RAIN FADE PREDICTION AND DIVERSITY MODELS FOR KU-BAND SATELLITE IN MALAYSIA
BY
ALI KADHIM LWAS
A thesis submitted in fulfilment of the requirement for the degree of Doctor of Philosophy (Engineering)
Kulliyyah of Engineering
International Islamic University Malaysia
NOVEMBER 2017
ii
ABSTRACT
Tropical climate and equatorial climate experience heavy precipitation all over the year and Earth-to-satellite links that operate at frequencies higher than 10 GHz suffer from severe degradation of performance. In order to overcome such problems, link designers solely depend on prediction models most of which are developed based on measurements in temperate regions. Accurate estimation of rain attenuation leads to propose the appropriate and suitable mitigation technique for designing future high frequency Earth-to-satellite links. However available rain attenuation prediction models are unable to predict most of the measurements accurately in tropical regions.
This research uses two years rain rate and rain attenuation data at Ku-band measured in Penang (4.390°N, 100.980°E), Malaysia for analyzing and developing rain attenuation prediction and mitigation techniques. Predictions by ITU-R and dual-layer models are analyzed using measured data and found unable to predict the measurements. Synthetic storm technique is also investigated and found neither measured rain attenuation nor duration is reflected with storm velocity in synthetic storm technique prediction in tropical regions. Dual-layer model is modified based on the concept of effective path length, rain rate variations along the slant path and the rain height model by considering either rain and melting layer or only rain layer. A control parameter rho ( ) is also introduced to represent the rain intensity variations along the satellite path. The value of the parameter is proposed based on measured data. The proposed model is validated using data measured in tropical climate of Malaysia and Philippine and found good agreement. The time diversity technique is investigated using one year measured rain fade and found very good improvement in system. Time diversity gain estimated from measured one-minute rain attenuation for one year period is utilized to develop a prediction model which can predict time diversity gain as a function of rain attenuation levels and time delay. Proposed model is validated using the measured data and found very good agreement. Site diversity technique is also analyzed using one year measurement in two locations separated by 37.36 km in Malaysia. It is found that 10 raining events occurred concurrently in both sites out of 381 measured events in a year and 0.000381% of outage probability can be achieved by considering highest 18 mm/hr rainfall rate for design. These findings will be useful tools for link designers to predict rain fade and apply time or site diversity as a rain fades mitigation technique in earth-satellite communications systems.
iii
ﺚﺤﺒﻟا ﺔﺻﻼﺧ
رﺎﻄﻣﻸﻟ ﻒﻴﺜﻛ ﻞﻃﺎﻬﺘﺑ ﻲﺋاﻮﺘﺳﻻا خﺎﻨﳌاو يراﺪﳌا خﺎﻨﳌا ﻒﺼﺘﻳ ءادا ﻰﻠﻋ ﲑﺒﻛ ﻞﻜﺸﺑ ﺮﺛﺆﻳ ﺎﳑ ،ﺔﻨﺴﻟا مﺎﻳأ لﻼﺧ
ﻦﻣ ﻰﻠﻋأ تاددﺮﺗ ﻖﻓو ﻞﻤﻌﺗ ﱵﻟا ﺔﻴﻠﺗﺎﺴﻟا ﺔﻴﺿرﻷا تﻼﺻﻮﻟا 10
ﺰﺗﺮﻫ ﺎﺠﻴﺟ .
،ﻞﻛﺎﺸﳌا ﻩﺬﻫ ﻰﻠﻋ ﺐﻠﻐﺘﻟا ﻞﺟأ ﻦﻣو
ﺔﻟﺪﺘﻌﻣ ﻢﻴﻟﺎﻗأ ﰲ تﺎﺳﺎﻴﻗ ﻰﻠﻋ ًءﺎﻨﺑ ﺎﻬﻤﻈﻌﻣ ﻢِﻤُﺻ ﺆﺒﻨﺗ جذﺎﳕ ﻰﻠﻋ سﺎﺳأ ﻞﻜﺸﺑ نوﺪﻤﺘﻌﻳ تﻼﺻﻮﻟا ﻲﻤﻤﺼﻣ نﺈﻓ خﺎﻨﳌا . نإ حاﱰﻗا ﻪﻴﻠﻋ ﺐﺗﱰﻴﺳ يﺮﻄﳌا ﲔﻫﻮﺘﻠﻟ ﻖﻴﻗﺪﻟا ﺮﻳﺪﻘﺘﻟا
ﻞﺒﻘﺘﺴﳌا ﰲ ﺮﺛأ ﻦﻣ ﺪﺤﻠﻟ ﺔﻤﺋﻼﻣو ﺔﺒﺳﺎﻨﻣ ﻒﻴﻔﲣ تﺎﻴﻨﻘﺗ
ءادا ﻰﻠﻋ رﺎﻄﻣﻷا
ﻦﻣ ﻰﻠﻋأ تاددﺮﺗ ﻖﻓو ﻞﻤﻌﺗ ﱵﻟا ﺔﻴﻠﺗﺎﺴﻟا ﺔﻴﺿرﻷا تﻼﺻﻮﻟا 10
ﺰﺗﺮﻫ ﺎﺠﻴﺟ .
