The Quantification of the Influence of Rain Attenuation on Received Power at Ka Band

ABSTRACT 

The quality of satellite communication link can be seriously affected by variable climatic phenomena such as rain, gases, and scintillation. As the frequency of operation increases 8 beyond 10GHz, the effect of rain becomes very severe with the growing need for high bandwidth frequencies such as frequencies in the Ku-band and Ka- band hence the need for better fade mitigation becomes necessary. In order to identify the appropriate rain fade mitigation technique, there is need to quantify the amount of fading experienced due to rain. This project aims to identify an appropriate rain fade calculation technique for Nigeria. After the technique is identified, rain rate data is then obtained from Nsukka, Enugu State in Nigeria and used to obtain the rain fade margin. In performing a link power budget analysis, the fade margin (FM) is a critical component. Often times, the inclusion of a large FM is not cost efficient or technically feasible. Therefore FMTs must be integrated into the overall system design. This thesis is aimed at presenting a comprehensive review of current and future satellite communication technologies and applications, paving the way for a comprehensive analysis of current and proposed FMTs catering for rain attenuation. This analysis spans techniques such as; Diversity, Adaptive Signal Processing, Adaptive Source Sharing, Uplink and Downlink Power Control, and others. These techniques are comparatively analyzed with their advantages and disadvantages qualified and quantified to deduce quantifiably the influence of rain attenuation on received signal power on Ka-band frequencies. This data is now made available to organizations interested in building earth-space communication links over Nigeria.

TABLE OF CONTENT

TITLE PAGE ...…………………………………………………………………………………………………………….…………I

APPROVAL................................................................................................................................II

CERTIFICATION.........................................................................................................................III

ACKNOWLEDGEMENT..............................................................................................................IV

ABSTRACT.................................................................................................................................V

TABLE OF CONTENTS...............................................................................................................VII

LIST OF FIGURES..................................................................................................................................VIII

LIST OF TABLES........................................................................................................................IX

LIST OF ACRONYMS..................................................................................................................X

CHAPTER ONE: INTRODUCTION

1INTRODUCTION…………………………………………………………………………………..……………………..1

1.1 PROBLEM STATEMENT………………………………………………………………………………….……………….2

1.2 MOTIVATION………………………………………………………………………………………………………………….3

1.3 THESIS STRUCTURE…………………………………………………………………………………………………………5

CHAPTER TWO: BACKGROUND RESEARCH

2.1 SATELLITE SYSTEMS ARCHITECTURE……………………………………………………………………….8

2.1.1 The Earth Segment 8

2.1.2 The Space Segment 10

2.1.3 THE RECEIVED POWER ON A SATELLITE DOWNLINK 13

2.2 SIGNAL ATTENUATION…………………………………………………………………………………………..13

2.2.1 Atmospheric Absorption 14

2.2.2 Ionospheric Scintillation 14

2.2.3 Tropospheric Scintillation 15

2.2.4 Cloud and Fog Attenuation 15

2.2.5 Rain Attenuation 16

2.3 RAIN ATTENUATION PREDICTION MODELS……………………………………………………………………….18

2.3.1 Rice-Holmberg Model 18

2.3.2 Dutton-Dougherty Model 20

2.3.3 The Crane Global Model 21

2.3.4 ITU-R Rain Attenuation Model 24

CHAPTER THREE:METHODOLOGY/EXPERIMENTATION

3.1 EXPERIMENTAL DESCRIPTION AND SET-UP…………….……………………………………………… 30

3.2 PURPOSE OF EXPERIMENT………………..…………………………………………………………………… 30

3.3 EQUIPMENT AND INSTRUMENTATION…………………………………………………………………… 30

3.4 ENVIRONMENT……………………………………………………………………………………………………… 32

3.5 EXPERIMENTAL SET-U..……………………………………………………………………………………………32

3.6 MEASUREMENTS PROCEDURE………………………………………………………………………………..34

3.7 EXPERIMENTAL RESULTS…………………………………………………………………………………………34

3.7.1Case 1: UNN Campus, Nsukka 34

3.7.2THRESHOLD LEVEL 35

3.7.3COMPARISON OF AVERAGE CUMULATIVE DISTRIBUTION OF RAINFALL RATES 36

3.7.4CASE 2: UNIVERSITY OF ABUJA 37

3.7.5THRESHOLD LEVEL 38

3.7.6COMPARISON OF AVERAGE CUMULATIVE DISTRIBUTION OF RAINFALL RATES 38

3.7.7CASE 3: KOGI STATE UNIVERSITY, AYINGBA 39

3.7.8THRESHOLD LEVEL 40

3.7.9COMPARISON OF AVERAGE CUMULATIVE DISTRIBUTION OF RAINFALL RATES AT TWO DIFFERENT INTEGRATIONTIMES 41

3.7.10 RAIN INDUCED ATTENUATIONON SATELLITE TO EARTH LINKS OVER THE THREE STATIONS…………………………………………………………………………………………….………………… 42

CHAPTER FOUR:DATA PRESENTATION AND ANALYSIS

4.1 FMT CONCEPTS…………………………………………………………………………………………………….44

4.1.1 Power control 45

4.1.2 Adaptive waveform 46

4.1.3 Diversity 47

4.1.4 Layer 2 47

4.2 INTERFERENCE ISSUES……………………………………………………………….…………………………. 48

4.3 INTERFERENCE SOURCES ON THE UPLINK……………………………….……………………………...48

4.4 INTERFERENCE SOURCES ON THE DOWNLINK……………………………………………………….. 53

4.5 PRELIMINARY ANALYSIS OF THE IMPACT OF FMT ON INTERFERENCE………………………55

4.5.1PowerControl 55

4.5.2OtherFMTs 56

CHAPTER FIVE: CONCLUSION

11

5Conclusion……………………………………………………………………………….………………………………58

5.1 Contribution of Theses……………………………………………..………………..……………..……………58

REFERENCES………………………………………………………………………………………….………………………….…59