Coding for Optical Channels (eBook)

Preface 6
Contents 8
About the Authors 14
1 Introduction 15
1.1 Historical Perspective of Optical Communications 16
1.2 Optical Transmission and Optical Networking 18
1.3 Optical Communications Trends 23
1.3.1 Migration to 100Gb/s Ethernet and Beyond 23
1.3.2 Dynamically Reconfigurable Optical Networks 24
1.3.3 Software-Defined Optical Transmission 25
1.3.4 Digital Signal Processing and Coherent Detection 27
1.3.5 OFDM for Optical Communications 28
1.4 Forward Error Correction for Optical Communications and Networks 30
1.5 Organization of the Book 34
References 36
2 Fundamentals of Optical Communication 39
2.1 Introduction 39
2.2 Key Optical Components 40
2.2.1 Optical Transmitters 44
2.2.2 Optical Receivers 49
2.2.3 Optical Fibers 51
2.2.4 Optical Amplifiers 54
2.2.5 Other Optical Components 58
2.3 Direct Detection Modulation Schemes 63
2.3.1 Non-Return-to-Zero 63
2.3.2 Return-to-Zero 64
2.3.3 Alternate Mark Inversion 64
2.3.4 Duobinary Modulation Format 65
2.3.5 Carrier-Suppressed Return-to-Zero 66
2.3.6 NRZ-DPSK 68
2.3.7 RZ-DPSK 68
2.4 Coherent Detection Modulation Schemes 69
2.4.1 Optical Hybrids and Balanced Receivers 75
2.4.2 Dominant Coherent Detector Noise Sources 77
2.4.3 Homodyne Coherent Detection 81
2.4.4 Phase Diversity Receivers 82
2.4.5 Polarization Control and Polarization Diversity 83
2.4.6 Polarization Multiplexing and Coded Modulation 84
2.5 Summary 86
References 86
3 Channel Impairments and Optical Communication Systems Engineering 89
3.1 Noise Sources 89
3.1.1 Mode Partition Noise 90
3.1.2 Reflection-Induced Noise 90
3.1.3 Relative Intensity Noise (RIN) and Laser Phase Noise 90
3.1.4 Modal Noise 92
3.1.5 Quantum Shot Noise 93
3.1.6 Dark Current Noise 94
3.1.7 Thermal Noise 94
3.1.8 Spontaneous Emission Noise 94
3.1.9 Noise Beat Components 95
3.1.10 Crosstalk Components 96
3.2 Channel Impairments 98
3.2.1 Fiber Attenuation 98
3.2.2 Insertion Losses 99
3.2.3 Chromatic Dispersion and Single Mode Fibers 99
3.2.4 Multimode Dispersion and Multimode Fibers 108
3.2.5 Polarization-Mode Dispersion 111
3.2.6 Fiber Nonlinearities 114
3.2.6.1 Self-Phase Modulation 117
3.2.6.2 Cross-Phase Modulation 118
3.2.6.3 Four-Wave Mixing 119
3.2.6.4 Stimulated Raman Scattering 120
3.2.6.5 Stimulated Brillouin Scattering 122
3.3 Transmission System Performance Assessmentand System Design 124
3.3.1 Quantum Limit for Photodetection 126
3.3.2 Shot Noise and Thermal Noise Limit 127
3.3.3 Receiver Sensitivity for Receivers with Optical Preamplifier 128
3.3.4 Optical Signal-to-Noise Ratio 128
3.3.5 Power Penalty Due to Extinction Ratio 129
3.3.6 Power Penalty Due to Intensity Noise 129
3.3.7 Power Penalty Due to Timing Jitter 130
3.3.8 Power Penalty Due to GVD 130
3.3.9 Power Penalty Due to Signal Crosstalk 131
3.3.10 Accumulation Effects 131
3.3.11 Systems Design 133
3.3.12 Optical Performance Monitoring 134
3.4 Summary 135
References 135
4 Channel Coding for Optical Channels 137
4.1 Channel Coding Preliminaries 138
4.2 Linear Block Codes 144
4.2.1 Generator Matrix for Linear Block Code 145
4.2.2 Parity-Check Matrix for Linear Block Code 146
4.2.3 Distance Properties of Linear Block Codes 148
4.2.5 Coding Gain 149
4.2.6 Syndrome Decoding and Standard Array 151
4.2.7 Important Coding Bounds 155
4.3 Cyclic Codes 156
4.4 Bose–Chaudhuri–Hocquenghem Codes 162
4.4.1 Galois Fields 162
4.4.2 The Structure and Decoding of BCH Codes 165
4.5 Reed–Solomon Codes, Concatenated Codes, and Product Codes 172
4.6 Trellis Description of Linear Block Codesand Viterbi Algorithm 175
4.7 Convolutional Codes 180
4.7.1 Distance Properties of Convolutional Codes 186
4.7.2 Bounds on the Bit-Error Ratio of Convolutional Codes 188
4.8 Summary 190
References 191
5 Graph-Based Codes 193
5.1 Overview of Graph-Based Codes 193
5.2 Convolutional Turbo Codes 195
5.2.1 Performance Characteristics of Parallel and Serial Turbo Codes 196
5.2.2 The PCCC Iterative Decoder 198
5.2.2.1 The BCJR Algorithm 200
5.2.2.2 The Iterative Decoder 201
5.2.3 The SCCC Iterative Decoder 205
5.3 Block Turbo Codes 207
5.3.1 Overview of Turbo Decoding of BTCs 207
5.4 LDPC Codes 210
5.4.1 Matrix Representation 210
5.4.2 Graphical Representation 211
5.4.3 LDPC Code Design Approaches 212