ةرﺎﺷﻹا رﺪﲡ ﻪﻧأ ﻻإ
و يﺮﻄﳌا ﲔﻫﻮﺘﻟﺎﺑ ﺆﺒﻨﺘﻠﻟ ﺔﺣﺎﺘﳌا جذﺎﻤﻨﻟا نأ ﱃإ ﰲ ﻖﻴﻗد ﻞﻜﺸﺑ تﺎﺳﺎﻴﻘﻟا ﻢﻈﻌﲟ ﺆﺒﻨﺘﻟا ﻰﻠﻋ ةردﺎﻗ ﲑﻏ ﻪﻨﻣ ﻒﻴﻔﺨﺘﻟا
ﺔﻔﻴﺜﻜﻟا رﺎﻄﻣﻷا تاذ ﺔﻴﺋاﻮﺘﺳﻻا ﻖﻃﺎﻨﳌا .
رﺎﻄﻣﻷا لﻮﻄﻫ لﺪﻌﳌ ﲔﻣﺎﻋ ىﺪﻣ ﻰﻠﻋ ﺔﻨﻣاﺰﺘﻣ تﺎﺳﺎﻴﻗ ﺔﺳارﺪﻟا ﻩﺬﻫ ضﺮﻌﺗ
ﻎﻧﺎﻨﺑ ﺔﻳﻻو ﰲ ﻲﻛ قﺎﻄﻧ ﻦﻤﺿ يﺮﻄﳌا ﲔﻫﻮﺘﻟاو (4.390°N, 100.980°E)
ﻬﻣاﺪﺨﺘﺳا ﻢﺘﻳ ﱵﻟا ﺎﻳﺰﻴﻟﺎﲟ ﻞﻴﻠﺤﺘﻟ ﺎ
ﲔﻫﻮﺘﻟا ةﺪﺣ ﻦﻣ ﻒﻴﻔﺨﺘﻟاو ﺆﺒﻨﺘﻟا تﺎﻴﻨﻘﺗ ﺎﻬﻨﻣ ﺖﺒﺜﺘﻟاو ﺎﻬﻨﻴﺴﲢو يﺮﻄﳌا
. دﺎﲢﻻا جذﺎﳕ ﻰﻠﻋ ﺔﻴﻨﺒﳌا تاﺆﺒﻨﺘﻟا ﻞﻴﻠﲢ ﰎ
ﺆﺒﻨﺘﻟا ﻰﻠﻋ ﺎ رﺪﻗ مﺪﻋ ﲔﺒﺗو ،ﺔﺳﺎﻘﳌا تﺎﻧﺎﻴﺒﻟا ماﺪﺨﺘﺳا لﻼﺧ ﻦﻣ ﺔﺟودﺰﳌا ﺔﻘﺒﻄﻟا جذﺎﳕو ،تﻻﺎﺼﺗﻼﻟ ﱄوﺪﻟا تﺎﺳﺎﻴﻘﻟﺎﺑ ﻣ ﻖﻘﺤﺘﻟا ﺎًﻀﻳأ ﰎ ﺎﻤﻛ .
ﺔﻋﺮﺳ ﺎﺴﻜﻌﻳ ﱂةﱰﻔﻟاو سﺎﻘﳌا يﺮﻄﳌا ﲔﻫﻮﺘﻟا نأ ﲔﺒﺗو ﺔﻴﻋﺎﻨﻄﺻﻻا ﺔﻔﺻﺎﻌﻟا ﺔﻴﻨﻘﺗ ﻦ
ﺔﻳراﺪﳌا ﻖﻃﺎﻨﳌا ﰲ ﺔﻴﻋﺎﻨﻄﺻﻻا ﺔﻔﺻﺎﻌﻟا ﺔﻴﻨﻘﺗ ﻰﻠﻋ ﲏﺒﳌا ﺆﺒﻨﺘﻟا ﰲ ﺔﻔﺻﺎﻌﻟا .
ﺔﺟودﺰﻣ ﺔﻘﺒﻃ جذﻮﳕ ﺔﺳارﺪﻟا ﻩﺬﻫ حﱰﻘﺗ
تﺎﻧﺎﻴﺒﻟا ﻰﻠﻋ ًءﺎﻨﺑ ﺔﻳراﺪﳌا ﻖﻃﺎﻨﳌا ﰲ يﺮﻄﳌا ﲔﻫﻮﺘﻟﺎﺑ ﺆﺒﻨﺘﻠﻟ لﺪﻌﻣ ﺔﺳﺎﻘﳌا
ﻰﻠﻋ ًءﺎﻨﺑ ﺔﺟودﺰﳌا ﺔﻘﺒﻄﻟا جذﻮﳕ ﻞﻳﺪﻌﺗ ﰎ .
عﺎﻔﺗرا جذﻮﳕ و ﻞﺋﺎﳌا رﺎﺴﳌا لﻮﻃ ﻰﻠﻋ رﺎﻄﻣﻷا لﻮﻄﻫ لﺪﻌﻣ ﻰﻠﻋ ﺔﺋرﺎﻄﻟا تاﲑﻐﺘﻟاو ،رﺎﺴﻤﻠﻟ لﺎﻌﻔﻟا لﻮﻄﻟا أﺪﺒﻣ ﻂﻘﻓ ﺔﻳﺮﻄﳌا ﺔﻘﺒﻄﻟا وأ نﺎﺑوﺬﻟا ﺔﻘﺒﻃو ﺮﻄﳌا ﺔﻘﺒﻃ ﻦﻣ ﻼﻛ رﺎﺒﺘﻋﻻا ﲔﻌﺑ ﺬﺧﻸﻟ رﺎﻄﻣﻷا .
