Radio over Fiber for Wireless Communications
From Fundamentals to Advanced Topics
IEEE Press Series

A comprehensive evaluation of Fi-Wi,  enabling readers to design links using channel estimation and equalization algorithms 

This book provides a detailed study of radio over fiber (ROF) based wireless communication systems, otherwise called fiber wireless (Fi-Wi) systems. This is an emerging hot topic where the abundant bandwidth of optical fiber is directly combined with the flexibility and mobility of wireless networks to provide broadband connectivity.  Its application is increasing because of the growing demand for broadband wireless services. In such a system the transmission of the radio signals over a fiber is an important task. This book provides substantial material on the radio over fiber part of the complete fiber-wireless system, including new research results on the compensation methods. 

The early chapters provide fundamental knowledge required for a non-expert engineering professional as well as senior/graduate level students to learn this topic from scratch. The latter part of the book covers advanced topics useful for researchers and senior students. Therefore, this book provides a comprehensive understanding of the system for readers who will gain enough knowledge to design Fi-Wi links of their own by learning how to develop Fi-Wi channel estimation and equalization algorithms. This concept is completely novel in current literature and has been patented by the author. 

Readers are expected to have a basic understanding of fiber optics and wireless communications to easily follow the book and to appreciate the concepts. Basics of the Fi-Wi system and signal processing approaches are clearly explained. It covers a multidisciplinary topic and acts as a bridge between optical and wireless communication domains. In the increasingly demanding telecommunications profession, engineers are expected to have knowledge in both optical and wireless communications and expected design combined/hybrid systems. Hence, the book is written in such a way that both optical and wireless professionals will be able to easily understand and perceive the concepts. 

• follows a logical process from basic principles through to advanced topics, providing a wide range of interest for researchers, practicing engineers, students, and those required to build such networks
• explains detailed system design concepts and the limitations and advantages in each configuration, appealing to design engineers, and largely avoiding system specifics
• demonstrates the author?s exclusive patent, showing how to develop baseband signal processing algorithms for Fi-Wi systems, which is a key requirement for the successful deployment of Fi-Wi systems
• contains tables, numerical examples and case studies, facilitating a good quantitative understanding of the topic

Foreword ix

Preface xi

Acknowledgements xv

1 Introduction 1

1.1 Motivation 1

1.2 Basic Fi-Wi System Architecture 10

1.3 Major Issues 12

1.4 Other Fiber Feeder Approaches 13

1.5 Book Outline 14

2Important Fi-Wi Link Elements 17

2.1 RF-Optical Modulation 17

2.2 The Fiber Channel 29

2.3 Optical Receiver 36

2.4 Brief Review of Baseband-RF Modulation Techniques 40

2.5 The Wireless Channel 42

3Power Link Budget and Cumulating SNR 49

3.1 Introduction 49

3.2 System Description 50

3.3 Optical Signal to Noise Ratio (OSNR) 51

3.4 Cumulative Signal to Noise Ratio (cSNR) 57

3.5 RAP Design Considerations 58

3.6 Summary 62

4An Improved Expression for Relative Intensity Noise 63

4.1 Basics 63

4.2 The Fundamental Noise Processes in Radio over Fiber Links 64

4.3 The Signal to Noise Ratio 69

4.4 Numerical Evaluation and Discussion 71

4.5 Summary 72

5Subcarrier Multiplexed ROF Downlink 75

5.1 Introduction 75

5.2 Background 75

5.3 The ROF Downlink Channel 77

5.4 The Wireless Downlink Channel 91

5.5 Numerical Evaluation and Discussion 92

6Subcarrier Multiplexed ROF Uplink 97

6.1 The Wireless Uplink Channel 97

6.2 The ROF Uplink Channel 99

6.3 Signals to Distortion, Interference and Noise Ratios 111

6.4 Numerical Evaluations and Discussion 113

6.5 Summary 115

7Externally Modulated ROF Links 121

7.1 Mach-Zehnder Modulator 121

7.2 Electro-Absorption Modulator (EAM) 125

7.3 Reflective Semiconductor Optical Amplifier (RSOA) 128

7.4 Optimization of the MZI Bias Voltage 128

7.5 Subcarrier Multiplexed Signals in MZI 135

8DSP Modeling of the ROF Link Nonlinearity 141

8.1 Introduction 141

8.2 Various Attempts to Reduce NLD 142

8.3 DSP Approaches 144

8.4 Basics of DSP for Nonlinear Systems 146

8.5 Baseband Representation of a Passband Complex Nonlinear System 148

8.6 Nonlinear Modeling of Fi-Wi Link 149

9Adaptive Compensation for the ROF Link Nonlinearity 151

9.1 Adaptive Modeling of the ROF Link 151

9.2 Asymmetric Compensation 159

9.3 Summary 169

10Joint Estimation of the Fiber Wireless Channel 171

10.1  The Wiener and Hammerstein System Model for Fi-Wi Links 171

10.2 Fiber-Wireless Channel Estimation 172

10.3 Case Study 180

10.4 Summary 182

11Joint Equalization for the Fiber Wireless Channel 185

11.1 Equalization of the Wireless Channel 185

11.2 Optimization of Polynomial Filter Parameters 189

11.3 Optimization of Linear Filter Parameters 191

11.4 Summary 196

12Performance Evaluation of the Hammerstein type DFE 197

12.1 Evaluation of the Polynomial Filter 197

12.2 Evaluation of Linear Filters 203

12.3 Case Study 204

12.4 Summary 212

13Multiuser CDMA Fi-Wi Systems 213

13.1 Multiuser Fi-Wi Uplink Model 213

13.2 Correlation Relationships 215

13.3 ROF Channel Estimation 220

13.4 Case Study 221

13.5 Fiber-Wireless Uplink Equalization 224

13.6 Equalization: Simulation Results and Discussion 225

13.7 Summary 227

14Fi-Wi for 4G, 5G and OFDM Wireless Networks 229

14.1 Brief History of Cellular Communication Systems 230

14.2 Wireless Access Schemes 232

14.3 Peak to Average Power Ratio Reduction Techniques 235

14.4 OFDM ROF System Improvement 237

14.5 Combinations of OFDMA and CDMA 241

14.6 Summary 242

References 243

References 248

List of Abbreviations 249

Xavier Fernando, Professor and Director, Ryerson Communications Laboratory, Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada.  Xavier Fernando has been working Fi-Wi systems for over 15 years. He did his PhD in this area at the University of Calgary in affiliation with TRLabs. His PhD work has been patented and won the Canadian best paper award in 2001. He joined Ryerson University in 2001 where now he is a full professor.  Professor Fernando is an IEEE Communications Society Distinguished Lecturer and the Chair of the IEEE Toronto Section, Canada. He has been working in multiple aspects of wireless communications, having a special interest in radio over fiber systems. He has delivered invited talks worldwide including at the Cambridge University (UK), National Research Council (Canada), Athens Institute of Technology (Greece), Indian Institute of Science (India) and Princeton University (USA) on radio over fiber systems. He has co-authored close to 100 research articles, two patents and few non-disclosure agreements.