Seasonal Variation of Mobile Radio Propagation Characteristics in Kaduna Metropolis and Environs
ABSTRACT
This research investigated the effects of greater ground conductivity and increased foliage on mobile networks. The wet season is known to be characterized by greater ground conductivity and increased foliage due to the increased moisture content.
Global System for Mobile Communications (GSM) signal strength measurements of two networks was taken during the dry season at particular points and these measurements were repeated during the rainy season.
These data were then processed to determine the relationship between the signal strength and ground conductivity and foliage. To ensure greater accuracy of results, two networks (Airtel and MTN) were evaluated.
Furthermore, signal strength measurements were conducted in rural areas around Kaduna. The results obtained were compared with those of Kaduna Metropolis. GSM signals were discovered to suffer greater losses during the rainy season due to increased foliage and greater ground conductivity.
Losses of between 5 dBm and 10 dBm were observed in rural/suburban areas while the losses observed in the metropolis were between 0dB and 4 dBm. These losses, though not significant in urban areas, were quite significant in the rural/suburban areas.
An inverse relationship was also established between increased foliage/greater ground conductivity and GSM signal strength within a particular environment.
Finally, the results obtained were compared with the Wiessberger and International Telecommunication Union (ITU) models and reasonable agreement with these foliage models was observed.
TABLE OF CONTENTS
Title Page
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgments v
Abstract vi
Table of Contents vii
List of Figures x
List of Tables xii
List of Abbreviations xiv
CHAPTER ONE – GENERAL INTRODUCTION 1
1.0 Introduction 1
1.1 Problem Definition 1
1.2 Thesis Objectives 2
1.3 Motivation 2
1.4 Scope of Work 3
1.5 Thesis Outline 3
CHAPTER TWO – LITERATURE REVIEW AND THEORETICAL
BACKGROUND 4
2.0 Introduction 4
2.1 Literature Review 4
2.2 Basic Theory of Mobile Radio Propagation 6
2.2.1 Diffraction 6
2.2.2 Reflection 7
2.2.3 Scattering 7
2.3 Propagation Losses in the Mobile Environment 7
2.3.1 Free Path Loss 7
2.3.2 Foliage Loss 9
2.4 Foliage Models 9
2.4.1 Weissberger’s Model 10
2.4.2 Early ITU Vegetation Model 10
2.4.3 Updated ITU Vegetation Model 11
2.4.3.1 Terrestrial Path with One Terminal in Woodland 12
2.4.3.2 Single Vegetative Obstruction 12
CHAPTER THREE – METHODOLOGY 13
3.0 Introduction 13
3.1 Research Steps 13
3.2 Choice of Experiment Sites 14
3.2.1 Kaduna Metropolis 14
3.2.2 Suburban/Rural Areas 14
3.3 Description of the Measurement Environments 15
3.3.1 Kaduna Metropolis 15
3.3.2 Suburban/Rural Areas 15
3.4 Measurement Equipment and Parameters 17
3.5 Measurement Procedure 18
3.5.1 Wet Season Measurements 18
3.5.2 Dry Season Measurements 18
CHAPTER FOUR – DATA PRESENTATION ANALYSIS AND RESULTS 19
4.0 Introduction 19
4.1 Wet Season Measurements 19
4.2 Dry Season Measurements 23
4.3 Comparison of Wet and Dry Earth Measurements 27
4.4 Difference in Signal Strengths between Wet and Dry Earth 32
4.5 Comparison of Results with Foliage Model 37
4.5.1 Comparison of Results with Weissberger’s Model 37
4.5.2 Comparison of Results with ITU Model 38
CHAPTER FIVE – CONCLUSION AND RECOMMENDATION 40
5.0 Introduction 40
5.1 Summary of Results 40
5.2 Significance of Results and Application 41
5.3 Limitations/Problems Encountered 42
5.4 Conclusion 42
5.5 Recommendation for Further Work 43
REFERENCES 44
INTRODUCTION
1.1 Background Information
Since the introduction of GSM into Nigeria in August 2001, the mobile telecommunications industry has grown tremendously. This growth made it possible for urban as well as rural dwellers to gain access to mobile phones.
However, this growth came with attendant problems. Some of which include poor signal reception at various points dropped calls, and congestion. GSM service providers in Nigeria have thus been trying to evolve methods of tackling these problems.
Some of these problems are not peculiar to any specific region whereas others are. For instance, the vegetation cover in the area where these networks are deployed could pose specific problems to the operators and thus solutions peculiar to these environments need to be sought.
Nigeria as a country has varied vegetation that ranges from thick vegetation in the South to the savannah grassland in the middle belt to the semi-desert or Sahel savannah regions of the extreme North.
The middle belt region of Nigeria experiences between 4 to 6 months (between April and October) of the rainy season every year.
The increased earth moisture content during this period gives rise to greater ground conductivity and increased foliage.
This condition is likely to affect GSM signal strength. For GSM operators to ensure all year-round quality service delivery, the relationship or effects of greater ground conductivity and increased foliage on signal strength needs to be understood particularly in the specific region where such networks are deployed.
REFERENCES
Abdullahi, T.S. (2008). Network Optimization in a GSM System: A Case Study of MTN Nigeria Communications Limited. MSc Thesis. Electrical Engineering Department, Ahmadu Bello University Zaria.
Batariere, M.D et al. (2004). Seasonal Variations in Path Loss in the 3.7 GHz Band. IEEE Radio and Wireless Conference, 399 – 402.
Bruce, L.C. (2006). Prediction of Seasonal Trends in Cellular Dropped Call Probability. IEEE Proceedings of the International Conference on Electro/Information Technology, 613-618.
Douglas, O.R. (1973). Some Propagation Experiments Relating Foliage Loss and Diffraction Loss at X-Band and UHF Frequencies. IEEE Transactions on Vehicular Technology, 22(4), 114.
Fraizer, E.W. (1984). Handbook of Radio Wave Propagation Loss (100 – 10,000 MHz). A Technical Report, National Telecommunications and Information Administration, Annapolis Maryland, 24.