ﻂﺑﺎﺿ لﺎﺧدإ ﰎ ﺎﻤﻛ ﻢﻜﲢ
ﻲﻠﺗﺎﺴﻟا رﺎﺴﳌا لﻮﻃ ﻰﻠﻋ رﺎﻄﻣﻷا لﻮﻄﻫ ةﺪﺷ ﻰﻠﻋ ﺔﺋرﺎﻄﻟا تاﲑﻐﺘﻟا ﻞﺜﻤﻴﻟ ﻰﻠﻋ ًءﺎﻨﺑ ﻂﺑﺎﻀﻟا ﺔﻤﻴﻗ حاﱰﻗا ﰎ ﺪﻗو .
ﺔﺳﺎﻘﳌا تﺎﻧﺎﻴﺒﻟا .
ﺪﺟوو ﲔﺒﻠﻔﻟاو ،ﺎﻳﺰﻴﻟﺎﳌ يراﺪﳌا خﺎﻨﳌا ﰲ ﺔﺳﺎﻘﻣ تﺎﻧﺎﻴﺑ ماﺪﺨﺘﺳا لﻼﺧ ﻦﻣ جذﻮﻤﻨﻟا ﻦﻣ ﺖﺒﺜﺘﻟا ﰎو
ﳌا تﺎﻧﺎﻴﺒﻟا ﻊﻣ ﻖﺑﺎﻄﻣ لﺪﻌﳌا جذﻮﻤﻨﻟا ﺔﺳﺎﻘ
. ﺔﻨﺳ ىﺪﻣ ﻰﻠﻋ سﺎﻘﳌا ﺮﻄﳌﺎﺑ ﻮﺒﳋا ﻰﻠﻋ ﺖﻴﻗﻮﺘﻟا ﻊﻳﻮﻨﺗ ﺔﻴﻨﻘﺗ ﻦﻣ ﻖﻘﺤﺘﻟا ﰎ
مﺎﻈﻨﻠﻟ ﻦﻜﻤﳌا ﲔﺴﺤﺘﻟا راﺪﻘﻣ ﻰﻠﻋ فﺮﻌﺘﻟا ﻞﺟأ ﻦﻣ ﺔﻠﻣﺎﻛ .
مﺎﻈﻨﻟا ﰲ اﺪﺟﺪﻴﺟ ﻦﺴﲢ كﺎﻨﻫ نا ﺪﺟوو .
ﰎ ﺪﻗو
اﺪﻣ ﻰﻠﻋ ةﺪﺣاو ﺔﻘﻴﻗد ةﺪﳌ سﺎﻘﳌا يﺮﻄﳌا ﲔﻫﻮﺘﻟا ﻦﻣ ةرﺪﻘﳌا ﲏﻣﺰﻟا عﻮﻨﺘﻟا ﺐﺳﺎﻜﻣ ماﺪﺨﺘﺳا حاﱰﻗاو ﺮﻳﻮﻄﺘﻟ ﻞﻣﺎﻛ مﺎﻋ ر
ﲏﻣﺰﻟا ﺮﺧﺄﺘﻟاو يﺮﻄﳌا ﲔﻫﻮﺘﻟا تﺎﻳﻮﺘﺴﻣ ﻰﻠﻋ ﺔﻟاد ﺎﻬﻔﺻﻮﺑ ﲏﻣﺰﻟا عﻮﻨﺘﻟا ﺐﺳﺎﻜﲟ ﺆﺒﻨﺘﻟا ﻰﻠﻋ ردﺎﻗ ﺆﺒﻨﺗ جذﻮﳕ .
ﰎو
اًﺪﺟ ﺪﻴﺟ ﻖﻓاﻮﺗ كﺎﻨﻫ نﺎﻛو ، ﺔﺳﺎﻘﻣ تﺎﻧﺎﻴﺑ ماﺪﺨﺘﺳﺎﺑ حﱰﻘﳌا جذﻮﻤﻨﻟا ﻦﻣ ﺖﺒﺜﺘﻟا .
ﱐﺎﻜﳌا عﻮﻨﺘﻟا ﺔﻴﻨﻘﺗ ﻞﻴﻠﲢ ﰎ ﺎﻤﻛ
ﺳﺎﻴﻗ ماﺪﺨﺘﺳﺎﺑ ﺔﻓﺎﺴﻣ ناﺪﻌﺒﻳ ﲔﻌﻗﻮﻣ ﰲ ﻞﻣﺎﻛ مﺎﻋ ىﺪﻣ ﻰﻠﻋ تﺎ
37.36 ﺎﻳﺰﻴﻟﺎﻣ ﰲ ﺎﻤﻬﻀﻌﺑ ﻦﻋ ﱰﻣﻮﻠﻴﻛ .
