Tài liệu OPTICAL WIRELESS COMMUNICATION SYSTEM doc

MODELING INTERSATELLITE OPTICAL WIRELESS COMMUNICATION SYSTEM AIDA HASFIZA BINTI HASHIM UNIVERSITI TEKNOLOGI MALAYSIA MODELING INTERSATELLITE OPTICAL WIRELESS COMMUNICATION SYSTEM AIDA HASFIZA BINTI HASHIM A thesis submitted in fulfillment of the requirements for the award of the degree Bachelor of Electrical Engineering (Telecommunication) Faculty of Electrical Engineering Universiti Teknologi Malaysia MAY 2009 ii iii To those who matters most to me. iv ACKNOWLEDGEMENT My undivided gratitude to Allah S.W.T that has given me blessings and strength to complete this project entitled “Modeling Intersatellite Optical Wireless Communication System” successfully. I wish to express my sincere appreciation to my Supervisor, Dr. Sevia M. Idrus, for her constant guidance, counsels, and putting much effort upon the completion of this project. I also would like to thank my lecturers in the Faculty of Electrical Engineering who have taught me throughout the semesters. I am also grateful to the Ministry of Higher Education for supporting this project under vote number 78289. Credits also given towards the researchers and staffs in Photonics Technology Centre who are always willing to lend their hands and show me guidance. Many thanks also to my mother, my sisters and the rest of my family members for their encouragement, love and support. Last but not least, for all my friends – Nadia, Norli, Farah, Huda, Julia and the rest of my Electrical-Telecommunication Engineering classmates that had shared their knowledge and experience with me throughout these four years of study. The kindness, cooperation and support from all of them will always be remembered. Thank you. v ABSTRACT Optical communications systems have evolved from lengthy fibers to powerful wireless system. This has hence resulted in the use of optical wireless communication system in space communications. As the number of satellites orbiting Earth increase year by year, a network between the satellites provides a method for them to communicate with each other. This is important for satellites to send information to one another and also to relay the information from one satellite to another satellite and then to the ground stations. In this research, the intersatellite communication link is studied and optical wireless communication was proposed for the link. The intersatellite optical wireless communication (IsOWC) system was designed and simulated for performance characterization. The intersatellite link was modeled and simulated using a commercial optical system simulator named OptiSystem by Optiwave. The findings of this project shows that by using laser satellite communication system, the satellites can be connected with data rates up to 10Gbps. This thesis fully discusses the free space optic system technology for intersatellite communication link for future development of large data transfer between satellites with high Quality of Service (QoS). The system performance including bit rates, receiver sensitivity and distance of LEO and GEO intersatellite links were analyzed. vi ABSTRAK Sistem komunikasi optik telah berkembang dari kabel-kabel fiber ke sistem wayarles yang canggih. Ini telah mengembangkan penggunaan teknologi optik ke sistem komunikasi angkasa lepas. Dengan pertambahan bilangan satelit di orbit dari tahun ke tahun, jaringan perhubungan antara satelit-satelit ini dapat memberi satu kaedah untuk ia berhubung. Ini adalah penting untuk satu satelit menerima dan menghantar data dari satu satelit ke satelit yang lain dan juga ke bumi. Dalam kajian ini, komunikasi antara satelit telah dipelajari dan komukasi optik wayarles telah dicadangkan. Sistem komunikasi optik wayarles antara satelit (IsOWC) telah direkabentuk dan disimulasi untuk kajian prestasi sistem. Talian antara satelit itu telah dimodel dan disimulasi menggunakan perisian OptiSystem dari Optiwave. Hasil daripada kajian ini telah menunjukkan bahawa dengan menggunakan sistem komunikasi laser, satelit-satelit dapat dihubungkandengan kadar data mencecah 10Gbps. Tesis ini membincangkan secara keseluruhan sistem teknologi optik ruang bebas untuk talian komunikasi antara satelit dengan perpindahan data yang besar dan juga kualiti servis (QoS) yg tinggi untuk masa hadapan. Prestasi sistem seperti kadar data, sensitiviti penerima, dan jarak antara satelit-satelit LEO dan GEO telah dikaji. vii TABLE OF CONTENTS CHAPTER TITLE PAGE DECLARATION DEDICATION ACKNOWLEDGEMENT ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS ii iii iv v vi vii x xi xiii 1 INTRODUCTION 1.1 Introduction 1.2 Overview of Satellites 1.3 Project Objectives 1.4 Scope of Work 1.5 Problem Statement 1.6 Thesis Outline 1 3 4 5 5 6 2 BASIC CONCEPT AND THEORIES 2.1 Introduction 2.2 Intersatellite Link Developments 2.3 Optical Wireless Communication Concepts 2.3.1 Optical Wireless System 8 8 9 10 [...]