5.4.4 LDPC Decoding Algorithms 213
5.4.5 Reduced Complexity Decoders 216
5.4.5.1 The Min-Sum Decoder 216
5.4.5.2 The Min-Sum-Plus-Correction-Factor Decoder 217
5.5 Concluding Remarks 219
References 219
6 Coded Modulation 221
6.1 Multilevel Modulation Schemes 221
6.2 Single-Carrier-Coded Modulation Schemes 225
6.3 Multidimensional Coded Modulation Schemes 232
6.4 Coded OFDM in Fiber-Optics Communication Systems 237
6.4.1 Coded OFDM in Fiber-optics Communication Systems with Direct Detection 238
6.4.2 Coded OFDM in Fiber-Optics Communication Systems with Coherent Detection 245
6.4.2.1 Description of PMD Channel Model 248
6.4.2.2 PMD Compensation by Coded OFDM in Fiber-Optics Communication Systems with Coherent Detection 250
6.5 Summary 258
References 259
7 Turbo Equalization in Fiber-Optics Communication Systems 263
7.1 Channel Equalization Preliminaries 264
7.2 Turbo Equalization in Fiber-Optics Communication Systems with Direct Detection 271
7.2.1 Description of LDPC-Coded Turbo Equalizer 272
7.2.2 Large-Girth LDPC Codes 276
7.2.3 Suppression of Intrachannel Nonlinearities by LDPC-Coded Turbo Equalization 279
7.2.4 Chromatic Dispersion Compensation 281
7.2.5 PMD Compensation 283
7.3 Multilevel Turbo Equalization in Fiber-Optics Communication Systems with Coherent Detection 285
7.3.1 Description of Multilevel Turbo Equalizer 285
7.3.2 Mitigation of Intrachannel Nonlinearities by LDPC-Coded Turbo Equalization Based on Multilevel BCJR Algorithm 291
7.3.3 PMD Compensation in Polarization Multiplexed Multilevel Modulations by Turbo Equalization 293
7.4 Summary 296
References 296
8 Constrained Coding for Optical Communication 299
8.1 Introduction 299
8.2 Fundamentals of Constrained Systems 300
8.3 Construction of Finite-State Encoders 304
8.4 Decoders for Constrained Codes 308
8.5 Applications to Optical Communications 313
8.5.1 Use of Constrained Encoding 314
8.5.2 Combined Constrained and Error Control Coding 319
8.5.3 Deliberate Error Insertion 320
8.6 Concluding Remarks 322
References 323
9 Coding for Free-space Optical Channels 325
9.1 Atmospheric Turbulence Channel Modeling 326
9.1.1 Zero Inner Scale 327
9.1.2 Nonzero Inner Scale 327
9.1.3 Temporal Correlation FSO Channel Model 329
9.2 Coded MIMO FSO Communication 331
9.2.1 LDPC-Coded MIMO Concept and Space-Time Coding 331
9.2.2 Bit-Interleaved LDPC-coded Pulse-AmplitudeModulation 336
9.2.3 Bit-Interleaved LDPC-coded Pulse-PositionModulation 340
9.3 FSO-OFDM Transmission System 342
9.4 OFDM in Hybrid Optical Networks 351
9.4.1 Hybrid Optical Networks 352
9.4.2 Description of Receiver and Transmission Diversity Scheme 355
9.4.3 Performance Evaluation of Hybrid Optical Networks 357
9.5 Raptor Codes for Temporally Correlated FSO Channels 360
9.6 Summary 364
References 364
10 Optical Channel Capacity 367
10.1 Channel Capacity Preliminaries 368
10.2 Calculation of Information Capacity by Forward Recursion of BCJR Algorithm 374
10.3 Information Capacity of Fiber-Optics Communication Systems with Direct Detection 378
10.4 Information Capacity of Multilevel Fiber-Optics Communication Systems with Coherent Detection 384
10.5 On the Channel Capacity of Optical OFDM Systems for ASE-Noise-Dominated Scenario 386
10.5.1 Power-Variable Rate-AdaptivePolarization-Multiplexed Coherent-Coded OFDM 387
10.5.2 Adaptive-Coded OFDM for Communication Over GI-POF Links 390
10.5.3 Adpative-Coded OFDM for Radio-over-Fiber Technologies 392
10.6 On the Channel Capacity of Hybrid Free-Space Optical-Wireless Channels 395
10.6.1 Hybrid FSO-Wireless System Description 395
10.6.2 Adaptive Modulation and Coding 398
10.7 On the Channel Capacity of Optical MIMO MMF Systems 405
References 410
11 Future Research Directions in Coding for Optical Channels 413
11.1 Binary QC-LDPC Codes of Large Girth 415
11.1.1 Design of Large-Girth QC-LDPC Codes 415
11.1.2 FPGA Implementation of Large-Girth LDPC Codes 416
11.2 Nonbinary QC-LDPC Codes 419
11.3 Nonbinary LDPC-Coded Modulation for Beyond 100Gb/s Transmission 422
11.4 Adaptive Nonbinary LDPC-Coded Modulation 427
11.5 Adaptive LDPC-Coded OFDM 430
11.6 Generalized LDPC Codes 434
11.7 LDPC-Coded Hybrid Frequency/Amplitude/Phase/Polarization Modulation 438
11.8 Concluding Remarks 442
References 443
Index 447