نا ﺪﺟوو
كﺎﻨﻫ 10 ﻞﺻأ ﻦﻣ رﺎﻄﻣﻷا لﻮﻄﳍ ﲔﻌﻗﻮﳌا ﻼﻛ ﰲ ﺔﻨﻣاﺰﺘﻣ ثاﺪﺣأ 381
ﺔﻴﻟﺎﻤﺘﺣا نأو ،ﻞﻣﺎﻛ مﺎﻋ ﰲ سﺎﻘﻣ ثﺪﺣ
ﻎﻠﺒﺗ عﺎﻄﻘﻧا 0.000381
% ﻣأ لﻮﻄﻫ لﺪﻌﻣ رﺎﺒﺘﻋﻻﺎﺑ ﺬﺧﻷا لﻼﺧ ﻦﻣ ﺎﻬﻘﻴﻘﲢ ﻦﻜﳝ ﻎﻠﺒﻳ رﺎﻄ
18 ﺔﻋﺎﺴﻟﺎﺑ ﱰﻤﻴﻠﻣ
ﻢﻴﻤﺼﺘﻟا ﺪﻨﻋ .
ﺔﻴﻨﻘﺗ ﻖﻴﺒﻄﺗو ،ﺮﻄﳌﺎﺑ ﻮﺒﳋا ﺆﺒﻨﺗ ﻞﺟأ ﻦﻣ تﻼﺻﻮﻟا ﻲﻤﻤﺼﳌ ةﺪﻴﻔﻣ تاودأ ﺔﺑﺎﺜﲟ ﺞﺋﺎﺘﻨﻟا ﻩﺬﻫ نﻮﻜﺘﺳ
ﺔﻴﻠﺗﺎﺴﻟا ﺔﻴﺿرﻷا تﻻﺎﺼﺗﻻا ﺔﻤﻈﻧأ ﰲ ﺮﻄﳌﺎﺑ ﻮﺒﳋا ﻦﻣ ﻒﻴﻔﺨﺘﻠﻟ نﺎﺘﻴﻨﻘﺗ ﺎﻤﻬﻔﺻﻮﺑ ﱐﺎﻜﳌا وأ ﱐﺎﻣﺰﻟا عﻮﻨﺘﻟا
.
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APPROVAL PAGE
The thesis of Ali Kadhim Lwas has been approved by the following:
_____________________________
Md. Rafiqul Islam Supervisor
_____________________________
Mohamed Hadi Habaebi Co-Supervisor
_____________________________
Ahmad Fadzil Ismail Co-Supervisor
_____________________________
Mandeep Singh Jit Singh Field Supervisor
_____________________________
Aisha Abdalla Hashim Internal Examiner
__________________________
Tharek Abd Rahman External Examiner
_____________________________
Mahamod Ismail External Examiner
_____________________________
Mohamad Fauzan Noordin Chairman
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DECLARATION
I hereby declare that this dissertation is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.
Ali Kadhim Lwas
Signature ... Date ...
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COPYRIGHT PAGE
INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH
RAIN FADE PREDICTION AND DIVERSITY MODELS FOR KU- BAND SATELLITE IN MALAYSIA
I declare that the copyright holders of this dissertation are jointly owned by the student and IIUM.
Copyright © 2017 Ali Kadhim Lwas and International Islamic University Malaysia. All rights reserved.
No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below
1. Any material contained in or derived from this unpublished research may be used by others in their writing with due acknowledgement.
2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.
3. The IIUM library will have the right to make, store in a retrieved system and supply copies of this unpublished research if requested by other universities and research libraries.
By signing this form, I acknowledged that I have read and understand theIIUM Intellectual Property Right and Commercialization policy.
Affirmed by Ali Kadhim Lwas
……..……….. ………..
Signature Date
vii
ACKNOWLEDGEMENTS
Praise to Allah, the lord and the Creator whom give me successful occasion. This work could be not completed without His guidance and grant. I pray to Allah that He fulfils me this humble work.
Special thanks my parents, who have passed away during my study. May Allah bless their souls. Thanks are also to my wife, daughters and my siblings for their consistently encouragement, supporting me to fulfil my study. Without them, I may not accomplish. May Allah bless and reward them all for this Dunia and hereafter.
I sincerely appreciate from the bottom of my heart to Professor Dr. Md Rafiqul Islam for his tremendous supervision, support, patient and continuously encouragement from the beginning.
I would like also to express my deep gratitude to my co-supervisors, Dr.Mohamed Hadi Habaebi, Dr. Ahmad Fadzil Ismail and Dr.Mandeep Singh Jit Singh for their excellent suggestion, consultation and assistance. May Allah reward and bless them all.
I am grateful to Universiti Sains Malaysia to provide two years data measured in the satellite lab. I wish to express my appreciation and thanks to those who provided their time, effort and support for this project.
Special thanks to Alhareth Zyoud, Marwan Badran and Mohammed Abduljwad. May Allah reward them all.
