| Preface | 5 |
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| Contents | 6 |
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| 1 Introduction | 9 |
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| 1.1 Motivations | 9 |
| 1.2 Challenges | 10 |
| 1.2.1 Energy Saving with Spatially Random Relays | 10 |
| 1.2.2 Cooperative Diversity with Multiple Relays | 10 |
| 1.3 Outline | 11 |
| References | 12 |
| 2 Related Works on Cooperative Wireless Networks | 14 |
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| 2.1 Cooperative Communications | 14 |
| 2.2 Cooperation Scenarios | 16 |
| 2.3 Three Categories of Cooperative MAC Protocols | 19 |
| 2.3.1 Category-I | 20 |
| 2.3.2 Category-II | 22 |
| 2.3.3 Category-III | 24 |
| 2.4 Research Issues for MAC-Layer Cooperation | 26 |
| 2.4.1 New Categories | 26 |
| 2.4.2 Cooperative Diversity | 27 |
| 2.4.3 User Mobility | 28 |
| 2.4.4 Energy Saving | 29 |
| References | 30 |
| 3 Energy-Efficient Uncoordinated Cooperative MAC with Uncertain Relay Distribution Intensity | 33 |
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| 3.1 Motivation and Overview | 33 |
| 3.2 System Model and Problem Formulation | 34 |
| 3.2.1 System Model | 34 |
| 3.2.2 Problem Formulation | 37 |
| 3.3 Relay Intensity Estimation | 38 |
| 3.4 Energy-Efficient Cooperative Scheme and Its Analysis | 43 |
| 3.4.1 An Energy-Efficient Cooperative Scheme | 43 |
| 3.4.2 Analysis of Collision Probability | 47 |
| 3.5 Numerical and Simulation Results | 49 |
| 3.5.1 Relay Intensity Estimation | 49 |
| 3.5.2 Energy Saving Strategy | 50 |
| 3.5.3 Performance Evaluation | 52 |
| 3.6 Summary | 55 |
| Appendix A: Extended Proof of Lemma 3.2 with N Relays | 55 |
| Appendix B: Proof of (3.34) and (3.35) | 56 |
| References | 57 |
| 4 Energy-Aware Cooperative MAC with Uncoordinated Group Relays | 59 |
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| 4.1 Motivation and Overview | 59 |
| 4.2 System Model and Problem Formulation | 60 |
| 4.2.1 System Model | 60 |
| 4.2.2 Problem Formulation | 62 |
| 4.3 Energy-Aware Cooperation Strategy | 63 |
| 4.3.1 Cooperation Criteria | 63 |
| 4.3.2 Distributed Cooperation Strategy | 64 |
| 4.4 Performance Analysis | 66 |
| 4.4.1 Upper Bound of Collision Probability | 66 |
| 4.4.2 Lower Bound of Transmission Success Probability | 69 |
| 4.4.3 Upper Bound of Transmission Success Probability | 70 |
| 4.5 Numerical and Simulation Results | 71 |
| 4.5.1 Transmission Success Probability | 73 |
| 4.5.2 Average Delay and Delay Outage Probability | 73 |
| 4.5.3 Energy Saving and Energy Balance | 75 |
| 4.5.4 Scalability | 77 |
| 4.6 Summary | 79 |
| Appendix A: Proof of (4.17) | 79 |
| Appendix B: Proof of (4.25) | 80 |
| References | 81 |
| 5 Opportunistic Cooperative Relaying with Backoff-BasedContention | 82 |
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| 5.1 Motivation and Overview | 82 |
| 5.2 System Model | 83 |
| 5.3 Cooperative Relaying Strategies | 85 |
| 5.3.1 Inter-Group Backoff-Based Contention | 86 |
| 5.3.2 Intra-Group Contention | 86 |
| 5.3.2.1 Backoff-Based Strategy | 86 |
| 5.3.2.2 Probabilistic Strategy | 87 |
| 5.4 Performance Analysis | 88 |
| 5.4.1 Probability Distributions of Spatial Random Relays | 89 |
| 5.4.2 Performance of Two-Level Backoff-Based Strategy | 91 |
| 5.4.3 Performance of Hybrid Relaying Strategy | 94 |
| 5.5 Numerical Results and Discussions | 95 |
| 5.5.1 CDF of Transmission Success Probability | 96 |
| 5.5.2 Performance Upper and Lower Bounds | 98 |
| 5.5.3 Relay Success Probability | 99 |
| 5.5.4 Backoff Delay of Relay Selection | 103 |
| 5.6 Summary | 105 |
| Appendix: Calculation of the CDF F?,l(x) of ?RD,l | 106 |
| References | 108 |
| 6 Diversity Relaying with Spatially Random Mobile Relays | 110 |
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| 6.1 Motivation and Overview | 110 |
| 6.2 System Model | 112 |
| 6.2.1 Channel Model | 112 |
| 6.2.2 Mobility Model and Poisson Point Process | 113 |
| 6.2.3 Distributed Cooperative Transmission | 113 |
| 6.2.4 MAC for Multi-Helper Coordination | 114 |
| 6.2.5 MRC and Upper Bound of Total SNR | 116 |
| 6.3 Unconditional Success Probability and Delay | 117 |
| 6.3.1 Exact Unconditional PDF of SNR Upper Bound | 117 |
| 6.3.2 Approximate Unconditional PDF of SNR Upper Bound | 119 |
| 6.3.3 Approximation of Unconditional Success Probability | 120 |
| 6.3.4 Delay Analysis of MAC Coordination Schemes | 121 |
| 6.3.5 Outage-Delay Tradeoff | 123 |
| 6.4 Numerical and Simulation Results | 124 |
| 6.4.1 Analysis Validation | 125 |
| 6.4.2 Outage-Delay Tradeoff | 128 |
| 6.5 Summary | 129 |
| Appendix: Proof of Lemma 6.1 | 130 |
| References | 131 |
| 7 Conclusions and Future Directions | 133 |
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| 7.1 Conclusions | 133 |
| 7.2 Future Work | 134 |