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DEVELOPMENT OF VHF AND UHF SPECTRUM OPTIMIZATION FOR DIGITAL SERVICES IN SELECTED STATES OF NIGERIA

by GBENGA-ILORI, ABIODUN OMOWUNMI, PhD

Abstract (Summary)
The key objective of this research is to address the problem of optimal use of the VHF and UHF spectrum in order to accommodate new digital communication services in Nigeria. The use of VHF and UHF frequency bands for communication services is highly attractive for digital communication services. However, the challenge is the less than optimal use of these frequency bands by analogue television. This inefficiency has led to the development of digital television technology. With the aid of the compression technique employed in digital broadcasting, more than one television programme can be transmitted using only one analogue television channel. The objective was achieved by first determining the present usage of the VHF and UHF spectrum by analogue television broadcasting services in Nigeria by using an appropriate deterministic propagation model known as the IRT propagation model. This propagation model has been tested suitable for the Nigerian environment by comparing field strength from three different propagation models with those obtained from a field strength survey conducted at different locations in some States in Nigeria. The results from the comparison showed that the IRT propagation model produced field strength closest to measured values within the selected states. The states selected are the Yoruba-speaking states comprising of the south-western states as well as Kogi and Kwara states. The choice of the states is for network planning feasibility since local content is important in broadcasting and all these Yoruba-speaking viewers can be put on the same digital multiplex. The IRT model was later used to determine the present analogue television coverage and future digital television coverage in the selected states. The coverage result was used to assess the level of co-existence of present analogue and future digital television during simulcast period and also to determine the digital television coverage possible after switch-off of analogue television. Results show that digital television coverage of 62% is possible for the selected states during the simulcast period. After switch-off of analogue television, digital television was predicted to achieve up to 95.3% coverage. The result of the digital television coverage was used to estimate spectrum use by future digital television services by determining the number of programmes that could be accommodated in a multiplex. This was used to estimate the spectrum utilization efficiency. Results show that a total VHF and UHF spectrum saving of 74.8% could be achieved in the selected states after transition to digital. This means that more spectrum can be made available for new digital services. The analysis of the data used in this work was done at the Institut fur Rundfunktechnik (IRT), Germany. The research concludes that the spectrum released from the transition from analogue to digital television, digital dividend, would meet the growing demand for the VHF and UHF spectrum in Nigeria. Recommendations with regards to the use of digital dividend are made in a way that allows the country bridge the present digital divide and help improve the social and economic needs of the Nigerian citizens
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Bibliographical Information:

Advisor:PROF. T.S. IBIYEMI

School:University of Ilorin

School Location:Nigeria

Source Type:Doctoral Dissertation

Keywords:VHF, UHF, FREQUENCY SPECTRUM, PROPAGATION, SIMULCAST, DETERMINISTIC PROPAGATION MODEL

ISBN:

Date of Publication:08/30/2010

Document Text (Pages 1-10)

DEVELOPMENT OF VHF AND UHF SPECTRUM OPTIMIZATION
FOR DIGITAL SERVICES IN SELECTED STATES OF NIGERIA

BY

GBENGA-ILORI, ABIODUN OMOWUNMI

(00/68GJ001)

A Thesis
Submitted to the Department of Electrical Engineering,
University of Ilorin
In Partial Fulfillment of the Requirements
For the Award of

Doctor of Philosophy

Degree in Electrical Engineering

2010.

i


Page 2

CERTIFICATION
Development of VHF and UHF Spectrum Optimization for Digital Services in
Selected States of Nigeria, (Gbenga -Ilori Abiodun Omowunmi, B.Sc. Electrical
and Electronics Engineering (U.I. 1997), M.Eng. Communications Engineering
(FUTA 2000)).

This is to certify that this thesis has been read and approved as meeting the
requirements of the Department of Electrical Engineering, University of Ilorin for
the award of Doctor of Philosophy degree in Electrical Engineering.

Professor T. S Ibiyemi
Supervisor
Date

Dr Y.A. Adediran
Chief Examiner
Date

External Examiner
Prof. U.G. Danbatta
Date

------------------------------------------ ---------------------------

Internal Examiners
Dr. A.A. Ayeni
Date

ii


Page 3

DEDICATION

Dedicated to God Almighty for His guidance through life and for His Words that
made me know that achievement is not just aiming but hitting my target.