viii
TABLE OF CONTENTS
Abstract ... ii
Approval Page ... iv
Declaration ... v
Copyright Page ... vi
Acknowledgements ... vii
Table of Contents ... viii
List of Tables ... xi
List of Figures ... xii
List of Abbreviations ... xvi
List of Symbols ... xviii
CHAPTER ONE: INTRODUCTION ... 1
1.1 Background ... 1
1.2 Problem Statement ... 4
1.3 Research Objectives... 5
1.4 Research Scope ... 5
1.5 Thesis Organization ... 6
CHAPTER TWO: LITERATURE REVIEW ... 8
2.1 Introduction... 8
2.2 Propagation Effects ... 9
2.3 Rain Structures... 10
2.4 Rain Attenuation Prediction Models ... 11
2.4.1 Simple Attenuation Model ... 13
2.4.2 Dah Model ... 15
2.4.3 Crane Rain Attenuation Model ... 15
2.4.4 Bryant Model ... 17
2.4.5 ITU-R Model ... 17
2.4.6 Mandeep Model ... 21
2.4.7 Abdulrahman Model ... 21
2.4.8 Synthetic Storm Technique (SST) ... 22
2.4.9 GEO Satellite Link ... 27
2.5 Fade Mitigation Techniques ... 31
2.5.1 Power Control Techniques ... 32
2.5.1.1 Uplink Power Control ... 33
2.5.1.2 Downlink Power Control (DLPC) ... 34
2.5.2 Diversity Techniques ... 35
2.5.2.1 Site Diversity ... 35
2.5.2.2 Orbit Diversity ... 38
2.5.2.3 Frequency Diversity ... 39
2.5.2.4 Polarization Diversity ... 39
2.5.2.5 Time Diversity ... 40
2.6 Previous Works Related To Time Diversity ... 42
2.7 Previous Works Related To Site Diversity ... 46
2.8 Chapter Summary ... 53
ix
CHAPTER THREE: RESEARCH METHODOLOGY ... 55
3.1 Introduction... 55
3.2 The Overall Research Methodology ... 55
3.3 Procurement And Collection Of Data... 58
3.4 Rainfall Measurement System ... 60
3.5 Rain Rate Data Processing ... 62
3.6 Extraction Of Rain Attenuation ... 67
3.7 Rain Rate Distribution ... 70
3.8 Rain Attenuation Distribution... 72
3.9 Chapter Summary ... 73
CHAPTER FOUR: RAIN ATTENUATION PREDICTION MODELING .... 75
4.1 Introduction... 75
4.2 Measured Rain Attenuation Analysis ... 75
4.3 Prediction By ITU-R Model And Measurement ... 76
4.4 Evaluation Of Synthetic Storm Technique ... 78
4.5 Rain Structure And Height In Dual-Layer Model ... 84
4.6 Prediction By Dual-Layer Model And Measurement ... 86
4.7 Modification Of Two Layer Model ... 87
4.8 Evaluation Of Modified Two Layer Model For Optimum Rho ... 92
4.9 Validation Of Proposed Model ... 95
4.9.1 Measurement At USM In Malaysia ... 96
4.9.2 Measurement At IIUM In Malaysia ... 96
4.10 Comparison With Previous Work In Tropical Region ... 99
4.11 Chapter Summary ... 101
CHAPTER FIVE: MITIGATION ANALYSIS USING TIME AND SITE DIVERSITY TECHNIQUE ... 103
5.1 Introduction... 103
5.2 Time Diversity Gain ... 104
5.3 Development Of Time Diversity Gain Model ... 106
5.4 Validation Of Proposed Model ... 112
5.5 Site Diversity Analysis Based On Measured Rain Rate ... 113
5.6 Comparison Of Site Diversity Gain And Improvement ... 124
5.7 Chapter Summary ... 128
CHAPTER SIX: CONCLUSIONS AND FUTURE WORKS ... 130
6.1 Conclusions ... 130
6.2 Thesis Contributions ... 133
6.3 Future Works ... 134
x
REFERENCES ... 135
LIST OF PUBLICATIONS ... 144
APPENDICES ... 145
Appendix A ... 145
Appendix B ... 147
Appendix C ... 149
xi
LIST OF TABLES
Page No.
Table 2.1 Comparisons among rain attenuation prediction models 22
Table 2.2 The conditions to determine azimuth angle 30
Table 2.3 Summary of time diversity studies 46
Table 2.4 Summary of previous works for site diversity technique. 53 Table 3.1 Summaries of measurements data are used in this research 59
Table 3.2 Satellite and antenna specifications 60
Table 3.3 Casella tipping bucket rain gauge specification 61 Table 3.4 Sample of raw data collected with 10 s integration time for
19/10/2015. 64
Table 3.5 Rain rate calculated in mm/h. 65
Table 3.6 Sample of raw data and processed data collected with 1-minute
integration on September 17, 2008 at USM. 66
Table 3.7 Sample of raw and processed data of received signal level and
rainfall collected on October 5, 2009 at USM. 69
Table 4.1 Percentages of error between the predicted rain attenuation and
that measured at IIUM in Malaysia. 98
Table 4.2 Percentages of error between the predicted rain attenuation and
that measured at AdMU in Philippines. 100
Table 5.1 Chi-square test, measured data was carried out at Penang-
Malaysia at 12.255 GHz for 2008. 110
Table 5.2 Chi-square test, measured data was carried out at Penang-
Malaysia at 112
Table 5.3 Concurrent rainfall events between IIUM and UKM. 115 Table 5.4 Duration and outage probability of simultaneously occurred
rainfall. 123
Table 5.5 Technical parameters of the outdoor system. 124
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LIST OF FIGURES
Page No.
