QoS Packet Scheduler Design and Fixed Relay Frequency Reuse Policies in Mobile Networks
이동통신 네트워크에서의 QoS 패킷 스케줄러 설계 및 고정 릴레이 관련 주파수 재사용 관리 기법 연구

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dc.description학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 박세웅.-
dc.description.abstractThe main interest of this paper is to understand a basic approach to provide more efficient method to allocate radio resources in the mobile communication systems, especially in which radio resources could be allocated by both frequency and time division multiple access. So, we consider OFDMA system and the ideas described in this paper could be easily applied to the current and next generation mobile communication systems. This paper studies two basic research themes-
dc.description.abstracta QoS packet scheduler design and fixed relay resource management policies based on frequency reuse in mobile networks.

This paper considers novel scheduler structures that are executable in the environments of multiple traffic classes and multiple frequency channels. To design a scheduler structure for multiple traffic classes, we first propose a scheduler selection rule that uses the priority of traffic class and the urgency level of each packet. Then we relax the barrier of traffic class priority when a high priority packet has some room in waiting time. This gives us a chance to exploit multiuser diversity, thereby giving more flexibility in scheduling. Our considered scheduler can achieve higher throughput compared to the simple extension of conventional modified largest weighted delay first (MLWDF) scheduler while maintaining the delay performance for QoS class traffic. We also design a scheduler structure for multiple frequency channels that chooses a good channel for each user whenever possible to exploit frequency diversity. The simulation results show that our proposed scheduler increases the total system throughput by up to 50% without degrading the delay performance.

This paper also introduces radio resource management schemes based on frequency reuse for fixed relay stations in mobile cellular networks. Mobile stations in the cell boundary experience poor spectral efficiency due to the path loss and interference from adjacent cells. Therefore, satisfying QoS requirements of each MS at the cell boundary has been an important issue. To resolve this spectral efficiency problem at the cell boundary, deploying fixed relay stations has been actively considered. In this paper, we consider radio resource management policies based on frequency reuse for fixed relays that include path selection rules, frequency reuse pattern matching, and frame transmission pattern matching among cells. We evaluate performance of each policy by varying parameter values such as relay stations position and frequency reuse factor. Through Monte Carlo simulations and mathematical analysis, we suggest some optimal parameter values for each policy and discuss some implementation issues that need to be considered in practical deployment of relay stations.

We also surveyed further works that many researchers have been studied to tackle the similar problems of QoS scheduling and resource management for relay with our proposed work. We expect that there would be more future works by priority-based approach and energy-aware approach for QoS scheduling. Also current trends such as the rising interest in IoT system, discussion of densification of cells and D2D communications in 5G systems make us expect that the researches in these topics related with relays would be popular in the future. We also think that there are many interesting problems regarding QoS support and resource management still waiting to be tackled, especially combined with recent key topics in mobile communication systems such as 5G standardization, AI and NFV/SDN.
dc.description.tableofcontentsChapter 1 Introduction 1
1.1 QoS Packet Scheduler 4
1.2 Fixed Relay Frequency Reuse Policies 6
Chapter 2 Scheduler Design for Multiple Traffic Classes in OFDMA Networks 10
2.1 Proposed Schedulers 10
2.1.1 Scheduler Structures 12
2.1.2 MLWDF scheduler for Multiple Traffic Classes 13
2.1.3 Joint Scheduler 13
2.2 System Model 18
2.3 Performance Evaluation 19
2.3.1 Schedulers for Multiple Traffic Classes 20
2.3.2 Impact of Scheduler Selection Rule 25
2.3.3 Frame Based Schedulers 27
2.3.4 Impact of Partial Feedback 30
2.3.5 Adaptive Threshold Version Schedulers 33
2.4 Conclusion 36
Chapter 3 Frequency Reuse Policies for Fixed Relays in Cellular Networks 40
3.1 System Model 40
3.1.1 Frame Transmission and Frequency Reuse Patterns among RSs 42
3.1.2 Positioning of RSs and Channel Capacity 44
3.1.3 Area Spectral Efficiency 45
3.2 Radio Resource Management Policies Based on Frequency Reuse 46
3.2.1 Path Selection Rule 46
3.2.2 Frequency Reuse and Frame Transmission Pattern Matchings among Cells 52
3.3 Monte Carlo Simulation and Results 53
3.4 Consideration of Practical Issues 80
3.5 Conclusion 81
Chapter 4 Surveys of Further Works 83
4.1 Further Works on QoS Schedulers 83
4.1.1 WiMAX Schedulers 85
4.1.2 LTE Schedulers 92
4.2 Further Works on Radio Resource Management in Relay Systems 98
4.3 Future Challenges 100
Chapter 5 Conclusion 104
Bibliography 107
초록 127
dc.format.extent3911370 bytes-
dc.publisher서울대학교 대학원-
dc.subjectFixed Relay-
dc.subjectFrequency Reuse-
dc.subjectCellular Networks-
dc.titleQoS Packet Scheduler Design and Fixed Relay Frequency Reuse Policies in Mobile Networks-
dc.title.alternative이동통신 네트워크에서의 QoS 패킷 스케줄러 설계 및 고정 릴레이 관련 주파수 재사용 관리 기법 연구-
dc.contributor.AlternativeAuthorWon-Hyoung Park-
dc.contributor.affiliation공과대학 전기·컴퓨터공학부-
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Electrical and Computer Engineering (전기·정보공학부)Theses (Ph.D. / Sc.D._전기·정보공학부)
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