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Page 4

ACKNOWLEDGEMENTS

I give thanks and glory to the Almighty God for giving me the grace to start and complete this
work. I would like to also specially thank my supervisor, Professor T.S. Ibiyemi who besides
guiding me on the winding path to a Ph.D. thesis, also has provided encouragement and drive for
the completion of the work. Professor Ibiyemi’s broad knowledge of engineering is as rich and
varied as anyone I have ever known and working with him has proved to be consistently
challenging and exciting. I also owe a debt of gratitude to Dr. S.A. Aliu and Dr. A.J. Falade for
their support during the period of this research work.

Next, I would like to acknowledge friends and colleagues at the Institut fur Rundfunktechnik
(IRT), Germany for being a great source of help and inspiration during my six-month research
visit. I will like to specially thank Dr. Roland Brugger for his encouragement, advice and
friendship. I also thank Mrs. Philip for her help on all administrative matters during my stay
there.

I would like to appreciate friends and colleagues at the University of Lagos. First, I would like to
acknowledge the Dean of Engineering, Professor M.A. Salau, and the head of department,
Electrical and Electronics Engineering department, Professor F.N. Okafor, for their support to
my research work. I would especially like to mention Engr. M.A.K. Adelabu, Engr. (Mrs.) A.
Abdulsalam, Engr. Adeola Balogun, Engr. (Mrs.) F. Olobaniyi, Engr. Oluseyi and Engr.
Adetona. Other friends worth mentioning are Engr. Segun Afolabi and Engr. Obiseye Obiyemi. I
consider all of you good friends.

Writing a thesis is a demanding task and this thesis could not have been written without the
support and understanding of my family. I especially want to appreciate my husband, Gbenga,
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Page 5

for believing in me. I do not think I would have been able to complete this work without your
support. You are really the best. I also want to express my love and appreciation to my children:
Ibukunoluwa, Oreoluwa, and Boluwatife for being patient and understanding, especially when
the research work led to a temporary separation from them. My parents, Chief and Mrs. J. Ola
Idowu, have also been wonderful throughout the period of this research. I hope you all know
how much I value your support and I thank you for it.

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Page 6

ABSTRACT

The key objective of this research is to address the problem of optimal use of the VHF and UHF
spectrum in order to accommodate new digital communication services in Nigeria. The use of
VHF and UHF frequency bands for communication services is highly attractive for digital
communication services. However, the challenge is the less than optimal use of these frequency
bands by analogue television. This inefficiency has led to the development of digital television
technology. With the aid of the compression technique employed in digital broadcasting, more
than one television programme can be transmitted using only one analogue television channel.
The objective was achieved by first determining the present usage of the VHF and UHF
spectrum by analogue television broadcasting services in Nigeria by using an appropriate
deterministic propagation model known as the IRT propagation model. This propagation model
has been tested suitable for the Nigerian environment by comparing field strength from three
different propagation models with those obtained from a field strength survey conducted at
different locations in some States in Nigeria. The results from the comparison showed that the
IRT propagation model produced field strength closest to measured values within the selected
states. The states selected are the Yoruba-speaking states comprising of the south-western states
as well as Kogi and Kwara states. The choice of the states is for network planning feasibility
since local content is important in broadcasting and all these Yoruba-speaking viewers can be put
on the same digital multiplex.
The IRT model was later used to determine the present analogue television coverage and future
digital television coverage in the selected states. The coverage result was used to assess the level
of co-existence of present analogue and future digital television during simulcast period and also
to determine the digital television coverage possible after switch-off of analogue television.
Results show that digital television coverage of 62% is possible for the selected states during the
simulcast period. After switch-off of analogue television, digital television was predicted to
achieve up to 95.3% coverage. The result of the digital television coverage was used to estimate
spectrum use by future digital television services by determining the number of programmes that
could be accommodated in a multiplex. This was used to estimate the spectrum utilization
efficiency. Results show that a total VHF and UHF spectrum saving of 74.8% could be achieved
in the selected states after transition to digital. This means that more spectrum can be made
available for new digital services. The analysis of the data used in this work was done at the
Institut fur Rundfunktechnik (IRT), Germany. The outcome of this research has produced four
articles published in International Journals and Conference Proceedings.
The research concludes that the spectrum released from the transition from analogue to digital
television, digital dividend, would meet the growing demand for the VHF and UHF spectrum in
Nigeria. Recommendations with regards to the use of digital dividend are made in a way that
allows the country bridge the present digital divide and help improve the social and economic
needs of the Nigerian citizens.

