Foreword ix
Preface xi
Acknowledgments xv
Acronyms xvii
Notation xxi
1 Introduction 1
1.1 Conventional Communications versus Semantic Communications 2
1.1.1 Three-level Communications 2
1.1.2 History of Semantic Communications 3
1.2 Introducing Deep Learning to Semantic Communications 4
1.2.1 Deep Learning Basics 4
1.2.2 Deep Learning Enabled Semantic Communications 11
1.3 Semantic Communications for Further Networks 13
References 15
2 Semantic Information Theory 19
2.1 Semantic Entropy 19
2.1.1 Logical Probability Based 19
2.1.2 Synonymous Mapping Based 21
2.1.3 Fuzzy Theory Based 23
2.1.4 Task Based 24
2.2 Semantic Channel Capacity 24
2.2.1 Logical Probability Based 24
2.2.2 Synonymous Mapping Based 25
2.3 Semantic Source Coding Theorem 26
2.3.1 Logical Probability Based 26
2.3.2 Synonymous Mapping Based 27
2.4 Semantic Channel Coding Theorem 28
2.4.1 Logical Probability Based 28
2.4.2 Synonymous Mapping Based 28
2.5 Information Bottleneck 29
2.5.1 Classical Information Bottleneck 29
2.5.2 Knowledge Collision-based Information Bottleneck 30
References 30
3 Joint Semantic-channel Coding for Source Reconstruction 33
3.1 Semantic Communications for Text 34
3.1.1 Joint Semantic-channel Coding for Text 35
3.2 Semantic Communications for Speech 38
3.2.1 Joint Semantic-channel Coding for Speech 39
3.3 Semantic Communications for Image 42
3.3.1 Joint Semantic-channel Coding for Image 42
3.4 Performance Metrics 48
3.4.1 Performance Metrics for Text Accuracy 48
3.4.2 Performance Metrics for Speech Quality 49
3.4.3 Performance Metrics for Image Quality 49
References 52
4 Task-oriented Semantic Communications 55
4.1 Single-modal Task-oriented Semantic Communications 55
4.1.1 Semantic Communications for Machine Translation 56
4.1.2 Semantic Communications for Speech Recognition and Synthesis 59
4.2 Multimodal Task-oriented Semantic Communications 69
4.2.1 Semantic Communication Systems for Visual Question Answering 69
References 74
5 Joint Sensing and Semantic Communications 77
5.1 Introduction and Framework of Joint Sampling and Coding 77
5.1.1 Semantic Sampling 78
5.1.2 Semantic Reconstruction 79
5.2 Joint Semantic Sampling and Coding for Image 79
5.2.1 Semantic-aware Image Compressed Sensing 80
5.2.2 Adaptive Sampling and Semantic-channel Coding 84
5.3 Joint Semantic Sampling and Coding for Video 89
5.3.1 Semantic-based Video Sampling and Reconstruction 92
References 95
6 Semantic Impairments in Communications 97
6.1 JSCC Framework with Semantic Impairments 98
6.2 Source Semantic Impairments Suppression 100
6.2.1 Robust Semantic Communications for Text 100
6.2.2 Robust Semantic Communications for Speech 106
6.2.3 Robust Semantic Communications for Image 113
6.3 Knowledge Base Semantic Impairments Suppression 120
6.3.1 Robust SKB 120
References 125
7 Generative AI-enabled Semantic Communications 129
7.1 Introducing Generative Models to Semantic Communications 129
7.2 Framework of Generative Semantic Communications 131
7.2.1 Main Components of Generative Semantic Communication System 133
7.2.2 Key Interactions and Processes 135
7.3 Demonstration of Generative Semantic Communication for Video Conferencing 136
7.4 Applications of Semantic Communications in Other Scenarios 138
7.4.1 Immersive Communications 138
7.4.2 Autonomous Driving 139
7.4.3 Smart Cities 140
7.4.4 Satellite Networks 141
References 142
8 Conclusion and Challenges 145
Index 149