Figure 2.1 Components of the atmosphere impacting radio wave frequency
on space communications (Ippolito, 2017) 10
Figure 2.2 Schematic depicts an Earth-space path of communication link giving the parameters to be input into the rain attenuation
prediction process. 18
Figure 2.3 Illustration of parameters in SST model with two layers of
precipitation and the satellite link geometry. 24
Figure 2.4 Elevation angle definitions 28
Figure 2.5 Open loop uplink power control using downlink control signal
(Dao, 2013). 33
Figure 2.6 Close loop uplink power control (Ippolito, 2017). 34
Figure 2.7 Concept of site diversity 36
Figure 2.8 Definition of diversity gain (Ippolito, 2017) 37
Figure 2.9 Definition of diversity improvement 38
Figure 2.10 Time diversity performance for various delays (20 GHz data for
Earth-satellite links in Japan) 43
Figure 2.11 Cumulative distribution of the attenuation with respect to the
free space (AFS) at 11.198 GHz. 49
Figure 3.1 Flowchart of research methodology 58
Figure 3.2 Rain gauge (Casella) and the logger. 62
Figure 3.3 Complementary cumulative distribution functions of measured rain rate for August, 2009 which was collected at USM campus. 71 Figure 3.4 Complementary cumulative distribution functions of measured
rain rate at USM campus in Malaysia for two years, 2008 and
2009. 72
Figure 3.5 Complementary cumulative distribution functions of measured rain attenuation for August, 2009 which was collected at USM
campus. 73
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Figure 4.1 Complementary cumulative distribution functions of measured rain attenuation at USM campus in Malaysia for two years, 2008
and 2009. 76
Figure 4.2 Comparison of rain attenuation prediction by ITU-R with measured rain attenuation of 12.255 GHz at USM, 2008 and
2009. 78
Figure 4.3 Probability of maximum value of storm speed for all events
measured in 1 year. 78
Figure 4.4 Probability distribution of storm speed for 1 year at USM
campus in Malaysia. 79
Figure 4.5 Rain attenuation and storm speed for one rain event measured on
Feb. 26, 2009 at USM Campus in Malaysia. 80
Figure 4.6 Rain attenuation and storm speed for one rain event measured on
Apr. 2, 2009 at USM Campus in Malaysia. 80
Figure 4.7 Comparison between measured rain attenuation and predicted rain attenuation time-series by SST as a function of storm speed for rain event measured on February 26, 2009 at USM in
Malaysia. 81
Figure 4.8 Comparison between measured rain attenuation and predicted rain attenuation time-series by SST as a function of the storm speed for one rain event measured on April 2, 2009 at USM in
Malaysia. 81
Figure 4.9 Comparison between the measured and predicted rain attenuation by SST for different storm speeds at USM in
Malaysia for the year 2009. 82
Figure 4.10 Illustration of parameters for dual-layer model of precipitation
and the satellite link geometry. 86
Figure 4.11 Comparison between cumulative distribution of measured attenuation and that predicted by dual layer model from measured rain rate for the year of 2008 at USM campus in
Malaysia. 87
Figure 4.12 A diagram showing the propagation path, whereby hR is the rain height and Leff is the effective path length. 89 Figure 4.13 (a) Maximum and (b) minimum values of rho for several
measured data using modified model. 94
Figure 4.14 Comparison between measured rain attenuation and predicted rain attenuation by proposed model as function of rho ( )
values. 95
xiv
Figure 4.15 Comparison between cumulative distribution of measured rain attenuation for the year of 2009 at USM campus in Penang, Malaysia and that predicted by dual layer model and proposed
model. 96
Figure 4.16 Comparison between cumulative distribution of measured rain attenuation for 2009 and 2010 at IIUM campus in Kuala Lumpur, Malaysia and that predicted by dual layer model and
proposed model. 98
Figure 4.17 Comparison between cumulative distribution of measured rain attenuation at AdMU in Philippines and that predicted by dual
layer model and proposed model. 100
Figure 5.1 An Example, which illustrates the use of time diversity technique in the signal of a satellite-Earth link for an event,
measured at Penang-Malaysia on 10/28/2009. 104
Figure 5.2 Measured rain attenuation at Penang -Malaysia for the year 2008 and complementary cumulative distributions of rain attenuation
for several time delays. 105
Figure 5.3 Complementary cumulative distributions of measured time
diversity gain for several time delays. 106
Figure 5.4 Diversity gain (dB) as a function of time delay (min) for several
attenuation values from 5 dB to 27.5 dB at 12.255 GHz. 108
Figure 5.5 Coefficient a versus rain attenuation A. 109
Figure 5.6 Coefficient a versus time delay δt. 109
Figure 5.7 Complementary cumulative distribution function of time diversity gain predicted by the proposed model at different time delays compared with measured data in Penang-Malaysia at
12.255 GHz for the year 2008. 111
Figure 5.8 Comparison between measured and proposed diversity gain (dB) as a function of time delay (min) for several attenuation values from 5 dB to 27.5 dB at 12.255 GHz in Penang-Malaysia for the
year 2008. 112
Figure 5.9 Comparison between measured data and the proposed model for time diversity statistics in Penang-Malaysia at 12.255 GHz for
the year 2009. 113
Figure 5.10 Locations of IIUM in Gombak and UKM in Bangi. 115 Figure 5.11 Concurrent event on February 13, 2015 for duration 8 minutes. 116 Figure 5.12 Concurrent event on March 21, 2015 for duration 14 minutes. 117
xv
