Title Page

Contents

List of Notations 12

Abstract 15

Chapter 1. Introduction 17

1.1. Motivation 19

1.2. Contributions 22

1.3. Organization 24

Chapter 2. Literature Review 25

2.1. Medium Access in IEEE 802.11 Networks 25

2.1.1. Distributed Coordination function 26

2.1.2. Enhanced Distributed Channel Access 29

2.1.3. Orthogonal Frequency Division Multiple Access 32

2.2. Related Work 36

Chapter 3. Traffic-Aware Scheduling for Uplink Transmissions in Wi-Fi OFDMA 41

3.1. System Model 44

3.2. Proposed Methodology 45

3.2.1. QoS Rank-based Weight Calculation 45

3.2.2. Precedence Value Calculation 46

Chapter 4. Performance Evaluation 50

4.1. Evaluation Metrics 50

4.1.1. End-to-End Delay 50

4.1.2. Throughput 51

4.1.3. Fairness 51

4.2. Network Simulator-3 (NS-3) 51

4.2.1. Flow Monitor 52

4.3. Simulation Environment 52

4.4. Results and Analysis 54

4.4.1. Analysis of End-to-End Delay 54

4.4.2. Analysis of Throughput 60

4.4.3. Analysis of Fairness 65

4.4.4. Time Complexity Analysis 67

Chapter 5. Conclusion 68

Bibliography 70

요약 76

Table 3.1. Relation between the RU Type, number of 26-tone RUs, and occupancy levels of the STA buffer. 48

Table 4.1. The evaluation parameters used in the simulations. 53

Figure. 1.1. An illustration of connected healthcare for continuous health monitoring in an AAL system. 20

Figure. 2.1. MAC architecture in IEEE 802.11ax WLANs. DCF is the primary MAC protocol supported by HCF, PCF, MCF, and OFDMA. 26

Figure. 2.2. Basic channel access method using the DCF. 27

Figure. 2.3. The differentiation of traffic queues in EDCA. Each AC has a distinct priority. 31

Figure. 2.4. Trigger-based UL multi-user transmission sequence in IEEE 802.11ax WLAN. 33

Figure. 3.1. An example scenario for our proposed UL Scheduler. 45

Figure. 4.1. Average end-to-end delay performance under constant data rate. 55

Figure. 4.2. Average end-to-end delay performance under constant data genera- tion rate for all ACs. 56

Figure. 4.3. Average end-to-end delay performance at different traffic generation rates. 58

Figure. 4.4. Average end-to-end delay performance in mobility. 59

Figure. 4.5. Success rate of data packets of all ACs at a constant data generation rate. 60

Figure. 4.6. Average UL Throughput. 62

Figure. 4.7. Throughput performance at different traffic generation rates. 63

Figure. 4.8. Throughput performance in mobility conditions. 64

Figure. 4.9. Fairness performance with different number of STAs. 65