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TABLE OF CONTENTS

TITLE PAGE i
CERTIFICATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT vi
TABLE OF CONTENT vii
LIST OF FIGURES xii
LIST OF TABLES xv
GLOSSARY OF TERMS xvi
CHAPTER 1: INTRODUCTION 1
1.1 Background to Study 1
1.2 Research Problem 4
1.3 Research Objectives 6
1.4 Justification for the Research 7
1.5 Outline of the Report 8
1.6 Research Scope and Justification 9
1.7 Operational Definition of Terms 10
1.8 Summary 11
CHAPTER 2: RADIO PROPAGATION PREDICTIONS 12
2.1 Introduction 12
2.2 Radio Wave Propagation in Free Space 12
2.3 Radio Wave Propagation in the VHF and UHF Bands 14
2.3.1 Reflection 14
2.3.2 Diffraction 15
2.3.2.1 Multiple Diffraction Losses 19
2.3.2.2 Rounded Obstacle Losses 21
2.3.3 Scattering 22
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2.3.4 Atmospheric Attenuation 24
2.4 Propagation Models for Irregular Terrain 24
2.4.1 Semi-Empirical Models 25
2.4.1.1 Okumura Model 26
2.4.1.2 Hata Model 27
2.4.1.3 ITU-R/P Recommendations 28
2.4.2 Deterministic Models 29
2.4.2.1 Longley-Rice Model 29
2.4.2.2 TIREM Model 30
2.5 GIS in Radio Propagation Studies 30
2.5.1 Data Format for GIS 31
2.5.2 Geographic Data Sources 32
2.6 Chapter Summary 32
CHAPTER 3: COMPARISON OF FIELD STRENGTH MEASUREMENTS AND
PREDICTION MODELS 33
3.1 Introduction 33
3.2 Measurement Program 33
3.2.1 Measurement Experiment Setup 35
3.2.2 Measurement Procedure 37
3.3 Prediction Models and Methods 38
3.3.1 ITU-R P.1546(3) 40
3.3.2 IRT Prediction Method 43
3.3.3 Modified ITM Method 45
3.3.4 FRANSY 48
3.3.5 Data 49
3.3.5.1 Terrain Data 49
3.3.5.2 Land Cover Data 50

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3.3.5.3 GIS Data 51
3.3.6 Field Strength Prediction Result 53
3.4 Comparison of Measured and Predicted Field Strength 53
3.5 Summary 77
CHAPTER 4: TELEVISION COVERAGE PLANNING 78
4.1 Introduction 78
4.2 Television Coverage Analysis 79
4.3 Analogue Television Coverage in Selected States 83
4.3.1 Analogue Television Coverage Results 84
4.4 Predicted Digital Television Coverage in Selected States 87
4.4.1 Assumptions and Proposals made in Digital Television Network planning 88
4.4.2 Digital Television Coverage during the Simulcast Period 90
4.4.2.1 Digital Television (Simulcast) Results 92
4.4.3 Digital Television Coverage after Analogue Television Switch-off 93
4.4.3.1 Digital Television (Switch-Off) Results 95
4.5 Summary 96
CHAPTER 5: ESTIMATION OF DIGITAL DIVIDEND 97
5.1 Introduction 97
5.2 Television Spectrum Efficiency 97
5.3 Current Analogue Television Spectrum Use in Nigeria 99
5.3.1 Analogue Television Spectrum Utilization Efficiency 101
5.4 Predicted Digital Television Spectrum Utilization Efficiency 102
5.5 Possible Future Spectrum Savings in Nigeria 103
5.5.1 Improving Digital Television Spectrum Efficiency 105
5.6 Estimating Future Spectrum Savings 107
5.7 Summary 111
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CHAPTER 6:USE OF DIGITAL DIVIDEND 113
6.1 Introduction 113
6.2 Potential Services for the Use of Digital Dividend 114
6.3 Technical Preconditions for the Use of Released Spectrum 117
6.4 Approaches for Analyzing Areas of Application 118
6.4.1 Economic Evaluation 118
6.4.1.1 More SDTV Programmes 118
6.4.1.2 HDTV Programmes 118
6.4.1.3 Mobile Television 119
6.4.1.4 Fixed Wireless Access (FWA) for Fixed Reception 119
6.4.1.5 Mobile Broadband and Telephony 119
6.4.1.6 Summary of Revenue Potential 120
6.4.2 Social Evaluation 120
6.4.2.1 Education 121
6.4.2.2 Democracy 122
6.4.2.3 Promotion of Culture 122
6.4.2.4 Belonging to a Community 123
6.4.2.5 Access and Inclusion 123
6.4.2.6 Quality of Life 124
6.4.3 Summary of Social Evaluation 124
6.5 Proposed VHF and UHF Digital Dividend Spectrum Use 125
6.6 Summary 126
CHAPTER 7: CONCLUSION AND RECOMMENDATIONS 128
7.1 Conclusion 128

x

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