... possible Figure 2.1 shows the overview of optical communication link between Artemis and SPOT-4 [7] Optical link Figure 2.1 Optical intersatellite link between Artemis and SPOT-4 first achieved in March 2003 2.3 Optical Wireless Communication Concepts Different from RF links, OWC uses light at near-infrared frequency to communicate OWC system still consists of three main communication parts which 10 are transmitter,... Figure 1.2 1.3 Earth Satellite Communication Orbits Project Objectives This project was done to fulfill these objectives: i) To study the optical wireless communication system for intersatellite links ii) To design the intersatellite optical wireless communication system for GEO and LEO satellites iii) To model and characterization simulate the intersatellite link for performance 5 1.4 Scope of Work... models basic optical communication system where no advanced modulation, multiplexing or coding technique is used The software that is used to model the IsOWC system is Optiwave’s OptiSystem Therefore, the result of system performance relies on the software and the channel characteristic follows the software’s OWC channel characteristic To analyze the system, parameters that can affect the system performance... 10dBm 44 xiii LIST OF ABBREVIATIONS OWC - Optical Wireless Communication IsOWC - Intersatellite Optical Wireless Communication RF - Radio Frequency SCORE - Signal Communication by Orbital Relay LEO - Low Earth Orbit MEO - Medium Earth Orbit GEO - Geosynchronous Orbit BER - Bit Error Rate NASA - National American Space Agency TDRSS - Tracking and Data Relay Satellite System ESA - European Space Agency SPOT-4... propagation channel and receiver The OWC system is not much different from free space optics and fiber optic communication where the difference relies in the propagation medium OWC channel is considered to be outer space where it is assumed to be vacuum and free from atmospheric attenuation factors 2.3.1 Optical Wireless System As mentioned, the optical wireless system consists of transmitter, propagation... connection The paper also presents an advanced block diagram of an intersatellite optical transceiver as in Figure 2.8 [2] The transceiver system includes tracking system and attitude control system to point the transceiver to the other satellite 19 Figure 2.8 2.5 High-level optical intersatellite communication system Intersatellite Optical Link Applications There are many applications of IsOWC, applications... this thesis report Chapter 4 presents the system model that had been designed The OptiSystem software that is used to model the IsOWC system is briefly discussed Each subsystem in the system is also explained in the chapter The findings of this project are presented in Chapter 5 The system performance is presented in graphs and figures and is then discussed System performance is measured in Q-factor... is now able to send information at data rates up to several Gbps and at distance of thousands of kilometers apart This has open up the idea to adapt optical wireless communication technology into space technology; hence intersatellite optical wireless communication (IsOWC) is developed IsOWC can be used to connect one satellite to another, whether the satellite is in the same orbit or in different... wavelength are varied The performance of the system is measured in terms of the bit error rate (BER), Q-factor and received power retrieved from the software 1.5 Problem Statement Conventional communication between satellites and also to Earth is by using RF system The problem with RF system is that there are many limitations in the 6 systems, limitation that optical links can recover Frequency is one... light emitted by LED Hence, ILD is used for IsOWC system The electrical signal from TT&C system and optical signal from the laser will be modulated by an optical modulator before it is transmitted out to space An optical modulator varies the intensity or amplitude of the input light signal from ILD according to the electrical signal This is done by changing optical parameters such as refractive index, reflection . Optical communications systems have evolved from lengthy fibers to powerful wireless system. This has hence resulted in the use of optical wireless communication. intersatellite communication link is studied and optical wireless communication was proposed for the link. The intersatellite optical wireless communication