.0 121.354 -65.9 -61.354 -82.7
Huye_BS-G.S Parents de
Butare
7.9 121.255 -67.7 -61.255 -82.7
Huye_BS-Petit Seminaire
Baptiste
7.8 121.067 -67.0 -61.067 -82.7
Huye_BS-Petit Seminaire Virgo Fidelis
6.2 119.156 -64.1 -59.156 -82.7
Huye_BS-G.Scolaire
Gamysheer
6.2 119.156 -69.5 -59.156 -82.7
Huye_BS-Ecole
Secondaire Maza
66 119.68 -65.3 -59.129 -82.7
Table 4.2: Comparison of calculated and simulation results
37
4.6. Received power in dBm
Figure 4.9: Received power diagram
4.7. Simulation tool limits
When one uses software simulation tool, the software doesn‟t consider some real environmental
parameters and effects, this strongly contributes in the mismatching of the results on the field.
But when the used parameters are well chosen the deviation in results cannot be such high,
which means that the software simulation tool can be used (of course with some imperfections)
to determine in advance the behavior of a system before deploying the real equipments on the
field. It should then be necessary to make a test before confirming any field installation after the
simulation.
According to the limited time and material resources, it was not possible to perform the field test,
but it is strongly recommended to implement the test before the installation of the real
equipments. This test can be done in different way, but the aim is to be sure on the specified
places and the link reliability (LOS, clearance of the link, type of the obstacle to overcome).
Therefore we can assure that the installation of a WiMAX system in Huye district is possible, but
the only big challenge will be the access to the electricity.
-70
-60
-50
-40
-30
-20
-10
0
38
CHAPTER 5.CONCLUSION AND RECOMMENDATION
5.1. Conclusion
This research project consists of designing a WiMAX network system in Huye district, by taking
into considerations the way to make connection between Schools in the district. The aim of this
work is to evaluate the feasibility of installation of such network. After examining its features
and the provided services, WiMAX was found to be the best wireless and powerful technology to
use in rural or remote areas. The biggest challenge is lack of electricity in many of these schools.
To overcome this, we strongly advise the use of solar energy.
Finally the feasibility of this project has been confirmed by simulation work using Radio mobile
software and calculations of received power level. The comparison between the two results
(Calculated received power and Receiver sensitivity threshold) for sample schools has been
made and we concluded that all schools will receive good signal. The feasibility of this project
will be accelerated by the implemented WiMAX technology by the National University of
Rwanda. Because of infrastructures and the capability of doing maintenance, the National
University of Rwanda is where we propose to allocate the server.
5.2. Recommendation
We cannot finish our work without making some recommendation due to different observations
we have made during the project research. Our recommendation is addressed:
First, to the Education Ministry, in collaboration with the NUR, to follow up the project of
linking schools as network facilities are already implemented. To next researchers, we
recommend them to design a server which will be located at the National University of Rwanda
as proposed that will allow easy communication of schools.
We also recommend the National University of Rwanda and especially to the applied sciences to
include in course program the new technologies and enable student to exploit the simulation
tools.
39
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41
APPENDICES
Appendix 1: WiMAX Antenna Specifications
These specifications include:
Sectorial antenna, Azimuth Beam width 600 and Elevation Beam width 10
0
Gain 16dBi
Frequency 3.3-3.8 GHz
N-Type connector 50Ω impedance
Appendix 2: Modulations bite rate specification
3.5MHz 1.75MHz
Rate Nr
Modulation Bit rate Sensitivity [dBm] @ PER 1e-2
Bit rate Sensitivity [dBm] @ PER 1e-2
1 BPSK ½ 1.41 Mbps -100 0.71Mbps -103
2 BPSK ¾ 2.12 Mbps -98 1.06Mbps -101
3 QPSK ½ 2.82 Mbps -97 1.41Mbps -100
4 QPSK ¾ 4.23 Mbps -94 2.12Mbps -97
5 QAM 16 ½ 5.64 Mbps -91 2.82Mbps -94
6 QAM 16 ¾ 8.47 Mbps -88 4.24Mbps -91
7 QAM 64 2/3 11.29 Mbps -83 5.65Mbps -86
8 QAM 64 ¾ 12.71 Mbps -82 6.35Mbps -85
42
Appendix 3: BreezeMAX CPE_PRO Specification
Appendix 4: Alvarion BS Antenna Radio pattern
Appendix 5: Alvarion the BreezeMAX Product Family
43
APPENDIX 6: The installation process of WiMAX System