Figure 5.13 Concurrent event on April 19, 2015 for duration 6 minutes. 117 Figure 5.14 Concurrent event on July 1, 2015 for duration 10 minutes. 118 Figure 5.15 Concurrent event on July 2, 2015 for duration 17 minutes. 119 Figure 5.16 Concurrent event on August 4, 2015 for duration 10 minutes. 119 Figure 5.17 Concurrent event on November 5, 2015 for duration 13 minutes. 120 Figure 5.18 Concurrent event on November 13, 2015 for duration 14
minutes. 120
Figure 5.19 Concurrent event on November 15, 2015 for duration 7 minutes. 121 Figure 5.20 Concurrent event on November 25, 2015 for 14 minutes
duration. 121
Figure 5.21 Cumulative Distribution Function of Rain Intensity of IIUM and
Joint Distribution of IIUM and UKM Measured during 2015. 123 Figure 5.22 Cumulative Distribution Function of converted rain attenuation
of IIUM and Joint Distribution of IIUM and UKM using
measured rain rate for 2015. 124
Figure 5.23 Comparison of site diversity gain prediction models with measured site diversity gain for base line orientation of 90
degree in Kuala Lumpur, Malaysia. 125
Figure 5.24 Comparison of site diversity gain prediction models with measured site diversity gain for base line orientation of 0 degree
in Kuala Lumpur, Malaysia. 126
Figure 5.25 Comparison of site diversity gain prediction models with
measured site diversity gain in Singapore. 127
Figure 5.26 Comparison between time percentage of site diversity for IIUM and UKM, P2, and IIUM site, P1, for measured data, ITU-R
model and Panagopoulos model. 128
xvi
LIST OF ABBREVIATIONS
ACM Adaptive Coding and Modulation AdMU Anteneode Manila University
CCDF Complimentary Cumulative Distribution Functions DLPC Down-Link Power Control
DAH Dissanayake, Allnutt, and Haidara EHF Extremely High Frequency EIRP Effective Isotropic Radiated Power FMTs Fade Mitigation Techniques FSS Fixed Satellite Service GEO Geostationary earth orbit GTD Time Diversity Gain
IIUM International Islamic University Malaysia
ITU-R International Telecommunication Union - Radio communication MSS Mobile Satellite Service
OBBS On-Board Beam Shaping RSL Received Signal Level SAM Simple Attenuation Model SD Site Diversity
SST Synthetic Storm Technique TD Time Diversity
TEC Total Electron Content
TRMM Tropical Rainfall Measuring Mission UKM Universiti Kebangsaan Malaysia
xvii ULPC Up-Link Power Control USM Universiti Sains Malaysia
xviii
LIST OF SYMBOLS
A Attenuation
dBm A unit of power in decibel scale, referenced to one milliwatt dBw A unit of power in decibel scale, referenced to one watt (w) Ep% Percentage of error
f Frequency (GHz) in operating
Gd Gain contributed by spatial separation Gf Gain contributed by frequency
Gβ Gain contributed by baseline dependent term Gθ Gain contributed by elevation angle
ho height of 0°C isotherm hR Effective height of rain (km)
hs Height of the earth station (km) above mean sea level I Diversity improvement factor
k and a Coefficients related with frequency and polarization that given Leff Effective Length
Ls Length of the slant path
M Binary operator
R Rainfall rate
R0.01 Rain rate for the location for 0.01% of an average year (mm/h) RA Rain rate of rain layer
RB Rain rate of melting layer
Re Earth effective radius (8 500 km)
T Time duration
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R Specific rain attenuation
β Baseline angle
δt time delay
θ Elevation angle (deg.) of the satellite -Earth link
σ Standard deviation
τ Polarization angle of the satellite -Earth link (deg) φ Latitude of the location of earth station (deg.)
ψ Azimuth angle
Parameter controlling the rate of the horizontal profile decays
1
CHAPTER ONE INTRODUCTION
1.1 BACKGROUND
Rapid growth in wireless communications, which led to the expansion of its services provided to customers, had to move to higher frequencies. However, use of frequencies higher than 10 GHz can be limited by several wave propagation effects in atmosphere. Rain is the main source for signal degradation through tropospheric layer.
The prediction of rain attenuation is an essential step when designing an Earth- satellite links operating in high frequencies (Zhou et al., 1999; Mandeep, 2009a).
Since, knowledge about the outage probability of a satellite system is fundamental for any satellite communication system designer, it is very important to determine and analyze the rain fade probability and its characteristics in-depth. Accurate estimation of rain attenuation leads to propose the appropriate and suitable mitigation technique for the rain effect.
Tropical regions are located between the Tropic of Cancer at 23.5 degrees north latitude and the Tropic of Capricorn at 23.5 degrees south latitude. Weather remains hot during the year, with frequent heavy rainfall and slight temperature variation. Malaysia is considered as in tropical region (Ismail, 2001). Temperate regions are located between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere. It is between the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere. Weather generally has cold winter, warm summer and moderate autumn and spring. It does not have extremes in temperature or precipitation (Mansy, 2006). Most of European countries are considered as temperate region.
2
The majority of the studies concerning rain attenuation and their effect on satellite–
Earth links and mitigation techniques have been carried out in regions where climate is of a temperate nature. This type of climate is characterized by stratiform type with large rain cell size and rain drops that are light and small in diameter (Dissanayake et al, 1997; Mandeep et al, 2007; Pan et al, 2001). On the other hand, rain in the tropical regions is often convectional, which is generally heavy with large rain drops sizes and relatively small rain-cell diameter (Ramachandaran and Kumar, 2007). Definitely, this difference in rain structure between temperate and tropical regions will result in diverse spatial distribution.
In tropical and equatorial regions, satellite signals at higher frequencies are seriously affected by atmospheric impairments. The presence of rain in the path of the transmission is the major cause for satellite signal degradation due to absorption and scattering when operating at Ku-band and above (Zhou et al., 2000). The absorption and scattering of the radio waves depend on raindrop sizes, shapes and wavelengths that cause the attenuation for the satellite signal and the reduction for overall availability of the system (De Maagt et al, 1995; Kumar and Ramachandran, 2004;
Emiliani et al., 2005; Mandeep, 2009a). In equatorial and tropical regions, there are insufficient measurements at high frequencies to investigate available rain attenuation prediction models or to derive accurate prediction method (Emiliani et al., 2005; Del Pino et al., 2005; Mandeep, 2009a). Therefore, to determine the effect of the rain and availability precisely, measured rain attenuation and rain rate data in these regions is a great importance. Measured data are necessitated to design the reliable satellite communications systems or evaluate their performance. These data are necessary to propose cost effective and efficient mitigation techniques to overcome the attenuation due to rain (Del Pino et al., 2005). Therefore, the scarcity of measured beacon of
3
satellite-Earth and its effects due to rain cause the discrepancies between available predictions models and direct measured data from tropical and equatorial climates.
Most of these existing rain attenuation prediction models do not appear to perform well in high rainfall regions (Dissanayake et al, 1997; García and da Silva Mello, 2004; Mandeep et al, 2007; Mandeep and Allnutt, 2007). The ITU-R model is currently being widely used by many researchers. Recent measurements show that the ITU-R model underestimates the measured rain attenuation cumulative distribution when applied to tropical regions, leading to a poor prediction (Ong and Zhu, 1997;
Mandeep et al,2007; Mandeep and Allnutt, 2007; Lakanchanh et al, 2006; Lam et al, 20012; Abdulrahman et al, 2013). Dual- layer model was proposed based two layers concept such as rain layer and melting layer. It was proposed based on data measured in temperate region to predict rain attenuation at any specific outage time in percentage (Matricciani, 1996). However recent studies show that in tropical climate, melting layer is disappeared during convective type of rains (Azlan et al, 2011).
Synthetic storm technique is a suitable method to convert the instantaneous rain rate measurements to rain-attenuation time series for Ku-, Ka-, and V-bands. Synthetic storm technique was developed based on data collected from temperate regions (Sánchez-Lago et al, 2007).
Therefore, it is an urgent need to develop more accurate rain attenuation prediction model for tropical climate based on rain characteristics and measurements.
Several fade mitigation techniques have been proposed in the literature to handle the signal attenuation during rain. Techniques such as power control (Chen and Chu, 2007), site diversity (Castanet et al, 2003; Panagopoulos et al, 2004), frequency diversity (Capsoni et al, 2009) and time diversity (Ismail and Watson, 2000) show a promising results. However, these techniques are not thoroughly investigated with
4
tropical measurements. The time and site diversity techniques are considered the most attractive in terms of efficient implementation for satellite applications. Hence, the applicability of time and site diversity gain and improvement models needs to be investigated based on tropical measurements like Malaysia.
1.2 PROBLEM STATEMENT
Congestion of low frequency bands has forced satellite communications services providers to move to higher frequency bands, which can support numerous users.
However, rain-induced attenuation is the major issue at frequencies above 10 GHz, more especially in tropical regions which face heavy rainfall with different characteristics. The majority of the studies concerning rain attenuation and their effect on satellite–Earth links and mitigation techniques have been carried out in regions where climate is of a temperate in nature. The difference in rain structure and diverse spatial distribution between temperate and tropical regions results in discrepancies in performance of prediction models. Most of rain attenuation prediction models including widely used model proposed by ITU-R do not appear to perform well in tropical region like Malaysia. Dual-layer models were proposed based two layers concept such as rain layer and melting layer. However recent studies show that in tropical climate, melting layer is disappeared during convective type of rains (Azlan et al, 2011). It also considers uniform spatial rain intensity distribution along the slant path, which is found varying with rain intensities (Adhikari et al, 2011). Therefore, it is an urgent need to develop more accurate rain attenuation prediction model for tropical climate based on rain structure, spatial distribution and measurements.
To encounter rain attenuation problem on Earth-to- satellite links, performance of site and time diversity gain and improvement are not been investigated thoroughly in
5
tropical climate, even though those are found mitigating well for temperate regions.
Hence to investigate the diversity gain and improvement and develop prediction methods are important requirements to design future high frequencies systems.
1.3 RESEARCH OBJECTIVES
The main objectives of this research are
1- To investigate rain attenuation prediction for Earth to satellite link using Ku-band data measured in Malaysia.
2- To develop an accurate rain attenuation prediction model based on rain cell structure and spatial distribution using data measured in Malaysia.
3- To analyze time and site diversity techniques to mitigate Earth-to-satellite rain fade and propose a time diversity gain prediction model based on measured data.
1.4 RESEARCH SCOPE
Two years concurrently measured rain rate and rain attenuation for Earth-to-satellite link at Ku-band in Penang, Malaysia are main data in this research for evaluating, modifying and deriving prediction models. Several measured data at Ku band were collected in Kuala Lumpur-Malaysia, Anteneo de Manila University-Phillipine, which are used to validate proposed models. In addition, 1-minute rain rate in two locations separated by 37.36 Km were measured at Kuala Lumpur in Malaysia which are used to analyze site diversity. Site diversity gain is also evaluated by using data measured on two earth stations separated by 12.3 km in Singapore.
